Merge branch 'vendor/LIBRESSL'

[dragonfly.git] / sys / dev / drm / i915 / i915_gem.c

/*
 * Copyright © 2008-2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include <drm/drmP.h>
#include <drm/drm_vma_manager.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "i915_vgpu.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/pci.h>

#define RQ_BUG_ON(expr)

static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj);
static void
i915_gem_object_retire__write(struct drm_i915_gem_object *obj);
static void
i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring);

static bool cpu_cache_is_coherent(struct drm_device *dev,
                                  enum i915_cache_level level)
{
        return HAS_LLC(dev) || level != I915_CACHE_NONE;
}

static bool cpu_write_needs_clflush(struct drm_i915_gem_object *obj)
{
        if (!cpu_cache_is_coherent(obj->base.dev, obj->cache_level))
                return true;

        return obj->pin_display;
}

/* some bookkeeping */
static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
                                  size_t size)
{
        spin_lock(&dev_priv->mm.object_stat_lock);
        dev_priv->mm.object_count++;
        dev_priv->mm.object_memory += size;
        spin_unlock(&dev_priv->mm.object_stat_lock);
}

static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
                                     size_t size)
{
        spin_lock(&dev_priv->mm.object_stat_lock);
        dev_priv->mm.object_count--;
        dev_priv->mm.object_memory -= size;
        spin_unlock(&dev_priv->mm.object_stat_lock);
}

static int
i915_gem_wait_for_error(struct i915_gpu_error *error)
{
        int ret;

#define EXIT_COND (!i915_reset_in_progress(error) || \
                   i915_terminally_wedged(error))
        if (EXIT_COND)
                return 0;

        /*
         * Only wait 10 seconds for the gpu reset to complete to avoid hanging
         * userspace. If it takes that long something really bad is going on and
         * we should simply try to bail out and fail as gracefully as possible.
         */
        ret = wait_event_interruptible_timeout(error->reset_queue,
                                               EXIT_COND,
                                               10*HZ);
        if (ret == 0) {
                DRM_ERROR("Timed out waiting for the gpu reset to complete\n");
                return -EIO;
        } else if (ret < 0) {
                return ret;
        }
#undef EXIT_COND

        return 0;
}

int i915_mutex_lock_interruptible(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
        if (ret)
                return ret;

        ret = mutex_lock_interruptible(&dev->struct_mutex);
        if (ret)
                return ret;

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

int
i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_get_aperture *args = data;
        struct i915_gtt *ggtt = &dev_priv->gtt;
        struct i915_vma *vma;
        size_t pinned;

        pinned = 0;
        mutex_lock(&dev->struct_mutex);
        list_for_each_entry(vma, &ggtt->base.active_list, vm_link)
                if (vma->pin_count)
                        pinned += vma->node.size;
        list_for_each_entry(vma, &ggtt->base.inactive_list, vm_link)
                if (vma->pin_count)
                        pinned += vma->node.size;
        mutex_unlock(&dev->struct_mutex);

        args->aper_size = dev_priv->gtt.base.total;
        args->aper_available_size = args->aper_size - pinned;

        return 0;
}

#if 0
static int
i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
{
        struct address_space *mapping = file_inode(obj->base.filp)->i_mapping;
        char *vaddr = obj->phys_handle->vaddr;
        struct sg_table *st;
        struct scatterlist *sg;
        int i;

        if (WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
                return -EINVAL;

        for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                struct page *page;
                char *src;

                page = shmem_read_mapping_page(mapping, i);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                src = kmap_atomic(page);
                memcpy(vaddr, src, PAGE_SIZE);
                drm_clflush_virt_range(vaddr, PAGE_SIZE);
                kunmap_atomic(src);

                put_page(page);
                vaddr += PAGE_SIZE;
        }

        i915_gem_chipset_flush(obj->base.dev);

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (st == NULL)
                return -ENOMEM;

        if (sg_alloc_table(st, 1, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        sg = st->sgl;
        sg->offset = 0;
        sg->length = obj->base.size;

        sg_dma_address(sg) = obj->phys_handle->busaddr;
        sg_dma_len(sg) = obj->base.size;

        obj->pages = st;
        return 0;
}

static void
i915_gem_object_put_pages_phys(struct drm_i915_gem_object *obj)
{
        int ret;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (ret) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                WARN_ON(ret != -EIO);
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        if (obj->dirty) {
                struct address_space *mapping = file_inode(obj->base.filp)->i_mapping;
                char *vaddr = obj->phys_handle->vaddr;
                int i;

                for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                        struct page *page;
                        char *dst;

                        page = shmem_read_mapping_page(mapping, i);
                        if (IS_ERR(page))
                                continue;

                        dst = kmap_atomic(page);
                        drm_clflush_virt_range(vaddr, PAGE_SIZE);
                        memcpy(dst, vaddr, PAGE_SIZE);
                        kunmap_atomic(dst);

                        set_page_dirty(page);
                        if (obj->madv == I915_MADV_WILLNEED)
                                mark_page_accessed(page);
                        put_page(page);
                        vaddr += PAGE_SIZE;
                }
                obj->dirty = 0;
        }

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

static void
i915_gem_object_release_phys(struct drm_i915_gem_object *obj)
{
        drm_pci_free(obj->base.dev, obj->phys_handle);
}

static const struct drm_i915_gem_object_ops i915_gem_phys_ops = {
        .get_pages = i915_gem_object_get_pages_phys,
        .put_pages = i915_gem_object_put_pages_phys,
        .release = i915_gem_object_release_phys,
};
#endif

static int
drop_pages(struct drm_i915_gem_object *obj)
{
        struct i915_vma *vma, *next;
        int ret;

        drm_gem_object_reference(&obj->base);
        list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link)
                if (i915_vma_unbind(vma))
                        break;

        ret = i915_gem_object_put_pages(obj);
        drm_gem_object_unreference(&obj->base);

        return ret;
}

int
i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
                            int align)
{
        drm_dma_handle_t *phys;
        int ret;

        if (obj->phys_handle) {
                if ((unsigned long)obj->phys_handle->vaddr & (align -1))
                        return -EBUSY;

                return 0;
        }

        if (obj->madv != I915_MADV_WILLNEED)
                return -EFAULT;

#if 0
        if (obj->base.filp == NULL)
                return -EINVAL;
#endif

        ret = drop_pages(obj);
        if (ret)
                return ret;

        /* create a new object */
        phys = drm_pci_alloc(obj->base.dev, obj->base.size, align);
        if (!phys)
                return -ENOMEM;

        obj->phys_handle = phys;
#if 0
        obj->ops = &i915_gem_phys_ops;
#endif

        return i915_gem_object_get_pages(obj);
}

static int
i915_gem_phys_pwrite(struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pwrite *args,
                     struct drm_file *file_priv)
{
        struct drm_device *dev = obj->base.dev;
        void *vaddr = (char *)obj->phys_handle->vaddr + args->offset;
        char __user *user_data = to_user_ptr(args->data_ptr);
        int ret = 0;

        /* We manually control the domain here and pretend that it
         * remains coherent i.e. in the GTT domain, like shmem_pwrite.
         */
        ret = i915_gem_object_wait_rendering(obj, false);
        if (ret)
                return ret;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);
        if (__copy_from_user_inatomic_nocache(vaddr, user_data, args->size)) {
                unsigned long unwritten;

                /* The physical object once assigned is fixed for the lifetime
                 * of the obj, so we can safely drop the lock and continue
                 * to access vaddr.
                 */
                mutex_unlock(&dev->struct_mutex);
                unwritten = copy_from_user(vaddr, user_data, args->size);
                mutex_lock(&dev->struct_mutex);
                if (unwritten) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        drm_clflush_virt_range(vaddr, args->size);
        i915_gem_chipset_flush(dev);

out:
        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
        return ret;
}

void *i915_gem_object_alloc(struct drm_device *dev)
{
        return kmalloc(sizeof(struct drm_i915_gem_object),
            M_DRM, M_WAITOK | M_ZERO);
}

void i915_gem_object_free(struct drm_i915_gem_object *obj)
{
        kfree(obj);
}

static int
i915_gem_create(struct drm_file *file,
                struct drm_device *dev,
                uint64_t size,
                uint32_t *handle_p)
{
        struct drm_i915_gem_object *obj;
        int ret;
        u32 handle;

        size = roundup(size, PAGE_SIZE);
        if (size == 0)
                return -EINVAL;

        /* Allocate the new object */
        obj = i915_gem_alloc_object(dev, size);
        if (obj == NULL)
                return -ENOMEM;

        ret = drm_gem_handle_create(file, &obj->base, &handle);
        /* drop reference from allocate - handle holds it now */
        drm_gem_object_unreference_unlocked(&obj->base);
        if (ret)
                return ret;

        *handle_p = handle;
        return 0;
}

int
i915_gem_dumb_create(struct drm_file *file,
                     struct drm_device *dev,
                     struct drm_mode_create_dumb *args)
{
        /* have to work out size/pitch and return them */
        args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
        args->size = args->pitch * args->height;
        return i915_gem_create(file, dev,
                               args->size, &args->handle);
}

/**
 * Creates a new mm object and returns a handle to it.
 */
int
i915_gem_create_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_create *args = data;

        return i915_gem_create(file, dev,
                               args->size, &args->handle);
}

static inline int
__copy_to_user_swizzled(char __user *cpu_vaddr,
                        const char *gpu_vaddr, int gpu_offset,
                        int length)
{
        int ret, cpu_offset = 0;

        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                ret = __copy_to_user(cpu_vaddr + cpu_offset,
                                     gpu_vaddr + swizzled_gpu_offset,
                                     this_length);
                if (ret)
                        return ret + length;

                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        return 0;
}

static inline int
__copy_from_user_swizzled(char *gpu_vaddr, int gpu_offset,
                          const char __user *cpu_vaddr,
                          int length)
{
        int ret, cpu_offset = 0;

        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                ret = __copy_from_user(gpu_vaddr + swizzled_gpu_offset,
                                       cpu_vaddr + cpu_offset,
                                       this_length);
                if (ret)
                        return ret + length;

                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        return 0;
}

/*
 * Pins the specified object's pages and synchronizes the object with
 * GPU accesses. Sets needs_clflush to non-zero if the caller should
 * flush the object from the CPU cache.
 */
int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
                                    int *needs_clflush)
{
        int ret;

        *needs_clflush = 0;

#if 0
        if (WARN_ON((obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE) == 0))
                return -EINVAL;
#endif

        if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU)) {
                /* If we're not in the cpu read domain, set ourself into the gtt
                 * read domain and manually flush cachelines (if required). This
                 * optimizes for the case when the gpu will dirty the data
                 * anyway again before the next pread happens. */
                *needs_clflush = !cpu_cache_is_coherent(obj->base.dev,
                                                        obj->cache_level);
                ret = i915_gem_object_wait_rendering(obj, true);
                if (ret)
                        return ret;
        }

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_pin_pages(obj);

        return ret;
}

/* Per-page copy function for the shmem pread fastpath.
 * Flushes invalid cachelines before reading the target if
 * needs_clflush is set. */
static int
shmem_pread_fast(struct vm_page *page, int shmem_page_offset, int page_length,
                 char __user *user_data,
                 bool page_do_bit17_swizzling, bool needs_clflush)
{
        char *vaddr;
        int ret;

        if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;

        vaddr = kmap_atomic(page);
        if (needs_clflush)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        ret = __copy_to_user_inatomic(user_data,
                                      vaddr + shmem_page_offset,
                                      page_length);
        kunmap_atomic(vaddr);

        return ret ? -EFAULT : 0;
}

static void
shmem_clflush_swizzled_range(char *addr, unsigned long length,
                             bool swizzled)
{
        if (unlikely(swizzled)) {
                unsigned long start = (unsigned long) addr;
                unsigned long end = (unsigned long) addr + length;

                /* For swizzling simply ensure that we always flush both
                 * channels. Lame, but simple and it works. Swizzled
                 * pwrite/pread is far from a hotpath - current userspace
                 * doesn't use it at all. */
                start = round_down(start, 128);
                end = round_up(end, 128);

                drm_clflush_virt_range((void *)start, end - start);
        } else {
                drm_clflush_virt_range(addr, length);
        }

}

/* Only difference to the fast-path function is that this can handle bit17
 * and uses non-atomic copy and kmap functions. */
static int
shmem_pread_slow(struct vm_page *page, int shmem_page_offset, int page_length,
                 char __user *user_data,
                 bool page_do_bit17_swizzling, bool needs_clflush)
{
        char *vaddr;
        int ret;

        vaddr = kmap(page);
        if (needs_clflush)
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);

        if (page_do_bit17_swizzling)
                ret = __copy_to_user_swizzled(user_data,
                                              vaddr, shmem_page_offset,
                                              page_length);
        else
                ret = __copy_to_user(user_data,
                                     vaddr + shmem_page_offset,
                                     page_length);
        kunmap(page);

        return ret ? - EFAULT : 0;
}

static int
i915_gem_shmem_pread(struct drm_device *dev,
                     struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pread *args,
                     struct drm_file *file)
{
        char __user *user_data;
        ssize_t remain;
        loff_t offset;
        int shmem_page_offset, page_length, ret = 0;
        int obj_do_bit17_swizzling, page_do_bit17_swizzling;
        int prefaulted = 0;
        int needs_clflush = 0;
        struct sg_page_iter sg_iter;

        user_data = to_user_ptr(args->data_ptr);
        remain = args->size;

        obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        ret = i915_gem_obj_prepare_shmem_read(obj, &needs_clflush);
        if (ret)
                return ret;

        offset = args->offset;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
                         offset >> PAGE_SHIFT) {
                struct vm_page *page = sg_page_iter_page(&sg_iter);

                if (remain <= 0)
                        break;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset_in_page(offset);
                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;

                page_do_bit17_swizzling = obj_do_bit17_swizzling &&
                        (page_to_phys(page) & (1 << 17)) != 0;

                ret = shmem_pread_fast(page, shmem_page_offset, page_length,
                                       user_data, page_do_bit17_swizzling,
                                       needs_clflush);
                if (ret == 0)
                        goto next_page;

                mutex_unlock(&dev->struct_mutex);

                if (likely(!i915.prefault_disable) && !prefaulted) {
                        ret = fault_in_multipages_writeable(user_data, remain);
                        /* Userspace is tricking us, but we've already clobbered
                         * its pages with the prefault and promised to write the
                         * data up to the first fault. Hence ignore any errors
                         * and just continue. */
                        (void)ret;
                        prefaulted = 1;
                }

                ret = shmem_pread_slow(page, shmem_page_offset, page_length,
                                       user_data, page_do_bit17_swizzling,
                                       needs_clflush);

                mutex_lock(&dev->struct_mutex);

                if (ret)
                        goto out;

next_page:
                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out:
        i915_gem_object_unpin_pages(obj);

        return ret;
}

/**
 * Reads data from the object referenced by handle.
 *
 * On error, the contents of *data are undefined.
 */
int
i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_pread *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        if (args->size == 0)
                return 0;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Bounds check source.  */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto out;
        }

        /* prime objects have no backing filp to GEM pread/pwrite
         * pages from.
         */

        trace_i915_gem_object_pread(obj, args->offset, args->size);

        ret = i915_gem_shmem_pread(dev, obj, args, file);

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/* This is the fast write path which cannot handle
 * page faults in the source data
 */

static inline int
fast_user_write(struct io_mapping *mapping,
                loff_t page_base, int page_offset,
                char __user *user_data,
                int length)
{
        void __iomem *vaddr_atomic;
        void *vaddr;
        unsigned long unwritten;

        vaddr_atomic = io_mapping_map_atomic_wc(mapping, page_base);
        /* We can use the cpu mem copy function because this is X86. */
        vaddr = (char __force*)vaddr_atomic + page_offset;
        unwritten = __copy_from_user_inatomic_nocache(vaddr,
                                                      user_data, length);
        io_mapping_unmap_atomic(vaddr_atomic);
        return unwritten;
}

/**
 * This is the fast pwrite path, where we copy the data directly from the
 * user into the GTT, uncached.
 */
static int
i915_gem_gtt_pwrite_fast(struct drm_device *dev,
                         struct drm_i915_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        ssize_t remain;
        loff_t offset, page_base;
        char __user *user_data;
        int page_offset, page_length, ret;

        ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_MAPPABLE | PIN_NONBLOCK);
        if (ret)
                goto out;

        ret = i915_gem_object_set_to_gtt_domain(obj, true);
        if (ret)
                goto out_unpin;

        ret = i915_gem_object_put_fence(obj);
        if (ret)
                goto out_unpin;

        user_data = to_user_ptr(args->data_ptr);
        remain = args->size;

        offset = i915_gem_obj_ggtt_offset(obj) + args->offset;

        intel_fb_obj_invalidate(obj, ORIGIN_GTT);

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                page_base = offset & ~PAGE_MASK;
                page_offset = offset_in_page(offset);
                page_length = remain;
                if ((page_offset + remain) > PAGE_SIZE)
                        page_length = PAGE_SIZE - page_offset;

                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 */
                if (fast_user_write(dev_priv->gtt.mappable, page_base,
                                    page_offset, user_data, page_length)) {
                        ret = -EFAULT;
                        goto out_flush;
                }

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out_flush:
        intel_fb_obj_flush(obj, false, ORIGIN_GTT);
out_unpin:
        i915_gem_object_ggtt_unpin(obj);
out:
        return ret;
}

/* Per-page copy function for the shmem pwrite fastpath.
 * Flushes invalid cachelines before writing to the target if
 * needs_clflush_before is set and flushes out any written cachelines after
 * writing if needs_clflush is set. */
static int
shmem_pwrite_fast(struct vm_page *page, int shmem_page_offset, int page_length,
                  char __user *user_data,
                  bool page_do_bit17_swizzling,
                  bool needs_clflush_before,
                  bool needs_clflush_after)
{
        char *vaddr;
        int ret;

        if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;

        vaddr = kmap_atomic(page);
        if (needs_clflush_before)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        ret = __copy_from_user_inatomic(vaddr + shmem_page_offset,
                                        user_data, page_length);
        if (needs_clflush_after)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        kunmap_atomic(vaddr);

        return ret ? -EFAULT : 0;
}

/* Only difference to the fast-path function is that this can handle bit17
 * and uses non-atomic copy and kmap functions. */
static int
shmem_pwrite_slow(struct vm_page *page, int shmem_page_offset, int page_length,
                  char __user *user_data,
                  bool page_do_bit17_swizzling,
                  bool needs_clflush_before,
                  bool needs_clflush_after)
{
        char *vaddr;
        int ret;

        vaddr = kmap(page);
        if (unlikely(needs_clflush_before || page_do_bit17_swizzling))
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);
        if (page_do_bit17_swizzling)
                ret = __copy_from_user_swizzled(vaddr, shmem_page_offset,
                                                user_data,
                                                page_length);
        else
                ret = __copy_from_user(vaddr + shmem_page_offset,
                                       user_data,
                                       page_length);
        if (needs_clflush_after)
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);
        kunmap(page);

        return ret ? -EFAULT : 0;
}

static int
i915_gem_shmem_pwrite(struct drm_device *dev,
                      struct drm_i915_gem_object *obj,
                      struct drm_i915_gem_pwrite *args,
                      struct drm_file *file)
{
        ssize_t remain;
        loff_t offset;
        char __user *user_data;
        int shmem_page_offset, page_length, ret = 0;
        int obj_do_bit17_swizzling, page_do_bit17_swizzling;
        int hit_slowpath = 0;
        int needs_clflush_after = 0;
        int needs_clflush_before = 0;
        struct sg_page_iter sg_iter;

        user_data = to_user_ptr(args->data_ptr);
        remain = args->size;

        obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);

        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                /* If we're not in the cpu write domain, set ourself into the gtt
                 * write domain and manually flush cachelines (if required). This
                 * optimizes for the case when the gpu will use the data
                 * right away and we therefore have to clflush anyway. */
                needs_clflush_after = cpu_write_needs_clflush(obj);
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;
        }
        /* Same trick applies to invalidate partially written cachelines read
         * before writing. */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0)
                needs_clflush_before =
                        !cpu_cache_is_coherent(dev, obj->cache_level);

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);

        i915_gem_object_pin_pages(obj);

        offset = args->offset;
        obj->dirty = 1;

        VM_OBJECT_LOCK(obj->base.vm_obj);
        vm_object_pip_add(obj->base.vm_obj, 1);

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
                         offset >> PAGE_SHIFT) {
                struct vm_page *page = sg_page_iter_page(&sg_iter);
                int partial_cacheline_write;

                if (remain <= 0)
                        break;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset_in_page(offset);

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;

                /* If we don't overwrite a cacheline completely we need to be
                 * careful to have up-to-date data by first clflushing. Don't
                 * overcomplicate things and flush the entire patch. */
                partial_cacheline_write = needs_clflush_before &&
                        ((shmem_page_offset | page_length)
                                & (cpu_clflush_line_size - 1));

                page_do_bit17_swizzling = obj_do_bit17_swizzling &&
                        (page_to_phys(page) & (1 << 17)) != 0;

                ret = shmem_pwrite_fast(page, shmem_page_offset, page_length,
                                        user_data, page_do_bit17_swizzling,
                                        partial_cacheline_write,
                                        needs_clflush_after);
                if (ret == 0)
                        goto next_page;

                hit_slowpath = 1;
                mutex_unlock(&dev->struct_mutex);
                ret = shmem_pwrite_slow(page, shmem_page_offset, page_length,
                                        user_data, page_do_bit17_swizzling,
                                        partial_cacheline_write,
                                        needs_clflush_after);

                mutex_lock(&dev->struct_mutex);

                if (ret)
                        goto out;

next_page:
                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }
        vm_object_pip_wakeup(obj->base.vm_obj);
        VM_OBJECT_UNLOCK(obj->base.vm_obj);

out:
        i915_gem_object_unpin_pages(obj);

        if (hit_slowpath) {
                /*
                 * Fixup: Flush cpu caches in case we didn't flush the dirty
                 * cachelines in-line while writing and the object moved
                 * out of the cpu write domain while we've dropped the lock.
                 */
                if (!needs_clflush_after &&
                    obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                        if (i915_gem_clflush_object(obj, obj->pin_display))
                                needs_clflush_after = true;
                }
        }

        if (needs_clflush_after)
                i915_gem_chipset_flush(dev);
        else
                obj->cache_dirty = true;

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
        return ret;
}

/**
 * Writes data to the object referenced by handle.
 *
 * On error, the contents of the buffer that were to be modified are undefined.
 */
int
i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_pwrite *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        if (args->size == 0)
                return 0;

        if (likely(!i915.prefault_disable)) {
                ret = fault_in_multipages_readable(to_user_ptr(args->data_ptr),
                                                   args->size);
                if (ret)
                        return -EFAULT;
        }

        intel_runtime_pm_get(dev_priv);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto put_rpm;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Bounds check destination. */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto out;
        }

        /* prime objects have no backing filp to GEM pread/pwrite
         * pages from.
         */

        trace_i915_gem_object_pwrite(obj, args->offset, args->size);

        ret = -EFAULT;
        /* We can only do the GTT pwrite on untiled buffers, as otherwise
         * it would end up going through the fenced access, and we'll get
         * different detiling behavior between reading and writing.
         * pread/pwrite currently are reading and writing from the CPU
         * perspective, requiring manual detiling by the client.
         */
        if (obj->tiling_mode == I915_TILING_NONE &&
            obj->base.write_domain != I915_GEM_DOMAIN_CPU &&
            cpu_write_needs_clflush(obj)) {
                ret = i915_gem_gtt_pwrite_fast(dev, obj, args, file);
                /* Note that the gtt paths might fail with non-page-backed user
                 * pointers (e.g. gtt mappings when moving data between
                 * textures). Fallback to the shmem path in that case. */
        }

        if (ret == -EFAULT || ret == -ENOSPC) {
                if (obj->phys_handle)
                        ret = i915_gem_phys_pwrite(obj, args, file);
                else
                        ret = i915_gem_shmem_pwrite(dev, obj, args, file);
        }

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
put_rpm:
        intel_runtime_pm_put(dev_priv);

        return ret;
}

int
i915_gem_check_wedge(struct i915_gpu_error *error,
                     bool interruptible)
{
        if (i915_reset_in_progress(error)) {
                /* Non-interruptible callers can't handle -EAGAIN, hence return
                 * -EIO unconditionally for these. */
                if (!interruptible)
                        return -EIO;

                /* Recovery complete, but the reset failed ... */
                if (i915_terminally_wedged(error))
                        return -EIO;

                /*
                 * Check if GPU Reset is in progress - we need intel_ring_begin
                 * to work properly to reinit the hw state while the gpu is
                 * still marked as reset-in-progress. Handle this with a flag.
                 */
                if (!error->reload_in_reset)
                        return -EAGAIN;
        }

        return 0;
}

static void fake_irq(unsigned long data)
{
        wakeup_one((void *)data);
}

static bool missed_irq(struct drm_i915_private *dev_priv,
                       struct intel_engine_cs *ring)
{
        return test_bit(ring->id, &dev_priv->gpu_error.missed_irq_rings);
}

#if 0
static int __i915_spin_request(struct drm_i915_gem_request *req, int state)
{
        unsigned long timeout;
        unsigned cpu;

        /* When waiting for high frequency requests, e.g. during synchronous
         * rendering split between the CPU and GPU, the finite amount of time
         * required to set up the irq and wait upon it limits the response
         * rate. By busywaiting on the request completion for a short while we
         * can service the high frequency waits as quick as possible. However,
         * if it is a slow request, we want to sleep as quickly as possible.
         * The tradeoff between waiting and sleeping is roughly the time it
         * takes to sleep on a request, on the order of a microsecond.
         */

        if (req->ring->irq_refcount)
                return -EBUSY;

        /* Only spin if we know the GPU is processing this request */
        if (!i915_gem_request_started(req, true))
                return -EAGAIN;

        timeout = local_clock_us(&cpu) + 5;
        while (!need_resched()) {
                if (i915_gem_request_completed(req, true))
                        return 0;

                if (signal_pending_state(state, current))
                        break;

                if (busywait_stop(timeout, cpu))
                        break;

                cpu_relax_lowlatency();
        }

        if (i915_gem_request_completed(req, false))
                return 0;

        return -EAGAIN;
}
#endif

/**
 * __i915_wait_request - wait until execution of request has finished
 * @req: duh!
 * @reset_counter: reset sequence associated with the given request
 * @interruptible: do an interruptible wait (normally yes)
 * @timeout: in - how long to wait (NULL forever); out - how much time remaining
 *
 * Note: It is of utmost importance that the passed in seqno and reset_counter
 * values have been read by the caller in an smp safe manner. Where read-side
 * locks are involved, it is sufficient to read the reset_counter before
 * unlocking the lock that protects the seqno. For lockless tricks, the
 * reset_counter _must_ be read before, and an appropriate smp_rmb must be
 * inserted.
 *
 * Returns 0 if the request was found within the alloted time. Else returns the
 * errno with remaining time filled in timeout argument.
 */
int __i915_wait_request(struct drm_i915_gem_request *req,
                        unsigned reset_counter,
                        bool interruptible,
                        s64 *timeout,
                        struct intel_rps_client *rps)
{
        struct intel_engine_cs *ring = i915_gem_request_get_ring(req);
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        const bool irq_test_in_progress =
                ACCESS_ONCE(dev_priv->gpu_error.test_irq_rings) & intel_ring_flag(ring);
        unsigned long timeout_expire;
        s64 before = 0; /* Only to silence a compiler warning. */
        int ret, sl_timeout = 1;

        WARN(!intel_irqs_enabled(dev_priv), "IRQs disabled");

        if (list_empty(&req->list))
                return 0;

        if (i915_gem_request_completed(req, true))
                return 0;

        timeout_expire = 0;
        if (timeout) {
                if (WARN_ON(*timeout < 0))
                        return -EINVAL;

                if (*timeout == 0)
                        return -ETIME;

                timeout_expire = jiffies + nsecs_to_jiffies_timeout(*timeout);

                /*
                 * Record current time in case interrupted by signal, or wedged.
                 */
                before = ktime_get_raw_ns();
        }

        if (INTEL_INFO(dev_priv)->gen >= 6)
                gen6_rps_boost(dev_priv, rps, req->emitted_jiffies);

        trace_i915_gem_request_wait_begin(req);

        /* Optimistic spin for the next jiffie before touching IRQs */
#if 0
        ret = __i915_spin_request(req);
        if (ret == 0)
                goto out;
#endif

        if (!irq_test_in_progress && WARN_ON(!ring->irq_get(ring))) {
                ret = -ENODEV;
                goto out;
        }

        lockmgr(&ring->irq_queue.lock, LK_EXCLUSIVE);
        for (;;) {
                struct timer_list timer;

                /* We need to check whether any gpu reset happened in between
                 * the caller grabbing the seqno and now ... */
                if (reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter)) {
                        /* ... but upgrade the -EAGAIN to an -EIO if the gpu
                         * is truely gone. */
                        ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
                        if (ret == 0)
                                ret = -EAGAIN;
                        break;
                }

                if (i915_gem_request_completed(req, false)) {
                        ret = 0;
                        break;
                }

                if (interruptible && signal_pending(curthread->td_lwp)) {
                        ret = -ERESTARTSYS;
                        break;
                }

                if (timeout && time_after_eq(jiffies, timeout_expire)) {
                        ret = -ETIME;
                        break;
                }

                timer.function = NULL;
                if (timeout || missed_irq(dev_priv, ring)) {
                        unsigned long expire;

                        setup_timer_on_stack(&timer, fake_irq, (unsigned long)&ring->irq_queue);
                        expire = missed_irq(dev_priv, ring) ? jiffies + 1 : timeout_expire;
                        sl_timeout = expire - jiffies;
                        if (sl_timeout < 1)
                                sl_timeout = 1;
                        mod_timer(&timer, expire);
                }

#if 0
                io_schedule();
#endif

                if (timer.function) {
                        del_singleshot_timer_sync(&timer);
                        destroy_timer_on_stack(&timer);
                }

                lksleep(&ring->irq_queue, &ring->irq_queue.lock,
                        interruptible ? PCATCH : 0, "lwe", sl_timeout);
        }
        lockmgr(&ring->irq_queue.lock, LK_RELEASE);
        if (!irq_test_in_progress)
                ring->irq_put(ring);

out:
        trace_i915_gem_request_wait_end(req);

        if (timeout) {
                s64 tres = *timeout - (ktime_get_raw_ns() - before);

                *timeout = tres < 0 ? 0 : tres;

                /*
                 * Apparently ktime isn't accurate enough and occasionally has a
                 * bit of mismatch in the jiffies<->nsecs<->ktime loop. So patch
                 * things up to make the test happy. We allow up to 1 jiffy.
                 *
                 * This is a regrssion from the timespec->ktime conversion.
                 */
                if (ret == -ETIME && *timeout < jiffies_to_usecs(1)*1000)
                        *timeout = 0;
        }

        return ret;
}

int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
                                   struct drm_file *file)
{
        struct drm_i915_private *dev_private;
        struct drm_i915_file_private *file_priv;

        WARN_ON(!req || !file || req->file_priv);

        if (!req || !file)
                return -EINVAL;

        if (req->file_priv)
                return -EINVAL;

        dev_private = req->ring->dev->dev_private;
        file_priv = file->driver_priv;

        spin_lock(&file_priv->mm.lock);
        req->file_priv = file_priv;
        list_add_tail(&req->client_list, &file_priv->mm.request_list);
        spin_unlock(&file_priv->mm.lock);

        req->pid = curproc->p_pid;

        return 0;
}

static inline void
i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
{
        struct drm_i915_file_private *file_priv = request->file_priv;

        if (!file_priv)
                return;

        spin_lock(&file_priv->mm.lock);
        list_del(&request->client_list);
        request->file_priv = NULL;
        spin_unlock(&file_priv->mm.lock);

#if 0
        put_pid(request->pid);
        request->pid = NULL;
#endif
}

static void i915_gem_request_retire(struct drm_i915_gem_request *request)
{
        trace_i915_gem_request_retire(request);

        /* We know the GPU must have read the request to have
         * sent us the seqno + interrupt, so use the position
         * of tail of the request to update the last known position
         * of the GPU head.
         *
         * Note this requires that we are always called in request
         * completion order.
         */
        request->ringbuf->last_retired_head = request->postfix;

        list_del_init(&request->list);
        i915_gem_request_remove_from_client(request);

        i915_gem_request_unreference(request);
}

static void
__i915_gem_request_retire__upto(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->ring;
        struct drm_i915_gem_request *tmp;

        lockdep_assert_held(&engine->dev->struct_mutex);

        if (list_empty(&req->list))
                return;

        do {
                tmp = list_first_entry(&engine->request_list,
                                       typeof(*tmp), list);

                i915_gem_request_retire(tmp);
        } while (tmp != req);

        WARN_ON(i915_verify_lists(engine->dev));
}

/**
 * Waits for a request to be signaled, and cleans up the
 * request and object lists appropriately for that event.
 */
int
i915_wait_request(struct drm_i915_gem_request *req)
{
        struct drm_device *dev;
        struct drm_i915_private *dev_priv;
        bool interruptible;
        int ret;

        BUG_ON(req == NULL);

        dev = req->ring->dev;
        dev_priv = dev->dev_private;
        interruptible = dev_priv->mm.interruptible;

        BUG_ON(!mutex_is_locked(&dev->struct_mutex));

        ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
        if (ret)
                return ret;

        ret = __i915_wait_request(req,
                                  atomic_read(&dev_priv->gpu_error.reset_counter),
                                  interruptible, NULL, NULL);
        if (ret)
                return ret;

        __i915_gem_request_retire__upto(req);
        return 0;
}

/**
 * Ensures that all rendering to the object has completed and the object is
 * safe to unbind from the GTT or access from the CPU.
 */
int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
                               bool readonly)
{
        int ret, i;

        if (!obj->active)
                return 0;

        if (readonly) {
                if (obj->last_write_req != NULL) {
                        ret = i915_wait_request(obj->last_write_req);
                        if (ret)
                                return ret;

                        i = obj->last_write_req->ring->id;
                        if (obj->last_read_req[i] == obj->last_write_req)
                                i915_gem_object_retire__read(obj, i);
                        else
                                i915_gem_object_retire__write(obj);
                }
        } else {
                for (i = 0; i < I915_NUM_RINGS; i++) {
                        if (obj->last_read_req[i] == NULL)
                                continue;

                        ret = i915_wait_request(obj->last_read_req[i]);
                        if (ret)
                                return ret;

                        i915_gem_object_retire__read(obj, i);
                }
                RQ_BUG_ON(obj->active);
        }

        return 0;
}

static void
i915_gem_object_retire_request(struct drm_i915_gem_object *obj,
                               struct drm_i915_gem_request *req)
{
        int ring = req->ring->id;

        if (obj->last_read_req[ring] == req)
                i915_gem_object_retire__read(obj, ring);
        else if (obj->last_write_req == req)
                i915_gem_object_retire__write(obj);

        __i915_gem_request_retire__upto(req);
}

/* A nonblocking variant of the above wait. This is a highly dangerous routine
 * as the object state may change during this call.
 */
static __must_check int
i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
                                            struct intel_rps_client *rps,
                                            bool readonly)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_request *requests[I915_NUM_RINGS];
        unsigned reset_counter;
        int ret, i, n = 0;

        BUG_ON(!mutex_is_locked(&dev->struct_mutex));
        BUG_ON(!dev_priv->mm.interruptible);

        if (!obj->active)
                return 0;

        ret = i915_gem_check_wedge(&dev_priv->gpu_error, true);
        if (ret)
                return ret;

        reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);

        if (readonly) {
                struct drm_i915_gem_request *req;

                req = obj->last_write_req;
                if (req == NULL)
                        return 0;

                requests[n++] = i915_gem_request_reference(req);
        } else {
                for (i = 0; i < I915_NUM_RINGS; i++) {
                        struct drm_i915_gem_request *req;

                        req = obj->last_read_req[i];
                        if (req == NULL)
                                continue;

                        requests[n++] = i915_gem_request_reference(req);
                }
        }

        mutex_unlock(&dev->struct_mutex);
        for (i = 0; ret == 0 && i < n; i++)
                ret = __i915_wait_request(requests[i], reset_counter, true,
                                          NULL, rps);
        mutex_lock(&dev->struct_mutex);

        for (i = 0; i < n; i++) {
                if (ret == 0)
                        i915_gem_object_retire_request(obj, requests[i]);
                i915_gem_request_unreference(requests[i]);
        }

        return ret;
}

static struct intel_rps_client *to_rps_client(struct drm_file *file)
{
        struct drm_i915_file_private *fpriv = file->driver_priv;
        return &fpriv->rps;
}

/**
 * Called when user space prepares to use an object with the CPU, either
 * through the mmap ioctl's mapping or a GTT mapping.
 */
int
i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_gem_set_domain *args = data;
        struct drm_i915_gem_object *obj;
        uint32_t read_domains = args->read_domains;
        uint32_t write_domain = args->write_domain;
        int ret;

        /* Only handle setting domains to types used by the CPU. */
        if (write_domain & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        if (read_domains & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        /* Having something in the write domain implies it's in the read
         * domain, and only that read domain.  Enforce that in the request.
         */
        if (write_domain != 0 && read_domains != write_domain)
                return -EINVAL;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Try to flush the object off the GPU without holding the lock.
         * We will repeat the flush holding the lock in the normal manner
         * to catch cases where we are gazumped.
         */
        ret = i915_gem_object_wait_rendering__nonblocking(obj,
                                                          to_rps_client(file),
                                                          !write_domain);
        if (ret)
                goto unref;

        if (read_domains & I915_GEM_DOMAIN_GTT)
                ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);
        else
                ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);

        if (write_domain != 0)
                intel_fb_obj_invalidate(obj,
                                        write_domain == I915_GEM_DOMAIN_GTT ?
                                        ORIGIN_GTT : ORIGIN_CPU);

unref:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Called when user space has done writes to this buffer
 */
int
i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file)
{
        struct drm_i915_gem_sw_finish *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Pinned buffers may be scanout, so flush the cache */
        if (obj->pin_display)
                i915_gem_object_flush_cpu_write_domain(obj);

        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * Maps the contents of an object, returning the address it is mapped
 * into.
 *
 * While the mapping holds a reference on the contents of the object, it doesn't
 * imply a ref on the object itself.
 *
 * IMPORTANT:
 *
 * DRM driver writers who look a this function as an example for how to do GEM
 * mmap support, please don't implement mmap support like here. The modern way
 * to implement DRM mmap support is with an mmap offset ioctl (like
 * i915_gem_mmap_gtt) and then using the mmap syscall on the DRM fd directly.
 * That way debug tooling like valgrind will understand what's going on, hiding
 * the mmap call in a driver private ioctl will break that. The i915 driver only
 * does cpu mmaps this way because we didn't know better.
 */
int
i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_mmap *args = data;
        struct drm_gem_object *obj;
        unsigned long addr;

        struct proc *p = curproc;
        vm_map_t map = &p->p_vmspace->vm_map;
        vm_size_t size;
        int error = 0, rv;

        if (args->flags & ~(I915_MMAP_WC))
                return -EINVAL;

        obj = drm_gem_object_lookup(dev, file, args->handle);
        if (obj == NULL)
                return -ENOENT;

        if (args->size == 0)
                goto out;

        size = round_page(args->size);
        if (map->size + size > p->p_rlimit[RLIMIT_VMEM].rlim_cur) {
                error = -ENOMEM;
                goto out;
        }

        /* prime objects have no backing filp to GEM mmap
         * pages from.
         */

        /*
         * Call hint to ensure that NULL is not returned as a valid address
         * and to reduce vm_map traversals. XXX causes instability, use a
         * fixed low address as the start point instead to avoid the NULL
         * return issue.
         */

        addr = PAGE_SIZE;

        /*
         * Use 256KB alignment.  It is unclear why this matters for a
         * virtual address but it appears to fix a number of application/X
         * crashes and kms console switching is much faster.
         */
        vm_object_hold(obj->vm_obj);
        vm_object_reference_locked(obj->vm_obj);
        vm_object_drop(obj->vm_obj);

        rv = vm_map_find(map, obj->vm_obj, NULL,
                         args->offset, &addr, args->size,
                         256 * 1024, /* align */
                         TRUE, /* fitit */
                         VM_MAPTYPE_NORMAL, VM_SUBSYS_DRM_GEM,
                         VM_PROT_READ | VM_PROT_WRITE, /* prot */
                         VM_PROT_READ | VM_PROT_WRITE, /* max */
                         MAP_SHARED /* cow */);
        if (rv != KERN_SUCCESS) {
                vm_object_deallocate(obj->vm_obj);
                error = -vm_mmap_to_errno(rv);
        } else {
                args->addr_ptr = (uint64_t)addr;
        }
out:
        drm_gem_object_unreference(obj);
        return (error);
}

/**
 * i915_gem_fault - fault a page into the GTT
 *
 * vm_obj is locked on entry and expected to be locked on return.
 *
 * The vm_pager has placemarked the object with an anonymous memory page
 * which we must replace atomically to avoid races against concurrent faults
 * on the same page.  XXX we currently are unable to do this atomically.
 *
 * If we are to return an error we should not touch the anonymous page,
 * the caller will deallocate it.
 *
 * XXX Most GEM calls appear to be interruptable, but we can't hard loop
 * in that case.  Release all resources and wait 1 tick before retrying.
 * This is a huge problem which needs to be fixed by getting rid of most
 * of the interruptability.  The linux code does not retry but does appear
 * to have some sort of mechanism (VM_FAULT_NOPAGE ?) for the higher level
 * to be able to retry.
 *
 * --
 * @vma: VMA in question
 * @vmf: fault info
 *
 * The fault handler is set up by drm_gem_mmap() when a object is GTT mapped
 * from userspace.  The fault handler takes care of binding the object to
 * the GTT (if needed), allocating and programming a fence register (again,
 * only if needed based on whether the old reg is still valid or the object
 * is tiled) and inserting a new PTE into the faulting process.
 *
 * Note that the faulting process may involve evicting existing objects
 * from the GTT and/or fence registers to make room.  So performance may
 * suffer if the GTT working set is large or there are few fence registers
 * left.
 *
 * vm_obj is locked on entry and expected to be locked on return.  The VM
 * pager has placed an anonymous memory page at (obj,offset) which we have
 * to replace.
 */
int i915_gem_fault(vm_object_t vm_obj, vm_ooffset_t offset, int prot, vm_page_t *mres)
{
        struct drm_i915_gem_object *obj = to_intel_bo(vm_obj->handle);
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct i915_ggtt_view view = i915_ggtt_view_normal;
        unsigned long page_offset;
        vm_page_t m, oldm = NULL;
        int ret = 0;
        bool write = !!(prot & VM_PROT_WRITE);

        intel_runtime_pm_get(dev_priv);

        /* We don't use vmf->pgoff since that has the fake offset */
        page_offset = (unsigned long)offset;

retry:
        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto out;

        trace_i915_gem_object_fault(obj, page_offset, true, write);

        /* Try to flush the object off the GPU first without holding the lock.
         * Upon reacquiring the lock, we will perform our sanity checks and then
         * repeat the flush holding the lock in the normal manner to catch cases
         * where we are gazumped.
         */
        ret = i915_gem_object_wait_rendering__nonblocking(obj, NULL, !write);
        if (ret)
                goto unlock;

        /* Access to snoopable pages through the GTT is incoherent. */
        if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev)) {
                ret = -EFAULT;
                goto unlock;
        }

        /* Use a partial view if the object is bigger than the aperture. */
        if (obj->base.size >= dev_priv->gtt.mappable_end &&
            obj->tiling_mode == I915_TILING_NONE) {
#if 0
                static const unsigned int chunk_size = 256; // 1 MiB

                memset(&view, 0, sizeof(view));
                view.type = I915_GGTT_VIEW_PARTIAL;
                view.params.partial.offset = rounddown(page_offset, chunk_size);
                view.params.partial.size =
                        min_t(unsigned int,
                              chunk_size,
                              (vma->vm_end - vma->vm_start)/PAGE_SIZE -
                              view.params.partial.offset);
#endif
        }

        /* Now pin it into the GTT if needed */
        ret = i915_gem_object_ggtt_pin(obj, &view, 0, PIN_MAPPABLE);
        if (ret)
                goto unlock;

        ret = i915_gem_object_set_to_gtt_domain(obj, write);
        if (ret)
                goto unpin;

        ret = i915_gem_object_get_fence(obj);
        if (ret)
                goto unpin;

        /*
         * START FREEBSD MAGIC
         *
         * Add a pip count to avoid destruction and certain other
         * complex operations (such as collapses?) while unlocked.
         */
        vm_object_pip_add(vm_obj, 1);

        /*
         * XXX We must currently remove the placeholder page now to avoid
         * a deadlock against a concurrent i915_gem_release_mmap().
         * Otherwise concurrent operation will block on the busy page
         * while holding locks which we need to obtain.
         */
        if (*mres != NULL) {
                oldm = *mres;
                if ((oldm->flags & PG_BUSY) == 0)
                        kprintf("i915_gem_fault: Page was not busy\n");
                else
                        vm_page_remove(oldm);
                *mres = NULL;
        } else {
                oldm = NULL;
        }

        ret = 0;
        m = NULL;

        /*
         * Since the object lock was dropped, another thread might have
         * faulted on the same GTT address and instantiated the mapping.
         * Recheck.
         */
        m = vm_page_lookup(vm_obj, OFF_TO_IDX(offset));
        if (m != NULL) {
                /*
                 * Try to busy the page, retry on failure (non-zero ret).
                 */
                if (vm_page_busy_try(m, false)) {
                        kprintf("i915_gem_fault: PG_BUSY\n");
                        ret = -EINTR;
                        goto unlock;
                }
                goto have_page;
        }
        /*
         * END FREEBSD MAGIC
         */

        obj->fault_mappable = true;

        /* Finally, remap it using the new GTT offset */
        m = vm_phys_fictitious_to_vm_page(dev_priv->gtt.mappable_base +
                        i915_gem_obj_ggtt_offset_view(obj, &view) + offset);
        if (m == NULL) {
                ret = -EFAULT;
                goto unpin;
        }
        KASSERT((m->flags & PG_FICTITIOUS) != 0, ("not fictitious %p", m));
        KASSERT(m->wire_count == 1, ("wire_count not 1 %p", m));

        /*
         * Try to busy the page.  Fails on non-zero return.
         */
        if (vm_page_busy_try(m, false)) {
                kprintf("i915_gem_fault: PG_BUSY(2)\n");
                ret = -EINTR;
                goto unpin;
        }
        m->valid = VM_PAGE_BITS_ALL;

#if 0
        if (unlikely(view.type == I915_GGTT_VIEW_PARTIAL)) {
                /* Overriding existing pages in partial view does not cause
                 * us any trouble as TLBs are still valid because the fault
                 * is due to userspace losing part of the mapping or never
                 * having accessed it before (at this partials' range).
                 */
                unsigned long base = vma->vm_start +
                                     (view.params.partial.offset << PAGE_SHIFT);
                unsigned int i;

                for (i = 0; i < view.params.partial.size; i++) {
                        ret = vm_insert_pfn(vma, base + i * PAGE_SIZE, pfn + i);
                        if (ret)
                                break;
                }

                obj->fault_mappable = true;
        } else {
                if (!obj->fault_mappable) {
                        unsigned long size = min_t(unsigned long,
                                                   vma->vm_end - vma->vm_start,
                                                   obj->base.size);
                        int i;

                        for (i = 0; i < size >> PAGE_SHIFT; i++) {
                                ret = vm_insert_pfn(vma,
                                                    (unsigned long)vma->vm_start + i * PAGE_SIZE,
                                                    pfn + i);
                                if (ret)
                                        break;
                        }

                        obj->fault_mappable = true;
                } else
                        ret = vm_insert_pfn(vma,
                                            (unsigned long)vmf->virtual_address,
                                            pfn + page_offset);
#endif
                        vm_page_insert(m, vm_obj, OFF_TO_IDX(offset));
#if 0
        }
#endif

have_page:
        *mres = m;

        i915_gem_object_ggtt_unpin_view(obj, &view);
        mutex_unlock(&dev->struct_mutex);
        ret = VM_PAGER_OK;
        goto done;

        /*
         * ALTERNATIVE ERROR RETURN.
         *
         * OBJECT EXPECTED TO BE LOCKED.
         */
unpin:
        i915_gem_object_ggtt_unpin_view(obj, &view);
unlock:
        mutex_unlock(&dev->struct_mutex);
out:
        switch (ret) {
        case -EIO:
                /*
                 * We eat errors when the gpu is terminally wedged to avoid
                 * userspace unduly crashing (gl has no provisions for mmaps to
                 * fail). But any other -EIO isn't ours (e.g. swap in failure)
                 * and so needs to be reported.
                 */
                if (!i915_terminally_wedged(&dev_priv->gpu_error)) {
//                      ret = VM_FAULT_SIGBUS;
                        break;
                }
        case -EAGAIN:
                /*
                 * EAGAIN means the gpu is hung and we'll wait for the error
                 * handler to reset everything when re-faulting in
                 * i915_mutex_lock_interruptible.
                 */
        case -ERESTARTSYS:
        case -EINTR:
                VM_OBJECT_UNLOCK(vm_obj);
                int dummy;
                tsleep(&dummy, 0, "delay", 1); /* XXX */
                VM_OBJECT_LOCK(vm_obj);
                goto retry;
        default:
                WARN_ONCE(ret, "unhandled error in i915_gem_fault: %i\n", ret);
                ret = VM_PAGER_ERROR;
                break;
        }

done:
        if (oldm != NULL)
                vm_page_free(oldm);
        vm_object_pip_wakeup(vm_obj);

        intel_runtime_pm_put(dev_priv);
        return ret;
}

/**
 * i915_gem_release_mmap - remove physical page mappings
 * @obj: obj in question
 *
 * Preserve the reservation of the mmapping with the DRM core code, but
 * relinquish ownership of the pages back to the system.
 *
 * It is vital that we remove the page mapping if we have mapped a tiled
 * object through the GTT and then lose the fence register due to
 * resource pressure. Similarly if the object has been moved out of the
 * aperture, than pages mapped into userspace must be revoked. Removing the
 * mapping will then trigger a page fault on the next user access, allowing
 * fixup by i915_gem_fault().
 */
void
i915_gem_release_mmap(struct drm_i915_gem_object *obj)
{
        vm_object_t devobj;
        vm_page_t m;
        int i, page_count;

        if (!obj->fault_mappable)
                return;

        devobj = cdev_pager_lookup(obj);
        if (devobj != NULL) {
                page_count = OFF_TO_IDX(obj->base.size);

                VM_OBJECT_LOCK(devobj);
                for (i = 0; i < page_count; i++) {
                        m = vm_page_lookup_busy_wait(devobj, i, TRUE, "915unm");
                        if (m == NULL)
                                continue;
                        cdev_pager_free_page(devobj, m);
                }
                VM_OBJECT_UNLOCK(devobj);
                vm_object_deallocate(devobj);
        }

        obj->fault_mappable = false;
}

void
i915_gem_release_all_mmaps(struct drm_i915_private *dev_priv)
{
        struct drm_i915_gem_object *obj;

        list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list)
                i915_gem_release_mmap(obj);
}

uint32_t
i915_gem_get_gtt_size(struct drm_device *dev, uint32_t size, int tiling_mode)
{
        uint32_t gtt_size;

        if (INTEL_INFO(dev)->gen >= 4 ||
            tiling_mode == I915_TILING_NONE)
                return size;

        /* Previous chips need a power-of-two fence region when tiling */
        if (INTEL_INFO(dev)->gen == 3)
                gtt_size = 1024*1024;
        else
                gtt_size = 512*1024;

        while (gtt_size < size)
                gtt_size <<= 1;

        return gtt_size;
}

/**
 * i915_gem_get_gtt_alignment - return required GTT alignment for an object
 * @obj: object to check
 *
 * Return the required GTT alignment for an object, taking into account
 * potential fence register mapping.
 */
uint32_t
i915_gem_get_gtt_alignment(struct drm_device *dev, uint32_t size,
                           int tiling_mode, bool fenced)
{
        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (INTEL_INFO(dev)->gen >= 4 || (!fenced && IS_G33(dev)) ||
            tiling_mode == I915_TILING_NONE)
                return 4096;

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        return i915_gem_get_gtt_size(dev, size, tiling_mode);
}

static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int ret;

#if 0
        if (drm_vma_node_has_offset(&obj->base.vma_node))
                return 0;
#endif

        dev_priv->mm.shrinker_no_lock_stealing = true;

        ret = drm_gem_create_mmap_offset(&obj->base);
        if (ret != -ENOSPC)
                goto out;

        /* Badly fragmented mmap space? The only way we can recover
         * space is by destroying unwanted objects. We can't randomly release
         * mmap_offsets as userspace expects them to be persistent for the
         * lifetime of the objects. The closest we can is to release the
         * offsets on purgeable objects by truncating it and marking it purged,
         * which prevents userspace from ever using that object again.
         */
        i915_gem_shrink(dev_priv,
                        obj->base.size >> PAGE_SHIFT,
                        I915_SHRINK_BOUND |
                        I915_SHRINK_UNBOUND |
                        I915_SHRINK_PURGEABLE);
        ret = drm_gem_create_mmap_offset(&obj->base);
        if (ret != -ENOSPC)
                goto out;

        i915_gem_shrink_all(dev_priv);
        ret = drm_gem_create_mmap_offset(&obj->base);
out:
        dev_priv->mm.shrinker_no_lock_stealing = false;

        return ret;
}

static void i915_gem_object_free_mmap_offset(struct drm_i915_gem_object *obj)
{
        drm_gem_free_mmap_offset(&obj->base);
}

int
i915_gem_mmap_gtt(struct drm_file *file,
                  struct drm_device *dev,
                  uint32_t handle,
                  uint64_t *offset)
{
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_DEBUG("Attempting to mmap a purgeable buffer\n");
                ret = -EFAULT;
                goto out;
        }

        ret = i915_gem_object_create_mmap_offset(obj);
        if (ret)
                goto out;

        *offset = DRM_GEM_MAPPING_OFF(obj->base.map_list.key) |
            DRM_GEM_MAPPING_KEY;

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
 * @dev: DRM device
 * @data: GTT mapping ioctl data
 * @file: GEM object info
 *
 * Simply returns the fake offset to userspace so it can mmap it.
 * The mmap call will end up in drm_gem_mmap(), which will set things
 * up so we can get faults in the handler above.
 *
 * The fault handler will take care of binding the object into the GTT
 * (since it may have been evicted to make room for something), allocating
 * a fence register, and mapping the appropriate aperture address into
 * userspace.
 */
int
i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file)
{
        struct drm_i915_gem_mmap_gtt *args = data;

        return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
}

/* Immediately discard the backing storage */
static void
i915_gem_object_truncate(struct drm_i915_gem_object *obj)
{
        vm_object_t vm_obj;

        vm_obj = obj->base.vm_obj;
        VM_OBJECT_LOCK(vm_obj);
        vm_object_page_remove(vm_obj, 0, 0, false);
        VM_OBJECT_UNLOCK(vm_obj);

        obj->madv = __I915_MADV_PURGED;
}

/* Try to discard unwanted pages */
static void
i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
{
#if 0
        struct address_space *mapping;
#endif

        switch (obj->madv) {
        case I915_MADV_DONTNEED:
                i915_gem_object_truncate(obj);
        case __I915_MADV_PURGED:
                return;
        }

#if 0
        if (obj->base.filp == NULL)
                return;

        mapping = file_inode(obj->base.filp)->i_mapping,
        invalidate_mapping_pages(mapping, 0, (loff_t)-1);
#endif
}

static void
i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
{
        struct sg_page_iter sg_iter;
        int ret;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (ret) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                WARN_ON(ret != -EIO);
                i915_gem_clflush_object(obj, true);
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        i915_gem_gtt_finish_object(obj);

        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_save_bit_17_swizzle(obj);

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) {
                struct vm_page *page = sg_page_iter_page(&sg_iter);

                if (obj->dirty)
                        set_page_dirty(page);

                if (obj->madv == I915_MADV_WILLNEED)
                        mark_page_accessed(page);

                vm_page_busy_wait(page, FALSE, "i915gem");
                vm_page_unwire(page, 1);
                vm_page_wakeup(page);
        }
        obj->dirty = 0;

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

int
i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
{
        const struct drm_i915_gem_object_ops *ops = obj->ops;

        if (obj->pages == NULL)
                return 0;

        if (obj->pages_pin_count)
                return -EBUSY;

        BUG_ON(i915_gem_obj_bound_any(obj));

        /* ->put_pages might need to allocate memory for the bit17 swizzle
         * array, hence protect them from being reaped by removing them from gtt
         * lists early. */
        list_del(&obj->global_list);

        ops->put_pages(obj);
        obj->pages = NULL;

        i915_gem_object_invalidate(obj);

        return 0;
}

static int
i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int page_count, i;
        vm_object_t vm_obj;
        struct sg_table *st;
        struct scatterlist *sg;
        struct sg_page_iter sg_iter;
        struct vm_page *page;
        unsigned long last_pfn = 0;     /* suppress gcc warning */
        int ret;

        /* Assert that the object is not currently in any GPU domain. As it
         * wasn't in the GTT, there shouldn't be any way it could have been in
         * a GPU cache
         */
        BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);
        BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);

        st = kmalloc(sizeof(*st), M_DRM, M_WAITOK);
        if (st == NULL)
                return -ENOMEM;

        page_count = obj->base.size / PAGE_SIZE;
        if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        /* Get the list of pages out of our struct file.  They'll be pinned
         * at this point until we release them.
         *
         * Fail silently without starting the shrinker
         */
        vm_obj = obj->base.vm_obj;
        VM_OBJECT_LOCK(vm_obj);
        sg = st->sgl;
        st->nents = 0;
        for (i = 0; i < page_count; i++) {
                page = shmem_read_mapping_page(vm_obj, i);
                if (IS_ERR(page)) {
                        i915_gem_shrink(dev_priv,
                                        page_count,
                                        I915_SHRINK_BOUND |
                                        I915_SHRINK_UNBOUND |
                                        I915_SHRINK_PURGEABLE);
                        page = shmem_read_mapping_page(vm_obj, i);
                }
                if (IS_ERR(page)) {
                        /* We've tried hard to allocate the memory by reaping
                         * our own buffer, now let the real VM do its job and
                         * go down in flames if truly OOM.
                         */
                        i915_gem_shrink_all(dev_priv);
                        page = shmem_read_mapping_page(vm_obj, i);
                        if (IS_ERR(page)) {
                                ret = PTR_ERR(page);
                                goto err_pages;
                        }
                }
#ifdef CONFIG_SWIOTLB
                if (swiotlb_nr_tbl()) {
                        st->nents++;
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                        sg = sg_next(sg);
                        continue;
                }
#endif
                if (!i || page_to_pfn(page) != last_pfn + 1) {
                        if (i)
                                sg = sg_next(sg);
                        st->nents++;
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                } else {
                        sg->length += PAGE_SIZE;
                }
                last_pfn = page_to_pfn(page);

                /* Check that the i965g/gm workaround works. */
        }
#ifdef CONFIG_SWIOTLB
        if (!swiotlb_nr_tbl())
#endif
                sg_mark_end(sg);
        obj->pages = st;
        VM_OBJECT_UNLOCK(vm_obj);

        ret = i915_gem_gtt_prepare_object(obj);
        if (ret)
                goto err_pages;

        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_do_bit_17_swizzle(obj);

        if (obj->tiling_mode != I915_TILING_NONE &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES)
                i915_gem_object_pin_pages(obj);

        return 0;

err_pages:
        sg_mark_end(sg);
        for_each_sg_page(st->sgl, &sg_iter, st->nents, 0) {
                page = sg_page_iter_page(&sg_iter);
                vm_page_busy_wait(page, FALSE, "i915gem");
                vm_page_unwire(page, 0);
                vm_page_wakeup(page);
        }
        VM_OBJECT_UNLOCK(vm_obj);
        sg_free_table(st);
        kfree(st);

        /* shmemfs first checks if there is enough memory to allocate the page
         * and reports ENOSPC should there be insufficient, along with the usual
         * ENOMEM for a genuine allocation failure.
         *
         * We use ENOSPC in our driver to mean that we have run out of aperture
         * space and so want to translate the error from shmemfs back to our
         * usual understanding of ENOMEM.
         */
        if (ret == -ENOSPC)
                ret = -ENOMEM;

        return ret;
}

/* Ensure that the associated pages are gathered from the backing storage
 * and pinned into our object. i915_gem_object_get_pages() may be called
 * multiple times before they are released by a single call to
 * i915_gem_object_put_pages() - once the pages are no longer referenced
 * either as a result of memory pressure (reaping pages under the shrinker)
 * or as the object is itself released.
 */
int
i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        const struct drm_i915_gem_object_ops *ops = obj->ops;
        int ret;

        if (obj->pages)
                return 0;

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_DEBUG("Attempting to obtain a purgeable object\n");
                return -EFAULT;
        }

        BUG_ON(obj->pages_pin_count);

        ret = ops->get_pages(obj);
        if (ret)
                return ret;

        list_add_tail(&obj->global_list, &dev_priv->mm.unbound_list);

        obj->get_page.sg = obj->pages->sgl;
        obj->get_page.last = 0;

        return 0;
}

void i915_vma_move_to_active(struct i915_vma *vma,
                             struct drm_i915_gem_request *req)
{
        struct drm_i915_gem_object *obj = vma->obj;
        struct intel_engine_cs *ring;

        ring = i915_gem_request_get_ring(req);

        /* Add a reference if we're newly entering the active list. */
        if (obj->active == 0)
                drm_gem_object_reference(&obj->base);
        obj->active |= intel_ring_flag(ring);

        list_move_tail(&obj->ring_list[ring->id], &ring->active_list);
        i915_gem_request_assign(&obj->last_read_req[ring->id], req);

        list_move_tail(&vma->vm_link, &vma->vm->active_list);
}

static void
i915_gem_object_retire__write(struct drm_i915_gem_object *obj)
{
        RQ_BUG_ON(obj->last_write_req == NULL);
        RQ_BUG_ON(!(obj->active & intel_ring_flag(obj->last_write_req->ring)));

        i915_gem_request_assign(&obj->last_write_req, NULL);
        intel_fb_obj_flush(obj, true, ORIGIN_CS);
}

static void
i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring)
{
        struct i915_vma *vma;

        RQ_BUG_ON(obj->last_read_req[ring] == NULL);
        RQ_BUG_ON(!(obj->active & (1 << ring)));

        list_del_init(&obj->ring_list[ring]);
        i915_gem_request_assign(&obj->last_read_req[ring], NULL);

        if (obj->last_write_req && obj->last_write_req->ring->id == ring)
                i915_gem_object_retire__write(obj);

        obj->active &= ~(1 << ring);
        if (obj->active)
                return;

        /* Bump our place on the bound list to keep it roughly in LRU order
         * so that we don't steal from recently used but inactive objects
         * (unless we are forced to ofc!)
         */
        list_move_tail(&obj->global_list,
                       &to_i915(obj->base.dev)->mm.bound_list);

        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                if (!list_empty(&vma->vm_link))
                        list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
        }

        i915_gem_request_assign(&obj->last_fenced_req, NULL);
        drm_gem_object_unreference(&obj->base);
}

static int
i915_gem_init_seqno(struct drm_device *dev, u32 seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        int ret, i, j;

        /* Carefully retire all requests without writing to the rings */
        for_each_ring(ring, dev_priv, i) {
                ret = intel_ring_idle(ring);
                if (ret)
                        return ret;
        }
        i915_gem_retire_requests(dev);

        /* Finally reset hw state */
        for_each_ring(ring, dev_priv, i) {
                intel_ring_init_seqno(ring, seqno);

                for (j = 0; j < ARRAY_SIZE(ring->semaphore.sync_seqno); j++)
                        ring->semaphore.sync_seqno[j] = 0;
        }

        return 0;
}

int i915_gem_set_seqno(struct drm_device *dev, u32 seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        if (seqno == 0)
                return -EINVAL;

        /* HWS page needs to be set less than what we
         * will inject to ring
         */
        ret = i915_gem_init_seqno(dev, seqno - 1);
        if (ret)
                return ret;

        /* Carefully set the last_seqno value so that wrap
         * detection still works
         */
        dev_priv->next_seqno = seqno;
        dev_priv->last_seqno = seqno - 1;
        if (dev_priv->last_seqno == 0)
                dev_priv->last_seqno--;

        return 0;
}

int
i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        /* reserve 0 for non-seqno */
        if (dev_priv->next_seqno == 0) {
                int ret = i915_gem_init_seqno(dev, 0);
                if (ret)
                        return ret;

                dev_priv->next_seqno = 1;
        }

        *seqno = dev_priv->last_seqno = dev_priv->next_seqno++;
        return 0;
}

/*
 * NB: This function is not allowed to fail. Doing so would mean the the
 * request is not being tracked for completion but the work itself is
 * going to happen on the hardware. This would be a Bad Thing(tm).
 */
void __i915_add_request(struct drm_i915_gem_request *request,
                        struct drm_i915_gem_object *obj,
                        bool flush_caches)
{
        struct intel_engine_cs *ring;
        struct drm_i915_private *dev_priv;
        struct intel_ringbuffer *ringbuf;
        u32 request_start;
        int ret;

        if (WARN_ON(request == NULL))
                return;

        ring = request->ring;
        dev_priv = ring->dev->dev_private;
        ringbuf = request->ringbuf;

        /*
         * To ensure that this call will not fail, space for its emissions
         * should already have been reserved in the ring buffer. Let the ring
         * know that it is time to use that space up.
         */
        intel_ring_reserved_space_use(ringbuf);

        request_start = intel_ring_get_tail(ringbuf);
        /*
         * Emit any outstanding flushes - execbuf can fail to emit the flush
         * after having emitted the batchbuffer command. Hence we need to fix
         * things up similar to emitting the lazy request. The difference here
         * is that the flush _must_ happen before the next request, no matter
         * what.
         */
        if (flush_caches) {
                if (i915.enable_execlists)
                        ret = logical_ring_flush_all_caches(request);
                else
                        ret = intel_ring_flush_all_caches(request);
                /* Not allowed to fail! */
                WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
        }

        /* Record the position of the start of the request so that
         * should we detect the updated seqno part-way through the
         * GPU processing the request, we never over-estimate the
         * position of the head.
         */
        request->postfix = intel_ring_get_tail(ringbuf);

        if (i915.enable_execlists)
                ret = ring->emit_request(request);
        else {
                ret = ring->add_request(request);

                request->tail = intel_ring_get_tail(ringbuf);
        }

        /* Not allowed to fail! */
        WARN(ret, "emit|add_request failed: %d!\n", ret);

        request->head = request_start;

        /* Whilst this request exists, batch_obj will be on the
         * active_list, and so will hold the active reference. Only when this
         * request is retired will the the batch_obj be moved onto the
         * inactive_list and lose its active reference. Hence we do not need
         * to explicitly hold another reference here.
         */
        request->batch_obj = obj;

        request->emitted_jiffies = jiffies;
        request->previous_seqno = ring->last_submitted_seqno;
        ring->last_submitted_seqno = request->seqno;
        list_add_tail(&request->list, &ring->request_list);

        trace_i915_gem_request_add(request);

        i915_queue_hangcheck(ring->dev);

        queue_delayed_work(dev_priv->wq,
                           &dev_priv->mm.retire_work,
                           round_jiffies_up_relative(HZ));
        intel_mark_busy(dev_priv->dev);

        /* Sanity check that the reserved size was large enough. */
        intel_ring_reserved_space_end(ringbuf);
}

static bool i915_context_is_banned(struct drm_i915_private *dev_priv,
                                   const struct intel_context *ctx)
{
        unsigned long elapsed;

        elapsed = get_seconds() - ctx->hang_stats.guilty_ts;

        if (ctx->hang_stats.banned)
                return true;

        if (ctx->hang_stats.ban_period_seconds &&
            elapsed <= ctx->hang_stats.ban_period_seconds) {
                if (!i915_gem_context_is_default(ctx)) {
                        DRM_DEBUG("context hanging too fast, banning!\n");
                        return true;
                } else if (i915_stop_ring_allow_ban(dev_priv)) {
                        if (i915_stop_ring_allow_warn(dev_priv))
                                DRM_ERROR("gpu hanging too fast, banning!\n");
                        return true;
                }
        }

        return false;
}

static void i915_set_reset_status(struct drm_i915_private *dev_priv,
                                  struct intel_context *ctx,
                                  const bool guilty)
{
        struct i915_ctx_hang_stats *hs;

        if (WARN_ON(!ctx))
                return;

        hs = &ctx->hang_stats;

        if (guilty) {
                hs->banned = i915_context_is_banned(dev_priv, ctx);
                hs->batch_active++;
                hs->guilty_ts = get_seconds();
        } else {
                hs->batch_pending++;
        }
}

void i915_gem_request_free(struct kref *req_ref)
{
        struct drm_i915_gem_request *req = container_of(req_ref,
                                                 typeof(*req), ref);
        struct intel_context *ctx = req->ctx;

        if (req->file_priv)
                i915_gem_request_remove_from_client(req);

        if (ctx) {
                if (i915.enable_execlists && ctx != req->i915->kernel_context)
                        intel_lr_context_unpin(ctx, req->ring);

                i915_gem_context_unreference(ctx);
        }

        kfree(req);
}

static inline int
__i915_gem_request_alloc(struct intel_engine_cs *ring,
                         struct intel_context *ctx,
                         struct drm_i915_gem_request **req_out)
{
        struct drm_i915_private *dev_priv = to_i915(ring->dev);
        struct drm_i915_gem_request *req;
        int ret;

        if (!req_out)
                return -EINVAL;

        *req_out = NULL;

        req = kzalloc(sizeof(*req), GFP_KERNEL);
        if (req == NULL)
                return -ENOMEM;

        ret = i915_gem_get_seqno(ring->dev, &req->seqno);
        if (ret)
                goto err;

        kref_init(&req->ref);
        req->i915 = dev_priv;
        req->ring = ring;
        req->ctx  = ctx;
        i915_gem_context_reference(req->ctx);

        if (i915.enable_execlists)
                ret = intel_logical_ring_alloc_request_extras(req);
        else
                ret = intel_ring_alloc_request_extras(req);
        if (ret) {
                i915_gem_context_unreference(req->ctx);
                goto err;
        }

        /*
         * Reserve space in the ring buffer for all the commands required to
         * eventually emit this request. This is to guarantee that the
         * i915_add_request() call can't fail. Note that the reserve may need
         * to be redone if the request is not actually submitted straight
         * away, e.g. because a GPU scheduler has deferred it.
         */
        if (i915.enable_execlists)
                ret = intel_logical_ring_reserve_space(req);
        else
                ret = intel_ring_reserve_space(req);
        if (ret) {
                /*
                 * At this point, the request is fully allocated even if not
                 * fully prepared. Thus it can be cleaned up using the proper
                 * free code.
                 */
                i915_gem_request_cancel(req);
                return ret;
        }

        *req_out = req;
        return 0;

err:
        kfree(req);
        return ret;
}

/**
 * i915_gem_request_alloc - allocate a request structure
 *
 * @engine: engine that we wish to issue the request on.
 * @ctx: context that the request will be associated with.
 *       This can be NULL if the request is not directly related to
 *       any specific user context, in which case this function will
 *       choose an appropriate context to use.
 *
 * Returns a pointer to the allocated request if successful,
 * or an error code if not.
 */
struct drm_i915_gem_request *
i915_gem_request_alloc(struct intel_engine_cs *engine,
                       struct intel_context *ctx)
{
        struct drm_i915_gem_request *req;
        int err;

        if (ctx == NULL)
                ctx = to_i915(engine->dev)->kernel_context;
        err = __i915_gem_request_alloc(engine, ctx, &req);
        return err ? ERR_PTR(err) : req;
}

void i915_gem_request_cancel(struct drm_i915_gem_request *req)
{
        intel_ring_reserved_space_cancel(req->ringbuf);

        i915_gem_request_unreference(req);
}

struct drm_i915_gem_request *
i915_gem_find_active_request(struct intel_engine_cs *ring)
{
        struct drm_i915_gem_request *request;

        list_for_each_entry(request, &ring->request_list, list) {
                if (i915_gem_request_completed(request, false))
                        continue;

                return request;
        }

        return NULL;
}

static void i915_gem_reset_ring_status(struct drm_i915_private *dev_priv,
                                       struct intel_engine_cs *ring)
{
        struct drm_i915_gem_request *request;
        bool ring_hung;

        request = i915_gem_find_active_request(ring);

        if (request == NULL)
                return;

        ring_hung = ring->hangcheck.score >= HANGCHECK_SCORE_RING_HUNG;

        i915_set_reset_status(dev_priv, request->ctx, ring_hung);

        list_for_each_entry_continue(request, &ring->request_list, list)
                i915_set_reset_status(dev_priv, request->ctx, false);
}

static void i915_gem_reset_ring_cleanup(struct drm_i915_private *dev_priv,
                                        struct intel_engine_cs *ring)
{
        struct intel_ringbuffer *buffer;

        while (!list_empty(&ring->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&ring->active_list,
                                       struct drm_i915_gem_object,
                                       ring_list[ring->id]);

                i915_gem_object_retire__read(obj, ring->id);
        }

        /*
         * Clear the execlists queue up before freeing the requests, as those
         * are the ones that keep the context and ringbuffer backing objects
         * pinned in place.
         */

        if (i915.enable_execlists) {
                spin_lock_irq(&ring->execlist_lock);

                /* list_splice_tail_init checks for empty lists */
                list_splice_tail_init(&ring->execlist_queue,
                                      &ring->execlist_retired_req_list);

                spin_unlock_irq(&ring->execlist_lock);
                intel_execlists_retire_requests(ring);
        }

        /*
         * We must free the requests after all the corresponding objects have
         * been moved off active lists. Which is the same order as the normal
         * retire_requests function does. This is important if object hold
         * implicit references on things like e.g. ppgtt address spaces through
         * the request.
         */
        while (!list_empty(&ring->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&ring->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                i915_gem_request_retire(request);
        }

        /* Having flushed all requests from all queues, we know that all
         * ringbuffers must now be empty. However, since we do not reclaim
         * all space when retiring the request (to prevent HEADs colliding
         * with rapid ringbuffer wraparound) the amount of available space
         * upon reset is less than when we start. Do one more pass over
         * all the ringbuffers to reset last_retired_head.
         */
        list_for_each_entry(buffer, &ring->buffers, link) {
                buffer->last_retired_head = buffer->tail;
                intel_ring_update_space(buffer);
        }
}

void i915_gem_reset(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        int i;

        /*
         * Before we free the objects from the requests, we need to inspect
         * them for finding the guilty party. As the requests only borrow
         * their reference to the objects, the inspection must be done first.
         */
        for_each_ring(ring, dev_priv, i)
                i915_gem_reset_ring_status(dev_priv, ring);

        for_each_ring(ring, dev_priv, i)
                i915_gem_reset_ring_cleanup(dev_priv, ring);

        i915_gem_context_reset(dev);

        i915_gem_restore_fences(dev);

        WARN_ON(i915_verify_lists(dev));
}

/**
 * This function clears the request list as sequence numbers are passed.
 */
void
i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
{
        WARN_ON(i915_verify_lists(ring->dev));

        /* Retire requests first as we use it above for the early return.
         * If we retire requests last, we may use a later seqno and so clear
         * the requests lists without clearing the active list, leading to
         * confusion.
         */
        while (!list_empty(&ring->request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&ring->request_list,
                                           struct drm_i915_gem_request,
                                           list);

                if (!i915_gem_request_completed(request, true))
                        break;

                i915_gem_request_retire(request);
        }

        /* Move any buffers on the active list that are no longer referenced
         * by the ringbuffer to the flushing/inactive lists as appropriate,
         * before we free the context associated with the requests.
         */
        while (!list_empty(&ring->active_list)) {
                struct drm_i915_gem_object *obj;

                obj = list_first_entry(&ring->active_list,
                                      struct drm_i915_gem_object,
                                      ring_list[ring->id]);

                if (!list_empty(&obj->last_read_req[ring->id]->list))
                        break;

                i915_gem_object_retire__read(obj, ring->id);
        }

        if (unlikely(ring->trace_irq_req &&
                     i915_gem_request_completed(ring->trace_irq_req, true))) {
                ring->irq_put(ring);
                i915_gem_request_assign(&ring->trace_irq_req, NULL);
        }

        WARN_ON(i915_verify_lists(ring->dev));
}

bool
i915_gem_retire_requests(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        bool idle = true;
        int i;

        for_each_ring(ring, dev_priv, i) {
                i915_gem_retire_requests_ring(ring);
                idle &= list_empty(&ring->request_list);
                if (i915.enable_execlists) {
                        spin_lock_irq(&ring->execlist_lock);
                        idle &= list_empty(&ring->execlist_queue);
                        spin_unlock_irq(&ring->execlist_lock);

                        intel_execlists_retire_requests(ring);
                }
        }

        if (idle)
                mod_delayed_work(dev_priv->wq,
                                   &dev_priv->mm.idle_work,
                                   msecs_to_jiffies(100));

        return idle;
}

static void
i915_gem_retire_work_handler(struct work_struct *work)
{
        struct drm_i915_private *dev_priv =
                container_of(work, typeof(*dev_priv), mm.retire_work.work);
        struct drm_device *dev = dev_priv->dev;
        bool idle;

        /* Come back later if the device is busy... */
        idle = false;
        if (mutex_trylock(&dev->struct_mutex)) {
                idle = i915_gem_retire_requests(dev);
                mutex_unlock(&dev->struct_mutex);
        }
        if (!idle)
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work,
                                   round_jiffies_up_relative(HZ));
}

static void
i915_gem_idle_work_handler(struct work_struct *work)
{
        struct drm_i915_private *dev_priv =
                container_of(work, typeof(*dev_priv), mm.idle_work.work);
        struct drm_device *dev = dev_priv->dev;
        struct intel_engine_cs *ring;
        int i;

        for_each_ring(ring, dev_priv, i)
                if (!list_empty(&ring->request_list))
                        return;

        /* we probably should sync with hangcheck here, using cancel_work_sync.
         * Also locking seems to be fubar here, ring->request_list is protected
         * by dev->struct_mutex. */

        intel_mark_idle(dev);

        if (mutex_trylock(&dev->struct_mutex)) {
                struct intel_engine_cs *ring;
                int i;

                for_each_ring(ring, dev_priv, i)
                        i915_gem_batch_pool_fini(&ring->batch_pool);

                mutex_unlock(&dev->struct_mutex);
        }
}

/**
 * Ensures that an object will eventually get non-busy by flushing any required
 * write domains, emitting any outstanding lazy request and retiring and
 * completed requests.
 */
static int
i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
{
        int i;

        if (!obj->active)
                return 0;

        for (i = 0; i < I915_NUM_RINGS; i++) {
                struct drm_i915_gem_request *req;

                req = obj->last_read_req[i];
                if (req == NULL)
                        continue;

                if (list_empty(&req->list))
                        goto retire;

                if (i915_gem_request_completed(req, true)) {
                        __i915_gem_request_retire__upto(req);
retire:
                        i915_gem_object_retire__read(obj, i);
                }
        }

        return 0;
}

/**
 * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
 * @DRM_IOCTL_ARGS: standard ioctl arguments
 *
 * Returns 0 if successful, else an error is returned with the remaining time in
 * the timeout parameter.
 *  -ETIME: object is still busy after timeout
 *  -ERESTARTSYS: signal interrupted the wait
 *  -ENONENT: object doesn't exist
 * Also possible, but rare:
 *  -EAGAIN: GPU wedged
 *  -ENOMEM: damn
 *  -ENODEV: Internal IRQ fail
 *  -E?: The add request failed
 *
 * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
 * non-zero timeout parameter the wait ioctl will wait for the given number of
 * nanoseconds on an object becoming unbusy. Since the wait itself does so
 * without holding struct_mutex the object may become re-busied before this
 * function completes. A similar but shorter * race condition exists in the busy
 * ioctl
 */
int
i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_wait *args = data;
        struct drm_i915_gem_object *obj;
        struct drm_i915_gem_request *req[I915_NUM_RINGS];
        unsigned reset_counter;
        int i, n = 0;
        int ret;

        if (args->flags != 0)
                return -EINVAL;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->bo_handle));
        if (&obj->base == NULL) {
                mutex_unlock(&dev->struct_mutex);
                return -ENOENT;
        }

        /* Need to make sure the object gets inactive eventually. */
        ret = i915_gem_object_flush_active(obj);
        if (ret)
                goto out;

        if (!obj->active)
                goto out;

        /* Do this after OLR check to make sure we make forward progress polling
         * on this IOCTL with a timeout == 0 (like busy ioctl)
         */
        if (args->timeout_ns == 0) {
                ret = -ETIME;
                goto out;
        }

        drm_gem_object_unreference(&obj->base);
        reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);

        for (i = 0; i < I915_NUM_RINGS; i++) {
                if (obj->last_read_req[i] == NULL)
                        continue;

                req[n++] = i915_gem_request_reference(obj->last_read_req[i]);
        }

        mutex_unlock(&dev->struct_mutex);

        for (i = 0; i < n; i++) {
                if (ret == 0)
                        ret = __i915_wait_request(req[i], reset_counter, true,
                                                  args->timeout_ns > 0 ? &args->timeout_ns : NULL,
                                                  to_rps_client(file));
                i915_gem_request_unreference__unlocked(req[i]);
        }
        return ret;

out:
        drm_gem_object_unreference(&obj->base);
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

static int
__i915_gem_object_sync(struct drm_i915_gem_object *obj,
                       struct intel_engine_cs *to,
                       struct drm_i915_gem_request *from_req,
                       struct drm_i915_gem_request **to_req)
{
        struct intel_engine_cs *from;
        int ret;

        from = i915_gem_request_get_ring(from_req);
        if (to == from)
                return 0;

        if (i915_gem_request_completed(from_req, true))
                return 0;

        if (!i915_semaphore_is_enabled(obj->base.dev)) {
                struct drm_i915_private *i915 = to_i915(obj->base.dev);
                ret = __i915_wait_request(from_req,
                                          atomic_read(&i915->gpu_error.reset_counter),
                                          i915->mm.interruptible,
                                          NULL,
                                          &i915->rps.semaphores);
                if (ret)
                        return ret;

                i915_gem_object_retire_request(obj, from_req);
        } else {
                int idx = intel_ring_sync_index(from, to);
                u32 seqno = i915_gem_request_get_seqno(from_req);

                WARN_ON(!to_req);

                if (seqno <= from->semaphore.sync_seqno[idx])
                        return 0;

                if (*to_req == NULL) {
                        struct drm_i915_gem_request *req;

                        req = i915_gem_request_alloc(to, NULL);
                        if (IS_ERR(req))
                                return PTR_ERR(req);

                        *to_req = req;
                }

                trace_i915_gem_ring_sync_to(*to_req, from, from_req);
                ret = to->semaphore.sync_to(*to_req, from, seqno);
                if (ret)
                        return ret;

                /* We use last_read_req because sync_to()
                 * might have just caused seqno wrap under
                 * the radar.
                 */
                from->semaphore.sync_seqno[idx] =
                        i915_gem_request_get_seqno(obj->last_read_req[from->id]);
        }

        return 0;
}

/**
 * i915_gem_object_sync - sync an object to a ring.
 *
 * @obj: object which may be in use on another ring.
 * @to: ring we wish to use the object on. May be NULL.
 * @to_req: request we wish to use the object for. See below.
 *          This will be allocated and returned if a request is
 *          required but not passed in.
 *
 * This code is meant to abstract object synchronization with the GPU.
 * Calling with NULL implies synchronizing the object with the CPU
 * rather than a particular GPU ring. Conceptually we serialise writes
 * between engines inside the GPU. We only allow one engine to write
 * into a buffer at any time, but multiple readers. To ensure each has
 * a coherent view of memory, we must:
 *
 * - If there is an outstanding write request to the object, the new
 *   request must wait for it to complete (either CPU or in hw, requests
 *   on the same ring will be naturally ordered).
 *
 * - If we are a write request (pending_write_domain is set), the new
 *   request must wait for outstanding read requests to complete.
 *
 * For CPU synchronisation (NULL to) no request is required. For syncing with
 * rings to_req must be non-NULL. However, a request does not have to be
 * pre-allocated. If *to_req is NULL and sync commands will be emitted then a
 * request will be allocated automatically and returned through *to_req. Note
 * that it is not guaranteed that commands will be emitted (because the system
 * might already be idle). Hence there is no need to create a request that
 * might never have any work submitted. Note further that if a request is
 * returned in *to_req, it is the responsibility of the caller to submit
 * that request (after potentially adding more work to it).
 *
 * Returns 0 if successful, else propagates up the lower layer error.
 */
int
i915_gem_object_sync(struct drm_i915_gem_object *obj,
                     struct intel_engine_cs *to,
                     struct drm_i915_gem_request **to_req)
{
        const bool readonly = obj->base.pending_write_domain == 0;
        struct drm_i915_gem_request *req[I915_NUM_RINGS];
        int ret, i, n;

        if (!obj->active)
                return 0;

        if (to == NULL)
                return i915_gem_object_wait_rendering(obj, readonly);

        n = 0;
        if (readonly) {
                if (obj->last_write_req)
                        req[n++] = obj->last_write_req;
        } else {
                for (i = 0; i < I915_NUM_RINGS; i++)
                        if (obj->last_read_req[i])
                                req[n++] = obj->last_read_req[i];
        }
        for (i = 0; i < n; i++) {
                ret = __i915_gem_object_sync(obj, to, req[i], to_req);
                if (ret)
                        return ret;
        }

        return 0;
}

static void i915_gem_object_finish_gtt(struct drm_i915_gem_object *obj)
{
        u32 old_write_domain, old_read_domains;

        /* Force a pagefault for domain tracking on next user access */
        i915_gem_release_mmap(obj);

        if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
                return;

        /* Wait for any direct GTT access to complete */
        mb();

        old_read_domains = obj->base.read_domains;
        old_write_domain = obj->base.write_domain;

        obj->base.read_domains &= ~I915_GEM_DOMAIN_GTT;
        obj->base.write_domain &= ~I915_GEM_DOMAIN_GTT;

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);
}

static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
{
        struct drm_i915_gem_object *obj = vma->obj;
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        int ret;

        if (list_empty(&vma->obj_link))
                return 0;

        if (!drm_mm_node_allocated(&vma->node)) {
                i915_gem_vma_destroy(vma);
                return 0;
        }

        if (vma->pin_count)
                return -EBUSY;

        BUG_ON(obj->pages == NULL);

        if (wait) {
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;
        }

        if (vma->is_ggtt && vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) {
                i915_gem_object_finish_gtt(obj);

                /* release the fence reg _after_ flushing */
                ret = i915_gem_object_put_fence(obj);
                if (ret)
                        return ret;
        }

        trace_i915_vma_unbind(vma);

        vma->vm->unbind_vma(vma);
        vma->bound = 0;

        list_del_init(&vma->vm_link);
        if (vma->is_ggtt) {
                if (vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) {
                        obj->map_and_fenceable = false;
                } else if (vma->ggtt_view.pages) {
                        sg_free_table(vma->ggtt_view.pages);
                        kfree(vma->ggtt_view.pages);
                }
                vma->ggtt_view.pages = NULL;
        }

        drm_mm_remove_node(&vma->node);
        i915_gem_vma_destroy(vma);

        /* Since the unbound list is global, only move to that list if
         * no more VMAs exist. */
        if (list_empty(&obj->vma_list))
                list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);

        /* And finally now the object is completely decoupled from this vma,
         * we can drop its hold on the backing storage and allow it to be
         * reaped by the shrinker.
         */
        i915_gem_object_unpin_pages(obj);

        return 0;
}

int i915_vma_unbind(struct i915_vma *vma)
{
        return __i915_vma_unbind(vma, true);
}

int __i915_vma_unbind_no_wait(struct i915_vma *vma)
{
        return __i915_vma_unbind(vma, false);
}

int i915_gpu_idle(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        int ret, i;

        /* Flush everything onto the inactive list. */
        for_each_ring(ring, dev_priv, i) {
                if (!i915.enable_execlists) {
                        struct drm_i915_gem_request *req;

                        req = i915_gem_request_alloc(ring, NULL);
                        if (IS_ERR(req))
                                return PTR_ERR(req);

                        ret = i915_switch_context(req);
                        if (ret) {
                                i915_gem_request_cancel(req);
                                return ret;
                        }

                        i915_add_request_no_flush(req);
                }

                ret = intel_ring_idle(ring);
                if (ret)
                        return ret;
        }

        WARN_ON(i915_verify_lists(dev));
        return 0;
}

static bool i915_gem_valid_gtt_space(struct i915_vma *vma,
                                     unsigned long cache_level)
{
        struct drm_mm_node *gtt_space = &vma->node;
        struct drm_mm_node *other;

        /*
         * On some machines we have to be careful when putting differing types
         * of snoopable memory together to avoid the prefetcher crossing memory
         * domains and dying. During vm initialisation, we decide whether or not
         * these constraints apply and set the drm_mm.color_adjust
         * appropriately.
         */
        if (vma->vm->mm.color_adjust == NULL)
                return true;

        if (!drm_mm_node_allocated(gtt_space))
                return true;

        if (list_empty(&gtt_space->node_list))
                return true;

        other = list_entry(gtt_space->node_list.prev, struct drm_mm_node, node_list);
        if (other->allocated && !other->hole_follows && other->color != cache_level)
                return false;

        other = list_entry(gtt_space->node_list.next, struct drm_mm_node, node_list);
        if (other->allocated && !gtt_space->hole_follows && other->color != cache_level)
                return false;

        return true;
}

/**
 * Finds free space in the GTT aperture and binds the object or a view of it
 * there.
 */
static struct i915_vma *
i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
                           struct i915_address_space *vm,
                           const struct i915_ggtt_view *ggtt_view,
                           unsigned alignment,
                           uint64_t flags)
{
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 fence_alignment, unfenced_alignment;
        u32 search_flag, alloc_flag;
        u64 start, end;
        u64 size, fence_size;
        struct i915_vma *vma;
        int ret;

        if (i915_is_ggtt(vm)) {
                u32 view_size;

                if (WARN_ON(!ggtt_view))
                        return ERR_PTR(-EINVAL);

                view_size = i915_ggtt_view_size(obj, ggtt_view);

                fence_size = i915_gem_get_gtt_size(dev,
                                                   view_size,
                                                   obj->tiling_mode);
                fence_alignment = i915_gem_get_gtt_alignment(dev,
                                                             view_size,
                                                             obj->tiling_mode,
                                                             true);
                unfenced_alignment = i915_gem_get_gtt_alignment(dev,
                                                                view_size,
                                                                obj->tiling_mode,
                                                                false);
                size = flags & PIN_MAPPABLE ? fence_size : view_size;
        } else {
                fence_size = i915_gem_get_gtt_size(dev,
                                                   obj->base.size,
                                                   obj->tiling_mode);
                fence_alignment = i915_gem_get_gtt_alignment(dev,
                                                             obj->base.size,
                                                             obj->tiling_mode,
                                                             true);
                unfenced_alignment =
                        i915_gem_get_gtt_alignment(dev,
                                                   obj->base.size,
                                                   obj->tiling_mode,
                                                   false);
                size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
        }

        start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
        end = vm->total;
        if (flags & PIN_MAPPABLE)
                end = min_t(u64, end, dev_priv->gtt.mappable_end);
        if (flags & PIN_ZONE_4G)
                end = min_t(u64, end, (1ULL << 32) - PAGE_SIZE);

        if (alignment == 0)
                alignment = flags & PIN_MAPPABLE ? fence_alignment :
                                                unfenced_alignment;
        if (flags & PIN_MAPPABLE && alignment & (fence_alignment - 1)) {
                DRM_DEBUG("Invalid object (view type=%u) alignment requested %u\n",
                          ggtt_view ? ggtt_view->type : 0,
                          alignment);
                return ERR_PTR(-EINVAL);
        }

        /* If binding the object/GGTT view requires more space than the entire
         * aperture has, reject it early before evicting everything in a vain
         * attempt to find space.
         */
        if (size > end) {
                DRM_DEBUG("Attempting to bind an object (view type=%u) larger than the aperture: size=%lu > %s aperture=%lu\n",
                          ggtt_view ? ggtt_view->type : 0,
                          size,
                          flags & PIN_MAPPABLE ? "mappable" : "total",
                          end);
                return ERR_PTR(-E2BIG);
        }

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ERR_PTR(ret);

        i915_gem_object_pin_pages(obj);

        vma = ggtt_view ? i915_gem_obj_lookup_or_create_ggtt_vma(obj, ggtt_view) :
                          i915_gem_obj_lookup_or_create_vma(obj, vm);

        if (IS_ERR(vma))
                goto err_unpin;

        if (flags & PIN_OFFSET_FIXED) {
                uint64_t offset = flags & PIN_OFFSET_MASK;

                if (offset & (alignment - 1) || offset + size > end) {
                        ret = -EINVAL;
                        goto err_free_vma;
                }
                vma->node.start = offset;
                vma->node.size = size;
                vma->node.color = obj->cache_level;
                ret = drm_mm_reserve_node(&vm->mm, &vma->node);
                if (ret) {
                        ret = i915_gem_evict_for_vma(vma);
                        if (ret == 0)
                                ret = drm_mm_reserve_node(&vm->mm, &vma->node);
                }
                if (ret)
                        goto err_free_vma;
        } else {
                if (flags & PIN_HIGH) {
                        search_flag = DRM_MM_SEARCH_BELOW;
                        alloc_flag = DRM_MM_CREATE_TOP;
                } else {
                        search_flag = DRM_MM_SEARCH_DEFAULT;
                        alloc_flag = DRM_MM_CREATE_DEFAULT;
                }

search_free:
                ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
                                                          size, alignment,
                                                          obj->cache_level,
                                                          start, end,
                                                          search_flag,
                                                          alloc_flag);
                if (ret) {
                        ret = i915_gem_evict_something(dev, vm, size, alignment,
                                                       obj->cache_level,
                                                       start, end,
                                                       flags);
                        if (ret == 0)
                                goto search_free;

                        goto err_free_vma;
                }
        }
        if (WARN_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level))) {
                ret = -EINVAL;
                goto err_remove_node;
        }

        trace_i915_vma_bind(vma, flags);
        ret = i915_vma_bind(vma, obj->cache_level, flags);
        if (ret)
                goto err_remove_node;

        list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
        list_add_tail(&vma->vm_link, &vm->inactive_list);

        return vma;

err_remove_node:
        drm_mm_remove_node(&vma->node);
err_free_vma:
        i915_gem_vma_destroy(vma);
        vma = ERR_PTR(ret);
err_unpin:
        i915_gem_object_unpin_pages(obj);
        return vma;
}

bool
i915_gem_clflush_object(struct drm_i915_gem_object *obj,
                        bool force)
{
        /* If we don't have a page list set up, then we're not pinned
         * to GPU, and we can ignore the cache flush because it'll happen
         * again at bind time.
         */
        if (obj->pages == NULL)
                return false;

        /*
         * Stolen memory is always coherent with the GPU as it is explicitly
         * marked as wc by the system, or the system is cache-coherent.
         */
        if (obj->stolen || obj->phys_handle)
                return false;

        /* If the GPU is snooping the contents of the CPU cache,
         * we do not need to manually clear the CPU cache lines.  However,
         * the caches are only snooped when the render cache is
         * flushed/invalidated.  As we always have to emit invalidations
         * and flushes when moving into and out of the RENDER domain, correct
         * snooping behaviour occurs naturally as the result of our domain
         * tracking.
         */
        if (!force && cpu_cache_is_coherent(obj->base.dev, obj->cache_level)) {
                obj->cache_dirty = true;
                return false;
        }

        trace_i915_gem_object_clflush(obj);
        drm_clflush_sg(obj->pages);
        obj->cache_dirty = false;

        return true;
}

/** Flushes the GTT write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_GTT)
                return;

        /* No actual flushing is required for the GTT write domain.  Writes
         * to it immediately go to main memory as far as we know, so there's
         * no chipset flush.  It also doesn't land in render cache.
         *
         * However, we do have to enforce the order so that all writes through
         * the GTT land before any writes to the device, such as updates to
         * the GATT itself.
         */
        wmb();

        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;

        intel_fb_obj_flush(obj, false, ORIGIN_GTT);

        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            old_write_domain);
}

/** Flushes the CPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj)
{
        uint32_t old_write_domain;

        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU)
                return;

        if (i915_gem_clflush_object(obj, obj->pin_display))
                i915_gem_chipset_flush(obj->base.dev);

        old_write_domain = obj->base.write_domain;
        obj->base.write_domain = 0;

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);

        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            old_write_domain);
}

/**
 * Moves a single object to the GTT read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        struct i915_vma *vma;
        int ret;

        if (obj->base.write_domain == I915_GEM_DOMAIN_GTT)
                return 0;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        /* Flush and acquire obj->pages so that we are coherent through
         * direct access in memory with previous cached writes through
         * shmemfs and that our cache domain tracking remains valid.
         * For example, if the obj->filp was moved to swap without us
         * being notified and releasing the pages, we would mistakenly
         * continue to assume that the obj remained out of the CPU cached
         * domain.
         */
        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_flush_cpu_write_domain(obj);

        /* Serialise direct access to this object with the barriers for
         * coherent writes from the GPU, by effectively invalidating the
         * GTT domain upon first access.
         */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
                mb();

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_GTT;
                obj->base.write_domain = I915_GEM_DOMAIN_GTT;
                obj->dirty = 1;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        /* And bump the LRU for this access */
        vma = i915_gem_obj_to_ggtt(obj);
        if (vma && drm_mm_node_allocated(&vma->node) && !obj->active)
                list_move_tail(&vma->vm_link,
                               &to_i915(obj->base.dev)->gtt.base.inactive_list);

        return 0;
}

/**
 * Changes the cache-level of an object across all VMA.
 *
 * After this function returns, the object will be in the new cache-level
 * across all GTT and the contents of the backing storage will be coherent,
 * with respect to the new cache-level. In order to keep the backing storage
 * coherent for all users, we only allow a single cache level to be set
 * globally on the object and prevent it from being changed whilst the
 * hardware is reading from the object. That is if the object is currently
 * on the scanout it will be set to uncached (or equivalent display
 * cache coherency) and all non-MOCS GPU access will also be uncached so
 * that all direct access to the scanout remains coherent.
 */
int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
                                    enum i915_cache_level cache_level)
{
        struct drm_device *dev = obj->base.dev;
        struct i915_vma *vma, *next;
        bool bound = false;
        int ret = 0;

        if (obj->cache_level == cache_level)
                goto out;

        /* Inspect the list of currently bound VMA and unbind any that would
         * be invalid given the new cache-level. This is principally to
         * catch the issue of the CS prefetch crossing page boundaries and
         * reading an invalid PTE on older architectures.
         */
        list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link) {
                if (!drm_mm_node_allocated(&vma->node))
                        continue;

                if (vma->pin_count) {
                        DRM_DEBUG("can not change the cache level of pinned objects\n");
                        return -EBUSY;
                }

                if (!i915_gem_valid_gtt_space(vma, cache_level)) {
                        ret = i915_vma_unbind(vma);
                        if (ret)
                                return ret;
                } else
                        bound = true;
        }

        /* We can reuse the existing drm_mm nodes but need to change the
         * cache-level on the PTE. We could simply unbind them all and
         * rebind with the correct cache-level on next use. However since
         * we already have a valid slot, dma mapping, pages etc, we may as
         * rewrite the PTE in the belief that doing so tramples upon less
         * state and so involves less work.
         */
        if (bound) {
                /* Before we change the PTE, the GPU must not be accessing it.
                 * If we wait upon the object, we know that all the bound
                 * VMA are no longer active.
                 */
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;

                if (!HAS_LLC(dev) && cache_level != I915_CACHE_NONE) {
                        /* Access to snoopable pages through the GTT is
                         * incoherent and on some machines causes a hard
                         * lockup. Relinquish the CPU mmaping to force
                         * userspace to refault in the pages and we can
                         * then double check if the GTT mapping is still
                         * valid for that pointer access.
                         */
                        i915_gem_release_mmap(obj);

                        /* As we no longer need a fence for GTT access,
                         * we can relinquish it now (and so prevent having
                         * to steal a fence from someone else on the next
                         * fence request). Note GPU activity would have
                         * dropped the fence as all snoopable access is
                         * supposed to be linear.
                         */
                        ret = i915_gem_object_put_fence(obj);
                        if (ret)
                                return ret;
                } else {
                        /* We either have incoherent backing store and
                         * so no GTT access or the architecture is fully
                         * coherent. In such cases, existing GTT mmaps
                         * ignore the cache bit in the PTE and we can
                         * rewrite it without confusing the GPU or having
                         * to force userspace to fault back in its mmaps.
                         */
                }

                list_for_each_entry(vma, &obj->vma_list, obj_link) {
                        if (!drm_mm_node_allocated(&vma->node))
                                continue;

                        ret = i915_vma_bind(vma, cache_level, PIN_UPDATE);
                        if (ret)
                                return ret;
                }
        }

        list_for_each_entry(vma, &obj->vma_list, obj_link)
                vma->node.color = cache_level;
        obj->cache_level = cache_level;

out:
        /* Flush the dirty CPU caches to the backing storage so that the
         * object is now coherent at its new cache level (with respect
         * to the access domain).
         */
        if (obj->cache_dirty &&
            obj->base.write_domain != I915_GEM_DOMAIN_CPU &&
            cpu_write_needs_clflush(obj)) {
                if (i915_gem_clflush_object(obj, true))
                        i915_gem_chipset_flush(obj->base.dev);
        }

        return 0;
}

int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL)
                return -ENOENT;

        switch (obj->cache_level) {
        case I915_CACHE_LLC:
        case I915_CACHE_L3_LLC:
                args->caching = I915_CACHING_CACHED;
                break;

        case I915_CACHE_WT:
                args->caching = I915_CACHING_DISPLAY;
                break;

        default:
                args->caching = I915_CACHING_NONE;
                break;
        }

        drm_gem_object_unreference_unlocked(&obj->base);
        return 0;
}

int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;
        enum i915_cache_level level;
        int ret;

        switch (args->caching) {
        case I915_CACHING_NONE:
                level = I915_CACHE_NONE;
                break;
        case I915_CACHING_CACHED:
                /*
                 * Due to a HW issue on BXT A stepping, GPU stores via a
                 * snooped mapping may leave stale data in a corresponding CPU
                 * cacheline, whereas normally such cachelines would get
                 * invalidated.
                 */
                if (IS_BXT_REVID(dev, 0, BXT_REVID_A1))
                        return -ENODEV;

                level = I915_CACHE_LLC;
                break;
        case I915_CACHING_DISPLAY:
                level = HAS_WT(dev) ? I915_CACHE_WT : I915_CACHE_NONE;
                break;
        default:
                return -EINVAL;
        }

        intel_runtime_pm_get(dev_priv);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto rpm_put;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        ret = i915_gem_object_set_cache_level(obj, level);

        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
rpm_put:
        intel_runtime_pm_put(dev_priv);

        return ret;
}

/*
 * Prepare buffer for display plane (scanout, cursors, etc).
 * Can be called from an uninterruptible phase (modesetting) and allows
 * any flushes to be pipelined (for pageflips).
 */
int
i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
                                     u32 alignment,
                                     const struct i915_ggtt_view *view)
{
        u32 old_read_domains, old_write_domain;
        int ret;

        /* Mark the pin_display early so that we account for the
         * display coherency whilst setting up the cache domains.
         */
        obj->pin_display++;

        /* The display engine is not coherent with the LLC cache on gen6.  As
         * a result, we make sure that the pinning that is about to occur is
         * done with uncached PTEs. This is lowest common denominator for all
         * chipsets.
         *
         * However for gen6+, we could do better by using the GFDT bit instead
         * of uncaching, which would allow us to flush all the LLC-cached data
         * with that bit in the PTE to main memory with just one PIPE_CONTROL.
         */
        ret = i915_gem_object_set_cache_level(obj,
                                              HAS_WT(obj->base.dev) ? I915_CACHE_WT : I915_CACHE_NONE);
        if (ret)
                goto err_unpin_display;

        /* As the user may map the buffer once pinned in the display plane
         * (e.g. libkms for the bootup splash), we have to ensure that we
         * always use map_and_fenceable for all scanout buffers.
         */
        ret = i915_gem_object_ggtt_pin(obj, view, alignment,
                                       view->type == I915_GGTT_VIEW_NORMAL ?
                                       PIN_MAPPABLE : 0);
        if (ret)
                goto err_unpin_display;

        i915_gem_object_flush_cpu_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        obj->base.write_domain = 0;
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        return 0;

err_unpin_display:
        obj->pin_display--;
        return ret;
}

void
i915_gem_object_unpin_from_display_plane(struct drm_i915_gem_object *obj,
                                         const struct i915_ggtt_view *view)
{
        if (WARN_ON(obj->pin_display == 0))
                return;

        i915_gem_object_ggtt_unpin_view(obj, view);

        obj->pin_display--;
}

/**
 * Moves a single object to the CPU read, and possibly write domain.
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        int ret;

        if (obj->base.write_domain == I915_GEM_DOMAIN_CPU)
                return 0;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        i915_gem_object_flush_gtt_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* Flush the CPU cache if it's still invalid. */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0) {
                i915_gem_clflush_object(obj, false);

                obj->base.read_domains |= I915_GEM_DOMAIN_CPU;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        /* If we're writing through the CPU, then the GPU read domains will
         * need to be invalidated at next use.
         */
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_CPU;
                obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        return 0;
}

/* Throttle our rendering by waiting until the ring has completed our requests
 * emitted over 20 msec ago.
 *
 * Note that if we were to use the current jiffies each time around the loop,
 * we wouldn't escape the function with any frames outstanding if the time to
 * render a frame was over 20ms.
 *
 * This should get us reasonable parallelism between CPU and GPU but also
 * relatively low latency when blocking on a particular request to finish.
 */
static int
i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_file_private *file_priv = file->driver_priv;
        unsigned long recent_enough = jiffies - DRM_I915_THROTTLE_JIFFIES;
        struct drm_i915_gem_request *request, *target = NULL;
        unsigned reset_counter;
        int ret;

        ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
        if (ret)
                return ret;

        ret = i915_gem_check_wedge(&dev_priv->gpu_error, false);
        if (ret)
                return ret;

        spin_lock(&file_priv->mm.lock);
        list_for_each_entry(request, &file_priv->mm.request_list, client_list) {
                if (time_after_eq(request->emitted_jiffies, recent_enough))
                        break;

                /*
                 * Note that the request might not have been submitted yet.
                 * In which case emitted_jiffies will be zero.
                 */
                if (!request->emitted_jiffies)
                        continue;

                target = request;
        }
        reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
        if (target)
                i915_gem_request_reference(target);
        spin_unlock(&file_priv->mm.lock);

        if (target == NULL)
                return 0;

        ret = __i915_wait_request(target, reset_counter, true, NULL, NULL);
        if (ret == 0)
                queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);

        i915_gem_request_unreference__unlocked(target);

        return ret;
}

static bool
i915_vma_misplaced(struct i915_vma *vma, uint32_t alignment, uint64_t flags)
{
        struct drm_i915_gem_object *obj = vma->obj;

        if (alignment &&
            vma->node.start & (alignment - 1))
                return true;

        if (flags & PIN_MAPPABLE && !obj->map_and_fenceable)
                return true;

        if (flags & PIN_OFFSET_BIAS &&
            vma->node.start < (flags & PIN_OFFSET_MASK))
                return true;

        if (flags & PIN_OFFSET_FIXED &&
            vma->node.start != (flags & PIN_OFFSET_MASK))
                return true;

        return false;
}

void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
{
        struct drm_i915_gem_object *obj = vma->obj;
        bool mappable, fenceable;
        u32 fence_size, fence_alignment;

        fence_size = i915_gem_get_gtt_size(obj->base.dev,
                                           obj->base.size,
                                           obj->tiling_mode);
        fence_alignment = i915_gem_get_gtt_alignment(obj->base.dev,
                                                     obj->base.size,
                                                     obj->tiling_mode,
                                                     true);

        fenceable = (vma->node.size == fence_size &&
                     (vma->node.start & (fence_alignment - 1)) == 0);

        mappable = (vma->node.start + fence_size <=
                    to_i915(obj->base.dev)->gtt.mappable_end);

        obj->map_and_fenceable = mappable && fenceable;
}

static int
i915_gem_object_do_pin(struct drm_i915_gem_object *obj,
                       struct i915_address_space *vm,
                       const struct i915_ggtt_view *ggtt_view,
                       uint32_t alignment,
                       uint64_t flags)
{
        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
        struct i915_vma *vma;
        unsigned bound;
        int ret;

        if (WARN_ON(vm == &dev_priv->mm.aliasing_ppgtt->base))
                return -ENODEV;

        if (WARN_ON(flags & (PIN_GLOBAL | PIN_MAPPABLE) && !i915_is_ggtt(vm)))
                return -EINVAL;

        if (WARN_ON((flags & (PIN_MAPPABLE | PIN_GLOBAL)) == PIN_MAPPABLE))
                return -EINVAL;

        if (WARN_ON(i915_is_ggtt(vm) != !!ggtt_view))
                return -EINVAL;

        vma = ggtt_view ? i915_gem_obj_to_ggtt_view(obj, ggtt_view) :
                          i915_gem_obj_to_vma(obj, vm);

        if (IS_ERR(vma))
                return PTR_ERR(vma);

        if (vma) {
                if (WARN_ON(vma->pin_count == DRM_I915_GEM_OBJECT_MAX_PIN_COUNT))
                        return -EBUSY;

                if (i915_vma_misplaced(vma, alignment, flags)) {
                        WARN(vma->pin_count,
                             "bo is already pinned in %s with incorrect alignment:"
                             " offset=%08x %08x, req.alignment=%x, req.map_and_fenceable=%d,"
                             " obj->map_and_fenceable=%d\n",
                             ggtt_view ? "ggtt" : "ppgtt",
                             upper_32_bits(vma->node.start),
                             lower_32_bits(vma->node.start),
                             alignment,
                             !!(flags & PIN_MAPPABLE),
                             obj->map_and_fenceable);
                        ret = i915_vma_unbind(vma);
                        if (ret)
                                return ret;

                        vma = NULL;
                }
        }

        bound = vma ? vma->bound : 0;
        if (vma == NULL || !drm_mm_node_allocated(&vma->node)) {
                vma = i915_gem_object_bind_to_vm(obj, vm, ggtt_view, alignment,
                                                 flags);
                if (IS_ERR(vma))
                        return PTR_ERR(vma);
        } else {
                ret = i915_vma_bind(vma, obj->cache_level, flags);
                if (ret)
                        return ret;
        }

        if (ggtt_view && ggtt_view->type == I915_GGTT_VIEW_NORMAL &&
            (bound ^ vma->bound) & GLOBAL_BIND) {
                __i915_vma_set_map_and_fenceable(vma);
                WARN_ON(flags & PIN_MAPPABLE && !obj->map_and_fenceable);
        }

        vma->pin_count++;
        return 0;
}

int
i915_gem_object_pin(struct drm_i915_gem_object *obj,
                    struct i915_address_space *vm,
                    uint32_t alignment,
                    uint64_t flags)
{
        return i915_gem_object_do_pin(obj, vm,
                                      i915_is_ggtt(vm) ? &i915_ggtt_view_normal : NULL,
                                      alignment, flags);
}

int
i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
                         const struct i915_ggtt_view *view,
                         uint32_t alignment,
                         uint64_t flags)
{
        if (WARN_ONCE(!view, "no view specified"))
                return -EINVAL;

        return i915_gem_object_do_pin(obj, i915_obj_to_ggtt(obj), view,
                                      alignment, flags | PIN_GLOBAL);
}

void
i915_gem_object_ggtt_unpin_view(struct drm_i915_gem_object *obj,
                                const struct i915_ggtt_view *view)
{
        struct i915_vma *vma = i915_gem_obj_to_ggtt_view(obj, view);

        BUG_ON(!vma);
        WARN_ON(vma->pin_count == 0);
        WARN_ON(!i915_gem_obj_ggtt_bound_view(obj, view));

        --vma->pin_count;
}

int
i915_gem_busy_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_busy *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        /* Count all active objects as busy, even if they are currently not used
         * by the gpu. Users of this interface expect objects to eventually
         * become non-busy without any further actions, therefore emit any
         * necessary flushes here.
         */
        ret = i915_gem_object_flush_active(obj);
        if (ret)
                goto unref;

        args->busy = 0;
        if (obj->active) {
                int i;

                for (i = 0; i < I915_NUM_RINGS; i++) {
                        struct drm_i915_gem_request *req;

                        req = obj->last_read_req[i];
                        if (req)
                                args->busy |= 1 << (16 + req->ring->exec_id);
                }
                if (obj->last_write_req)
                        args->busy |= obj->last_write_req->ring->exec_id;
        }

unref:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

int
i915_gem_throttle_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
{
        return i915_gem_ring_throttle(dev, file_priv);
}

int
i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_madvise *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        switch (args->madv) {
        case I915_MADV_DONTNEED:
        case I915_MADV_WILLNEED:
            break;
        default:
            return -EINVAL;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file_priv, args->handle));
        if (&obj->base == NULL) {
                ret = -ENOENT;
                goto unlock;
        }

        if (i915_gem_obj_is_pinned(obj)) {
                ret = -EINVAL;
                goto out;
        }

        if (obj->pages &&
            obj->tiling_mode != I915_TILING_NONE &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
                if (obj->madv == I915_MADV_WILLNEED)
                        i915_gem_object_unpin_pages(obj);
                if (args->madv == I915_MADV_WILLNEED)
                        i915_gem_object_pin_pages(obj);
        }

        if (obj->madv != __I915_MADV_PURGED)
                obj->madv = args->madv;

        /* if the object is no longer attached, discard its backing storage */
        if (obj->madv == I915_MADV_DONTNEED && obj->pages == NULL)
                i915_gem_object_truncate(obj);

        args->retained = obj->madv != __I915_MADV_PURGED;

out:
        drm_gem_object_unreference(&obj->base);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

void i915_gem_object_init(struct drm_i915_gem_object *obj,
                          const struct drm_i915_gem_object_ops *ops)
{
        int i;

        INIT_LIST_HEAD(&obj->global_list);
        for (i = 0; i < I915_NUM_RINGS; i++)
                INIT_LIST_HEAD(&obj->ring_list[i]);
        INIT_LIST_HEAD(&obj->obj_exec_link);
        INIT_LIST_HEAD(&obj->vma_list);
        INIT_LIST_HEAD(&obj->batch_pool_link);

        obj->ops = ops;

        obj->fence_reg = I915_FENCE_REG_NONE;
        obj->madv = I915_MADV_WILLNEED;

        i915_gem_info_add_obj(obj->base.dev->dev_private, obj->base.size);
}

static const struct drm_i915_gem_object_ops i915_gem_object_ops = {
        .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE,
        .get_pages = i915_gem_object_get_pages_gtt,
        .put_pages = i915_gem_object_put_pages_gtt,
};

struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
                                                  size_t size)
{
        struct drm_i915_gem_object *obj;
#if 0
        struct address_space *mapping;
        gfp_t mask;
#endif

        obj = i915_gem_object_alloc(dev);
        if (obj == NULL)
                return NULL;

        if (drm_gem_object_init(dev, &obj->base, size) != 0) {
                i915_gem_object_free(obj);
                return NULL;
        }

#if 0
        mask = GFP_HIGHUSER | __GFP_RECLAIMABLE;
        if (IS_CRESTLINE(dev) || IS_BROADWATER(dev)) {
                /* 965gm cannot relocate objects above 4GiB. */
                mask &= ~__GFP_HIGHMEM;
                mask |= __GFP_DMA32;
        }

        mapping = file_inode(obj->base.filp)->i_mapping;
        mapping_set_gfp_mask(mapping, mask);
#endif

        i915_gem_object_init(obj, &i915_gem_object_ops);

        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;

        if (HAS_LLC(dev)) {
                /* On some devices, we can have the GPU use the LLC (the CPU
                 * cache) for about a 10% performance improvement
                 * compared to uncached.  Graphics requests other than
                 * display scanout are coherent with the CPU in
                 * accessing this cache.  This means in this mode we
                 * don't need to clflush on the CPU side, and on the
                 * GPU side we only need to flush internal caches to
                 * get data visible to the CPU.
                 *
                 * However, we maintain the display planes as UC, and so
                 * need to rebind when first used as such.
                 */
                obj->cache_level = I915_CACHE_LLC;
        } else
                obj->cache_level = I915_CACHE_NONE;

        trace_i915_gem_object_create(obj);

        return obj;
}

static bool discard_backing_storage(struct drm_i915_gem_object *obj)
{
        /* If we are the last user of the backing storage (be it shmemfs
         * pages or stolen etc), we know that the pages are going to be
         * immediately released. In this case, we can then skip copying
         * back the contents from the GPU.
         */

        if (obj->madv != I915_MADV_WILLNEED)
                return false;

        if (obj->base.vm_obj == NULL)
                return true;

        /* At first glance, this looks racy, but then again so would be
         * userspace racing mmap against close. However, the first external
         * reference to the filp can only be obtained through the
         * i915_gem_mmap_ioctl() which safeguards us against the user
         * acquiring such a reference whilst we are in the middle of
         * freeing the object.
         */
#if 0
        return atomic_long_read(&obj->base.filp->f_count) == 1;
#else
        return false;
#endif
}

void i915_gem_free_object(struct drm_gem_object *gem_obj)
{
        struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct i915_vma *vma, *next;

        intel_runtime_pm_get(dev_priv);

        trace_i915_gem_object_destroy(obj);

        list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link) {
                int ret;

                vma->pin_count = 0;
                ret = i915_vma_unbind(vma);
                if (WARN_ON(ret == -ERESTARTSYS)) {
                        bool was_interruptible;

                        was_interruptible = dev_priv->mm.interruptible;
                        dev_priv->mm.interruptible = false;

                        WARN_ON(i915_vma_unbind(vma));

                        dev_priv->mm.interruptible = was_interruptible;
                }
        }

        /* Stolen objects don't hold a ref, but do hold pin count. Fix that up
         * before progressing. */
        if (obj->stolen)
                i915_gem_object_unpin_pages(obj);

        WARN_ON(obj->frontbuffer_bits);

        if (obj->pages && obj->madv == I915_MADV_WILLNEED &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES &&
            obj->tiling_mode != I915_TILING_NONE)
                i915_gem_object_unpin_pages(obj);

        if (WARN_ON(obj->pages_pin_count))
                obj->pages_pin_count = 0;
        if (discard_backing_storage(obj))
                obj->madv = I915_MADV_DONTNEED;
        i915_gem_object_put_pages(obj);
        i915_gem_object_free_mmap_offset(obj);

        BUG_ON(obj->pages);

#if 0
        if (obj->base.import_attach)
                drm_prime_gem_destroy(&obj->base, NULL);
#endif

        if (obj->ops->release)
                obj->ops->release(obj);

        drm_gem_object_release(&obj->base);
        i915_gem_info_remove_obj(dev_priv, obj->base.size);

        kfree(obj->bit_17);
        i915_gem_object_free(obj);

        intel_runtime_pm_put(dev_priv);
}

struct i915_vma *i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
                                     struct i915_address_space *vm)
{
        struct i915_vma *vma;
        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                if (vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL &&
                    vma->vm == vm)
                        return vma;
        }
        return NULL;
}

struct i915_vma *i915_gem_obj_to_ggtt_view(struct drm_i915_gem_object *obj,
                                           const struct i915_ggtt_view *view)
{
        struct i915_address_space *ggtt = i915_obj_to_ggtt(obj);
        struct i915_vma *vma;

        if (WARN_ONCE(!view, "no view specified"))
                return ERR_PTR(-EINVAL);

        list_for_each_entry(vma, &obj->vma_list, obj_link)
                if (vma->vm == ggtt &&
                    i915_ggtt_view_equal(&vma->ggtt_view, view))
                        return vma;
        return NULL;
}

void i915_gem_vma_destroy(struct i915_vma *vma)
{
        WARN_ON(vma->node.allocated);

        /* Keep the vma as a placeholder in the execbuffer reservation lists */
        if (!list_empty(&vma->exec_list))
                return;

        if (!vma->is_ggtt)
                i915_ppgtt_put(i915_vm_to_ppgtt(vma->vm));

        list_del(&vma->obj_link);

        kfree(vma);
}

static void
i915_gem_stop_ringbuffers(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        int i;

        for_each_ring(ring, dev_priv, i)
                dev_priv->gt.stop_ring(ring);
}

int
i915_gem_suspend(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret = 0;

        mutex_lock(&dev->struct_mutex);
        ret = i915_gpu_idle(dev);
        if (ret)
                goto err;

        i915_gem_retire_requests(dev);

        i915_gem_stop_ringbuffers(dev);
        mutex_unlock(&dev->struct_mutex);

        cancel_delayed_work_sync(&dev_priv->gpu_error.hangcheck_work);
        cancel_delayed_work_sync(&dev_priv->mm.retire_work);
#if 0
        flush_delayed_work(&dev_priv->mm.idle_work);
#endif

        /* Assert that we sucessfully flushed all the work and
         * reset the GPU back to its idle, low power state.
         */
        WARN_ON(dev_priv->mm.busy);

        return 0;

err:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

int i915_gem_l3_remap(struct drm_i915_gem_request *req, int slice)
{
        struct intel_engine_cs *ring = req->ring;
        struct drm_device *dev = ring->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 *remap_info = dev_priv->l3_parity.remap_info[slice];
        int i, ret;

        if (!HAS_L3_DPF(dev) || !remap_info)
                return 0;

        ret = intel_ring_begin(req, GEN7_L3LOG_SIZE / 4 * 3);
        if (ret)
                return ret;

        /*
         * Note: We do not worry about the concurrent register cacheline hang
         * here because no other code should access these registers other than
         * at initialization time.
         */
        for (i = 0; i < GEN7_L3LOG_SIZE / 4; i++) {
                intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
                intel_ring_emit_reg(ring, GEN7_L3LOG(slice, i));
                intel_ring_emit(ring, remap_info[i]);
        }

        intel_ring_advance(ring);

        return ret;
}

void i915_gem_init_swizzling(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        if (INTEL_INFO(dev)->gen < 5 ||
            dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_NONE)
                return;

        I915_WRITE(DISP_ARB_CTL, I915_READ(DISP_ARB_CTL) |
                                 DISP_TILE_SURFACE_SWIZZLING);

        if (IS_GEN5(dev))
                return;

        I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_SWZCTL);
        if (IS_GEN6(dev))
                I915_WRITE(ARB_MODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_SNB));
        else if (IS_GEN7(dev))
                I915_WRITE(ARB_MODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_IVB));
        else if (IS_GEN8(dev))
                I915_WRITE(GAMTARBMODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_BDW));
        else
                BUG();
}

static void init_unused_ring(struct drm_device *dev, u32 base)
{
        struct drm_i915_private *dev_priv = dev->dev_private;

        I915_WRITE(RING_CTL(base), 0);
        I915_WRITE(RING_HEAD(base), 0);
        I915_WRITE(RING_TAIL(base), 0);
        I915_WRITE(RING_START(base), 0);
}

static void init_unused_rings(struct drm_device *dev)
{
        if (IS_I830(dev)) {
                init_unused_ring(dev, PRB1_BASE);
                init_unused_ring(dev, SRB0_BASE);
                init_unused_ring(dev, SRB1_BASE);
                init_unused_ring(dev, SRB2_BASE);
                init_unused_ring(dev, SRB3_BASE);
        } else if (IS_GEN2(dev)) {
                init_unused_ring(dev, SRB0_BASE);
                init_unused_ring(dev, SRB1_BASE);
        } else if (IS_GEN3(dev)) {
                init_unused_ring(dev, PRB1_BASE);
                init_unused_ring(dev, PRB2_BASE);
        }
}

int i915_gem_init_rings(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        ret = intel_init_render_ring_buffer(dev);
        if (ret)
                return ret;

        if (HAS_BSD(dev)) {
                ret = intel_init_bsd_ring_buffer(dev);
                if (ret)
                        goto cleanup_render_ring;
        }

        if (HAS_BLT(dev)) {
                ret = intel_init_blt_ring_buffer(dev);
                if (ret)
                        goto cleanup_bsd_ring;
        }

        if (HAS_VEBOX(dev)) {
                ret = intel_init_vebox_ring_buffer(dev);
                if (ret)
                        goto cleanup_blt_ring;
        }

        if (HAS_BSD2(dev)) {
                ret = intel_init_bsd2_ring_buffer(dev);
                if (ret)
                        goto cleanup_vebox_ring;
        }

        return 0;

cleanup_vebox_ring:
        intel_cleanup_ring_buffer(&dev_priv->ring[VECS]);
cleanup_blt_ring:
        intel_cleanup_ring_buffer(&dev_priv->ring[BCS]);
cleanup_bsd_ring:
        intel_cleanup_ring_buffer(&dev_priv->ring[VCS]);
cleanup_render_ring:
        intel_cleanup_ring_buffer(&dev_priv->ring[RCS]);

        return ret;
}

int
i915_gem_init_hw(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        int ret, i, j;

#if 0
        if (INTEL_INFO(dev)->gen < 6 && !intel_enable_gtt())
                return -EIO;
#endif

        /* Double layer security blanket, see i915_gem_init() */
        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        if (dev_priv->ellc_size)
                I915_WRITE(HSW_IDICR, I915_READ(HSW_IDICR) | IDIHASHMSK(0xf));

        if (IS_HASWELL(dev))
                I915_WRITE(MI_PREDICATE_RESULT_2, IS_HSW_GT3(dev) ?
                           LOWER_SLICE_ENABLED : LOWER_SLICE_DISABLED);

        if (HAS_PCH_NOP(dev)) {
                if (IS_IVYBRIDGE(dev)) {
                        u32 temp = I915_READ(GEN7_MSG_CTL);
                        temp &= ~(WAIT_FOR_PCH_FLR_ACK | WAIT_FOR_PCH_RESET_ACK);
                        I915_WRITE(GEN7_MSG_CTL, temp);
                } else if (INTEL_INFO(dev)->gen >= 7) {
                        u32 temp = I915_READ(HSW_NDE_RSTWRN_OPT);
                        temp &= ~RESET_PCH_HANDSHAKE_ENABLE;
                        I915_WRITE(HSW_NDE_RSTWRN_OPT, temp);
                }
        }

        i915_gem_init_swizzling(dev);

        /*
         * At least 830 can leave some of the unused rings
         * "active" (ie. head != tail) after resume which
         * will prevent c3 entry. Makes sure all unused rings
         * are totally idle.
         */
        init_unused_rings(dev);

        BUG_ON(!dev_priv->kernel_context);

        ret = i915_ppgtt_init_hw(dev);
        if (ret) {
                DRM_ERROR("PPGTT enable HW failed %d\n", ret);
                goto out;
        }

        /* Need to do basic initialisation of all rings first: */
        for_each_ring(ring, dev_priv, i) {
                ret = ring->init_hw(ring);
                if (ret)
                        goto out;
        }

        /* We can't enable contexts until all firmware is loaded */
        if (HAS_GUC_UCODE(dev)) {
                ret = intel_guc_ucode_load(dev);
                if (ret) {
                        DRM_ERROR("Failed to initialize GuC, error %d\n", ret);
                        ret = -EIO;
                        goto out;
                }
        }

        /*
         * Increment the next seqno by 0x100 so we have a visible break
         * on re-initialisation
         */
        ret = i915_gem_set_seqno(dev, dev_priv->next_seqno+0x100);
        if (ret)
                goto out;

        /* Now it is safe to go back round and do everything else: */
        for_each_ring(ring, dev_priv, i) {
                struct drm_i915_gem_request *req;

                req = i915_gem_request_alloc(ring, NULL);
                if (IS_ERR(req)) {
                        ret = PTR_ERR(req);
                        i915_gem_cleanup_ringbuffer(dev);
                        goto out;
                }

                if (ring->id == RCS) {
                        for (j = 0; j < NUM_L3_SLICES(dev); j++)
                                i915_gem_l3_remap(req, j);
                }

                ret = i915_ppgtt_init_ring(req);
                if (ret && ret != -EIO) {
                        DRM_ERROR("PPGTT enable ring #%d failed %d\n", i, ret);
                        i915_gem_request_cancel(req);
                        i915_gem_cleanup_ringbuffer(dev);
                        goto out;
                }

                ret = i915_gem_context_enable(req);
                if (ret && ret != -EIO) {
                        DRM_ERROR("Context enable ring #%d failed %d\n", i, ret);
                        i915_gem_request_cancel(req);
                        i915_gem_cleanup_ringbuffer(dev);
                        goto out;
                }

                i915_add_request_no_flush(req);
        }

out:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
        return ret;
}

int i915_gem_init(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int ret;

        i915.enable_execlists = intel_sanitize_enable_execlists(dev,
                        i915.enable_execlists);

        mutex_lock(&dev->struct_mutex);

        if (!i915.enable_execlists) {
                dev_priv->gt.execbuf_submit = i915_gem_ringbuffer_submission;
                dev_priv->gt.init_rings = i915_gem_init_rings;
                dev_priv->gt.cleanup_ring = intel_cleanup_ring_buffer;
                dev_priv->gt.stop_ring = intel_stop_ring_buffer;
        } else {
                dev_priv->gt.execbuf_submit = intel_execlists_submission;
                dev_priv->gt.init_rings = intel_logical_rings_init;
                dev_priv->gt.cleanup_ring = intel_logical_ring_cleanup;
                dev_priv->gt.stop_ring = intel_logical_ring_stop;
        }

        /* This is just a security blanket to placate dragons.
         * On some systems, we very sporadically observe that the first TLBs
         * used by the CS may be stale, despite us poking the TLB reset. If
         * we hold the forcewake during initialisation these problems
         * just magically go away.
         */
        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        ret = i915_gem_init_userptr(dev);
        if (ret)
                goto out_unlock;

        i915_gem_init_global_gtt(dev);

        ret = i915_gem_context_init(dev);
        if (ret)
                goto out_unlock;

        ret = dev_priv->gt.init_rings(dev);
        if (ret)
                goto out_unlock;

        ret = i915_gem_init_hw(dev);
        if (ret == -EIO) {
                /* Allow ring initialisation to fail by marking the GPU as
                 * wedged. But we only want to do this where the GPU is angry,
                 * for all other failure, such as an allocation failure, bail.
                 */
                DRM_ERROR("Failed to initialize GPU, declaring it wedged\n");
                atomic_or(I915_WEDGED, &dev_priv->gpu_error.reset_counter);
                ret = 0;
        }

out_unlock:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

void
i915_gem_cleanup_ringbuffer(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_engine_cs *ring;
        int i;

        for_each_ring(ring, dev_priv, i)
                dev_priv->gt.cleanup_ring(ring);

    if (i915.enable_execlists)
            /*
             * Neither the BIOS, ourselves or any other kernel
             * expects the system to be in execlists mode on startup,
             * so we need to reset the GPU back to legacy mode.
             */
            intel_gpu_reset(dev);
}

static void
init_ring_lists(struct intel_engine_cs *ring)
{
        INIT_LIST_HEAD(&ring->active_list);
        INIT_LIST_HEAD(&ring->request_list);
}

void
i915_gem_load_init(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = dev->dev_private;
        int i;

        INIT_LIST_HEAD(&dev_priv->vm_list);
        INIT_LIST_HEAD(&dev_priv->context_list);
        INIT_LIST_HEAD(&dev_priv->mm.unbound_list);
        INIT_LIST_HEAD(&dev_priv->mm.bound_list);
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
        for (i = 0; i < I915_NUM_RINGS; i++)
                init_ring_lists(&dev_priv->ring[i]);
        for (i = 0; i < I915_MAX_NUM_FENCES; i++)
                INIT_LIST_HEAD(&dev_priv->fence_regs[i].lru_list);
        INIT_DELAYED_WORK(&dev_priv->mm.retire_work,
                          i915_gem_retire_work_handler);
        INIT_DELAYED_WORK(&dev_priv->mm.idle_work,
                          i915_gem_idle_work_handler);
        init_waitqueue_head(&dev_priv->gpu_error.reset_queue);

        dev_priv->relative_constants_mode = I915_EXEC_CONSTANTS_REL_GENERAL;

        if (INTEL_INFO(dev)->gen >= 7 && !IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev))
                dev_priv->num_fence_regs = 32;
        else if (INTEL_INFO(dev)->gen >= 4 || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                dev_priv->num_fence_regs = 16;
        else
                dev_priv->num_fence_regs = 8;

        if (intel_vgpu_active(dev))
                dev_priv->num_fence_regs =
                                I915_READ(vgtif_reg(avail_rs.fence_num));

        /*
         * Set initial sequence number for requests.
         * Using this number allows the wraparound to happen early,
         * catching any obvious problems.
         */
        dev_priv->next_seqno = ((u32)~0 - 0x1100);
        dev_priv->last_seqno = ((u32)~0 - 0x1101);

        /* Initialize fence registers to zero */
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
        i915_gem_restore_fences(dev);

        i915_gem_detect_bit_6_swizzle(dev);
        init_waitqueue_head(&dev_priv->pending_flip_queue);

        dev_priv->mm.interruptible = true;

        lockinit(&dev_priv->fb_tracking.lock, "drmftl", 0, LK_CANRECURSE);
}

void i915_gem_load_cleanup(struct drm_device *dev)
{
#if 0
        struct drm_i915_private *dev_priv = to_i915(dev);

        kmem_cache_destroy(dev_priv->requests);
        kmem_cache_destroy(dev_priv->vmas);
        kmem_cache_destroy(dev_priv->objects);
#endif
}

void i915_gem_release(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;

        /* Clean up our request list when the client is going away, so that
         * later retire_requests won't dereference our soon-to-be-gone
         * file_priv.
         */
        spin_lock(&file_priv->mm.lock);
        while (!list_empty(&file_priv->mm.request_list)) {
                struct drm_i915_gem_request *request;

                request = list_first_entry(&file_priv->mm.request_list,
                                           struct drm_i915_gem_request,
                                           client_list);
                list_del(&request->client_list);
                request->file_priv = NULL;
        }
        spin_unlock(&file_priv->mm.lock);

        if (!list_empty(&file_priv->rps.link)) {
                lockmgr(&to_i915(dev)->rps.client_lock, LK_EXCLUSIVE);
                list_del(&file_priv->rps.link);
                lockmgr(&to_i915(dev)->rps.client_lock, LK_RELEASE);
        }
}

int
i915_gem_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
    vm_ooffset_t foff, struct ucred *cred, u_short *color)
{
        *color = 0; /* XXXKIB */
        return (0);
}

void
i915_gem_pager_dtor(void *handle)
{
        struct drm_gem_object *obj;
        struct drm_device *dev;

        obj = handle;
        dev = obj->dev;

        mutex_lock(&dev->struct_mutex);
        drm_gem_free_mmap_offset(obj);
        i915_gem_release_mmap(to_intel_bo(obj));
        drm_gem_object_unreference(obj);
        mutex_unlock(&dev->struct_mutex);
}

int i915_gem_open(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_file_private *file_priv;
        int ret;

        DRM_DEBUG_DRIVER("\n");

        file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL);
        if (!file_priv)
                return -ENOMEM;

        file->driver_priv = file_priv;
        file_priv->dev_priv = dev->dev_private;
        file_priv->file = file;
        INIT_LIST_HEAD(&file_priv->rps.link);

        spin_init(&file_priv->mm.lock, "i915_priv");
        INIT_LIST_HEAD(&file_priv->mm.request_list);

        file_priv->bsd_ring = -1;

        ret = i915_gem_context_open(dev, file);
        if (ret)
                kfree(file_priv);

        return ret;
}

/**
 * i915_gem_track_fb - update frontbuffer tracking
 * @old: current GEM buffer for the frontbuffer slots
 * @new: new GEM buffer for the frontbuffer slots
 * @frontbuffer_bits: bitmask of frontbuffer slots
 *
 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
 * from @old and setting them in @new. Both @old and @new can be NULL.
 */
void i915_gem_track_fb(struct drm_i915_gem_object *old,
                       struct drm_i915_gem_object *new,
                       unsigned frontbuffer_bits)
{
        if (old) {
                WARN_ON(!mutex_is_locked(&old->base.dev->struct_mutex));
                WARN_ON(!(old->frontbuffer_bits & frontbuffer_bits));
                old->frontbuffer_bits &= ~frontbuffer_bits;
        }

        if (new) {
                WARN_ON(!mutex_is_locked(&new->base.dev->struct_mutex));
                WARN_ON(new->frontbuffer_bits & frontbuffer_bits);
                new->frontbuffer_bits |= frontbuffer_bits;
        }
}

/* All the new VM stuff */
u64 i915_gem_obj_offset(struct drm_i915_gem_object *o,
                        struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = o->base.dev->dev_private;
        struct i915_vma *vma;

        WARN_ON(vm == &dev_priv->mm.aliasing_ppgtt->base);

        list_for_each_entry(vma, &o->vma_list, obj_link) {
                if (vma->is_ggtt &&
                    vma->ggtt_view.type != I915_GGTT_VIEW_NORMAL)
                        continue;
                if (vma->vm == vm)
                        return vma->node.start;
        }

        WARN(1, "%s vma for this object not found.\n",
             i915_is_ggtt(vm) ? "global" : "ppgtt");
        return -1;
}

u64 i915_gem_obj_ggtt_offset_view(struct drm_i915_gem_object *o,
                                  const struct i915_ggtt_view *view)
{
        struct i915_address_space *ggtt = i915_obj_to_ggtt(o);
        struct i915_vma *vma;

        list_for_each_entry(vma, &o->vma_list, obj_link)
                if (vma->vm == ggtt &&
                    i915_ggtt_view_equal(&vma->ggtt_view, view))
                        return vma->node.start;

        WARN(1, "global vma for this object not found. (view=%u)\n", view->type);
        return -1;
}

bool i915_gem_obj_bound(struct drm_i915_gem_object *o,
                        struct i915_address_space *vm)
{
        struct i915_vma *vma;

        list_for_each_entry(vma, &o->vma_list, obj_link) {
                if (vma->is_ggtt &&
                    vma->ggtt_view.type != I915_GGTT_VIEW_NORMAL)
                        continue;
                if (vma->vm == vm && drm_mm_node_allocated(&vma->node))
                        return true;
        }

        return false;
}

bool i915_gem_obj_ggtt_bound_view(struct drm_i915_gem_object *o,
                                  const struct i915_ggtt_view *view)
{
        struct i915_address_space *ggtt = i915_obj_to_ggtt(o);
        struct i915_vma *vma;

        list_for_each_entry(vma, &o->vma_list, obj_link)
                if (vma->vm == ggtt &&
                    i915_ggtt_view_equal(&vma->ggtt_view, view) &&
                    drm_mm_node_allocated(&vma->node))
                        return true;

        return false;
}

bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o)
{
        struct i915_vma *vma;

        list_for_each_entry(vma, &o->vma_list, obj_link)
                if (drm_mm_node_allocated(&vma->node))
                        return true;

        return false;
}

unsigned long i915_gem_obj_size(struct drm_i915_gem_object *o,
                                struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = o->base.dev->dev_private;
        struct i915_vma *vma;

        WARN_ON(vm == &dev_priv->mm.aliasing_ppgtt->base);

        BUG_ON(list_empty(&o->vma_list));

        list_for_each_entry(vma, &o->vma_list, obj_link) {
                if (vma->is_ggtt &&
                    vma->ggtt_view.type != I915_GGTT_VIEW_NORMAL)
                        continue;
                if (vma->vm == vm)
                        return vma->node.size;
        }
        return 0;
}

bool i915_gem_obj_is_pinned(struct drm_i915_gem_object *obj)
{
        struct i915_vma *vma;
        list_for_each_entry(vma, &obj->vma_list, obj_link)
                if (vma->pin_count > 0)
                        return true;

        return false;
}

/* Like i915_gem_object_get_page(), but mark the returned page dirty */
struct vm_page *
i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, int n)
{
        struct vm_page *page;

        /* Only default objects have per-page dirty tracking */
        if (WARN_ON((obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE) == 0))
                return NULL;

        page = i915_gem_object_get_page(obj, n);
        set_page_dirty(page);
        return page;
}

/* Allocate a new GEM object and fill it with the supplied data */
struct drm_i915_gem_object *
i915_gem_object_create_from_data(struct drm_device *dev,
                                 const void *data, size_t size)
{
        struct drm_i915_gem_object *obj;
        struct sg_table *sg;
        size_t bytes;
        int ret;

        obj = i915_gem_alloc_object(dev, round_up(size, PAGE_SIZE));
        if (IS_ERR_OR_NULL(obj))
                return obj;

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (ret)
                goto fail;

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                goto fail;

        i915_gem_object_pin_pages(obj);
        sg = obj->pages;
        bytes = sg_copy_from_buffer(sg->sgl, sg->nents, data, size);
        obj->dirty = 1;         /* Backing store is now out of date */
        i915_gem_object_unpin_pages(obj);

        if (WARN_ON(bytes != size)) {
                DRM_ERROR("Incomplete copy, wrote %zu of %zu", bytes, size);
                ret = -EFAULT;
                goto fail;
        }

        return obj;

fail:
        drm_gem_object_unreference(&obj->base);
        return ERR_PTR(ret);
}