From: Ladi Prosek <lprosek@redhat.com>
Date: Wed, 21 Jun 2017 09:07:01 +0200
Subject: KVM: SVM: suppress unnecessary NMI singlestep on GIF=0 and nested exit
Git-commit: 1a5e1852941d0d8ae98a4b5c769ec998e3708158
Patch-mainline: v4.13-rc1
References: fate#323405
enable_nmi_window is supposed to be a no-op if we know that we'll see
a VM exit by the time the NMI window opens. This commit adds two more
cases:
* We intercept stgi so we don't need to singlestep on GIF=0.
* We emulate nested vmexit so we don't need to singlestep when nested
VM exit is required.
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/kvm/svm.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4699,6 +4699,12 @@ static void enable_nmi_window(struct kvm
== HF_NMI_MASK)
return; /* IRET will cause a vm exit */
+ if ((svm->vcpu.arch.hflags & HF_GIF_MASK) == 0)
+ return; /* STGI will cause a vm exit */
+
+ if (svm->nested.exit_required)
+ return; /* we're not going to run the guest yet */
+
/*
* Something prevents NMI from been injected. Single step over possible
* problem (IRET or exception injection or interrupt shadow)