Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     kvm@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jim Mattson <jmattson@google.com>
Subject: [PATCH RFC 1/5] x86: KVM: svm: don't pretend to advance RIP in case wrmsr_interception() results in #GP
Date:   Thu, 20 Jun 2019 13:02:36 +0200
Message-Id: <20190620110240.25799-2-vkuznets@redhat.com>
In-Reply-To: <20190620110240.25799-1-vkuznets@redhat.com>
References: <20190620110240.25799-1-vkuznets@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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