linux-kernel - Re: [PATCH 3/3] ghes_edac: add platform check to enable ghes

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Date:   Tue, 18 Jul 2017 21:20:44 +0000
From:   "Kani, Toshimitsu" <toshi.kani@....com>
To:     "tony.luck@...el.com" <tony.luck@...el.com>,
        "bp@...en8.de" <bp@...en8.de>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "srinivas.pandruvada@...ux.intel.com" 
        <srinivas.pandruvada@...ux.intel.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>
Subject: Re: [PATCH 3/3] ghes_edac: add platform check to enable ghes_edac

On Tue, 2017-07-18 at 10:08 +0200, Borislav Petkov wrote:
> On Tue, Jul 18, 2017 at 08:00:07AM +0200, Borislav Petkov wrote:
> > And I think we should try this first: have the firmware disable
> > detection methods so that the platform drivers don't load.
> 
> Btw, in looking at this more, what about the firmware-first thing?
> 
> I.e., the firmware-first detection with apei_osc_setup() at the end
> of ghes_init().
> 
> Can we make ghes_edac loading dependent on that? I mean, that was
> *the* predicate for exactly that - to have the firmware look at the
> errors first. No need for platform whitelisting and so on.

I agree that 'osc_sb_apei_support_acked' should be checked when
enabling ghes_edac.  I do not know the details of existing issues, but
it sounds unlikely that this will address all of them since bugs can be
everywhere.  For instance, ghes_edac relies on DMI/SMBIOS info, unlike
other EDAC drivers, which can be buggy regardless of this _OSC info.

> I'd still decouple ghes_edac loading from ghes_probe() even though
> loading the platform driver should've been done *after* the
> firmware-first detection regardless.
> 
> So what we could do is make ghes_edac a normal module and have the
> relevant x86 EDAC modules query FF mode and if enabled, fail loading.

I agree that making ghes_edac as a normal module is a good thing, but I
do not think it's going to solve this issue.

Thanks,
-Toshi