From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?Um9nZXIgUGF1IE1vbm7DqQ==?= Subject: Re: [RFT] x86/pvh: disable all MTRR CPU features on cpuid for dom0 Date: Fri, 27 Mar 2015 09:32:10 +0100 Message-ID: <5515158A.8090604@citrix.com> References: <1427412834-4624-1-git-send-email-mcgrof@do-not-panic.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YbPge-0006bv-JW for xen-devel@lists.xenproject.org; Fri, 27 Mar 2015 08:32:16 +0000 In-Reply-To: <1427412834-4624-1-git-send-email-mcgrof@do-not-panic.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Luis R. Rodriguez" , xen-devel@lists.xenproject.org Cc: jgross@suse.com, boris.ostrovsky@oracle.com, mcgrof@suse.com, david.vrabel@citrix.com List-Id: xen-devel@lists.xenproject.org El 27/03/15 a les 0.33, Luis R. Rodriguez ha escrit: > From: "Luis R. Rodriguez" > > Commit 586ab6a by Roger disabled the main MTRR CPU feature > on the cpuid when on pvh in order to avoid having MTRR code > run on the OS on dom0. This missed the fact that not all CPUs > use this cpuid to identify MTRR support, this complets that. > > This could in theory fix some potential issues where MTRR > code was previously enabled, for instance running cat /proc/mtrr > on a Linux system where MTRR was actually disabled. AFAICT we will never support PVH on those CPU types, so I'm not sure if it's worth disabling it. AMD K6, Centaur and VIA chips don't have the necessary hardware extensions to allow running PVH guests. Roger.