Commit 3439cc46 authored by Thomas Hellström's avatar Thomas Hellström Committed by Rodrigo Vivi
Browse files

drm/xe/bo: Avoid creating a system resource when allocating a fresh VRAM bo 



When creating a new bo, on the first move the bo->resource is typically
NULL. Our move callback rejected that instructing TTM to create a system
resource. In addition a struct ttm_tt with a page-vector was created,
although not populated with pages. Similarly when the clearing of VRAM
was complete, the system resource was put on a ghost object and freed
using the TTM delayed destroy mechanism.

This is a lot of pointless work. So avoid creating the system resource and
instead change the code to cope with a NULL bo->resource.

v2:
- Add some code comments (Matthew Brost)
v3:
- Fix a dereference of old_mem which might be NULL.

Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230626181741.32820-3-thomas.hellstrom@linux.intel.com


Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent bc2e0215

drivers/gpu/drm/xe/xe_bo.c

+27 −21
Original line number Diff line number Diff line
@@ -479,7 +479,6 @@ static int xe_bo_trigger_rebind(struct xe_device *xe, struct xe_bo *bo, 
 * to unconditionally call unmap_attachment() when moving out to system.

 */

static int xe_bo_move_dmabuf(struct ttm_buffer_object *ttm_bo,

			     struct ttm_resource *old_res,

			     struct ttm_resource *new_res)

{

	struct dma_buf_attachment *attach = ttm_bo->base.import_attach;
@@ -564,6 +563,7 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
	struct xe_device *xe = ttm_to_xe_device(ttm_bo->bdev);

	struct xe_bo *bo = ttm_to_xe_bo(ttm_bo);

	struct ttm_resource *old_mem = ttm_bo->resource;

	u32 old_mem_type = old_mem ? old_mem->mem_type : XE_PL_SYSTEM;

	struct ttm_tt *ttm = ttm_bo->ttm;

	struct xe_tile *tile = NULL;

	struct dma_fence *fence;
@@ -572,35 +572,29 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
	bool needs_clear;

	int ret = 0;



	if (!old_mem) {

		if (new_mem->mem_type != TTM_PL_SYSTEM) {

			hop->mem_type = TTM_PL_SYSTEM;

			hop->flags = TTM_PL_FLAG_TEMPORARY;

			ret = -EMULTIHOP;

			goto out;

		}



	/* Bo creation path, moving to system or TT. No clearing required. */

	if (!old_mem && ttm) {

		ttm_bo_move_null(ttm_bo, new_mem);

		goto out;

		return 0;

	}



	if (ttm_bo->type == ttm_bo_type_sg) {

		ret = xe_bo_move_notify(bo, ctx);

		if (!ret)

			ret = xe_bo_move_dmabuf(ttm_bo, old_mem, new_mem);

			ret = xe_bo_move_dmabuf(ttm_bo, new_mem);

		goto out;

	}



	tt_has_data = ttm && (ttm_tt_is_populated(ttm) ||

			      (ttm->page_flags & TTM_TT_FLAG_SWAPPED));



	move_lacks_source = !resource_is_vram(old_mem) && !tt_has_data;

	move_lacks_source = !mem_type_is_vram(old_mem_type) && !tt_has_data;



	needs_clear = (ttm && ttm->page_flags & TTM_TT_FLAG_ZERO_ALLOC) ||

		(!ttm && ttm_bo->type == ttm_bo_type_device);



	if ((move_lacks_source && !needs_clear) ||

	    (old_mem->mem_type == XE_PL_SYSTEM &&

	    (old_mem_type == XE_PL_SYSTEM &&

	     new_mem->mem_type == XE_PL_TT)) {

		ttm_bo_move_null(ttm_bo, new_mem);

		goto out;
@@ -610,7 +604,7 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
	 * Failed multi-hop where the old_mem is still marked as

	 * TTM_PL_FLAG_TEMPORARY, should just be a dummy move.

	 */

	if (old_mem->mem_type == XE_PL_TT &&

	if (old_mem_type == XE_PL_TT &&

	    new_mem->mem_type == XE_PL_TT) {

		ttm_bo_move_null(ttm_bo, new_mem);

		goto out;
@@ -622,7 +616,7 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
			goto out;

	}



	if (old_mem->mem_type == XE_PL_TT &&

	if (old_mem_type == XE_PL_TT &&

	    new_mem->mem_type == XE_PL_SYSTEM) {

		long timeout = dma_resv_wait_timeout(ttm_bo->base.resv,

						     DMA_RESV_USAGE_BOOKKEEP,
@@ -637,8 +631,8 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
	}



	if (!move_lacks_source &&

	    ((old_mem->mem_type == XE_PL_SYSTEM && resource_is_vram(new_mem)) ||

	     (resource_is_vram(old_mem) &&

	    ((old_mem_type == XE_PL_SYSTEM && resource_is_vram(new_mem)) ||

	     (mem_type_is_vram(old_mem_type) &&

	      new_mem->mem_type == XE_PL_SYSTEM))) {

		hop->fpfn = 0;

		hop->lpfn = 0;
@@ -652,8 +646,8 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
		tile = bo->tile;

	else if (resource_is_vram(new_mem))

		tile = mem_type_to_tile(xe, new_mem->mem_type);

	else if (resource_is_vram(old_mem))

		tile = mem_type_to_tile(xe, old_mem->mem_type);

	else if (mem_type_is_vram(old_mem_type))

		tile = mem_type_to_tile(xe, old_mem_type);



	XE_BUG_ON(!tile);

	XE_BUG_ON(!tile->migrate);
@@ -703,8 +697,20 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict, 
			xe_device_mem_access_put(xe);

			goto out;

		}

		ret = ttm_bo_move_accel_cleanup(ttm_bo, fence, evict, true,

						new_mem);

		if (!move_lacks_source) {

			ret = ttm_bo_move_accel_cleanup(ttm_bo, fence, evict,

							true, new_mem);

		} else {

			/*

			 * ttm_bo_move_accel_cleanup() may blow up if

			 * bo->resource == NULL, so just attach the

			 * fence and set the new resource.

			 */

			dma_resv_add_fence(ttm_bo->base.resv, fence,

					   DMA_RESV_USAGE_KERNEL);

			ttm_bo_move_null(ttm_bo, new_mem);

		}



		dma_fence_put(fence);

	}