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Commit 596f3142 authored by Radim Krčmář's avatar Radim Krčmář Committed by Paolo Bonzini
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KVM: SVM: fix cr8 intercept window 



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: default avatarRadim Krčmář <rkrcmar@redhat.com>
Reviewed-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6cbde825

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;