This is a note to let you know that I've just added the patch titled
KVM: SVM: check for progress after IRET interception
to the 2.6.38-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-check-for-progress-after-iret-interception.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From bd3d1ec3d26b61120bb4f60b18ee99aa81839e6b Mon Sep 17 00:00:00 2001
From: Avi Kivity <[email protected]>
Date: Thu, 3 Feb 2011 15:29:52 +0200
Subject: KVM: SVM: check for progress after IRET interception
From: Avi Kivity <[email protected]>
commit bd3d1ec3d26b61120bb4f60b18ee99aa81839e6b upstream.
When we enable an NMI window, we ask for an IRET intercept, since
the IRET re-enables NMIs. However, the IRET intercept happens before
the instruction executes, while the NMI window architecturally opens
afterwards.
To compensate for this mismatch, we only open the NMI window in the
following exit, assuming that the IRET has by then executed; however,
this assumption is not always correct; we may exit due to a host interrupt
or page fault, without having executed the instruction.
Fix by checking for forward progress by recording and comparing the IRET's
rip. This is somewhat of a hack, since an unchaging rip does not mean that
no forward progress has been made, but is the simplest fix for now.
Signed-off-by: Avi Kivity <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/kvm/svm.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -135,6 +135,8 @@ struct vcpu_svm {
u32 *msrpm;
+ ulong nmi_iret_rip;
+
struct nested_state nested;
bool nmi_singlestep;
@@ -2653,6 +2655,7 @@ static int iret_interception(struct vcpu
++svm->vcpu.stat.nmi_window_exits;
clr_intercept(svm, INTERCEPT_IRET);
svm->vcpu.arch.hflags |= HF_IRET_MASK;
+ svm->nmi_iret_rip = kvm_rip_read(&svm->vcpu);
return 1;
}
@@ -3474,7 +3477,12 @@ static void svm_complete_interrupts(stru
svm->int3_injected = 0;
- if (svm->vcpu.arch.hflags & HF_IRET_MASK) {
+ /*
+ * If we've made progress since setting HF_IRET_MASK, we've
+ * executed an IRET and can allow NMI injection.
+ */
+ if ((svm->vcpu.arch.hflags & HF_IRET_MASK)
+ && kvm_rip_read(&svm->vcpu) != svm->nmi_iret_rip) {
svm->vcpu.arch.hflags &= ~(HF_NMI_MASK | HF_IRET_MASK);
kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
}
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.38/kvm-svm-check-for-progress-after-iret-interception.patch
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