This is a note to let you know that I've just added the patch titled
KVM: SVM: fix cr8 intercept window
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-svm-fix-cr8-intercept-window.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 596f3142d2b7be307a1652d59e7b93adab918437 Mon Sep 17 00:00:00 2001
From: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Date: Tue, 11 Mar 2014 19:11:18 +0100
Subject: KVM: SVM: fix cr8 intercept window
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From: Radim Krčmář <rkrcmar@xxxxxxxxxx>
commit 596f3142d2b7be307a1652d59e7b93adab918437 upstream.
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.
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Reviewed-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/svm.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3007,10 +3007,8 @@ static int cr8_write_interception(struct
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;
@@ -3566,6 +3564,8 @@ static void update_cr8_intercept(struct
if (is_guest_mode(vcpu) && (vcpu->arch.hflags & HF_VINTR_MASK))
return;
+ clr_cr_intercept(svm, INTERCEPT_CR8_WRITE);
+
if (irr == -1)
return;
Patches currently in stable-queue which might be from rkrcmar@xxxxxxxxxx are
queue-3.4/kvm-svm-fix-cr8-intercept-window.patch
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