Commit 46c34cb0 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: fix KVM_SET_XCRS for CPUs that do not support XSAVE

The KVM_SET_XCRS ioctl must accept anything that KVM_GET_XCRS
could return.  XCR0's bit 0 is always 1 in real processors with
XSAVE, and KVM_GET_XCRS will always leave bit 0 set even if the
emulated processor does not have XSAVE.  So, KVM_SET_XCRS must
ignore that bit when checking for attempts to enable unsupported
save states.
Reviewed-by: default avatarGleb Natapov <>
Signed-off-by: default avatarPaolo Bonzini <>
parent e0f0bbc5
......@@ -577,6 +577,7 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
u64 xcr0;
u64 valid_bits;
/* Only support XCR_XFEATURE_ENABLED_MASK(xcr0) now */
......@@ -586,8 +587,16 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
return 1;
if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE))
return 1;
if (xcr0 & ~vcpu->arch.guest_supported_xcr0)
* Do not allow the guest to set bits that we do not support
* saving. However, xcr0 bit 0 is always set, even if the
* emulated CPU does not support XSAVE (see fx_init).
valid_bits = vcpu->arch.guest_supported_xcr0 | XSTATE_FP;
if (xcr0 & ~valid_bits)
return 1;
vcpu->arch.xcr0 = xcr0;
return 0;
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