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KVM: SVM: fix cr8 intercept window

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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>
This commit is contained in:
Radim Krčmář 2014-03-11 19:11:18 +01:00 committed by Paolo Bonzini
parent 6cbde8253a
commit 596f3142d2
1 changed files with 3 additions and 3 deletions
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6
arch/x86/kvm/svm.c
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@ -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;