Re: [Xen-devel] [PATCH v8 3/4] xen/arm: Make gic-v2 code handle hip04-d01 platform

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 03/03/15 15:36, Frediano Ziglio wrote:
>>
>> Hello Frediano,
>>
>> On 03/03/15 11:19, Frediano Ziglio wrote:
>>> The GIC in this platform is mainly compatible with the standard
>>> GICv2 beside:
>>> - ITARGET is extended to 16 bit to support 16 CPUs;
>>> - SGI mask is extended to support 16 CPUs;
>>> - maximum supported interrupt is 510;
>>
>> 510 is not a multiple of 32. Is it normal?
>>
>> This will result to having nr_lines = 512. What happen is we are trying
>> to access IRQ 510 and 511?
>>
> 
> I don't know. I think it's the same reason why in xen/arch/arm/gic.c the 
> limit for irq is 1021 and not 1024 (see "if ( likely(irq >= 16 && irq < 1021) 
> )" line)

IRQ 1021-1023 are reserved by the GIC as spurious interrupt.

If I understand correctly what you say, IRQ 510-511 may be considered
for spurious interrupt?

If so, the check (irq >= 16 && irq < 1021) needs to be changed.

>> Also, is it possible to have GICH.VirtualID >= 510?
>>
> 
> I think so, GICH have the same interface of normal GICv2.

But some offsets are different... so I'd like a confirmation based on
some spec.

For instance on GICv2 if we use some VirtualID (1021-1023) the behavior
is unpredictable.

So if you have the a similar things on your board we may need to
restrict the number of VirtualID in order to avoid introduce a possible
host denial from a guest.

>> [..]
>>
>>> -DT_DEVICE_START(gicv2, "GICv2", DEVICE_GIC)
>>> -        .dt_match = gicv2_dt_match,
>>> -        .init = gicv2_init,
>>> +DT_DEVICE_START(hip04gic, "GIC-HIP04", DEVICE_GIC)
>>> +    .dt_match = hip04gic_dt_match,
>>> +    .init = hip04gic_init,
>>>  DT_DEVICE_END
>>
>> Please keep the same indentation as before.
>>
> 
> I was wondering why the indentation is different. Ok

I'm not sure why ... but it looks like we use the same indentation
everywhere for DT_DEVICE_START.

Regards,

-- 
Julien Grall

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