Re: [PATCH 04/33] ACPI / PPTT: Find cache level by cache-id

Gavin Shan
2025-11-08T05:11:50Z

On 11/7/25 10:34 PM, Ben Horgan wrote:
> From: James Morse <james.morse@arm.com>
>
> The MPAM table identifies caches by id. The MPAM driver also wants to know
> the cache level to determine if the platform is of the shape that can be
> managed via resctrl. Cacheinfo has this information, but only for CPUs that
> are online.
>
> Waiting for all CPUs to come online is a problem for platforms where
> CPUs are brought online late by user-space.
>
> Add a helper that walks every possible cache, until it finds the one
> identified by cache-id, then return the level.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> Signed-off-by: Ben Horgan <ben.horgan@arm.com>
> ---
> Changes since v3:
> Tags dropped due to rework
> Fallout/simplification from adding acpi_pptt_cache_v1_full
> Look for each cache type before incrementing level
> ---
> drivers/acpi/pptt.c | 63 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/acpi.h | 5 ++++
> 2 files changed, 68 insertions(+)
>

Reviewed-by: Gavin Shan <gshan@redhat.com>