[v7,3/8] drm/xe: Add xe_ttm_access_memory

Commit Message

Matthew Brost Nov. 26, 2024, 5:46 p.m. UTC

Non-contiguous VRAM cannot easily be mapped in TTM nor can non-visible
VRAM easily be accessed. Add xe_ttm_access_memory which hooks into
ttm_bo_access to access such memory.

v4:
 - Assert memory access rather than taking RPM ref (Thomas / Auld)
 - Fix warning on xe_res_cursor.h for non-zero offset (Mika)

Reported-by: Christoph Manszewski <[e-mail]>
Suggested-by: Thomas Hellström <[e-mail]>
Signed-off-by: Matthew Brost <[e-mail]>
Reviewed-by: Matthew Auld <[e-mail]>
---
 drivers/gpu/drm/xe/xe_bo.c | 59 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 56 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index aaf54131c89e..9de28798ad1c 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -442,6 +442,14 @@  static void xe_ttm_tt_destroy(struct ttm_device *ttm_dev, struct ttm_tt *tt)
 	kfree(tt);
 }
 
+static bool xe_ttm_resource_visible(struct ttm_resource *mem)
+{
+	struct xe_ttm_vram_mgr_resource *vres =
+		to_xe_ttm_vram_mgr_resource(mem);
+
+	return vres->used_visible_size == mem->size;
+}
+
 static int xe_ttm_io_mem_reserve(struct ttm_device *bdev,
 				 struct ttm_resource *mem)
 {
@@ -453,11 +461,9 @@  static int xe_ttm_io_mem_reserve(struct ttm_device *bdev,
 		return 0;
 	case XE_PL_VRAM0:
 	case XE_PL_VRAM1: {
-		struct xe_ttm_vram_mgr_resource *vres =
-			to_xe_ttm_vram_mgr_resource(mem);
 		struct xe_mem_region *vram = res_to_mem_region(mem);
 
-		if (vres->used_visible_size < mem->size)
+		if (!xe_ttm_resource_visible(mem))
 			return -EINVAL;
 
 		mem->bus.offset = mem->start << PAGE_SHIFT;
@@ -1121,6 +1127,52 @@  static void xe_ttm_bo_swap_notify(struct ttm_buffer_object *ttm_bo)
 	}
 }
 
+static int xe_ttm_access_memory(struct ttm_buffer_object *ttm_bo,
+				unsigned long offset, void *buf, int len,
+				int write)
+{
+	struct xe_bo *bo = ttm_to_xe_bo(ttm_bo);
+	struct xe_device *xe = ttm_to_xe_device(ttm_bo->bdev);
+	struct iosys_map vmap;
+	struct xe_res_cursor cursor;
+	struct xe_mem_region *vram;
+	int bytes_left = len;
+
+	xe_bo_assert_held(bo);
+	xe_device_assert_mem_access(xe);
+
+	if (!mem_type_is_vram(ttm_bo->resource->mem_type))
+		return -EIO;
+
+	/* FIXME: Use GPU for non-visible VRAM */
+	if (!xe_ttm_resource_visible(ttm_bo->resource))
+		return -EIO;
+
+	vram = res_to_mem_region(ttm_bo->resource);
+	xe_res_first(ttm_bo->resource, offset & PAGE_MASK,
+		     bo->size - (offset & PAGE_MASK), &cursor);
+
+	do {
+		unsigned long page_offset = (offset & ~PAGE_MASK);
+		int byte_count = min((int)(PAGE_SIZE - page_offset), bytes_left);
+
+		iosys_map_set_vaddr_iomem(&vmap, (u8 __iomem *)vram->mapping +
+					  cursor.start);
+		if (write)
+			xe_map_memcpy_to(xe, &vmap, page_offset, buf, byte_count);
+		else
+			xe_map_memcpy_from(xe, buf, &vmap, page_offset, byte_count);
+
+		buf += byte_count;
+		offset += byte_count;
+		bytes_left -= byte_count;
+		if (bytes_left)
+			xe_res_next(&cursor, PAGE_SIZE);
+	} while (bytes_left);
+
+	return len;
+}
+
 const struct ttm_device_funcs xe_ttm_funcs = {
 	.ttm_tt_create = xe_ttm_tt_create,
 	.ttm_tt_populate = xe_ttm_tt_populate,
@@ -1130,6 +1182,7 @@  const struct ttm_device_funcs xe_ttm_funcs = {
 	.move = xe_bo_move,
 	.io_mem_reserve = xe_ttm_io_mem_reserve,
 	.io_mem_pfn = xe_ttm_io_mem_pfn,
+	.access_memory = xe_ttm_access_memory,
 	.release_notify = xe_ttm_bo_release_notify,
 	.eviction_valuable = ttm_bo_eviction_valuable,
 	.delete_mem_notify = xe_ttm_bo_delete_mem_notify,