drm/xe: Add xe_ttm_access_memory

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 <christoph.manszewski@intel.com>
Suggested-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241126174615.2665852-4-matthew.brost@intel.com

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index aaf54131c89e402673a96d4f72dd8e1447f33548..9de28798ad1cc6e55d9f6ecfe1823499e82fbcee 100644 (file)
--- 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,