linux-kernel - Re: [PATCH 2/8] x86, mce: remove redundant mce

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 20 Jun 2011 09:44:52 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Luck, Tony" <tony.luck@...el.com>
Subject: Re: [PATCH 2/8] x86, mce: remove redundant mce_available() checks

On Mon, Jun 20, 2011 at 12:47:57AM -0400, Hidetoshi Seto wrote:
> > I don't think this will ever happen so why complicate the code
> > needlessly? This can only be executed if at least one of the cores on
> > the system has CPUID(1)_EDX, bits 7 and 14 cleared and that's just
> > silly.
> 
> This is a guard against such silly situation, isn't it?
> I don't think it looks so complicated and needless.
> 
> I think this code will not run on systems with single socket as
> long as the processor vendors are in the right mind.
> But in cases when it is numa with strange nodes or when it is
> migrated to/from misconfigured virtual machine I can't say that
> with certainty.

Let me put it this way: are you talking about a concrete example where
there's machine with the BSP's MCA features enabled and the rest of the
cores are not or is this some theoretical thing you're conjecturing?

If it is the first I'd really like to know about it, if it's the second,
then my initial point stands - no need to handle purely theoretical
cases.

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/