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.Dd September 1, 2015
.Dt VMM 2
.Os
.Sh NAME
.Nm vmm_guest_ctl ,
.Nm vmm_guest_sync_addr
.Nd enter VMM mode / sync VMM threads
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/vmm.h
.Ft int
.Fn vmm_guest_ctl "int op" "struct vmm_guest_options *options"
.Ft int
.Fn vmm_guest_sync_addr "long *dstaddr" "long *srcaddr"
.Sh DESCRIPTION
In order to run a virtual machine on top of the host operating system, two
sets of page tables are needed (one each for the host and guest).
Older CPUs supports only one level of page tables and the second level had
to be emulated in software.
Modern CPUs have support for a second level of page table translations,
such as
.Tn Intel Ap s
EPT
or
.Tn AMD Ap s
RVI.
The
.Fn vmm_*
functions bring the guest virtual machine into a state in which
the hardware is able to walk two levels of page tables.
.Pp
The only
.Fa op
currently supported by
.Fn vmm_guest_ctl
is
.Dv VMM_GUEST_RUN ,
which bootstraps the calling process as a VMM process running with
extended/nested page table support (two layers of page tables).
The
.Ft vmm_guest_options
struct is defined in
.In sys/vmm.h .
.Pp
The
.Fn vmm_guest_sync_addr
function copies the content of
.Fa srcaddr
to
.Fa dstaddr ,
synchronizing with all CPUs which are in VMM mode (i.e., all CPUs will see
.Fa srcaddr Ap s
value at
.Fa dstaddr ) .
.Sh HISTORY
The
.Fn vmm_guest_ctl
and
.Fn vmm_guest_sync_addr
system calls were added in
.Dx 3.5 .
.Sh AUTHORS
.An Mihai Carabas