Re: [RFC PATCH V7 04/10] drm/xe: Link LRC BO and its execution Queue

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Apr 16, 2026 at 01:19:53PM +0530, Tejas Upadhyay wrote:
> To establish a link between an LRC BO (Logical Ring Context
> Buffer Object) and its corresponding execution Queue in the
> drm/xe driver, you need to store a back-pointer to the queue
> within the BO's private data structure. This allows the
> driver to identify and take corrective action on the specific
> queue if the LRC BO encounters an error (e.g., memory
> corruption or eviction issues).
> 
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_bo_types.h   | 3 +++
>  drivers/gpu/drm/xe/xe_exec_queue.c | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo_types.h b/drivers/gpu/drm/xe/xe_bo_types.h
> index 9d19940b8fc0..a647b775a65c 100644
> --- a/drivers/gpu/drm/xe/xe_bo_types.h
> +++ b/drivers/gpu/drm/xe/xe_bo_types.h
> @@ -20,6 +20,7 @@
>  struct xe_device;
>  struct xe_mem_pool_node;
>  struct xe_vm;
> +struct xe_exec_queue;
>  
>  #define XE_BO_MAX_PLACEMENTS	3
>  
> @@ -40,6 +41,8 @@ struct xe_bo {
>  	u32 flags;
>  	/** @vm: VM this BO is attached to, for extobj this will be NULL */
>  	struct xe_vm *vm;
> +	/** @q: Queue this BO is attached to, mostly for LRC BO, NULL otherwise */
> +	struct xe_exec_queue *q;
>  	/** @tile: Tile this BO is attached to (kernel BO only) */
>  	struct xe_tile *tile;
>  	/** @placements: valid placements for this BO */
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
> index 071b8c41df43..632c9603afc1 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -386,6 +386,7 @@ static int __xe_exec_queue_init(struct xe_exec_queue *q, u32 exec_queue_flags)
>  				goto err_lrc;
>  			}
>  
> +			lrc->bo->q = q;

I think we need a comment why this is safe.. Something like:

/*
 * The queue ref counts the LRCs, thus it safe for the LRC BO to hold a
 * pointer to queue without reference.
 */
lrc->bo->q = q;

Multi-q comes into play here... So I think the assignment
should actually be:

lrc->bo->q = xe_exec_queue_multi_queue_primary(q);

Then to be paranoid in xe_lrc_finish:

lrc->bo->q = NULL;

Before calling: xe_bo_unpin_map_no_vm(lrc->bo);

Matt

>  			xe_exec_queue_set_lrc(q, lrc, i);
>  
>  			if (__lrc)
> -- 
> 2.52.0
>