On 03/04/19 16:06, Vitaly Kuznetsov wrote:
> I noticed that apic test from kvm-unit-tests always hangs on my EPYC 7401P,
> the hanging test nmi-after-sti is trying to deliver 30000 NMIs and tracing
> shows that we're sometimes able to deliver a few but never all.
>
> When we're trying to inject an NMI we may fail to do so immediately for
> various reasons, however, we still need to inject it so enable_nmi_window()
> arms nmi_singlestep mode. #DB occurs as expected, but we're not checking
> for pending NMIs before entering the guest and unless there's a different
> event to process, the NMI will never get delivered.
>
> Make KVM_REQ_EVENT request on the vCPU from db_interception() to make sure
> pending NMIs are checked and possibly injected.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
> - I have to admit my RFC didn't gain much popularity, re-sending as
> non-RFC.
> ---
> arch/x86/kvm/svm.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 426039285fd1..69a0edb23c28 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2692,6 +2692,7 @@ static int npf_interception(struct vcpu_svm *svm)
> static int db_interception(struct vcpu_svm *svm)
> {
> struct kvm_run *kvm_run = svm->vcpu.run;
> + struct kvm_vcpu *vcpu = &svm->vcpu;
>
> if (!(svm->vcpu.guest_debug &
> (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) &&
> @@ -2702,6 +2703,8 @@ static int db_interception(struct vcpu_svm *svm)
>
> if (svm->nmi_singlestep) {
> disable_nmi_singlestep(svm);
> + /* Make sure we check for pending NMIs upon entry */
> + kvm_make_request(KVM_REQ_EVENT, vcpu);
> }
>
> if (svm->vcpu.guest_debug &
>
Queued, thanks.
Paolo
