Re: [PATCH v4 07/16] x86/mtrr: split generic_set_all()

From: Juergen Gross
Date: Wed Oct 26 2022 - 07:46:08 EST


On 26.10.22 12:37, Borislav Petkov wrote:
On Tue, Oct 04, 2022 at 10:10:14AM +0200, Juergen Gross wrote:
Split generic_set_all() into multiple parts, while moving the main
function body into cacheinfo.c.

Prepare the support of PAT without needing MTRR support by
moving the main function body of generic_set_all() into cacheinfo.c
while renaming it to cache_cpu_init(). The MTRR specific parts are
moved into a dedicated small function called by cache_cpu_init() in
order to make cache_cpu_init() as MTRR agnostic as possible.

The setting of smp_changes_mask is merged into the (new) function
mtrr_generic_set_state() used to call set_mtrr_state(). It was
probably split in ancient times, as atomic operations while running
uncached might be quite expensive, but OTOH only systems with a
broken BIOS should ever require to set any bit in smp_changes_mask,
so just hurting those devices with a penalty of a few microseconds
during boot shouldn't be a real issue.

This still needs addressing

"So the commit message should not say what you're doing - that should
be visible from the diff itself. It should talk more about the *why*
you're doing it."


The reason is "Prepare the support of PAT without needing MTRR support".

DYM I should just remove the rest of the commit message?


Juergen

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