[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20230721224337.2335137-3-seanjc@google.com>
Date: Fri, 21 Jul 2023 15:43:37 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
Greg Thelen <gthelen@...gle.com>,
Aaron Lewis <aaronlewis@...gle.com>
Subject: [PATCH 2/2] Revert "KVM: SVM: Skip WRMSR fastpath on VM-Exit if next
RIP isn't valid"
Now that handle_fastpath_set_msr_irqoff() acquires kvm->srcu, i.e. allows
dereferencing memslots during WRMSR emulation, drop the requirement that
"next RIP" is valid. In hindsight, acquiring kvm->srcu would have been a
better fix than avoiding the pastpath, but at the time it was thought that
accessing SRCU-protected data in the fastpath was a one-off edge case.
This reverts commit 5c30e8101e8d5d020b1d7119117889756a6ed713.
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
arch/x86/kvm/svm/svm.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index d381ad424554..cea08e5fa69b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3986,14 +3986,8 @@ static int svm_vcpu_pre_run(struct kvm_vcpu *vcpu)
static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
{
- struct vmcb_control_area *control = &to_svm(vcpu)->vmcb->control;
-
- /*
- * Note, the next RIP must be provided as SRCU isn't held, i.e. KVM
- * can't read guest memory (dereference memslots) to decode the WRMSR.
- */
- if (control->exit_code == SVM_EXIT_MSR && control->exit_info_1 &&
- nrips && control->next_rip)
+ if (to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
+ to_svm(vcpu)->vmcb->control.exit_info_1)
return handle_fastpath_set_msr_irqoff(vcpu);
return EXIT_FASTPATH_NONE;
--
2.41.0.487.g6d72f3e995-goog
Powered by blists - more mailing lists