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

Marc Zyngier
2017-10-05T09:37:11Z

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.

Thanks,

M.
--
Jazz is not dead. It just smells funny...