drm/i915/selftests: Add initial GuC selftest for scrubbing lost G2H

While debugging an issue with full GT resets I went down a rabbit hole
thinking the scrubbing of lost G2H wasn't working correctly. This proved
to be incorrect as this was working just fine but this chase inspired me
to write a selftest to prove that this works. This simple selftest
injects errors dropping various G2H and then issues a full GT reset
proving that the scrubbing of these G2H doesn't blow up.

v2:
(Daniel Vetter)
- Use ifdef instead of macros for selftests
v3:
(Checkpatch)
- A space after 'switch' statement
v4:
(Daniele)
- A comment saying GT won't idle if G2H are lost

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-12-matthew.brost@intel.com

drm/i915/selftest: Fix hangcheck self test for GuC submission

When GuC submission is enabled, the GuC controls engine resets. Rather
than explicitly triggering a reset, the driver must submit a hanging
context to GuC and wait for the reset to occur.

Conversely, one of the tests specifically sends hanging batches to the
engines but wants them to sit around until a manual reset of the full
GT (including GuC itself). That means disabling GuC based engine
resets to prevent those from killing the hanging batch too soon. So,
add support to the scheduling policy helper for disabling resets as
well as making them quicker!

In GuC submission mode, the 'is engine idle' test basically turns into
'is engine PM wakelock held'. Independently, there is a heartbeat
disable helper function that the tests use. For unexplained reasons,
this acquires the engine wakelock before disabling the heartbeat and
only releases it when re-enabling the heartbeat. As one of the tests
tries to do a wait for idle in the middle of a heartbeat disabled
section, it is therefore guaranteed to always fail. Added a 'no_pm'
variant of the heartbeat helper that allows the engine to be asleep
while also having heartbeats disabled.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210727002348.97202-31-matthew.brost@intel.com

drm/i915/selftest: Fix workarounds selftest for GuC submission

When GuC submission is enabled, the GuC controls engine resets. Rather
than explicitly triggering a reset, the driver must submit a hanging
context to GuC and wait for the reset to occur.

Signed-off-by: Rahul Kumar Singh <rahul.kumar.singh@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210727002348.97202-28-matthew.brost@intel.com