Re: [PATCH v2 01/29] ACPI / PPTT: Add a helper to fill a cpumask from a processor container

James Morse
2025-10-10T16:54:35Z

Hi Stan,

On 25/09/2025 10:32, Stanimir Varbanov wrote:
> On 9/10/25 11:42 PM, James Morse wrote:
>> The ACPI MPAM table uses the UID of a processor container specified in
>> the PPTT to indicate the subset of CPUs and cache topology that can
>> access each MPAM System Component (MSC).
>>
>> This information is not directly useful to the kernel. The equivalent
>> cpumask is needed instead.
>>
>> Add a helper to find the processor container by its id, then walk
>> the possible CPUs to fill a cpumask with the CPUs that have this
>> processor container as a parent.

>> +
>> +/**
>> + * acpi_pptt_get_cpus_from_container() - Populate a cpumask with all CPUs in a
>> + * processor container
>> + * @acpi_cpu_id: The UID of the processor container.
>> + * @cpus: The resulting CPU mask.
>> + *
>> + * Find the specified Processor Container, and fill @cpus with all the cpus
>> + * below it.
>> + *
>> + * Not all 'Processor' entries in the PPTT are either a CPU or a Processor
>> + * Container, they may exist purely to describe a Private resource. CPUs
>> + * have to be leaves, so a Processor Container is a non-leaf that has the
>> + * 'ACPI Processor ID valid' flag set.
>> + *
>> + * Return: 0 for a complete walk, or an error if the mask is incomplete.
>
> Leftover, drop this.

Good spot - thanks,

James