From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030246AbeE3J0k (ORCPT ); Wed, 30 May 2018 05:26:40 -0400 Received: from mx2.suse.de ([195.135.220.15]:43321 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968802AbeE3J0g (ORCPT ); Wed, 30 May 2018 05:26:36 -0400 Date: Wed, 30 May 2018 11:26:32 +0200 From: Borislav Petkov To: "Luck, Tony" Cc: "Williams, Dan J" , "Zhuo, Qiuxu" , "Raj, Ashok" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/3 V2] x86/mce: Fix incorrect "Machine check from unknown source" message Message-ID: <20180530092631.GA2599@zn.tnic> References: <52e049a497e86fd0b71c529651def8871c804df0.1527283897.git.tony.luck@intel.com> <20180528204923.GB30792@zn.tnic> <20180529161549.GB935@agluck-desk> <20180529174105.GF19870@zn.tnic> <3908561D78D1C84285E8C5FCA982C28F7D31E24F@ORSMSX110.amr.corp.intel.com> <20180529175313.GG19870@zn.tnic> <20180529185425.GA4174@agluck-desk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180529185425.GA4174@agluck-desk> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 29, 2018 at 11:54:25AM -0700, Luck, Tony wrote: > Couple of thoughts: Thanks for looking. > In "x86/mce: Carve out bank scanning code" you drop the extra > call to mce_severity() that I just added: Yeah, did that before we talked about it. > In "x86/mce: Exit properly when no banks to poll" you > leap right to the end. I'm wondering whether this can > ever happen? I mean, if there are no machine check banks, > then how did we get a machine check? Right, so this looks like some remnant from old times, lemme do some archeology... /me goes and dusts off the full history linux repo... I found this: commit 7dd1e1d805d15ca63d05badf40026629ba75cbc8 Author: Andi Kleen Date: Tue Feb 24 17:58:41 2004 -0800 [PATCH] New machine check handler for x86-64 and there's no mention why the !banks check is there. I'm wondering if we should simply remove it. I mean, as you say, if there are no MCA banks, we won't be running in here in the first place... > Both the original, and your new code, skip the: > > mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); > > which seems bad. That leaves MCG_STATUS.MCIP set ... so a second > machine check would just reset the machine. That's a good point. It goes away as an issue if we simply drop the check. > P.S. What happened to my "part 3/3" (updating the Skylake quirk) > ... does that belong in somebody else's tree? Simply hadn't reached it yet. I will take it too, eventually. Thx. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --