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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Joerg Roedel" <joro@8bytes.org>,
	"Jim Mattson" <jmattson@google.com>
Subject: [PATCH 1/5] x86: KVM: svm: don't pretend to advance RIP in case wrmsr_interception() results in #GP
Date: Thu,  1 Aug 2019 07:14:14 +0200	[thread overview]
Message-ID: <20190801051418.15905-2-vkuznets@redhat.com> (raw)
In-Reply-To: <20190801051418.15905-1-vkuznets@redhat.com>

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 <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 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);
 	}
 }
-- 
2.20.1


  reply	other threads:[~2019-08-01  5:14 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-01  5:14 [PATCH 0/5] x86: KVM: svm: get rid of hardcoded instructions lengths Vitaly Kuznetsov
2019-08-01  5:14 ` Vitaly Kuznetsov [this message]
2019-08-01  5:14 ` [PATCH 2/5] x86: KVM: svm: avoid flooding logs when skip_emulated_instruction() fails Vitaly Kuznetsov
2019-08-01  5:14 ` [PATCH 3/5] x86: KVM: svm: clear interrupt shadow on all paths in skip_emulated_instruction() Vitaly Kuznetsov
2019-08-01 14:18   ` Sean Christopherson
2019-08-01 14:43     ` Vitaly Kuznetsov
2019-08-01  5:14 ` [PATCH 4/5] x86: KVM: add xsetbv to the emulator Vitaly Kuznetsov
2019-08-01  5:14 ` [PATCH 5/5] x86: KVM: svm: remove hardcoded instruction length from intercepts Vitaly Kuznetsov

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