From 38827dbd3fb85a94a002fcf67b8735d5bc1a7e1a Mon Sep 17 00:00:00 2001
From: Nadav Amit <namit@cs.technion.ac.il>
Date: Sun, 2 Nov 2014 11:54:53 +0200
Subject: [PATCH] KVM: x86: Do not update EFLAGS on faulting emulation

If the emulation ends in fault, eflags should not be updated.  However, several
instruction emulations (actually all the fastops) currently update eflags, if
the fault was detected afterwards (e.g., #PF during writeback).

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/x86.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 641358865a0c..da1591eeb477 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5360,7 +5360,9 @@ restart:
 		kvm_rip_write(vcpu, ctxt->eip);
 		if (r == EMULATE_DONE)
 			kvm_vcpu_check_singlestep(vcpu, rflags, &r);
-		__kvm_set_rflags(vcpu, ctxt->eflags);
+		if (!ctxt->have_exception ||
+		    exception_type(ctxt->exception.vector) == EXCPT_TRAP)
+			__kvm_set_rflags(vcpu, ctxt->eflags);
 
 		/*
 		 * For STI, interrupts are shadowed; so KVM_REQ_EVENT will
-- 
2.42.0