[Intel-xe] [PATCH v2 1/1] drm/xe: Add a debugfs for faking gt reset failure.

[Francois Dugast]

On Mon, May 29, 2023 at 06:03:10PM +0530, Himal Prasad Ghimiray wrote:
> In case of gt reset failure, KMD notifies userspace about failure
> via uevent. To validate this notification we need to ensure gt
> reset fails and there is no mechanism to cause failure from hardware.
> Hence added a debugfs which will cause fake reset failure.
> 
> v1(Rodrigo)
> - Change the variable to fake_reset_failure_in_progress.
> - Drop usage of READ_ONCE and WRITE_ONCE.
> - Follow consistency for variable assignment. Either use
>   functions for all the assignments or don't use for any.
> 
> v2
> - Add description for variable.
> - Define xe_fake_reset(gt) function in xe_gt.c to set the
>   fake_reset_failure_in_progress.
> - No need to explicitly initialize the fake_reset_failure_in_progress
>   as false. (Rodrigo)
> - Return proper error code in case of fake reset. (Bala)
> 
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> cc: Francois Dugast <francois.dugast at intel.com>
> Cc: Mauro Carvalho Chehab <mchehab at kernel.org>
> Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan at intel.com>
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>

Rodrigo's comments were addressed. This debugfs will be moved to
danger_debugfs_list when available. LGTM.

Reviewed-by: Francois Dugast <francois.dugast at intel.com>

> ---
>  drivers/gpu/drm/xe/xe_gt.c         | 13 +++++++++++++
>  drivers/gpu/drm/xe/xe_gt.h         |  1 +
>  drivers/gpu/drm/xe/xe_gt_debugfs.c | 11 +++++++++++
>  drivers/gpu/drm/xe/xe_gt_types.h   |  5 +++++
>  4 files changed, 30 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
> index 18eda5b1377f..626d5e9f0520 100644
> --- a/drivers/gpu/drm/xe/xe_gt.c
> +++ b/drivers/gpu/drm/xe/xe_gt.c
> @@ -596,6 +596,11 @@ static int do_gt_restart(struct xe_gt *gt)
>  	return 0;
>  }
>  
> +void xe_gt_fake_reset(struct xe_gt *gt)
> +{
> +	gt->reset.fake_reset_failure_in_progress = true;
> +}
> +
>  static int gt_reset(struct xe_gt *gt)
>  {
>  	int err;
> @@ -609,6 +614,14 @@ static int gt_reset(struct xe_gt *gt)
>  	xe_gt_sanitize(gt);
>  
>  	xe_device_mem_access_get(gt_to_xe(gt));
> +
> +	if (gt->reset.fake_reset_failure_in_progress) {
> +		err = -ECANCELED;
> +		xe_gt_info(gt, "Fake GT reset failure is in progress\n");
> +		gt->reset.fake_reset_failure_in_progress = false;
> +		goto err_msg;
> +	}
> +
>  	err = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
>  	if (err)
>  		goto err_msg;
> diff --git a/drivers/gpu/drm/xe/xe_gt.h b/drivers/gpu/drm/xe/xe_gt.h
> index 086369f7ee6d..2031008aa57f 100644
> --- a/drivers/gpu/drm/xe/xe_gt.h
> +++ b/drivers/gpu/drm/xe/xe_gt.h
> @@ -25,6 +25,7 @@ void xe_gt_suspend_prepare(struct xe_gt *gt);
>  int xe_gt_suspend(struct xe_gt *gt);
>  int xe_gt_resume(struct xe_gt *gt);
>  void xe_gt_reset_async(struct xe_gt *gt);
> +void xe_gt_fake_reset(struct xe_gt *gt);
>  void xe_gt_migrate_wait(struct xe_gt *gt);
>  void xe_gt_sanitize(struct xe_gt *gt);
>  
> diff --git a/drivers/gpu/drm/xe/xe_gt_debugfs.c b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> index 339ecd5fad9b..cf2896858d36 100644
> --- a/drivers/gpu/drm/xe/xe_gt_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> @@ -138,6 +138,16 @@ static int workarounds(struct seq_file *m, void *data)
>  	return 0;
>  }
>  
> +static int fake_reset_failure(struct seq_file *m, void *data)
> +{
> +	struct xe_gt *gt = node_to_gt(m->private);
> +
> +	xe_gt_fake_reset(gt);
> +	xe_gt_reset_async(gt);
> +
> +	return 0;
> +}
> +
>  static const struct drm_info_list debugfs_list[] = {
>  	{"hw_engines", hw_engines, 0},
>  	{"force_reset", force_reset, 0},
> @@ -147,6 +157,7 @@ static const struct drm_info_list debugfs_list[] = {
>  	{"ggtt", ggtt, 0},
>  	{"register-save-restore", register_save_restore, 0},
>  	{"workarounds", workarounds, 0},
> +	{"fake_reset_failure", fake_reset_failure, 0},
>  };
>  
>  void xe_gt_debugfs_register(struct xe_gt *gt)
> diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
> index b83c834e7ced..3e0e9ad4f0c3 100644
> --- a/drivers/gpu/drm/xe/xe_gt_types.h
> +++ b/drivers/gpu/drm/xe/xe_gt_types.h
> @@ -168,6 +168,11 @@ struct xe_gt {
>  
>  	/** @reset: state for GT resets */
>  	struct {
> +		/**
> +		 * @fake_reset_failure_in_progress: A bool to indicate a fake reset
> +		 * failure has been triggered
> +		 */
> +		bool fake_reset_failure_in_progress;
>  		/**
>  		 * @worker: work so GT resets can done async allowing to reset
>  		 * code to safely flush all code paths
> -- 
> 2.25.1
>