KVM: SVM: fix cr8 intercept window (596f3142) · Commits · 戴 / test

We always disable cr8 intercept in its handler, but only re-enable it if handling KVM_REQ_EVENT, so there can be a window where we do not intercept cr8 writes, which allows an interrupt to disrupt a higher priority task. Fix this by disabling intercepts in the same function that re-enables them when needed. This fixes BSOD in Windows 2008. Cc: <stable@vger.kernel.org> Signed-off-by:

Radim Krčmář <rkrcmar@redhat.com> Reviewed-by:

Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -3002,10 +3002,8 @@ static int cr8_write_interception(struct vcpu_svm *svm)
		u8 cr8_prev = kvm_get_cr8(&svm->vcpu);
		/* instruction emulation calls kvm_set_cr8() */
		r = cr_interception(svm);
		if (irqchip_in_kernel(svm->vcpu.kvm)) {
		clr_cr_intercept(svm, INTERCEPT_CR8_WRITE);
		if (irqchip_in_kernel(svm->vcpu.kvm))
		return r;
		}
		if (cr8_prev <= kvm_get_cr8(&svm->vcpu))
		return r;
		kvm_run->exit_reason = KVM_EXIT_SET_TPR;
		@@ -3567,6 +3565,8 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)
		if (is_guest_mode(vcpu) && (vcpu->arch.hflags & HF_VINTR_MASK))
		return;

		clr_cr_intercept(svm, INTERCEPT_CR8_WRITE);

		if (irr == -1)
		return;

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