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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 <gleb@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e0f0bbc5

arch/x86/kvm/x86.c

+10 −1
Original line number Diff line number Diff line
@@ -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  */

	if (index != XCR_XFEATURE_ENABLED_MASK)
@@ -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;



	kvm_put_guest_xcr0(vcpu);

	vcpu->arch.xcr0 = xcr0;

	return 0;