drm/i915: Make ring submission compatible with obj->mm.lock removal, v2.

We map the initial context during first pin.

This allows us to remove pin_map from state allocation, which saves
us a few retry loops. We won't need this until first pin anyway.

intel_ring_submission_setup() is also reworked slightly to do all
pinning in a single ww loop.

Changes since v1:
- Handle -EDEADLK backoff in intel_ring_submission_setup() better.
- Handle smatch errors reported by Dan and testbot.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-20-maarten.lankhorst@linux.intel.com

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

@@ -466,6 +466,26 @@ static void ring_context_destroy(struct kref *ref)
 	intel_context_free(ce);
 }
 
+static int ring_context_init_default_state(struct intel_context *ce,
+					   struct i915_gem_ww_ctx *ww)
+{
+	struct drm_i915_gem_object *obj = ce->state->obj;
+	void *vaddr;
+
+	vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
+	if (IS_ERR(vaddr))
+		return PTR_ERR(vaddr);
+
+	shmem_read(ce->engine->default_state, 0,
+		   vaddr, ce->engine->context_size);
+
+	i915_gem_object_flush_map(obj);
+	__i915_gem_object_release_map(obj);
+
+	__set_bit(CONTEXT_VALID_BIT, &ce->flags);
+	return 0;
+}
+
 static int ring_context_pre_pin(struct intel_context *ce,
 				struct i915_gem_ww_ctx *ww,
 				void **unused)
@@ -473,6 +493,13 @@ static int ring_context_pre_pin(struct intel_context *ce,
 	struct i915_address_space *vm;
 	int err = 0;
 
+	if (ce->engine->default_state &&
+	    !test_bit(CONTEXT_VALID_BIT, &ce->flags)) {
+		err = ring_context_init_default_state(ce, ww);
+		if (err)
+			return err;
+	}
+
 	vm = vm_alias(ce->vm);
 	if (vm)
 		err = gen6_ppgtt_pin(i915_vm_to_ppgtt((vm)), ww);
@@ -528,22 +555,6 @@ alloc_context_vma(struct intel_engine_cs *engine)
 	if (IS_IVYBRIDGE(i915))
 		i915_gem_object_set_cache_coherency(obj, I915_CACHE_L3_LLC);
 
-	if (engine->default_state) {
-		void *vaddr;
-
-		vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
-		if (IS_ERR(vaddr)) {
-			err = PTR_ERR(vaddr);
-			goto err_obj;
-		}
-
-		shmem_read(engine->default_state, 0,
-			   vaddr, engine->context_size);
-
-		i915_gem_object_flush_map(obj);
-		__i915_gem_object_release_map(obj);
-	}
-
 	vma = i915_vma_instance(obj, &engine->gt->ggtt->vm, NULL);
 	if (IS_ERR(vma)) {
 		err = PTR_ERR(vma);
@@ -575,8 +586,6 @@ static int ring_context_alloc(struct intel_context *ce)
 			return PTR_ERR(vma);
 
 		ce->state = vma;
-		if (engine->default_state)
-			__set_bit(CONTEXT_VALID_BIT, &ce->flags);
 	}
 
 	return 0;
@@ -1176,37 +1185,15 @@ static int gen7_ctx_switch_bb_setup(struct intel_engine_cs * const engine,
 	return gen7_setup_clear_gpr_bb(engine, vma);
 }
 
-static int gen7_ctx_switch_bb_init(struct intel_engine_cs *engine)
+static int gen7_ctx_switch_bb_init(struct intel_engine_cs *engine,
+				   struct i915_gem_ww_ctx *ww,
+				   struct i915_vma *vma)
 {
-	struct drm_i915_gem_object *obj;
-	struct i915_vma *vma;
-	int size;
 	int err;
 
-	size = gen7_ctx_switch_bb_setup(engine, NULL /* probe size */);
-	if (size <= 0)
-		return size;
-
-	size = ALIGN(size, PAGE_SIZE);
-	obj = i915_gem_object_create_internal(engine->i915, size);
-	if (IS_ERR(obj))
-		return PTR_ERR(obj);
-
-	vma = i915_vma_instance(obj, engine->gt->vm, NULL);
-	if (IS_ERR(vma)) {
-		err = PTR_ERR(vma);
-		goto err_obj;
-	}
-
-	vma->private = intel_context_create(engine); /* dummy residuals */
-	if (IS_ERR(vma->private)) {
-		err = PTR_ERR(vma->private);
-		goto err_obj;
-	}
-
-	err = i915_vma_pin(vma, 0, 0, PIN_USER | PIN_HIGH);
+	err = i915_vma_pin_ww(vma, ww, 0, 0, PIN_USER | PIN_HIGH);
 	if (err)
-		goto err_private;
+		return err;
 
 	err = i915_vma_sync(vma);
 	if (err)
@@ -1221,17 +1208,53 @@ static int gen7_ctx_switch_bb_init(struct intel_engine_cs *engine)
 
 err_unpin:
 	i915_vma_unpin(vma);
-err_private:
-	intel_context_put(vma->private);
-err_obj:
-	i915_gem_object_put(obj);
 	return err;
 }
 
+static struct i915_vma *gen7_ctx_vma(struct intel_engine_cs *engine)
+{
+	struct drm_i915_gem_object *obj;
+	struct i915_vma *vma;
+	int size, err;
+
+	if (!IS_GEN(engine->i915, 7) || engine->class != RENDER_CLASS)
+		return 0;
+
+	err = gen7_ctx_switch_bb_setup(engine, NULL /* probe size */);
+	if (err < 0)
+		return ERR_PTR(err);
+	if (!err)
+		return NULL;
+
+	size = ALIGN(err, PAGE_SIZE);
+
+	obj = i915_gem_object_create_internal(engine->i915, size);
+	if (IS_ERR(obj))
+		return ERR_CAST(obj);
+
+	vma = i915_vma_instance(obj, engine->gt->vm, NULL);
+	if (IS_ERR(vma)) {
+		i915_gem_object_put(obj);
+		return ERR_CAST(vma);
+	}
+
+	vma->private = intel_context_create(engine); /* dummy residuals */
+	if (IS_ERR(vma->private)) {
+		err = PTR_ERR(vma->private);
+		vma->private = NULL;
+		i915_gem_object_put(obj);
+		return ERR_PTR(err);
+	}
+
+	return vma;
+}
+
 int intel_ring_submission_setup(struct intel_engine_cs *engine)
 {
+	struct i915_gem_ww_ctx ww;
 	struct intel_timeline *timeline;
 	struct intel_ring *ring;
+	struct i915_vma *gen7_wa_vma;
 	int err;
 
 	setup_common(engine);
@@ -1262,43 +1285,72 @@ int intel_ring_submission_setup(struct intel_engine_cs *engine)
 	}
 	GEM_BUG_ON(timeline->has_initial_breadcrumb);
 
-	err = intel_timeline_pin(timeline, NULL);
-	if (err)
-		goto err_timeline;
-
 	ring = intel_engine_create_ring(engine, SZ_16K);
 	if (IS_ERR(ring)) {
 		err = PTR_ERR(ring);
-		goto err_timeline_unpin;
+		goto err_timeline;
 	}
 
-	err = intel_ring_pin(ring, NULL);
-	if (err)
-		goto err_ring;
-
 	GEM_BUG_ON(engine->legacy.ring);
 	engine->legacy.ring = ring;
 	engine->legacy.timeline = timeline;
 
-	GEM_BUG_ON(timeline->hwsp_ggtt != engine->status_page.vma);
+	gen7_wa_vma = gen7_ctx_vma(engine);
+	if (IS_ERR(gen7_wa_vma)) {
+		err = PTR_ERR(gen7_wa_vma);
+		goto err_ring;
+	}
 
-	if (IS_GEN(engine->i915, 7) && engine->class == RENDER_CLASS) {
-		err = gen7_ctx_switch_bb_init(engine);
+	i915_gem_ww_ctx_init(&ww, false);
+
+retry:
+	err = i915_gem_object_lock(timeline->hwsp_ggtt->obj, &ww);
+	if (!err && gen7_wa_vma)
+		err = i915_gem_object_lock(gen7_wa_vma->obj, &ww);
+	if (!err && engine->legacy.ring->vma->obj)
+		err = i915_gem_object_lock(engine->legacy.ring->vma->obj, &ww);
+	if (!err)
+		err = intel_timeline_pin(timeline, &ww);
+	if (!err) {
+		err = intel_ring_pin(ring, &ww);
 		if (err)
-			goto err_ring_unpin;
+			intel_timeline_unpin(timeline);
+	}
+	if (err)
+		goto out;
+
+	GEM_BUG_ON(timeline->hwsp_ggtt != engine->status_page.vma);
+
+	if (gen7_wa_vma) {
+		err = gen7_ctx_switch_bb_init(engine, &ww, gen7_wa_vma);
+		if (err) {
+			intel_ring_unpin(ring);
+			intel_timeline_unpin(timeline);
+		}
 	}
 
+out:
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
+	if (err)
+		goto err_gen7_put;
+
 	/* Finally, take ownership and responsibility for cleanup! */
 	engine->release = ring_release;
 
 	return 0;
 
-err_ring_unpin:
-	intel_ring_unpin(ring);
+err_gen7_put:
+	if (gen7_wa_vma) {
+		intel_context_put(gen7_wa_vma->private);
+		i915_gem_object_put(gen7_wa_vma->obj);
+	}
 err_ring:
 	intel_ring_put(ring);
-err_timeline_unpin:
-	intel_timeline_unpin(timeline);
 err_timeline:
 	intel_timeline_put(timeline);
 err: