linux-kernel - RE: [PATCH] x86/mce: work around an erratum on fast string copy instructions.

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Message-ID: <3288f39e32f04d67a875775414dd1c14@AcuMS.aculab.com>
Date:   Wed, 16 Feb 2022 09:04:35 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Jue Wang' <juew@...gle.com>, Tony Luck <tony.luck@...el.com>,
        "Borislav Petkov" <bp@...en8.de>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>
Subject: RE: [PATCH] x86/mce: work around an erratum on fast string copy
 instructions.

From: Jue Wang
> Sent: 16 February 2022 05:56
> 
> The fast string copy instructions ("REP; MOVS*") could consume an
> uncorrectable memory error in the cache line _right after_ the
> desired region to copy and raise an MCE.

s/consume/trap due to/

Isn't this just putting off the inevitable panic when the
following cache line is accesses for real?

Or is this all due to that pseudo dynamic memory (xpoint?) that is
byte addressable but only really has the quality of a diak?
It which case I thought it wasn't actually usable for
normal memory anyway - so the copies are all ones which can fault.

	David

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