From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754298Ab0IOOsS (ORCPT ); Wed, 15 Sep 2010 10:48:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58915 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753350Ab0IOOsQ (ORCPT ); Wed, 15 Sep 2010 10:48:16 -0400 Date: Wed, 15 Sep 2010 11:48:01 -0300 From: Marcelo Tosatti To: "Roedel, Joerg" 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: <20100915144801.GA14336@amt.cnet> 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> <20100915084833.GH17759@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100915084833.GH17759@amd.com> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 15, 2010 at 10:48:33AM +0200, Roedel, Joerg wrote: > 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. Ah, OK. > 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. Well, i don't think it would be a common scenario. Ignore me.