From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Re: [PATCH 10/14] Nested Virtualization: svm specific implementation Date: Wed, 18 Aug 2010 09:48:32 +0200 Message-ID: <201008180948.33544.Christoph.Egger@amd.com> References: <201008051704.03074.Christoph.Egger@amd.com> <201008171749.55377.Christoph.Egger@amd.com> <20100817165755.GD20252@whitby.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100817165755.GD20252@whitby.uk.xensource.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Tim Deegan Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On Tuesday 17 August 2010 18:57:55 Tim Deegan wrote: > At 16:49 +0100 on 17 Aug (1282063795), Christoph Egger wrote: > > > Can you explain why we shouldn't sync the vTPR and the vlapic state > > > when the guest is in nested mode? > > > > When the vcpu is in guest mode then > > v->arch.hvm_svm.vmcb->vintr.fields.tpr represents the tpr of the l2 > > guest. The l2 guest is not allowed to touch the l1 guest's vTPR. > > Hmmm. I'm not sure I understand exactly what the hardware vTPR should > contain when the L2 is running; I'll have to think back about exactly > what the sync of vtpr <-> vlapic means and whether the L2 guest can > cause surprising things to happen by setting the vTPR. The l2 guest can confuse the l1 guest. E.g. Booting Windows 7 as l1 guest and the XP mode as l2 guest won't work when done incorrectly. The l1 guest handles the vtpr and vlapic for the l2 guest and noone else. Christoph -- ---to satisfy European Law for business letters: Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach b. Muenchen Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632