linux-kernel - Re: [PATCH] x86/mce: Add Skylake quirk for patrol scrub reported errors

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Date:   Wed, 17 Jun 2020 09:41:58 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     "Song, Youquan" <youquan.song@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/mce: Add Skylake quirk for patrol scrub reported
 errors

On Tue, Jun 16, 2020 at 10:33:08PM +0000, Luck, Tony wrote:
> If the BIOS option is left in the default setting, uncorrectable errors found
> by the patrol scrubber are reported with a machine check. Those MSCOD
> and MCACOD signatures are the same ... but that's not important because
> MCi_STATUS.UC==1. So Linux doesn't need to jump through hoops to
> "upgrade" the severity.

No, this is not what I meant: I meant when you have the setting enabled
to downgrade those errors, can they be detected as part of another MCE
being raised...

> > If so, then the adjusting needs to happen inside mce_log().
> So no, this adjust only needs to happen when polling the banks from
> CMCI or periodic timer.

... but since those downgraded errors raise CMCI then the answer to my
question is no.

> The point was to avoid the runtime test for CPU model on every error. But
> this isn't a performance critical path, so we can refactor if you think that
> looks cleaner.

Yes please.

> There is some new set of validation tests running now to check the effectiveness
> of this BIOS + OS change. So it may be a while before updated version is
> posted.

Ok, thx.

-- 
Regards/Gruss,
    Boris.

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