From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753353AbeAZOtc (ORCPT ); Fri, 26 Jan 2018 09:49:32 -0500 Received: from mail.skyhub.de ([5.9.137.197]:35570 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752630AbeAZOtb (ORCPT ); Fri, 26 Jan 2018 09:49:31 -0500 Date: Fri, 26 Jan 2018 15:49:19 +0100 From: Borislav Petkov To: Petr Oros Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/microcode/intel: print previous microcode revision during early update Message-ID: <20180126144918.7jiaezmdhjsiman5@pd.tnic> References: <20180126103451.16863-1-poros@redhat.com> <20180126104109.slxxoq4vkqytqjxd@pd.tnic> <1516967135.2801.1.camel@redhat.com> <20180126115800.bvqrzik2f3hmmiah@pd.tnic> <1516974600.2801.10.camel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1516974600.2801.10.camel@redhat.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 26, 2018 at 02:50:00PM +0100, Petr Oros wrote: > But what in production? Edit boot params, restart server, grep /proc/cpuinfo and > restart again? Why i can not read it just from dmesg? Because you don't need the previous revision. You only *happen* to need it now but that is being addressed too with the blacklisting. And when you have broken microcode, it will say: + pr_warn("Intel Spectre v2 broken microcode detected; disabling SPEC_CTRL\n"); and if you have microcode which doesn't have IBRS, there won't be "spec_ctrl" in /proc/cpuinfo. I don't want people to start paying attention to microcode revision numbers with the gazillion different revisions and family/model/steppings out there and the crazy confusion that will ensue from this. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.