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Revert "KVM: SVM: Skip WRMSR fastpath on VM-Exit if next RIP isn't valid"

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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 5c30e8101e.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230721224337.2335137-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2023-07-21 15:43:37 -07:00
committed by Paolo Bonzini
parent 3f2739bd1e
commit b439eb8ab5
1 changed files with 2 additions and 8 deletions
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10
arch/x86/kvm/svm/svm.c
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@@ -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) static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
{ {
struct vmcb_control_area *control = &to_svm(vcpu)->vmcb->control; if (to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
to_svm(vcpu)->vmcb->control.exit_info_1)
/*
* 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)
return handle_fastpath_set_msr_irqoff(vcpu); return handle_fastpath_set_msr_irqoff(vcpu);
return EXIT_FASTPATH_NONE; return EXIT_FASTPATH_NONE;