From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752984Ab0IOIvy (ORCPT ); Wed, 15 Sep 2010 04:51:54 -0400 Received: from tx2ehsobe004.messaging.microsoft.com ([65.55.88.14]:21326 "EHLO TX2EHSOBE007.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752385Ab0IOIvw (ORCPT ); Wed, 15 Sep 2010 04:51:52 -0400 X-SpamScore: -21 X-BigFish: VS-21(zz1432N98dNzz1202hzz15d4Rz32i2a8h87h43h) X-FB-DOMAIN-IP-MATCH: fail X-WSS-ID: 0L8S5RM-02-876-02 X-M-MSG: Date: Wed, 15 Sep 2010 10:48:33 +0200 From: "Roedel, Joerg" To: Marcelo Tosatti CC: Avi Kivity , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/2] KVM: MMU: Use base_role.nxe for mmu.nx Message-ID: <20100915084833.GH17759@amd.com> References: <1284479173-4515-1-git-send-email-joerg.roedel@amd.com> <1284479173-4515-3-git-send-email-joerg.roedel@amd.com> <20100914220836.GA3553@amt.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20100914220836.GA3553@amt.cnet> Organization: Advanced Micro Devices =?iso-8859-1?Q?GmbH?= =?iso-8859-1?Q?=2C_Karl-Hammerschmidt-Str=2E_34=2C_85609_Dornach_bei_M=FC?= =?iso-8859-1?Q?nchen=2C_Gesch=E4ftsf=FChrer=3A_Thomas_M=2E_McCoy=2C_Giuli?= =?iso-8859-1?Q?ano_Meroni=2C_Andrew_Bowd=2C_Sitz=3A_Dornach=2C_Gemeinde_A?= =?iso-8859-1?Q?schheim=2C_Landkreis_M=FCnchen=2C_Registergericht_M=FCnche?= =?iso-8859-1?Q?n=2C?= HRB Nr. 43632 User-Agent: Mutt/1.5.20 (2009-06-14) X-Reverse-DNS: unknown Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 14, 2010 at 06:08:37PM -0400, Marcelo Tosatti wrote: > > For tdp better set base_role.nxe to zero, otherwise duplicate tdp > pagetables can be created if the guest switches between nx/non-nx. > This does not work because bit 63 is marked as reserved if base_role.nxe is 0. If the walk_addr_generic function then runs with tdp enabled it would report a set nx bit as a rsvd fault. We also can't use is_nx() in those path because it does not distinguish between l1 and l2 nx. Are there guests that switch the efer.nx bit regularly enough so that it matters? If so I would suggest to drop this patch and keep mmu.nx. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632