Re: [PATCH v2 07/11] drm/xe/sriov: Add debugfs with scheduler groups information

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 12/7/2025 12:04 AM, Daniele Ceraolo Spurio wrote:
> Under a new subfolder, an entry is created for each group to list the
> engines assigned to them. We create enough entries for each possible
> group, with the disabled groups just returning an empty list.
> 
> v2: drop subfolders, always register debugfs for all groups (Michal)
> 
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c | 70 +++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c
> index 1be23809e624..15f5f3a40471 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c
> @@ -163,6 +163,10 @@ static void pf_add_policy_attrs(struct xe_gt *gt, struct dentry *parent)
>   *          :   ├── tile0
>   *              :   ├── gt0
>   *                  :   ├── sched_groups_mode
> + *                      ├── sched_groups
> + *                      :   ├── group0
> + *                          :
> + *                          └── groupN
>   */
>  
>  static const char *sched_group_mode_to_string(enum xe_sriov_sched_group_modes mode)
> @@ -260,8 +264,60 @@ static const struct file_operations sched_groups_fops = {
>  	.release = single_release,
>  };
>  
> +static ssize_t sched_group_engines_read(struct file *file, char __user *buf,
> +					size_t count, loff_t *ppos)
> +{
> +	struct dentry *dent = file_dentry(file);
> +	struct xe_gt *gt = extract_gt(dent->d_parent);
> +	struct xe_gt_sriov_scheduler_groups *groups = &gt->sriov.pf.policy.guc.sched_groups;
> +	u32 num_masks = groups->modes[groups->current_mode].num_masks;
> +	u32 *masks = groups->modes[groups->current_mode].masks;
> +	unsigned int group = GUC_MAX_SCHED_GROUPS;
> +	struct xe_hw_engine *hwe;
> +	enum xe_hw_engine_id id;
> +	char engines[128];
> +	int ret;
> +
> +	ret = sscanf(dent->d_name.name, "group%u", &group);

see below

> +	xe_gt_assert(gt, ret == 1 && group < GUC_MAX_SCHED_GROUPS);
> +
> +	engines[0] = '\0';
> +
> +	/* If there are no masks it means that all the engines are in group 0 */
> +	if (num_masks >= (group + 1) * GUC_MAX_ENGINE_CLASSES) {
> +		for_each_hw_engine(hwe, gt, id) {
> +			u8 guc_class = xe_engine_class_to_guc_class(hwe->class);
> +			u32 mask = masks[group * GUC_MAX_ENGINE_CLASSES + guc_class];
> +
> +			if (mask & BIT(hwe->logical_instance)) {
> +				strlcat(engines, hwe->name, sizeof(engines));
> +				strlcat(engines, " ", sizeof(engines));
> +			}
> +		}
> +		strlcat(engines, "\n", sizeof(engines));
> +	} else if (group == 0) {
> +		for_each_hw_engine(hwe, gt, id) {
> +			strlcat(engines, hwe->name, sizeof(engines));
> +			strlcat(engines, " ", sizeof(engines));
> +		}
> +		strlcat(engines, "\n", sizeof(engines));
> +	}
> +
> +	return simple_read_from_buffer(buf, count, ppos, engines, strlen(engines));
> +}
> +
> +static const struct file_operations sched_group_engines_fops = {
> +	.owner = THIS_MODULE,
> +	.open = simple_open,
> +	.read = sched_group_engines_read,
> +	.llseek = default_llseek,
> +};
> +
>  static void pf_add_sched_groups(struct xe_gt *gt, struct dentry *parent)
>  {
> +	struct dentry *groups;
> +	u8 g;

no cryptic names, please ;)

> +
>  	xe_gt_assert(gt, gt == extract_gt(parent));
>  	xe_gt_assert(gt, PFID == extract_vfid(parent));
>  
> @@ -274,11 +330,25 @@ static void pf_add_sched_groups(struct xe_gt *gt, struct dentry *parent)
>  	 * We should rework the flow so that debugfs is registered after the
>  	 * policy init, so that we check if there are valid groups before
>  	 * adding the debugfs files.
> +	 * Similarly, instead of using GUC_MAX_SCHED_GROUPS we could use
> +	 * gt->sriov.pf.policy.guc.sched_groups.max_number_of_groups.
>  	 */
>  	if (!xe_sriov_gt_pf_policy_has_sched_groups_support(gt))
>  		return;
>  
>  	debugfs_create_file("sched_groups_mode", 0644, parent, parent, &sched_groups_fops);
> +
> +	groups = debugfs_create_dir("sched_groups", parent);
> +	if (IS_ERR(groups))
> +		return;
> +	groups->d_inode->i_private = gt;

no need to store gt here, you can grab it from

	parent->d_parent
or
	parent->d_parent->d_parent

> +
> +	for (g = 0; g < GUC_MAX_SCHED_GROUPS; g++) {
> +		char name[10];
> +
> +		snprintf(name, sizeof(name), "group%u", g);
> +		debugfs_create_file(name, 0644, groups, parent, &sched_group_engines_fops);

why storing 'parent' as private data? 

better store group index there so you will not need to sscanf it back

and parent can always be retrieved from the dentry

> +	}
>  }
>  
>  /*