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[79.178.2.19]) by smtp.gmail.com with ESMTPSA id g2sm26365424qkb.27.2020.03.11.23.32.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2020 23:32:17 -0700 (PDT) Date: Thu, 12 Mar 2020 02:32:11 -0400 From: "Michael S. Tsirkin" To: David Gibson Subject: Re: Upstream QEMU guest support policy ? Re: [PATCH v3 0/2] spapr: Use vIOMMU translation for virtio by default Message-ID: <20200312023041-mutt-send-email-mst@kernel.org> References: <20200305043009.611636-1-david@gibson.dropbear.id.au> <20200310114343.GD3234052@redhat.com> <20200311011247.GT660117@umbus.fritz.box> <20200311031202-mutt-send-email-mst@kernel.org> <20200312011049.GC711223@umbus.fritz.box> MIME-Version: 1.0 In-Reply-To: <20200312011049.GC711223@umbus.fritz.box> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pair@us.ibm.com, Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , aik@ozlabs.ru, groug@kaod.org, qemu-devel@nongnu.org, paulus@samba.org, clg@kaod.org, mdroth@us.ibm.com, qemu-ppc@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Mar 12, 2020 at 12:10:49PM +1100, David Gibson wrote: > On Wed, Mar 11, 2020 at 03:33:59AM -0400, Michael S. Tsirkin wrote: > > On Wed, Mar 11, 2020 at 12:12:47PM +1100, David Gibson wrote: > > > I am wondering if we have to introduce an "svm=3Don" flag anyway. It= 's > > > pretty ugly, since all it would be doing is changing defaults here an= d > > > there for compatibilty with a possible future SVM transition, but > > > maybe it's the best we can do :/. > >=20 > > Frankly I'm surprised there's no way for the hypervisor to block VM > > transition to secure mode. To me an inability to disable DRM looks like > > a security problem. >=20 > Uh.. I don't immediately see how it's a security problem, though I'm > certainly convinced it's a problem in other ways. Well for one it breaks introspection, allowing guests to hide malicious code from hypervisors. > > Does not the ultravisor somehow allow > > enabling/disabling this functionality from the hypervisor? >=20 > Not at present, but as mentioned on the other thread, Paul and I came > up with a tentative plan to change that. >=20 > > It would be > > even better if the hypervisor could block the guest from poking at the > > ultravisor completely but I guess that would be too much to hope for. >=20 > Yeah, probably :/. >=20 > --=20 > David Gibson=09=09=09| I'll have my music baroque, and my code > david AT gibson.dropbear.id.au=09| minimalist, thank you. NOT _the_ _oth= er_ > =09=09=09=09| _way_ _around_! > http://www.ozlabs.org/~dgibson