linux-kernel - Re: [PATCH V2 01/10] x86/CPU: Expose if cache is inclusive of lower level caches

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Message-ID: <20190803094423.GA2100@zn.tnic>
Date:   Sat, 3 Aug 2019 11:44:23 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Reinette Chatre <reinette.chatre@...el.com>
Cc:     tglx@...utronix.de, fenghua.yu@...el.com, tony.luck@...el.com,
        kuo-lang.tseng@...el.com, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 01/10] x86/CPU: Expose if cache is inclusive of lower
 level caches

On Fri, Aug 02, 2019 at 01:11:13PM -0700, Reinette Chatre wrote:
> Will do. Do you prefer a new prepare patch that does the renaming before
> this patch or will you be ok with the renaming done within this patch?

Nah, within this patch is ok.

> This patch only makes it possible to determine whether cache is
> inclusive for some x86 platforms while all platforms of all
> architectures are given visibility into this new "inclusive" cache
> information field within the global "struct cacheinfo".

And this begs the question: do the other architectures even need that
thing exposed? As it is now, this is x86-only so I'm wondering whether
adding all that machinery to the generic struct cacheinfo is even needed
at this point.

TBH, I'd do it differently: read CPUID at init time and cache the
information whether the cache is inclusive locally and be done with it.
It is going to be a single system-wide bit anyway as I'd strongly assume
cache settings like inclusivity should be the same across the whole
system.

When the other arches do need it, we can extract that info "up" into the
generic layer.

Thx.

-- 
Regards/Gruss,
    Boris.

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