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    SubjectRe: [PATCH v3 1/2] x86/AMD: Fix cpu_llc_id for AMD Fam17h systems

    * Borislav Petkov <bp@suse.de> wrote:

    > Lemme clean up the commit message a bit more and add tags:
    >
    > ---
    > From: Yazen Ghannam <Yazen.Ghannam@amd.com>
    > Date: Tue, 1 Nov 2016 11:51:02 -0500
    > Subject: [PATCH] x86/AMD: Fix cpu_llc_id for AMD Fam17h systems
    >
    > cpu_llc_id (Last Level Cache ID) derivation on AMD Fam17h has an
    > underflow bug when extracting the socket_id value. It starts from 0
    > so subtracting 1 from it will result in an invalid value. This breaks
    > scheduling topology later on since the cpu_llc_id will be incorrect.
    >
    > The APIC ID is preset in APICx020 for bits 3 and above: they contain the
    > core complex, node and socket IDs.
    >
    > The LLC is at the core complex level so we can find a unique cpu_llc_id
    > by right shifting the APICID by 3 because then the least significant bit
    > will be the Core Complex ID.

    Same question as for the previous patch: what are the effects of the bug:

    - Outright bad scheduling?
    - Suboptimal scheduling?
    - Crash?
    - Something else?

    Such information needs to be in commit messages, _especially_ when a Cc: stable
    tag is added as well.

    Thanks,

    Ingo

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