linux-kernel - Re: [PATCH v2] x86/amd: Derive L3 shared_cpu_map from cpu_llc_shared

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Message-ID: <20170730034834.GA22240@nazgul.tnic>
Date:   Sun, 30 Jul 2017 05:48:34 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com
Subject: Re: [PATCH v2] x86/amd: Derive L3 shared_cpu_map from
 cpu_llc_shared_mask

On Thu, Jul 27, 2017 at 08:52:35PM -0500, Suravee Suthikulpanit wrote:
> For system with X86_FEATURE_TOPOEXT, current logic use APIC ID to
> calculate shared_cpu_map. However, since APIC IDs are not guaranteed
> to be contiguous for cores across different L3 (e.g. family17h system
> w/ downcore configuration). This breaks the logic, and results in
> incorrect L3 shared_cpu_map.
> 
> Instead, always use the previously calculated cpu_llc_shared_mask of
> each cpu to derive L3 shared_cpu_map. This has been tested on
> family15h and family17h systems, which has L3 and support
> X86_FEATURE_TOPOEXT.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  arch/x86/kernel/cpu/intel_cacheinfo.c | 32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)

Applied, thanks.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--