[PATCH] drm/ttm: warn when resv objs are mixed in a bulk_move

[Thomas Hellström]

On Tue, 2024-03-12 at 11:55 +0100, Christian König wrote:
> The BOs in a bulk move must share all the same reservation object
> to make sure that we lock the whole bulk during eviction.
> 
> Actually document and enforce that with a warning.
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>

Tested with Xe CI,

Reviewed-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>





> ---
>  drivers/gpu/drm/ttm/ttm_resource.c | 1 +
>  include/drm/ttm/ttm_resource.h     | 3 +++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_resource.c
> b/drivers/gpu/drm/ttm/ttm_resource.c
> index 65155f2013ca..be8d286513f9 100644
> --- a/drivers/gpu/drm/ttm/ttm_resource.c
> +++ b/drivers/gpu/drm/ttm/ttm_resource.c
> @@ -105,6 +105,7 @@ static void ttm_lru_bulk_move_add(struct
> ttm_lru_bulk_move *bulk,
>  		pos->first = res;
>  		pos->last = res;
>  	} else {
> +		WARN_ON(pos->first->bo->base.resv != res->bo-
> >base.resv);
>  		ttm_lru_bulk_move_pos_tail(pos, res);
>  	}
>  }
> diff --git a/include/drm/ttm/ttm_resource.h
> b/include/drm/ttm/ttm_resource.h
> index 7561023db43d..69769355139f 100644
> --- a/include/drm/ttm/ttm_resource.h
> +++ b/include/drm/ttm/ttm_resource.h
> @@ -251,6 +251,9 @@ struct ttm_lru_bulk_move_pos {
>   *
>   * Container for the current bulk move state. Should be used with
>   * ttm_lru_bulk_move_init() and ttm_bo_set_bulk_move().
> + * All BOs in a bulk_move structure need to share the same
> reservation object to
> + * ensure that the bulk as a whole is locked for eviction even if
> only one BO of
> + * the bulk is evicted.
>   */
>  struct ttm_lru_bulk_move {
>  	struct ttm_lru_bulk_move_pos
> pos[TTM_NUM_MEM_TYPES][TTM_MAX_BO_PRIORITY];