linux-kernel - Re: [PATCH 2/2] x86/mce: Add support for Extended Physical Address MCA changes

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Message-ID: <YMMSqS0Knb0Pk8GF@zn.tnic>
Date:   Fri, 11 Jun 2021 09:37:13 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Smita Koralahalli Channabasappa <skoralah@....com>
Cc:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-edac@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
        Yazen Ghannam <yazen.ghannam@....com>,
        Muralidhara M K <muralimk@....com>,
        Akshay Gupta <Akshay.Gupta@....com>,
        Youquan Song <youquan.song@...el.com>,
        Zhen Lei <thunder.leizhen@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 2/2] x86/mce: Add support for Extended Physical Address
 MCA changes

On Thu, Jun 10, 2021 at 10:36:44PM -0500, Smita Koralahalli Channabasappa wrote:
> The idea of defining a new struct was to keep SMCA specific stuff separate.
> Thought, it would be costly to include in existing struct mce_bank[] as it will be
> unnecessarily defined for each cpu and each bank across all vendors even if they
> aren't using it and would be a problem if they are constraint on resource and space.

That's very considerate of you to think about the other vendors - I wish
everyone would do that...

However, our mce_banks_array is defined unconditionally on all vendors
already. So it is there even now. So I wouldn't lose a single second of
sleep about adding an u64 bitfield there.

> Also, in the future we can use this newly defined struct smca_config[] to cache
> other MCA_CONFIG feature bits for different use cases if they are per bank and per
> cpu.

You can use other bits in that bitfield. I hope 64 are enough. :)

HTH.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette