From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755606AbZINQJB (ORCPT ); Mon, 14 Sep 2009 12:09:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752425AbZINQI7 (ORCPT ); Mon, 14 Sep 2009 12:08:59 -0400 Received: from mail-qy0-f185.google.com ([209.85.221.185]:56033 "EHLO mail-qy0-f185.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751250AbZINQI6 (ORCPT ); Mon, 14 Sep 2009 12:08:58 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type; b=EG0YwqCm9eQ165dNOgGoGN5q+A/9YnlmHch3x2a7IcLUptKoOTXGVsFpj2BggtwkEk zaiSkDA4lBRpCPKvMth4CYJfKl3eTh0H3mDDSNRiadyOfIaRTZ8K7J5vaIwTxaRukElK osy+Ms05mi9lLrQZWyr42ZwvwhMfa8Ho9opvg= Message-ID: <4AAE6A97.7090808@gmail.com> Date: Mon, 14 Sep 2009 12:08:55 -0400 From: Gregory Haskins User-Agent: Thunderbird 2.0.0.23 (Macintosh/20090812) MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: "Ira W. Snyder" , netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, linux-mm@kvack.org, akpm@linux-foundation.org, hpa@zytor.com, Rusty Russell , s.hetze@linux-ag.com Subject: Re: [PATCHv5 3/3] vhost_net: a kernel-level virtio server References: <20090827160750.GD23722@redhat.com> <20090903183945.GF28651@ovro.caltech.edu> <20090907101537.GH3031@redhat.com> <20090908172035.GB319@ovro.caltech.edu> <4AAA7415.5080204@gmail.com> <20090913120140.GA31218@redhat.com> In-Reply-To: <20090913120140.GA31218@redhat.com> X-Enigmail-Version: 0.96.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig4A7B9E21588ECA3868FA009B" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig4A7B9E21588ECA3868FA009B Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Michael S. Tsirkin wrote: > On Fri, Sep 11, 2009 at 12:00:21PM -0400, Gregory Haskins wrote: >> FWIW: VBUS handles this situation via the "memctx" abstraction. IOW, >> the memory is not assumed to be a userspace address. Rather, it is a >> memctx-specific address, which can be userspace, or any other type >> (including hardware, dma-engine, etc). As long as the memctx knows ho= w >> to translate it, it will work. >=20 > How would permissions be handled? Same as anything else, really. Read on for details. > it's easy to allow an app to pass in virtual addresses in its own addre= ss space. Agreed, and this is what I do. The guest always passes its own physical addresses (using things like __pa() in linux). This address passed is memctx specific, but generally would fall into the category of "virtual-addresses" from the hosts perspective. For a KVM/AlacrityVM guest example, the addresses are GPAs, accessed internally to the context via a gfn_to_hva conversion (you can see this occuring in the citation links I sent) For Ira's example, the addresses would represent a physical address on the PCI boards, and would follow any kind of relevant rules for converting a "GPA" to a host accessible address (even if indirectly, via a dma controller). > But we can't let the guest specify physical addresses. Agreed. Neither your proposal nor mine operate this way afaict. HTH Kind Regards, -Greg --------------enig4A7B9E21588ECA3868FA009B Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkquapcACgkQP5K2CMvXmqEsZQCfcQ2o0HqEYlWAuk3Qckq/ciWq JrgAn0itJih00Z/pLWaEa7xiy99pwjUj =Y/uW -----END PGP SIGNATURE----- --------------enig4A7B9E21588ECA3868FA009B--