drm/ttm: add the infrastructure for pipelined evictions

Free up the memory immediately, remember the last eviction for each domain and
make new allocations depend on the last eviction to be completed.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_bo.c

@@ -787,6 +787,34 @@ void ttm_bo_mem_put(struct ttm_buffer_object *bo, struct ttm_mem_reg *mem)
 }
 EXPORT_SYMBOL(ttm_bo_mem_put);
 
+/**
+ * Add the last move fence to the BO and reserve a new shared slot.
+ */
+static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo,
+				 struct ttm_mem_type_manager *man,
+				 struct ttm_mem_reg *mem)
+{
+	struct fence *fence;
+	int ret;
+
+	spin_lock(&man->move_lock);
+	fence = fence_get(man->move);
+	spin_unlock(&man->move_lock);
+
+	if (fence) {
+		reservation_object_add_shared_fence(bo->resv, fence);
+
+		ret = reservation_object_reserve_shared(bo->resv);
+		if (unlikely(ret))
+			return ret;
+
+		fence_put(bo->moving);
+		bo->moving = fence;
+	}
+
+	return 0;
+}
+
 /**
  * Repeatedly evict memory from the LRU for @mem_type until we create enough
  * space, or we've evicted everything and there isn't enough space.
@@ -813,10 +841,8 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 		if (unlikely(ret != 0))
 			return ret;
 	} while (1);
-	if (mem->mm_node == NULL)
-		return -ENOMEM;
 	mem->mem_type = mem_type;
-	return 0;
+	return ttm_bo_add_move_fence(bo, man, mem);
 }
 
 static uint32_t ttm_bo_select_caching(struct ttm_mem_type_manager *man,
@@ -886,6 +912,10 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 	bool has_erestartsys = false;
 	int i, ret;
 
+	ret = reservation_object_reserve_shared(bo->resv);
+	if (unlikely(ret))
+		return ret;
+
 	mem->mm_node = NULL;
 	for (i = 0; i < placement->num_placement; ++i) {
 		const struct ttm_place *place = &placement->placement[i];
@@ -919,9 +949,15 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 		ret = (*man->func->get_node)(man, bo, place, mem);
 		if (unlikely(ret))
 			return ret;
-		
-		if (mem->mm_node)
+
+		if (mem->mm_node) {
+			ret = ttm_bo_add_move_fence(bo, man, mem);
+			if (unlikely(ret)) {
+				(*man->func->put_node)(man, mem);
+				return ret;
+			}
 			break;
+		}
 	}
 
 	if ((type_ok && (mem_type == TTM_PL_SYSTEM)) || mem->mm_node) {
@@ -1290,6 +1326,7 @@ int ttm_bo_clean_mm(struct ttm_bo_device *bdev, unsigned mem_type)
 		       mem_type);
 		return ret;
 	}
+	fence_put(man->move);
 
 	man->use_type = false;
 	man->has_type = false;
@@ -1335,6 +1372,7 @@ int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
 	man->io_reserve_fastpath = true;
 	man->use_io_reserve_lru = false;
 	mutex_init(&man->io_reserve_mutex);
+	spin_lock_init(&man->move_lock);
 	INIT_LIST_HEAD(&man->io_reserve_lru);
 
 	ret = bdev->driver->init_mem_type(bdev, type, man);
@@ -1353,6 +1391,7 @@ int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
 	man->size = p_size;
 
 	INIT_LIST_HEAD(&man->lru);
+	man->move = NULL;
 
 	return 0;
 }

drivers/gpu/drm/ttm/ttm_bo_util.c

@@ -696,3 +696,95 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
 	return 0;
 }
 EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
+
+int ttm_bo_pipeline_move(struct ttm_buffer_object *bo,
+			 struct fence *fence, bool evict,
+			 struct ttm_mem_reg *new_mem)
+{
+	struct ttm_bo_device *bdev = bo->bdev;
+	struct ttm_mem_reg *old_mem = &bo->mem;
+
+	struct ttm_mem_type_manager *from = &bdev->man[old_mem->mem_type];
+	struct ttm_mem_type_manager *to = &bdev->man[new_mem->mem_type];
+
+	int ret;
+
+	reservation_object_add_excl_fence(bo->resv, fence);
+
+	if (!evict) {
+		struct ttm_buffer_object *ghost_obj;
+
+		/**
+		 * This should help pipeline ordinary buffer moves.
+		 *
+		 * Hang old buffer memory on a new buffer object,
+		 * and leave it to be released when the GPU
+		 * operation has completed.
+		 */
+
+		fence_put(bo->moving);
+		bo->moving = fence_get(fence);
+
+		ret = ttm_buffer_object_transfer(bo, &ghost_obj);
+		if (ret)
+			return ret;
+
+		reservation_object_add_excl_fence(ghost_obj->resv, fence);
+
+		/**
+		 * If we're not moving to fixed memory, the TTM object
+		 * needs to stay alive. Otherwhise hang it on the ghost
+		 * bo to be unbound and destroyed.
+		 */
+
+		if (!(to->flags & TTM_MEMTYPE_FLAG_FIXED))
+			ghost_obj->ttm = NULL;
+		else
+			bo->ttm = NULL;
+
+		ttm_bo_unreserve(ghost_obj);
+		ttm_bo_unref(&ghost_obj);
+
+	} else if (from->flags & TTM_MEMTYPE_FLAG_FIXED) {
+
+		/**
+		 * BO doesn't have a TTM we need to bind/unbind. Just remember
+		 * this eviction and free up the allocation
+		 */
+
+		spin_lock(&from->move_lock);
+		if (!from->move || fence_is_later(from->move, fence)) {
+			fence_put(from->move);
+			from->move = fence_get(fence);
+		}
+		spin_unlock(&from->move_lock);
+
+		ttm_bo_free_old_node(bo);
+
+		fence_put(bo->moving);
+		bo->moving = fence_get(fence);
+
+	} else {
+		/**
+		 * Last resort, wait for the move to be completed.
+		 *
+		 * Should never happen in pratice.
+		 */
+
+		ret = ttm_bo_wait(bo, false, false);
+		if (ret)
+			return ret;
+
+		if (to->flags & TTM_MEMTYPE_FLAG_FIXED) {
+			ttm_tt_destroy(bo->ttm);
+			bo->ttm = NULL;
+		}
+		ttm_bo_free_old_node(bo);
+	}
+
+	*old_mem = *new_mem;
+	new_mem->mm_node = NULL;
+
+	return 0;
+}
+EXPORT_SYMBOL(ttm_bo_pipeline_move);

include/drm/ttm/ttm_bo_driver.h

@@ -258,8 +258,10 @@ struct ttm_mem_type_manager_func {
  * reserved by the TTM vm system.
  * @io_reserve_lru: Optional lru list for unreserving io mem regions.
  * @io_reserve_fastpath: Only use bdev::driver::io_mem_reserve to obtain
+ * @move_lock: lock for move fence
  * static information. bdev::driver::io_mem_free is never used.
  * @lru: The lru list for this memory type.
+ * @move: The fence of the last pipelined move operation.
  *
  * This structure is used to identify and manage memory types for a device.
  * It's set up by the ttm_bo_driver::init_mem_type method.
@@ -286,6 +288,7 @@ struct ttm_mem_type_manager {
 	struct mutex io_reserve_mutex;
 	bool use_io_reserve_lru;
 	bool io_reserve_fastpath;
+	spinlock_t move_lock;
 
 	/*
 	 * Protected by @io_reserve_mutex:
@@ -298,6 +301,11 @@ struct ttm_mem_type_manager {
 	 */
 
 	struct list_head lru;
+
+	/*
+	 * Protected by @move_lock.
+	 */
+	struct fence *move;
 };
 
 /**
@@ -1014,6 +1022,22 @@ extern void ttm_bo_free_old_node(struct ttm_buffer_object *bo);
 extern int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
 				     struct fence *fence, bool evict,
 				     struct ttm_mem_reg *new_mem);
+
+/**
+ * ttm_bo_pipeline_move.
+ *
+ * @bo: A pointer to a struct ttm_buffer_object.
+ * @fence: A fence object that signals when moving is complete.
+ * @evict: This is an evict move. Don't return until the buffer is idle.
+ * @new_mem: struct ttm_mem_reg indicating where to move.
+ *
+ * Function for pipelining accelerated moves. Either free the memory
+ * immediately or hang it on a temporary buffer object.
+ */
+int ttm_bo_pipeline_move(struct ttm_buffer_object *bo,
+			 struct fence *fence, bool evict,
+			 struct ttm_mem_reg *new_mem);
+
 /**
  * ttm_io_prot
  *