Re: [PATCH v3 2/2] KVM: x86/xen: Stop Xen timer before changing IRQ

From: David Woodhouse
Date: Tue Aug 09 2022 - 10:36:34 EST


On Tue, 2022-08-09 at 16:31 +0200, Paolo Bonzini wrote:
> On 8/9/22 16:16, David Woodhouse wrote:
> > I find the new version a bit harder to follow, with its init-then-stop-
> > then-start logic:
> >
> > case KVM_XEN_VCPU_ATTR_TYPE_TIMER:
> > if (data->u.timer.port &&
> > data->u.timer.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL) {
> > r = -EINVAL;
> > break;
> > }
> >
> > if (!vcpu->arch.xen.timer.function)
> > kvm_xen_init_timer(vcpu);
> >
> > /* Stop the timer (if it's running) before changing the vector */
> > kvm_xen_stop_timer(vcpu);
> > vcpu->arch.xen.timer_virq = data->u.timer.port;
>
>
> I think this is fine, if anything the kvm_xen_stop_timer() call could be
> placed in an "else" but I'm leaning towards applying this version of the
> patch.

Fair enough. It should definitely work, and is functionally identical
in all interesting cases. In that case, for both of the patches from
this v3 series:

Acked-by: David Woodhouse <dwmw@xxxxxxxxxxxx>

Thanks.

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