From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47062) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ww3oS-0008Lf-Bu for qemu-devel@nongnu.org; Sun, 15 Jun 2014 02:21:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ww3oK-0004Qv-SO for qemu-devel@nongnu.org; Sun, 15 Jun 2014 02:21:08 -0400 Received: from mout.web.de ([212.227.15.3]:64442) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ww3oK-0004Qn-Ik for qemu-devel@nongnu.org; Sun, 15 Jun 2014 02:21:00 -0400 Message-ID: <539D3B35.2010706@web.de> Date: Sun, 15 Jun 2014 08:20:37 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <20140610184818.2e490419@nbschild1> <87r42uq2v8.fsf@rustcorp.com.au> <53993B7B.7010404@siemens.com> <87fvj9prdi.fsf@rustcorp.com.au> <539A98D3.3070601@siemens.com> <539ABA41.3070701@redhat.com> In-Reply-To: <539ABA41.3070701@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="cRLQKXi54eaooTwxxeJmKxnMFB25QgCqN" Subject: Re: [Qemu-devel] Using virtio for inter-VM communication List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Rusty Russell , Henning Schild , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org Cc: Jailhouse This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --cRLQKXi54eaooTwxxeJmKxnMFB25QgCqN Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2014-06-13 10:45, Paolo Bonzini wrote: > Il 13/06/2014 08:23, Jan Kiszka ha scritto: >>>> That would preserve zero-copy capabilities (as long as you can work >>>> against the shared mem directly, e.g. doing DMA from a physical NIC = or >>>> storage device into it) and keep the hypervisor out of the loop. >> > >> > This seems ill thought out. How will you program a NIC via the virt= io >> > protocol without a hypervisor? And how will you make it safe? You'= ll >> > need an IOMMU. But if you have an IOMMU you don't need shared memor= y. >> >> Scenarios behind this are things like driver VMs: You pass through the= >> physical hardware to a driver guest that talks to the hardware and >> relays data via one or more virtual channels to other VMs. This confin= es >> a certain set of security and stability risks to the driver VM. >=20 > I think implementing Xen hypercalls in jailhouse for grant table and > event channels would actually make a lot of sense. The Xen > implementation is 2.5kLOC and I think it should be possible to compact > it noticeably, especially if you limit yourself to 64-bit guests. At least the grant table model seems unsuited for Jailhouse. It allows a guest to influence the mapping of another guest during runtime. This we want (or even have) to avoid in Jailhouse. I'm therefore more in favor of a model where the shared memory region is defined on cell (guest) creation by adding a virtual device that comes with such a region. Jan >=20 > It should also be almost enough to run Xen PVH guests as jailhouse > partitions. >=20 > If later Xen starts to support virtio, you will get that for free. >=20 > Paolo --cRLQKXi54eaooTwxxeJmKxnMFB25QgCqN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlOdOzoACgkQitSsb3rl5xTyTwCgt5AKtLnT8cmZ5ILYh/bMgnva BmAAoL9HlHBp2eARliY8PicSwe2JuxQp =Vsxr -----END PGP SIGNATURE----- --cRLQKXi54eaooTwxxeJmKxnMFB25QgCqN--