Re: Xen 4.5 random freeze question

[Julien Grall <julien.grall@linaro.org>]

On 11/19/2014 12:40 PM, Andrii Tseglytskyi wrote:
> Hi Julien,
> 
> On Wed, Nov 19, 2014 at 2:23 PM, Julien Grall <julien.grall@linaro.org> wrote:
>> On 11/19/2014 12:17 PM, Stefano Stabellini wrote:
>>> On Wed, 19 Nov 2014, Ian Campbell wrote:
>>>> On Wed, 2014-11-19 at 11:42 +0000, Stefano Stabellini wrote:
>>>>> So it looks like there is not actually anything wrong, is just that you
>>>>> have too much inflight irqs? It should cause problems because in that
>>>>> case GICH_HCR_UIE should be set and you should get a maintenance
>>>>> interrupt when LRs become available (actually when "none, or only one,
>>>>> of the List register entries is marked as a valid interrupt").
>>>>>
>>>>> Maybe GICH_HCR_UIE is the one that doesn't work properly.
>>>>
>>>> How much testing did this aspect get when the no-maint-irq series
>>>> originally went in? Did you manage to find a workload which filled all
>>>> the LRs or try artificially limiting the number of LRs somehow in order
>>>> to provoke it?
>>>>
>>>> I ask because my intuition is that this won't happen very much, meaning
>>>> those code paths may not be as well tested...
>>>
>>> I did test it by artificially limiting the number of LRs to 1.
>>> However there have been many iterations of that series and I didn't run
>>> this test at every iteration.
>>
>> am I the only to think this may not be related to this bug? All the LRs
>> are full with IRQ of the same priority. So it's valid.
>>
>> As gic_restore_pending_irqs is called every time that we return to the
>> guest. It could be anything else.
>>
>> It would be interesting to see why we are trapping all the time in Xen.
>>
> 
> I may perform any test if you have some specific scenario.

I have no specific scenario in my mind :/.

It looks like I'm able to reproduce it on my ARM board by the restricted
the number of LRs to 1.

I will investigate.

Regards,

-- 
Julien Grall