drm/i915/execlists: Ensure the context is reloaded after a GPU reset

After we manipulate the context to allow replay after a GPU reset, force
that context to be reloaded. This should be a layer of paranoia, for if
the GPU was reset, the context will no longer be resident!
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190912092933.4729-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -2445,6 +2445,7 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	intel_ring_update_space(ce->ring);
 	__execlists_reset_reg_state(ce, engine);
 	__execlists_update_reg_state(ce, engine);
+	ce->lrc_desc |= CTX_DESC_FORCE_RESTORE; /* paranoid: GPU was reset! */
 	mutex_release(&ce->pin_mutex.dep_map, 0, _THIS_IP_);
 
 unwind: