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

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Date:   Fri, 26 Aug 2022 10:54:31 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Borislav Petkov <bp@...en8.de>, Jane Chu <jane.chu@...cle.com>
CC:     "tony.luck@...el.com" <tony.luck@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "hch@....de" <hch@....de>,
        "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>
Subject: Re: [PATCH v7] x86/mce: retrieve poison range from hardware

Borislav Petkov wrote:
> On Thu, Aug 25, 2022 at 04:29:47PM +0000, Jane Chu wrote:
> > Tony has replied.
> 
> Do you really think that I can't look up what field means?
> 
> What I said was
> 
> "What I'm missing from this text here is... "
> 
> IOW, what I'm trying to say is, you should formulate your commit message
> better, more human-friendly. Right now it reads like for insiders only.
> But that's not its purpose.
> 
> Do you catch my drift?

How about:

---

When memory poison consumption machine checks fire,
mce-notifier-handlers like nfit_handle_mce() record the impacted
physical address range. The error information includes data about blast
radius, i.e. how many cachelines did the hardware determine are
impacted. A recent change, commit 7917f9cdb503 ("acpi/nfit: rely on
mce->misc to determine poison granularity"), updated nfit_handle_mce()
to stop hard coding the blast radius value of 1 cacheline, and instead
rely on the blast radius reported in 'struct mce' which can be up to 4K
(64 cachelines).

It turns out that apei_mce_report_mem_error() had a similar problem in
that it hard coded a blast radius of 4K rather than checking the blast
radius in the error information. Fix apei_mce_report_mem_error() to
convey the proper poison granularity.

---