Re: [PATCH v2 1/2] drm/xe/guc: distinguish wedged from recoverable cancellation

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

On Thu, Jun 25, 2026 at 01:16:20AM +0530, Sk Anirban wrote:
> The CT layer returns -ECANCELED regardless of whether cancellation
> is due to a GT reset or a wedged device. Return -ENOTRECOVERABLE
> on wedge so callers don't need xe_device_wedged() checks
> to suppress spurious error logs.
> Also document the return codes of xe_guc_ct_send() in kernel-doc form.
> 
> v2: Fix -ECANCELED description (Matt)
> 
> Signed-off-by: Sk Anirban <sk.anirban@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_guc_ct.c | 40 +++++++++++++++++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index 21e0dad9a481..8ca7d37c79b6 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -1065,6 +1065,11 @@ static int __guc_ct_send_locked(struct xe_guc_ct *ct, const u32 *action,
>  	xe_gt_assert(gt, g2h_len || !num_g2h);
>  	lockdep_assert_held(&ct->lock);
>  
> +	if (xe_device_wedged(ct_to_xe(ct))) {
> +		ret = -ENOTRECOVERABLE;
> +		goto out;
> +	}
> +
>  	if (unlikely(ct->ctbs.h2g.info.broken)) {
>  		ret = -EPIPE;
>  		goto out;
> @@ -1236,6 +1241,36 @@ static int guc_ct_send(struct xe_guc_ct *ct, const u32 *action, u32 len,
>  	return ret;
>  }
>  
> +/**
> + * xe_guc_ct_send - Send an HXG message to the GuC over CT
> + * @ct: the &xe_guc_ct
> + * @action: dword array with the HXG message (can't be NULL)
> + * @len: length of the HXG message in dwords (can't be 0)
> + * @g2h_len: G2H response space to reserve in dwords, or 0
> + * @num_g2h: number of G2H messages expected, or 0
> + *
> + * Return codes from the non-blocking send helpers are:
> + *
> + * * -ENOTRECOVERABLE: the xe device is wedged. Stop submitting new GuC work; the
> + *   request cannot make progress until the device is recovered.
> + * * -EPIPE: the H2G CTB is marked broken. The channel stays unusable until the
> + *   CT is restarted, which clears the broken flag.
> + * * -ENODEV: the CT channel is disabled, messages not expected in this state.
> + *   Don't retry until it is enabled again.
> + * * -ECANCELED: the CT channel is stopped or a GT recovery is pending; the
> + *   message was dropped. Often benign. Cancel-tolerant callers (e.g. TLB
> + *   invalidations, GuC submission) rely on the stop/start flow to recover;
> + *   others should retry once the CT is re-enabled or the reset/recovery
> + *   completes.
> + * * -EDEADLK: no CTB room and the wait for space timed out. The send helpers
> + *   have already requested an async GT reset before returning this error.
> + *
> + * -ENOMEM may also be returned if an internal allocation fails; the blocking
> + * xe_guc_ct_send_recv() path retries that allocation. -EBUSY and
> + * -EAGAIN are internal flow-control results handled by the send helpers.
> + *
> + * Return: 0 on success, or a negative error code on failure.
> + */
>  int xe_guc_ct_send(struct xe_guc_ct *ct, const u32 *action, u32 len,
>  		   u32 g2h_len, u32 num_g2h)
>  {
> @@ -1388,7 +1423,7 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
>  	if (g2h_fence.fail) {
>  		if (g2h_fence.cancel) {
>  			xe_gt_dbg(gt, "H2G request %#x canceled!\n", action[0]);
> -			ret = -ECANCELED;
> +			ret = xe_device_wedged(ct_to_xe(ct)) ? -ENOTRECOVERABLE : -ECANCELED;
>  			goto unlock;
>  		}
>  		xe_gt_err(gt, "H2G request %#x failed: error %#x hint %#x\n",
> @@ -1724,6 +1759,9 @@ static int g2h_read(struct xe_guc_ct *ct, u32 *msg, bool fast_path)
>  	xe_gt_assert(gt, xe_guc_ct_initialized(ct));
>  	lockdep_assert_held(&ct->fast_lock);
>  
> +	if (xe_device_wedged(xe))
> +		return -ENOTRECOVERABLE;
> +
>  	if (ct->state == XE_GUC_CT_STATE_DISABLED)
>  		return -ENODEV;
>  
> -- 
> 2.43.0
>