Re: [Xen-devel] [PATCH v5 10/22] xen/arm: ITS: Add GITS registers emulation

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 01/08/15 09:50, Vijay Kilari wrote:
> On Wed, Jul 29, 2015 at 12:31 AM, Julien Grall <julien.grall@xxxxxxxxxx> 
> wrote:
>> Hi Vijay,
>>
>> On 27/07/15 12:11, vijay.kilari@xxxxxxxxx wrote:
>>> From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>
>>>
>>> Emulate GITS* registers
>>>
>>> Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>
>>> ---
>>> v4: - Removed GICR register emulation
>>> ---
> [...]
>>> +    case GITS_PIDR4:
>>> +        if ( dabt.size != DABT_WORD )
>>> +            goto bad_width;
>>> +        *r = GITS_PIDR4_VAL;
>>> +        return 1;
>>> +    case GITS_PIDR5 ... GITS_PIDR7:
>>> +        goto read_as_zero_32;
>>> +   default:
>>> +        dprintk(XENLOG_G_ERR,
>>> +                "%pv: vITS: unhandled read r%"PRId32" offset 
>>> 0x%#08"PRIx32"\n",
>>
>> Reg is definitely not a PRId32.
> 
> dabt.reg is unsigned long : 5. In vgic-v3.c it is printed using %d.
> [...]
>>> +/*
>>> + * GITS_BASER.Type[58:56], GITS_BASER.Entry_size[55:48]
>>> + * and GITS_BASER.Shareability[11:10] are read-only.
>>
>> As said on v4, implemented Shareability as fixed (i.e read-only) is
>> deprecated. I'd like to see a TODO here.
> 
>   What are you expecting to get fixed for shareability with TODO?

To be more explicit, you are implementing a behavior which is
deprecated. It means that we should avoid to use it knowingly in the
virtual ITS.

In this specific case, I would be ok with a TODO explaining that we need
to fix it or why we need to do read-only.

Regards,

-- 
Julien Grall

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