drm/i915: Add i915_vma_unbind_unlocked, and take obj lock for i915_vma_unbind, v2.

We want to remove more members of i915_vma, which requires the locking to
be held more often.

Start requiring gem object lock for i915_vma_unbind, as it's one of the
callers that may unpin pages.

Some special care is needed when evicting, because the last reference to
the object may be held by the VMA, so after __i915_vma_unbind, vma may be
garbage, and we need to cache vma->obj before unlocking.

Changes since v1:
- Make trylock failing a WARN. (Matt)
- Remove double i915_vma_wait_for_bind() (Matt)
- Move atomic_set to right before mutex_unlock(), to make it more clear
  they belong together. (Matt)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220114132320.109030-5-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/display/intel_fb_pin.c

@@ -47,7 +47,7 @@ intel_pin_fb_obj_dpt(struct drm_framebuffer *fb,
 		goto err;
 
 	if (i915_vma_misplaced(vma, 0, alignment, 0)) {
-		ret = i915_vma_unbind(vma);
+		ret = i915_vma_unbind_unlocked(vma);
 		if (ret) {
 			vma = ERR_PTR(ret);
 			goto err;

drivers/gpu/drm/i915/gem/selftests/huge_pages.c

@@ -641,7 +641,7 @@ static int igt_mock_ppgtt_misaligned_dma(void *arg)
 		 * pages.
 		 */
 		for (offset = 4096; offset < page_size; offset += 4096) {
-			err = i915_vma_unbind(vma);
+			err = i915_vma_unbind_unlocked(vma);
 			if (err)
 				goto out_unpin;
 

drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c

@@ -318,7 +318,7 @@ static int pin_buffer(struct i915_vma *vma, u64 addr)
 	int err;
 
 	if (drm_mm_node_allocated(&vma->node) && vma->node.start != addr) {
-		err = i915_vma_unbind(vma);
+		err = i915_vma_unbind_unlocked(vma);
 		if (err)
 			return err;
 	}

drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c

@@ -166,7 +166,9 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
 	kunmap(p);
 
 out:
+	i915_gem_object_lock(obj, NULL);
 	__i915_vma_put(vma);
+	i915_gem_object_unlock(obj);
 	return err;
 }
 
@@ -261,7 +263,9 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
 		if (err)
 			return err;
 
+		i915_gem_object_lock(obj, NULL);
 		__i915_vma_put(vma);
+		i915_gem_object_unlock(obj);
 
 		if (igt_timeout(end_time,
 				"%s: timed out after tiling=%d stride=%d\n",
@@ -1352,7 +1356,9 @@ static int __igt_mmap_revoke(struct drm_i915_private *i915,
 	 * for other objects. Ergo we have to revoke the previous mmap PTE
 	 * access as it no longer points to the same object.
 	 */
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_unbind(obj, I915_GEM_OBJECT_UNBIND_ACTIVE);
+	i915_gem_object_unlock(obj);
 	if (err) {
 		pr_err("Failed to unbind object!\n");
 		goto out_unmap;

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

@@ -129,22 +129,51 @@ void i915_ggtt_suspend_vm(struct i915_address_space *vm)
 
 	drm_WARN_ON(&vm->i915->drm, !vm->is_ggtt && !vm->is_dpt);
 
+retry:
+	i915_gem_drain_freed_objects(vm->i915);
+
 	mutex_lock(&vm->mutex);
 
 	/* Skip rewriting PTE on VMA unbind. */
 	open = atomic_xchg(&vm->open, 0);
 
 	list_for_each_entry_safe(vma, vn, &vm->bound_list, vm_link) {
+		struct drm_i915_gem_object *obj = vma->obj;
+
 		GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
-		i915_vma_wait_for_bind(vma);
 
-		if (i915_vma_is_pinned(vma))
+		if (i915_vma_is_pinned(vma) || !i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND))
 			continue;
 
+		/* unlikely to race when GPU is idle, so no worry about slowpath.. */
+		if (WARN_ON(!i915_gem_object_trylock(obj, NULL))) {
+			/*
+			 * No dead objects should appear here, GPU should be
+			 * completely idle, and userspace suspended
+			 */
+			i915_gem_object_get(obj);
+
+			atomic_set(&vm->open, open);
+			mutex_unlock(&vm->mutex);
+
+			i915_gem_object_lock(obj, NULL);
+			open = i915_vma_unbind(vma);
+			i915_gem_object_unlock(obj);
+
+			GEM_WARN_ON(open);
+
+			i915_gem_object_put(obj);
+			goto retry;
+		}
+
 		if (!i915_vma_is_bound(vma, I915_VMA_GLOBAL_BIND)) {
+			i915_vma_wait_for_bind(vma);
+
 			__i915_vma_evict(vma, false);
 			drm_mm_remove_node(&vma->node);
 		}
+
+		i915_gem_object_unlock(obj);
 	}
 
 	vm->clear_range(vm, 0, vm->total);
@@ -746,11 +775,21 @@ static void ggtt_cleanup_hw(struct i915_ggtt *ggtt)
 	atomic_set(&ggtt->vm.open, 0);
 
 	flush_workqueue(ggtt->vm.i915->wq);
+	i915_gem_drain_freed_objects(ggtt->vm.i915);
 
 	mutex_lock(&ggtt->vm.mutex);
 
-	list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link)
+	list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link) {
+		struct drm_i915_gem_object *obj = vma->obj;
+		bool trylock;
+
+		trylock = i915_gem_object_trylock(obj, NULL);
+		WARN_ON(!trylock);
+
 		WARN_ON(__i915_vma_unbind(vma));
+		if (trylock)
+			i915_gem_object_unlock(obj);
+	}
 
 	if (drm_mm_node_allocated(&ggtt->error_capture))
 		drm_mm_remove_node(&ggtt->error_capture);

drivers/gpu/drm/i915/i915_gem.c

@@ -119,6 +119,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
 	struct i915_vma *vma;
 	int ret;
 
+	assert_object_held(obj);
+
 	if (list_empty(&obj->vma.list))
 		return 0;
 

drivers/gpu/drm/i915/i915_vma.c

@@ -1622,8 +1622,16 @@ void i915_vma_parked(struct intel_gt *gt)
 		struct drm_i915_gem_object *obj = vma->obj;
 		struct i915_address_space *vm = vma->vm;
 
+		if (i915_gem_object_trylock(obj, NULL)) {
 			INIT_LIST_HEAD(&vma->closed_link);
 			__i915_vma_put(vma);
+			i915_gem_object_unlock(obj);
+		} else {
+			/* back you go.. */
+			spin_lock_irq(&gt->closed_lock);
+			list_add(&vma->closed_link, &gt->closed_vma);
+			spin_unlock_irq(&gt->closed_lock);
+		}
 
 		i915_gem_object_put(obj);
 		i915_vm_close(vm);
@@ -1742,6 +1750,7 @@ struct dma_fence *__i915_vma_evict(struct i915_vma *vma, bool async)
 	struct dma_fence *unbind_fence;
 
 	GEM_BUG_ON(i915_vma_is_pinned(vma));
+	assert_object_held_shared(vma->obj);
 
 	if (i915_vma_is_map_and_fenceable(vma)) {
 		/* Force a pagefault for domain tracking on next user access */
@@ -1808,6 +1817,7 @@ int __i915_vma_unbind(struct i915_vma *vma)
 	int ret;
 
 	lockdep_assert_held(&vma->vm->mutex);
+	assert_object_held_shared(vma->obj);
 
 	if (!drm_mm_node_allocated(&vma->node))
 		return 0;
@@ -1874,6 +1884,8 @@ int i915_vma_unbind(struct i915_vma *vma)
 	intel_wakeref_t wakeref = 0;
 	int err;
 
+	assert_object_held_shared(vma->obj);
+
 	/* Optimistic wait before taking the mutex */
 	err = i915_vma_sync(vma);
 	if (err)
@@ -1966,6 +1978,17 @@ int i915_vma_unbind_async(struct i915_vma *vma, bool trylock_vm)
 	return err;
 }
 
+int i915_vma_unbind_unlocked(struct i915_vma *vma)
+{
+	int err;
+
+	i915_gem_object_lock(vma->obj, NULL);
+	err = i915_vma_unbind(vma);
+	i915_gem_object_unlock(vma->obj);
+
+	return err;
+}
+
 struct i915_vma *i915_vma_make_unshrinkable(struct i915_vma *vma)
 {
 	i915_gem_object_make_unshrinkable(vma->obj);

drivers/gpu/drm/i915/i915_vma.h

@@ -217,6 +217,7 @@ struct dma_fence *__i915_vma_evict(struct i915_vma *vma, bool async);
 int __i915_vma_unbind(struct i915_vma *vma);
 int __must_check i915_vma_unbind(struct i915_vma *vma);
 int __must_check i915_vma_unbind_async(struct i915_vma *vma, bool trylock_vm);
+int __must_check i915_vma_unbind_unlocked(struct i915_vma *vma);
 void i915_vma_unlink_ctx(struct i915_vma *vma);
 void i915_vma_close(struct i915_vma *vma);
 void i915_vma_reopen(struct i915_vma *vma);

drivers/gpu/drm/i915/selftests/i915_gem_gtt.c

@@ -386,7 +386,7 @@ static void close_object_list(struct list_head *objects,
 
 		vma = i915_vma_instance(obj, vm, NULL);
 		if (!IS_ERR(vma))
-			ignored = i915_vma_unbind(vma);
+			ignored = i915_vma_unbind_unlocked(vma);
 
 		list_del(&obj->st_link);
 		i915_gem_object_put(obj);
@@ -497,7 +497,7 @@ static int fill_hole(struct i915_address_space *vm,
 						goto err;
 					}
 
-					err = i915_vma_unbind(vma);
+					err = i915_vma_unbind_unlocked(vma);
 					if (err) {
 						pr_err("%s(%s) (forward) unbind of vma.node=%llx + %llx failed with err=%d\n",
 						       __func__, p->name, vma->node.start, vma->node.size,
@@ -570,7 +570,7 @@ static int fill_hole(struct i915_address_space *vm,
 						goto err;
 					}
 
-					err = i915_vma_unbind(vma);
+					err = i915_vma_unbind_unlocked(vma);
 					if (err) {
 						pr_err("%s(%s) (backward) unbind of vma.node=%llx + %llx failed with err=%d\n",
 						       __func__, p->name, vma->node.start, vma->node.size,
@@ -656,7 +656,7 @@ static int walk_hole(struct i915_address_space *vm,
 				goto err_put;
 			}
 
-			err = i915_vma_unbind(vma);
+			err = i915_vma_unbind_unlocked(vma);
 			if (err) {
 				pr_err("%s unbind failed at %llx + %llx  with err=%d\n",
 				       __func__, addr, vma->size, err);
@@ -733,13 +733,13 @@ static int pot_hole(struct i915_address_space *vm,
 				pr_err("%s incorrect at %llx + %llx\n",
 				       __func__, addr, vma->size);
 				i915_vma_unpin(vma);
-				err = i915_vma_unbind(vma);
+				err = i915_vma_unbind_unlocked(vma);
 				err = -EINVAL;
 				goto err_obj;
 			}
 
 			i915_vma_unpin(vma);
-			err = i915_vma_unbind(vma);
+			err = i915_vma_unbind_unlocked(vma);
 			GEM_BUG_ON(err);
 		}
 
@@ -833,13 +833,13 @@ static int drunk_hole(struct i915_address_space *vm,
 				pr_err("%s incorrect at %llx + %llx\n",
 				       __func__, addr, BIT_ULL(size));
 				i915_vma_unpin(vma);
-				err = i915_vma_unbind(vma);
+				err = i915_vma_unbind_unlocked(vma);
 				err = -EINVAL;
 				goto err_obj;
 			}
 
 			i915_vma_unpin(vma);
-			err = i915_vma_unbind(vma);
+			err = i915_vma_unbind_unlocked(vma);
 			GEM_BUG_ON(err);
 
 			if (igt_timeout(end_time,
@@ -907,7 +907,7 @@ static int __shrink_hole(struct i915_address_space *vm,
 			pr_err("%s incorrect at %llx + %llx\n",
 			       __func__, addr, size);
 			i915_vma_unpin(vma);
-			err = i915_vma_unbind(vma);
+			err = i915_vma_unbind_unlocked(vma);
 			err = -EINVAL;
 			break;
 		}
@@ -1481,7 +1481,7 @@ static int igt_gtt_reserve(void *arg)
 			goto out;
 		}
 
-		err = i915_vma_unbind(vma);
+		err = i915_vma_unbind_unlocked(vma);
 		if (err) {
 			pr_err("i915_vma_unbind failed with err=%d!\n", err);
 			goto out;
@@ -1677,7 +1677,7 @@ static int igt_gtt_insert(void *arg)
 		GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
 		offset = vma->node.start;
 
-		err = i915_vma_unbind(vma);
+		err = i915_vma_unbind_unlocked(vma);
 		if (err) {
 			pr_err("i915_vma_unbind failed with err=%d!\n", err);
 			goto out;

drivers/gpu/drm/i915/selftests/i915_vma.c

@@ -340,7 +340,7 @@ static int igt_vma_pin1(void *arg)
 
 		if (!err) {
 			i915_vma_unpin(vma);
-			err = i915_vma_unbind(vma);
+			err = i915_vma_unbind_unlocked(vma);
 			if (err) {
 				pr_err("Failed to unbind single page from GGTT, err=%d\n", err);
 				goto out;
@@ -691,7 +691,7 @@ static int igt_vma_rotate_remap(void *arg)
 					}
 
 					i915_vma_unpin(vma);
-					err = i915_vma_unbind(vma);
+					err = i915_vma_unbind_unlocked(vma);
 					if (err) {
 						pr_err("Unbinding returned %i\n", err);
 						goto out_object;
@@ -852,7 +852,7 @@ static int igt_vma_partial(void *arg)
 
 				i915_vma_unpin(vma);
 				nvma++;
-				err = i915_vma_unbind(vma);
+				err = i915_vma_unbind_unlocked(vma);
 				if (err) {
 					pr_err("Unbinding returned %i\n", err);
 					goto out_object;
@@ -891,7 +891,7 @@ static int igt_vma_partial(void *arg)
 
 		i915_vma_unpin(vma);
 
-		err = i915_vma_unbind(vma);
+		err = i915_vma_unbind_unlocked(vma);
 		if (err) {
 			pr_err("Unbinding returned %i\n", err);
 			goto out_object;