linux-kernel - RE: [PATCHV2 3/3] x86, ras: Add mcsafe_memcpy() function to recover from machine checks

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Date:	Fri, 11 Dec 2015 22:35:17 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Andy Lutomirski <luto@...capital.net>,
	"Williams, Dan J" <dan.j.williams@...el.com>
CC:	Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	linux-nvdimm <linux-nvdimm@...1.01.org>, X86 ML <x86@...nel.org>
Subject: RE: [PATCHV2 3/3] x86, ras: Add mcsafe_memcpy() function to recover
 from machine checks

> Also, are there really PCOMMIT-capable CPUs that still forcibly
> broadcast MCE?  If, so, that's unfortunate.

PCOMMIT and LMCE arrive together ... though BIOS is in the decision
path to enable LMCE, so it is possible that some systems could still
broadcast if the BIOS writer decides to not allow local.

But a machine check safe copy_from_user() would be useful
current generation cpus that broadcast all the time.

-Tony