Re: [RFC v6 1/1] drm/xe/pf: Restrict device query responses in admin-only PF mode

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 3/24/2026 10:17 PM, Dixit, Ashutosh wrote:
> On Sun, 15 Mar 2026 23:41:02 -0700, Satyanarayana K V P wrote:
>>
>> ---
>> V5 -> V6:
>> - Updated commit message.
>> - Return number of engines and memory regions as zero instead of returning
>> query size as zero (Michal Wajdeczko).
>> - Allow all other query IOCTLs excepts query_engines and query_mem_regions
>> (Michal Wajdeczko).
> 
> Can someone explain the reason to move away from the approach in v5? Afais
> v6 has issues of this sort:
> 
> * query_engines will return 0 engines but query_hwconfig will return > 0
>   engines

but those are separate queries on purpose, right?
and I guess that even today there could be a mismatch between these numbers:

* query_engines = engines available for use by the user software
* query_hwconfig.engines = report engines present on the hardware

> * query_engines will return 0 engines but query_oa_units will list out the
>   engines

and that IMO should be considered as a desired outcome, as I guess (again)
that this will allow us to do some OA reporting, even if PF alone is not
submitting any workloads and we want to monitor how VFs are doing

> * query_oa_units will return valid oa support but observation ioctl will
>   fail

my initial idea [1] was to expose observation ioctl as well, maybe we need
to add it back?

[1] https://patchwork.freedesktop.org/patch/706445/?series=160349&rev=2#comment_1299475

> 
> v5 seems to have avoided contradictions of this sort. Or this doesn't
> matter? Thanks.

but since I'm not using any of those ioctls on daily basis, I might be wrong