linux-kernel - Re: [PATCH v5 04/34] ACPI / PPTT: Find cache level by cache-id

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Message-ID: <20251118153248.0000558a@huawei.com>
Date: Tue, 18 Nov 2025 15:32:48 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Ben Horgan <ben.horgan@....com>
CC: <james.morse@....com>, <amitsinght@...vell.com>,
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 Heng <zengheng4@...wei.com>
Subject: Re: [PATCH v5 04/34] ACPI / PPTT: Find cache level by cache-id

On Mon, 17 Nov 2025 16:59:43 +0000
Ben Horgan <ben.horgan@....com> wrote:

> From: James Morse <james.morse@....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@....com>
> Signed-off-by: Ben Horgan <ben.horgan@....com>
> Reviewed-by: Gavin Shan <gshan@...hat.com>
> Reviewed-by: Fenghua Yu <fenghuay@...dia.com>
> Tested-by: Fenghua Yu <fenghuay@...dia.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Tested-by: Carl Worth <carl@...amperecomputing.com>
> Tested-by: Gavin Shan <gshan@...hat.com>
> Tested-by: Zeng Heng <zengheng4@...wei.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>