drm/i915: Assert we idle in the kernel context

Now that we always switch to the kernel context upon idling, we can
make that assertion.

References: 4dfacb0bcbee ("drm/i915: Switch to kernel context before idling at runtime")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180531224057.6036-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem.c

@@ -3498,6 +3498,22 @@ new_requests_since_last_retire(const struct drm_i915_private *i915)
 		work_pending(&i915->gt.idle_work.work));
 }
 
+static void assert_kernel_context_is_current(struct drm_i915_private *i915)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	if (i915_terminally_wedged(&i915->gpu_error))
+		return;
+
+	GEM_BUG_ON(i915->gt.active_requests);
+	for_each_engine(engine, i915, id) {
+		GEM_BUG_ON(__i915_gem_active_peek(&engine->timeline.last_request));
+		GEM_BUG_ON(engine->last_retired_context !=
+			   to_intel_context(i915->kernel_context, engine));
+	}
+}
+
 static void
 i915_gem_idle_work_handler(struct work_struct *work)
 {
@@ -3560,6 +3576,8 @@ i915_gem_idle_work_handler(struct work_struct *work)
 
 	epoch = __i915_gem_park(dev_priv);
 
+	assert_kernel_context_is_current(dev_priv);
+
 	rearm_hangcheck = false;
 out_unlock:
 	mutex_unlock(&dev_priv->drm.struct_mutex);
@@ -4944,19 +4962,6 @@ void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj)
 		i915_gem_object_put(obj);
 }
 
-static void assert_kernel_context_is_current(struct drm_i915_private *i915)
-{
-	struct i915_gem_context *kctx = i915->kernel_context;
-	struct intel_engine_cs *engine;
-	enum intel_engine_id id;
-
-	GEM_BUG_ON(i915->gt.active_requests);
-	for_each_engine(engine, i915, id) {
-		GEM_BUG_ON(__i915_gem_active_peek(&engine->timeline.last_request));
-		GEM_BUG_ON(engine->last_retired_context->gem_context != kctx);
-	}
-}
-
 void i915_gem_sanitize(struct drm_i915_private *i915)
 {
 	struct intel_engine_cs *engine;