From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756440Ab2GYKnx (ORCPT ); Wed, 25 Jul 2012 06:43:53 -0400 Received: from osrc3.amd.com ([217.9.48.20]:34568 "EHLO mail.x86-64.org" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755533Ab2GYKnv (ORCPT ); Wed, 25 Jul 2012 06:43:51 -0400 Date: Wed, 25 Jul 2012 12:43:46 +0200 From: Borislav Petkov To: Vladimir Davydov Cc: Andre Przywara , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Borislav Petkov , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Andreas Herrmann , Pavel Emelianov , Konstantin Khorenko , Daniel Lezcano Subject: Re: [PATCH 2/2] cpu: intel, amd: mask cleared cpuid features Message-ID: <20120725104346.GA11152@aftab.osrc.amd.com> References: <73e09fb43e37de851acda10dc64bc495a5b68357.1342801662.git.vdavydov@parallels.com> <20120721103715.GA3632@aftab.osrc.amd.com> <500E4960.8040307@parallels.com> <500E5951.5020900@amd.com> <500E5CDF.5000504@parallels.com> <20120724101041.GA24739@aftab.osrc.amd.com> <500E8280.6050905@parallels.com> <500E9664.9030306@amd.com> <500FCAFB.4080301@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <500FCAFB.4080301@parallels.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 25, 2012 at 02:31:23PM +0400, Vladimir Davydov wrote: > So, you prefer adding some filtering of /proc/cpuinfo into the > mainstream kernel That's already there right? And your 1/2 patch was making toggling those bits easier. > (not now, later, for LXC to work) instead of enabling clearcpuid boot > option to mask CPUID features? IMO, the latter would look clearer. Yes, but for reasons noted earlier, you cannot tweak all hardware CPUID features as you want them. So, having a software-only layer of tweaking /proc/cpuinfo or something different you can come up with is the only option you have. And even in that case, applications running in the container which execute CPUID might fail in a strange manner when the corresponding /proc/cpuinfo flag was cleared by you intentionally but the hardware CPUID flag is there. In such situations, issues like that should probably be sorted on a case-by-case basis I guess. Thanks. -- 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