From: Antonio Huete Jimenez <tuxillo@quantumachine.net>
Date: Tue, 20 Sep 2016 22:03:05 +0000 (+0200)
Subject: vkernel - Fix a vkernel lockup on startup
X-Git-Tag: v4.8.0rc~989
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/4dd1b99459f58c096edd1945eb144cf12006d85a

vkernel - Fix a vkernel lockup on startup

- During ap_init() any pending IPIs is processed manually so
  clear gd_npoll as the real kernel does.
- Do not disable interrupts for vkernels during lwkt_send_ipiq3()
  because they don't seem to be re-enabled afterwards as they should.
  I'm not entirely sure this is the right fix, more investigation
  is required.
---

diff --git a/sys/kern/lwkt_ipiq.c b/sys/kern/lwkt_ipiq.c
index 5eb162d801..13104fcbe4 100644
--- a/sys/kern/lwkt_ipiq.c
+++ b/sys/kern/lwkt_ipiq.c
@@ -197,7 +197,7 @@ lwkt_send_ipiq3(globaldata_t target, ipifunc3_t func, void *arg1, int arg2)
 	func(arg1, arg2, NULL);
 	logipiq(send_end, func, arg1, arg2, gd, target);
 	return(0);
-    } 
+    }
     crit_enter();
     ++gd->gd_intr_nesting_level;
 #ifdef INVARIANTS
@@ -297,7 +297,9 @@ lwkt_send_ipiq3(globaldata_t target, ipifunc3_t func, void *arg1, int arg2)
      *	   just be made pending).
      */
     rflags = read_rflags();
+#ifndef _KERNEL_VIRTUAL
     cpu_disable_intr();
+#endif
 
     windex = ip->ip_windex & MAXCPUFIFO_MASK;
     ip->ip_info[windex].func = func;
diff --git a/sys/platform/vkernel64/x86_64/mp.c b/sys/platform/vkernel64/x86_64/mp.c
index 7dec8147d3..09b574c8f9 100644
--- a/sys/platform/vkernel64/x86_64/mp.c
+++ b/sys/platform/vkernel64/x86_64/mp.c
@@ -333,6 +333,14 @@ ap_init(void)
 	mdcpu->gd_fpending = 0;
 	mdcpu->gd_ipending = 0;
 	initclocks_pcpu();	/* clock interrupts (via IPIs) */
+
+	/*
+	 * Since we may have cleaned up the interrupt triggers, manually
+	 * process any pending IPIs before exiting our critical section.
+	 * Once the critical section has exited, normal interrupt processing
+	 * may occur.
+	 */
+	atomic_swap_int(&mycpu->gd_npoll, 0);
 	lwkt_process_ipiq();
 
         /*