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authorAvi Kivity <avi@redhat.com>2011-02-03 15:29:52 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2011-05-09 15:06:50 -0700
commit5ea2c1536c7e93485849c3eb05a022ea26144c6a (patch)
treee583a88c0666d3392f0285b115da440bd63a1d07
parentfcd9079e754fa9050ed50ef2ba294ccf5825b837 (diff)
KVM: SVM: check for progress after IRET interception
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 <avi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/x86/kvm/svm.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 63fec1531e89..d8a15a17d767 100644
--- 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 *svm)
++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(struct vcpu_svm *svm)
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);
}