linux-kernel - Re: [PATCH v7] x86/mce: retrieve poison range from hardware

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Message-ID: <YwUFlo3+my6bJHWj@zn.tnic>
Date:   Tue, 23 Aug 2022 18:51:34 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Jane Chu <jane.chu@...cle.com>
Cc:     tony.luck@...el.com, tglx@...utronix.de, mingo@...hat.com,
        dave.hansen@...ux.intel.com, x86@...nel.org,
        linux-edac@...r.kernel.org, dan.j.williams@...el.com,
        linux-kernel@...r.kernel.org, hch@....de, nvdimm@...ts.linux.dev
Subject: Re: [PATCH v7] x86/mce: retrieve poison range from hardware

On Tue, Aug 02, 2022 at 01:50:53PM -0600, Jane Chu wrote:
> With Commit 7917f9cdb503 ("acpi/nfit: rely on mce->misc to determine
> poison granularity") that changed nfit_handle_mce() callback to report
> badrange according to 1ULL << MCI_MISC_ADDR_LSB(mce->misc), it's been
> discovered that the mce->misc LSB field is 0x1000 bytes, hence injecting
> 2 back-to-back poisons and the driver ends up logging 8 badblocks,
> because 0x1000 bytes is 8 512-byte.

What I'm missing from this text here is, what *is* the mce->misc LSB
field in human speak? What does that field denote?

What effect does that field have on error injection?

And so on.

> Dan Williams noticed that apei_mce_report_mem_error() hardcode
> the LSB field to PAGE_SHIFT instead of consulting the input
> struct cper_sec_mem_err record.  So change to rely on hardware whenever
> support is available.

Rely on hardware? You're changing this to rely on what the firmware
reports.

That mem_err thing comes from a BIOS table AFAICT.

...

Thx.

-- 
Regards/Gruss,
    Boris.

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