Re: [PATCH for-4.15] xen/vgic: Implement write to ISPENDR in vGICv{2, 3}

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 23 Feb 2021, Julien Grall wrote:
> Hi Stefano,
> 
> On 23/02/2021 01:24, Stefano Stabellini wrote:
> > On Mon, 22 Feb 2021, Bertrand Marquis wrote:
> > > > On 20 Feb 2021, at 14:04, Julien Grall <julien@xxxxxxx> wrote:
> > The consequence of this patch is that a guest can cause vcpu_unblock(v),
> > hence vcpu_wake(v), to be called for its own vcpu, which basically
> > always changes v to RUNSTATE_runnable. However, that alone shouldn't
> > allow v to always come up ahead of any other vcpus in the queue, right?
> > It should be safe. I just wanted a second opinion on this :-)
> 
> vcpu_wake() only tells the scheduler that the vCPU can be run, it is then up
> to the scheduler to decide what to do. AFAIU, for credit{1, 2}, each vCPU will
> have some credit. If you run out of credit, then you vCPU will not be
> descheduled if there is work do it.

OK, great, it matches my understanding. Thanks for checking.

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>