Re: [PATCH i-g-t 3/5] lib/xe/xe_sriov_admin: Add SR-IOV admin sysfs accessors

["Bernatowicz, Marcin" <marcin.bernatowicz@linux.intel.com>]

On 11/14/2025 8:53 PM, Michal Wajdeczko wrote:
>
> On 11/14/2025 8:07 PM, Marcin Bernatowicz wrote:
>> Reflect recent kernel changes and expose SR-IOV admin sysfs helpers for
>> scheduling control. Add per-VF and bulk accessors for execution quantum,
>> preemption timeout, scheduling priority, VF stop and restoring defaults.
>>
>> Link: https://lore.kernel.org/intel-xe/20251030222348.186658-1-michal.wajdeczko@intel.com/
>> Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
>> Cc: Adam Miszczak <adam.miszczak@linux.intel.com>
>> Cc: Jakub Kolakowski <jakub1.kolakowski@intel.com>
>> Cc: Lukasz Laguna <lukasz.laguna@intel.com>
>> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> ---
> ...
>
>> +
>> +/* Parse a raw sched_priority line into current priority enum (required) and optional mask.
>> + * Behavior:
>> + *  - If prio_mask == NULL: validate only the bracketed (current) priority; ignore unknown others.
>> + *  - If prio_mask != NULL: validate all priorities; unknown priority causes -EOPNOTSUPP.
>> + * Returns 0 on success, -EOPNOTSUPP on semantic issues, or other -errno from callers.
>> + */
>> +static int parse_sched_prio_line(const char *line,
>> +				 enum xe_sriov_sched_priority *cur_prio,
>> +				 unsigned int *prio_mask)
> the idea behind
>
> 	"When read, this file will display the current and available
> 	scheduling priorities. The currently active priority level will
> 	be enclosed in square brackets"
>
> was that in the future we might want to add new priorities or the
> list of supported priorities will change based on the platform or
> firmware capability
>
> so you should start by adding a function that just looks for the item
> "enclosed in square brackets" and return it, and/or other function
> that will return list of all parsed items and the pointer to the
> selected item
>
> then in other function you can try to match returned string to your
> priority enum and decide whether you support that priority
> or just rely on the returned string everywhere
Thanks, makes sense.

I'll split this into two parts:

- Bare token parser – returns all strings + the bracketed one, no enum
   mapping, tolerant to unknown priorities. This will be used for ABI/format
   checks and to handle future FW/platform extensions.

- Strict helper on top – map known strings to our enum, build the mask, and
   return -EOPNOTSUPP when the current token or any masked token is unknown.
   This matches the existing enum-based helpers used by tests that need to
   understand LOW/NORMAL/HIGH semantics.

This should give us a future-proof parser while keeping the current strict
behaviour where tests depend on it.

>
>> +{
>> +	enum xe_sriov_sched_priority e;
>> +	const char *p = line, *start;
>> +	unsigned int mask = 0;
>> +	bool bracketed, have_cur = false;
>> +	char tok[16];
>> +	size_t len;
>> +
>> +	igt_assert(line && cur_prio);
>> +
>> +	while (*p) {
>> +		while (*p == ' ' || *p == '\t')
>> +			p++;
>> +		if (!*p)
>> +			break;
>> +
>> +		bracketed = (*p == '[');
>> +		start = p + (bracketed ? 1 : 0);
>> +
>> +		if (bracketed) {
>> +			while (*p && *p != ']')
>> +				p++;
>> +		} else {
>> +			while (*p && *p != ' ' && *p != '\t')
>> +				p++;
>> +		}
>> +
>> +		/* token bounds: [start, p) */
>> +		len = (size_t)(p - start);
>> +		if (len >= sizeof(tok))
>> +			len = sizeof(tok) - 1;
>> +		memcpy(tok, start, len);
>> +		tok[len] = '\0';
>> +
>> +		/* map token -> enum */
>> +		if (!xe_sriov_sched_priority_from_string(tok, &e)) {
>> +			if (e == XE_SRIOV_SCHED_PRIORITY_LOW)
>> +				mask |= XE_SRIOV_SCHED_PRIORITY_MASK_LOW;
>> +			else if (e == XE_SRIOV_SCHED_PRIORITY_NORMAL)
>> +				mask |= XE_SRIOV_SCHED_PRIORITY_MASK_NORMAL;
>> +			else if (e == XE_SRIOV_SCHED_PRIORITY_HIGH)
>> +				mask |= XE_SRIOV_SCHED_PRIORITY_MASK_HIGH;
>> +
>> +			if (bracketed) {
>> +				*cur_prio = e;
>> +				have_cur = true;
>> +			}
>> +		} else {
>> +			if (bracketed) {
>> +				igt_debug("unknown current scheduling priority '%s' (line='%s')\n",
>> +					  tok, line);
>> +				return -EOPNOTSUPP;
>> +			}
>> +
>> +			if (prio_mask) {
>> +				igt_debug("unknown scheduling priority '%s' (line='%s')\n",
>> +					  tok, line);
>> +				return -EOPNOTSUPP;
>> +			}
>> +
>> +			igt_debug("ignoring unknown scheduling priority '%s' (line='%s')\n",
>> +				  tok, line);
>> +		}
>> +
>> +		if (*p)
>> +			p++; /* skip ']' or the delimiter */
>> +	}
>> +
>> +	if (!have_cur)
>> +		return -EOPNOTSUPP;
>> +
>> +	if (prio_mask)
>> +		*prio_mask = mask;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * __xe_sriov_profile_get_sched_priority - Read VF scheduling priority + mask
>> + * @pf_fd:     PF device file descriptor.
>> + * @vf_num:    VF index (0 for PF, >0 for VFs).
>> + * @prio:      Output pointer for the effective priority.
>> + * @prio_mask: Output mask of allowed priorities.
>> + *
>> + * Returns: 0 on success or negative errno on error.
>> + */
>> +int __xe_sriov_profile_get_sched_priority(int pf_fd, unsigned int vf_num,
>> +					  enum xe_sriov_sched_priority *cur_prio,
>> +					  unsigned int *prio_mask)
>> +{
>> +	char path[PATH_MAX];
>> +	char line[256] = { 0 };
>> +	int sysfs, ret;
>> +
>> +	igt_assert(cur_prio);
>> +
>> +	sysfs = igt_sysfs_open(pf_fd);
>> +	if (sysfs < 0)
>> +		return sysfs;
>> +
>> +	fmt_profile_rel_path(path, sizeof(path), vf_num,
>> +			     "profile/sched_priority");
>> +	ret = igt_sysfs_scanf(sysfs, path, "%255[^\n]", line);
>> +	close(sysfs);
>> +
>> +	ret = ret_from_scanf_items(ret, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = parse_sched_prio_line(line, cur_prio, prio_mask);
>> +	if (ret)
>> +		igt_debug("sched prio: parse/map failed (err=%d), line='%s'\n",
>> +			  ret, line);
>> +	return ret;
>> +}
>> +
>> +/**
>> + * xe_sriov_profile_get_sched_priority - Assert wrapper for reading VF priority
>> + * @pf_fd:     PF device file descriptor.
>> + * @vf_num:    VF index (0 for PF, >0 for VFs).
>> + * @prio_mask: Output mask of supported priorities.
>> + *
>> + * Returns: effective priority; asserts on error.
>> + */
>> +enum xe_sriov_sched_priority
>> +xe_sriov_profile_get_sched_priority(int pf_fd, unsigned int vf_num,
>> +				    unsigned int *prio_mask)
>> +{
>> +	enum xe_sriov_sched_priority cur_prio;
>> +
>> +	igt_assert_eq(0,
>> +		      __xe_sriov_profile_get_sched_priority(pf_fd, vf_num, &cur_prio, prio_mask));
>> +
>> +	return cur_prio;
>> +}
>> +