Re: [PATCH 6/7] drm/xe: Don't block messages to the GPU scheduler

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

On Mon, Oct 13, 2025 at 04:25:03PM +0000, Stuart Summers wrote:
> Right now we are using the state of the GPU scheduler
> to determine whether we send and receive messages. There
> are some states, however, where we might intentionally
> pause the scheduler, like a device wedge, and expect that
> messages are resumed later once the user has taken the
> hardware state and is attempting to reset, like an unbind.
> 
> Remove these checks in the XeKMD and let the GPU scheduler
> handle state checks internally.
> 

We can't do this. The entire queue stop / starting mechanism relies on
getting exclusive access to the queue by ensuring the scheduler is fully
stopped - this includes messages. This will break job timeouts, GT reset
flows, and VF migration.

What exactly is the problem you are trying to solve? The device is
wedged and queues are stopped, then an unbind occurs? That is probably a
bug. IIRC even wedging a device / tearing down a queue we should always
start the queue again. We could assert in guc_submit_wedged_fini that
all queues are not paused.

Also if you having issues on unbind - there is this patch [1] which
fixes an issue too. I'm going to merge [1] now.

Matt

[1] https://patchwork.freedesktop.org/series/155417/

> Signed-off-by: Stuart Summers <stuart.summers@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gpu_scheduler.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.c b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> index f91e06d03511..d9d6fb641188 100644
> --- a/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
> @@ -7,8 +7,7 @@
>  
>  static void xe_sched_process_msg_queue(struct xe_gpu_scheduler *sched)
>  {
> -	if (!READ_ONCE(sched->base.pause_submit))
> -		queue_work(sched->base.submit_wq, &sched->work_process_msg);
> +	queue_work(sched->base.submit_wq, &sched->work_process_msg);
>  }
>  
>  static void xe_sched_process_msg_queue_if_ready(struct xe_gpu_scheduler *sched)
> @@ -43,9 +42,6 @@ static void xe_sched_process_msg_work(struct work_struct *w)
>  		container_of(w, struct xe_gpu_scheduler, work_process_msg);
>  	struct xe_sched_msg *msg;
>  
> -	if (READ_ONCE(sched->base.pause_submit))
> -		return;
> -
>  	msg = xe_sched_get_msg(sched);
>  	if (msg) {
>  		sched->ops->process_msg(msg);
> -- 
> 2.34.1
>