Re: [PATCH] xen/arm: Make local_events_need_delivery working with idle VPCU

[Julien Grall <julien.grall@citrix.com>]

On 05/05/15 13:29, Ian Campbell wrote:
> On Tue, 2015-05-05 at 13:00 +0100, Julien Grall wrote:
>>> I'm inclined to just go with this patch for now, unless Stefano is
>>> nacking it.
>>
>> This patch seem to turn into a workaround, would it be better to move
>> check idle_check in apply_p2m_check?
>>
>> I will prepare a follow-up to avoid properly the call
>> hypercall_preempt_check with idle_vcpu.
>>
>>> One question first: What aspect of local_events_need_delivery relies on
>>> the vcpu not being an idle one? I suppose something is not initialised,
>>> but what.
>>
>> Everything related to the vGIC is not initialized. It's used in
>> local_event_need_delivery_nomask (see irq_to_pending and
>> gic_events_need_devlivery).
> 
> Would it be better to arrange that vcpu_event_delivery_is_enabled is
> never true for an idle vcpu? Either with an explicit check or by
> arranging regs->cpsr to say that?

That could work.

Although, as discussed IRL, I will move the check of idle_vcpu in
apply_p2m_changes in a preempt variable.

Regards,

-- 
Julien Grall