Wanpeng Li <kernellwp@xxxxxxxxx> writes:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Analysis from Sean:
>
> | svm->next_rip is reset in svm_vcpu_run() only after calling
> | svm_exit_handlers_fastpath(), which will cause SVM's
> | skip_emulated_instruction() to write a stale RIP.
>
This should only happen when svm->vmcb->control.next_rip is not set by
hardware as skip_emulated_instruction() itself sets 'svm->next_rip'
otherwise, right?
> Let's get rid of handle_fastpath_set_msr_irqoff() in svm_exit_handlers_fastpath()
> to have a quick fix.
which in the light of the whole seeries seems to be appropriate, so:
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>
> Reported-by: Paul K. <kronenpj@xxxxxxxxxxxxxxxxxxx>
> Suggested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Cc: Paul K. <kronenpj@xxxxxxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v5.8-rc1+
> Fixes: 404d5d7bff0d (KVM: X86: Introduce more exit_fastpath_completion enum values)
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> arch/x86/kvm/svm/svm.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 19e622a..c61bc3b 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3349,11 +3349,6 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
>
> static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
> {
> - if (!is_guest_mode(vcpu) &&
> - 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;
> }
--
Vitaly
