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KVM: x86: support XSAVES usage in the host

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Userspace is expecting non-compacted format for KVM_GET_XSAVE, but
struct xsave_struct might be using the compacted format.  Convert
in order to preserve userspace ABI.

Likewise, userspace is passing non-compacted format for KVM_SET_XSAVE
but the kernel will pass it to XRSTORS, and we need to convert back.

Fixes: f31a9f7c71
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: stable@vger.kernel.org
Cc: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: Nadav Amit <namit@cs.technion.ac.il>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-11-21 19:05:07 +01:00
parent ba7b39203a
commit df1daba7d1
1 changed files with 83 additions and 7 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

90
arch/x86/kvm/x86.c
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@ -3132,15 +3132,89 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
return 0;
}
#define XSTATE_COMPACTION_ENABLED (1ULL << 63)
static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
{
struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave;
u64 xstate_bv = xsave->xsave_hdr.xstate_bv;
u64 valid;
/*
* Copy legacy XSAVE area, to avoid complications with CPUID
* leaves 0 and 1 in the loop below.
*/
memcpy(dest, xsave, XSAVE_HDR_OFFSET);
/* Set XSTATE_BV */
*(u64 *)(dest + XSAVE_HDR_OFFSET) = xstate_bv;
/*
* Copy each region from the possibly compacted offset to the
* non-compacted offset.
*/
valid = xstate_bv & ~XSTATE_FPSSE;
while (valid) {
u64 feature = valid & -valid;
int index = fls64(feature) - 1;
void *src = get_xsave_addr(xsave, feature);
if (src) {
u32 size, offset, ecx, edx;
cpuid_count(XSTATE_CPUID, index,
&size, &offset, &ecx, &edx);
memcpy(dest + offset, src, size);
}
valid -= feature;
}
}
static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
{
struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave;
u64 xstate_bv = *(u64 *)(src + XSAVE_HDR_OFFSET);
u64 valid;
/*
* Copy legacy XSAVE area, to avoid complications with CPUID
* leaves 0 and 1 in the loop below.
*/
memcpy(xsave, src, XSAVE_HDR_OFFSET);
/* Set XSTATE_BV and possibly XCOMP_BV. */
xsave->xsave_hdr.xstate_bv = xstate_bv;
if (cpu_has_xsaves)
xsave->xsave_hdr.xcomp_bv = host_xcr0 | XSTATE_COMPACTION_ENABLED;
/*
* Copy each region from the non-compacted offset to the
* possibly compacted offset.
*/
valid = xstate_bv & ~XSTATE_FPSSE;
while (valid) {
u64 feature = valid & -valid;
int index = fls64(feature) - 1;
void *dest = get_xsave_addr(xsave, feature);
if (dest) {
u32 size, offset, ecx, edx;
cpuid_count(XSTATE_CPUID, index,
&size, &offset, &ecx, &edx);
memcpy(dest, src + offset, size);
} else
WARN_ON_ONCE(1);
valid -= feature;
}
}
static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
struct kvm_xsave *guest_xsave)
{
if (cpu_has_xsave) {
memcpy(guest_xsave->region,
&vcpu->arch.guest_fpu.state->xsave,
vcpu->arch.guest_xstate_size);
*(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)] &=
vcpu->arch.guest_supported_xcr0 | XSTATE_FPSSE;
memset(guest_xsave, 0, sizeof(struct kvm_xsave));
fill_xsave((u8 *) guest_xsave->region, vcpu);
} else {
memcpy(guest_xsave->region,
&vcpu->arch.guest_fpu.state->fxsave,
@ -3164,8 +3238,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
*/
if (xstate_bv & ~kvm_supported_xcr0())
return -EINVAL;
memcpy(&vcpu->arch.guest_fpu.state->xsave,
guest_xsave->region, vcpu->arch.guest_xstate_size);
load_xsave(vcpu, (u8 *)guest_xsave->region);
} else {
if (xstate_bv & ~XSTATE_FPSSE)
return -EINVAL;
@ -6882,6 +6955,9 @@ int fx_init(struct kvm_vcpu *vcpu)
return err;
fpu_finit(&vcpu->arch.guest_fpu);
if (cpu_has_xsaves)
vcpu->arch.guest_fpu.state->xsave.xsave_hdr.xcomp_bv =
host_xcr0 | XSTATE_COMPACTION_ENABLED;
/*
* Ensure guest xcr0 is valid for loading