Re: [PATCH 5/5] KVM: arm/arm64: kvm_arch_vcpu_runnable: don't miss injected irqs

Andrew Jones
2017-10-10T13:27:38Z

On Thu, Oct 05, 2017 at 10:37:32AM +0100, Marc Zyngier wrote:
> On 29/09/17 12:30, Andrew Jones wrote:
> > When the vPMU is in use if a VCPU's perf event overflow handler
> > were to fire after the VCPU started waiting, then the wake up
> > done by the kvm_vcpu_kick() call in the handler would do nothing,
> > as no "pmu overflow" state is checked in kvm_arch_vcpu_runnable().
> > Fix this by checking the IRQ_PENDING VCPU request in runnable().
> > Checking the request also sufficiently covers all the cases that
> > kvm_vgic_vcpu_pending_irq() cover, so we can just replace that.
> >
> > Signed-off-by: Andrew Jones <drjones@redhat.com>
> > ---
> > virt/kvm/arm/arm.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> > index 5bc9b0d2fd0f..725527f491e4 100644
> > --- a/virt/kvm/arm/arm.c
> > +++ b/virt/kvm/arm/arm.c
> > @@ -423,7 +423,7 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
> > return !vcpu_should_sleep(vcpu) &&
> > (vcpu->arch.mp_state != KVM_MP_STATE_HALTED ||
> > (!!vcpu->arch.irq_lines ||
> > - kvm_vgic_vcpu_pending_irq(vcpu)));
> > + kvm_test_request(KVM_REQ_IRQ_PENDING, vcpu)));
> > }
> >
> > bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
> >
>
> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
>
> On a side note, I just had a look at our usage of KVM_REQ_IRQ_PENDING,
> and we always seem to have a make_request/kick pair (which definitely
> makes sense). Maybe there is room for a bit of consolidation there too.

I think Radim had a plan to do that with some more VCPU request cleanups.

Thanks,
drew

>
> Thanks,
>
> M.
> --
> Jazz is not dead. It just smells funny...