Re: [PATCH v2 22/29] arm_mpam: Add helpers to allocate monitors

James Morse
2025-10-06T14:57:23Z

Hi Jonathan,

On 12/09/2025 14:11, Jonathan Cameron wrote:
> On Wed, 10 Sep 2025 20:43:02 +0000
> James Morse <james.morse@arm.com> wrote:
>
>> MPAM's MSC support a number of monitors, each of which supports
>> bandwidth counters, or cache-storage-utilisation counters. To use
>> a counter, a monitor needs to be configured. Add helpers to allocate
>> and free CSU or MBWU monitors.
>>
>> Signed-off-by: James Morse <james.morse@arm.com>
>> Reviewed-by: Ben Horgan <ben.horgan@arm.com>
>
> One minor requested change inline that will probably otherwise get picked
> up by someone's cleanup script
>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

Thanks!

>> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
>> index 326ba9114d70..81c4c2bfea3d 100644
>> --- a/drivers/resctrl/mpam_internal.h
>> +++ b/drivers/resctrl/mpam_internal.h

>> +static inline int mpam_alloc_mbwu_mon(struct mpam_class *class)
>> +{
>> + struct mpam_props *cprops = &class->props;
>> +
>> + if (!mpam_has_feature(mpam_feat_msmon_mbwu, cprops))
>> + return -EOPNOTSUPP;
>> +
>> + return ida_alloc_range(&class->ida_mbwu_mon, 0,
>> + cprops->num_mbwu_mon - 1, GFP_KERNEL);
>
> ida_alloc_max() - which is just a wrapper that sets the minimum to 0
> but none the less perhaps conveys things slightly better.

Sure - I didn't spot that when I did this.

Thanks,

James