[v4,1/7] x86: KVM: svm: don't pretend to advance RIP in case wrmsr_interception() results in #GP

Commit Message

Vitaly Kuznetsov Aug. 13, 2019, 1:53 p.m. UTC

svm->next_rip is only used by skip_emulated_instruction() and in case
kvm_set_msr() fails we rightfully don't do that. Move svm->next_rip
advancement to 'else' branch to avoid creating false impression that
it's always advanced (and make it look like rdmsr_interception()).

This is a preparatory change to removing hardcoded RIP advancement
from instruction intercepts, no functional change.

Signed-off-by: Vitaly Kuznetsov <[e-mail]>
Reviewed-by: Sean Christopherson <[e-mail]>
---
 arch/x86/kvm/svm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7eafc6907861..7e843b340490 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4447,13 +4447,13 @@  static int wrmsr_interception(struct vcpu_svm *svm)
 	msr.index = ecx;
 	msr.host_initiated = false;
 
-	svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
 	if (kvm_set_msr(&svm->vcpu, &msr)) {
 		trace_kvm_msr_write_ex(ecx, data);
 		kvm_inject_gp(&svm->vcpu, 0);
 		return 1;
 	} else {
 		trace_kvm_msr_write(ecx, data);
+		svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
 		return kvm_skip_emulated_instruction(&svm->vcpu);
 	}
 }