Re: [PATCH v2 2/3] spapr: Add SPAPR_CAP_AIL_MODE_3 for AIL mode 3 support for H_SET_MODE hcall

["Cédric Le Goater" <clg@kaod.org>]

>>>> +    /* These tests match the CPU_FTR_P9_RADIX_PREFETCH_BUG flag in Linux */
>>>> +    if (((pcc->pvr & 0xffffff00) == CPU_POWERPC_POWER9_DD1) ||
>>>> +        ((pcc->pvr & 0xffffff00) == CPU_POWERPC_POWER9_DD20) ||
>>>> +        ((pcc->pvr & 0xffffff00) == CPU_POWERPC_POWER9_DD21)) {
>>>> +        return 0;
>>>> +    }
>>>
>>> Deducing what KVM supports rather than getting it to tell us
>>> explicitly with a cap is usually frowned upon.  However, given the
>>> earlier discussion, I'm satisfied that this is the least bad available
>>> option, at least for now.
>>
>> BTW this particular test doesn't work as I hoped because we only have
>> a power9 dd2.0 model.
> 
> Oh.. yes... IIRC dd2.0 is barely present in the wild, since it doesn't
> have vital Spectre mitigations....
> 
>> Adding a 2.2 or 2.3 would be possible. Maybe overkill.  I'll change
>> the test just to catch all POWER9 for now.
> 
> ... no, given the above, I think we should definitely add the newer
> models.  Maybe even remove dd2.0 and replace it with the newer ones.

yes. It's really not a big effort.

Thanks,

C.