[PATCH v3 6/8] ARM: Change MPIDR_AFFINITY_LEVEL to ignore Aff3

[Vladimir Murzin]

On 12/09/16 10:48, Marc Zyngier wrote:
> On 12/09/16 10:39, Vladimir Murzin wrote:
>> On 09/09/16 17:59, Marc Zyngier wrote:
>>> On 08/09/16 17:06, Vladimir Murzin wrote:
>>>> vgic-v3 driver queries CPU affinity level up to Aff3, which is valid
>>>> for arm64.  However, for arm up to Aff2 levels are supported, so
>>>> querying for third level ends with upper bits of MPIDR are treated as
>>>> valid affinity level which is not true. Make sure we report zero for
>>>> any affinity level above two.
>>>>
>>>> Signed-off-by: Vladimir Murzin <vladimir.murzin at arm.com>
>>>> ---
>>>>  arch/arm/include/asm/cputype.h |    3 ++-
>>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
>>>> index 1ee94c7..f08fac4 100644
>>>> --- a/arch/arm/include/asm/cputype.h
>>>> +++ b/arch/arm/include/asm/cputype.h
>>>> @@ -55,9 +55,10 @@
>>>>  
>>>>  #define MPIDR_LEVEL_BITS 8
>>>>  #define MPIDR_LEVEL_MASK ((1 << MPIDR_LEVEL_BITS) - 1)
>>>> +#define MPIDR_LEVEL_SHIFT(level) (MPIDR_LEVEL_BITS * level)
>>>>  
>>>>  #define MPIDR_AFFINITY_LEVEL(mpidr, level) \
>>>> -	((mpidr >> (MPIDR_LEVEL_BITS * level)) & MPIDR_LEVEL_MASK)
>>>> +	(((mpidr & MPIDR_HWID_BITMASK) >> MPIDR_LEVEL_SHIFT(level)) & MPIDR_LEVEL_MASK)
>>>>  
>>>>  #define ARM_CPU_IMP_ARM			0x41
>>>>  #define ARM_CPU_IMP_INTEL		0x69
>>>>
>>>
>>> There is something I don't quite get. Is this patch really necessary?
>>> Are there cases where we construct a MPIDR that can have Aff3 set on 32bit?
>>
>> I've just checked and it seems that I've been keeping the change for
>> MPIDR_AFFINITY_LEVEL() since vgic-old era where it was used with
>>
>> static u32 compress_mpidr(unsigned long mpidr)
>> {
>>         u32 ret;
>>
>>         ret = MPIDR_AFFINITY_LEVEL(mpidr, 0);
>>         ret |= MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8;
>>         ret |= MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16;
>>         ret |= MPIDR_AFFINITY_LEVEL(mpidr, 3) << 24;
>>
>>         return ret;
>> }
>>
>> and now that code gone and nobody passes level 3 into this macro, so I
>> can drop this change.
>>
>> However, I do need MPIDR_LEVEL_SHIFT() macro since it is used in vgic-v3.
>>
>> Should I leave patch as is or you have something in mind?
> 
> I think that for the sake of keeping the change minimal, it'd be better
> to just add the MPIDR_LEVEL_SHIFT macro, and drop the other changes.

Noted!

Thanks
Vladimir

> 
> Thanks,
> 
> 	M.
>