From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934094AbcKIQZB (ORCPT ); Wed, 9 Nov 2016 11:25:01 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:58706 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751847AbcKIQY7 (ORCPT ); Wed, 9 Nov 2016 11:24:59 -0500 Date: Wed, 9 Nov 2016 17:24:51 +0100 From: Sebastian Andrzej Siewior To: Borislav Petkov Cc: "Luck, Tony" , linux-kernel@vger.kernel.org, rt@linutronix.de, linux-edac@vger.kernel.org, x86@kernel.org, Thomas Gleixner Subject: Re: [PATCH 22/25] x86/mcheck: Do the init in one place Message-ID: <20161109162451.bkch53nj32rtqszy@linutronix.de> References: <20161103145021.28528-1-bigeasy@linutronix.de> <20161103145021.28528-23-bigeasy@linutronix.de> <20161107184532.xj6wzdjlzwhshcmf@pd.tnic> <20161107185524.GA2536@intel.com> <20161107201224.7xazmhgm7bogkrw5@pd.tnic> <20161108092302.wraci5m2cxqozlew@pd.tnic> <20161109142221.3r6xwhkxbckuv3bh@linutronix.de> <20161109153807.7mv7b5f4oqfijq2h@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20161109153807.7mv7b5f4oqfijq2h@pd.tnic> User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016-11-09 16:38:07 [+0100], Borislav Petkov wrote: > On Wed, Nov 09, 2016 at 03:22:21PM +0100, Sebastian Andrzej Siewior wrote: > > I want to get rid of non-symmetrical part and the arch hook which should > > be part of the hp notifier itself. I wouldn't be too much afraid about > > the when point in time when the notifier runs: It is the *first* > > notifier that will be invoked on the target CPU. This is only a few > > lines after the old hook. Nothing else long delaying should be invoked. > > So I'm not sure *everything* mcheck_cpu_init() does should be in hotplug > and toggle on and off. For example, we should set CR4.MCE once during > init and that's it. Not turn it on and off. It would be pretty pointless > IMO. > > That's why the hotplug callback mce_disable_cpu() doesn't fiddle with > CR4 - it only clears the bits in MCi_CTL. And I think we should remain > that way. The behaviour was not changed - it was only reorganized to keep in one spot. > The initial, one-time enabling of MCE features per core should be done > only once per boot and that's it. It is. You still want this in your hotplug code in case someone replaces (physically) your CPU (say a larger NUMA box). Sebastian