[Intel-gfx] [PATCH i-g-t] i915/gem_ctx_persistence: Check precision of hostile cancellation

[Tvrtko Ursulin]

On 25/02/2020 18:11, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2020-02-25 18:08:14)
>>
>> On 24/02/2020 21:56, Chris Wilson wrote:
>>> Check that if we have to remove a hostile request from a non-persistent
>>> context, we do so without harming any other concurrent users.
>>>
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>> ---
>>> +     /* All other spinners should be left unharmed */
>>> +     gem_quiescent_gpu(i915);
>>> +     igt_assert_eq(sync_fence_wait(fence, reset_timeout_ms), 0);
>>> +     igt_assert_eq(sync_fence_status(fence), 1);
>>
>> I don't quite get this test. Why would other spinners be unharmed? They
>> are non-preemptible as well. And non-persistent spinner is alone on the
>> engine. So what aspect you wanted to test?
> 
> Per-engine reset. Termination of the non-persistent context should be
> clean and precise, we don't allow creation of non-persistent contexts
> unless we have that level of surgical precision. Otherwise it becomes a
> new attack vector.

If it is just engine reset then it does what it says on the tin.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko