[Intel-gfx] [PATCH] drm/i915/gt: Scrub execlists state on resume

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-04-17 13:09:52)
> 
> On 16/04/2020 12:41, Chris Wilson wrote:
> > Before we resume, we reset the HW so we restart from a known good state.
> > However, as a part of the reset process, we drain our pending CS event
> > queue -- and if we are resuming that does not correspond to internal
> > state. On setup, we are scrubbing the CS pointers, but alas only on
> > setup.
> > 
> > Apply the sanitization not just to setup, but to all resumes.
> > 
> > Reported-by: Venkata Ramana Nayana <venkata.ramana.nayana at intel.com>
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Venkata Ramana Nayana <venkata.ramana.nayana at intel.com>
> > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > ---
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Tvrtko mentioned on irc that we could do some poisoning of assumed state
(like the HWSP here) in order to better catch these errors.
-Chris