KVM: x86: only copy XSAVE state for the supported features
This makes the interface more deterministic for userspace, which can expect
(after configuring only the features it supports) to get exactly the same
state from the kernel, independent of the host CPU and kernel version.
Suggested-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7d5c520..e8e2d09 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2984,11 +2984,13 @@
static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
struct kvm_xsave *guest_xsave)
{
- if (cpu_has_xsave)
+ if (cpu_has_xsave) {
memcpy(guest_xsave->region,
&vcpu->arch.guest_fpu.state->xsave,
- xstate_size);
- else {
+ vcpu->arch.guest_xstate_size);
+ *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)] &=
+ vcpu->arch.guest_supported_xcr0 | XSTATE_FPSSE;
+ } else {
memcpy(guest_xsave->region,
&vcpu->arch.guest_fpu.state->fxsave,
sizeof(struct i387_fxsave_struct));
@@ -3014,7 +3016,7 @@
if (xstate_bv & ~host_xcr0)
return -EINVAL;
memcpy(&vcpu->arch.guest_fpu.state->xsave,
- guest_xsave->region, xstate_size);
+ guest_xsave->region, vcpu->arch.guest_xstate_size);
} else {
if (xstate_bv & ~XSTATE_FPSSE)
return -EINVAL;
@@ -6951,6 +6953,7 @@
vcpu->arch.pv_time_enabled = false;
vcpu->arch.guest_supported_xcr0 = 0;
+ vcpu->arch.guest_xstate_size = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
kvm_async_pf_hash_reset(vcpu);
kvm_pmu_init(vcpu);