KVM: x86: fix KVM_SET_XCRS for CPUs that do not support XSAVE (46c34cb0) · Commits · 戴 / test

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:

Gleb Natapov <gleb@redhat.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

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;

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