[PATCH RFC 1/5] x86: KVM: svm: don't pretend to advance RIP in case wrmsr_interception() results in #GP

Vitaly Kuznetsov
2019-06-20T11:03:12Z

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.

By the way, rdmsr_interception() has it right already.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/svm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 5b2ea34bc9f2..982c6b9bfc90 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4430,13 +4430,13 @@ 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);
}
}
--
2.20.1