linux-kernel - Re: [PATCH V6 2/5] perf/x86/kvm: Avoid unnecessary work in guest filtering

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Message-ID: <20190204194306.GI29639@zn.tnic>
Date:   Mon, 4 Feb 2019 20:43:06 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        ak@...ux.intel.com, eranian@...gle.com
Subject: Re: [PATCH V6 2/5] perf/x86/kvm: Avoid unnecessary work in guest
 filtering

On Mon, Feb 04, 2019 at 01:57:49PM -0500, Liang, Kan wrote:
> You mean a given microcode revision X applying to multiple stepping,
> right?

Yes, the range thing. You specify a range of steppings:

kabylake mobile  with steppings 9-12
kabylake desktop with steppings 10-13

> I don't think so. I still think the KABYLAKE case is an uncommon case.

You mean it is uncommon because there are already *two* models which
need it or because this is only kabylake and it won't happen in the
future?

> Can we do something as below just for this case?

Of course not. _FOUR is just silly and if a *fifth* stepping appears,
you need to go fixup again.

If anything and if this kabylake thing is one off, I'd prefer we keep it
as is.

-- 
Regards/Gruss,
    Boris.

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