Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754373Ab1EQLvF (ORCPT ); Tue, 17 May 2011 07:51:05 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:42729 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754085Ab1EQLvE (ORCPT ); Tue, 17 May 2011 07:51:04 -0400 Date: Tue, 17 May 2011 13:50:41 +0200 From: Ingo Molnar To: Avi Kivity Cc: "H. Peter Anvin" , Fenghua Yu , Thomas Gleixner , Asit K Mallick , Linus Torvalds , Arjan van de Ven , Andrew Morton , Andi Kleen , linux-kernel , Pekka Enberg Subject: Re: [PATCH v2 0/4] Enable SMEP CPU Feature Message-ID: <20110517115041.GF13475@elte.hu> References: <4DD19C81.8000902@zytor.com> <20110517070527.GD22305@elte.hu> <4DD23CB6.3050503@redhat.com> <20110517092903.GJ22093@elte.hu> <4DD2409F.4030800@redhat.com> <20110517104654.GN22093@elte.hu> <4DD25D29.9040008@redhat.com> <20110517113851.GD13475@elte.hu> <4DD25FA4.7030307@redhat.com> <4DD2605A.90506@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DD2605A.90506@redhat.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1226 Lines: 40 * Avi Kivity wrote: > On 05/17/2011 02:44 PM, Avi Kivity wrote: > >On 05/17/2011 02:38 PM, Ingo Molnar wrote: > >>> > >>> Depends if the guest uses a read-modify-write pattern or not. > >>We could do it > >>> transparently in kvm.ko, since the real cr4 need not > >>corresponds to the guest > >>> notion (for example, we often set cr0.wp or cr0.ts even > >>though the guest > >>> wants them clear). > >> > >>Oh, being transparent is a nice touch when it comes to security measures > >>(catching attackers who think there's no SMEP and such) - but > >>that would need > >>KVM support and a new ioctl to configure it, right? > > > >Yes. > > > > btw, KVM support is required anyway, you can't set random bits in > cr4 (from either the guest or host userspace) - kvm needs to > understand them. Sure, that is the whole premise of this discussion. I meant to say: "but that would need KVM ABI support via a new ioctl to configure it, right?" Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/