From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751888Ab0FVVYl (ORCPT ); Tue, 22 Jun 2010 17:24:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34657 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751034Ab0FVVYk (ORCPT ); Tue, 22 Jun 2010 17:24:40 -0400 Subject: Re: [PATCH] Xen-SWIOTBL v0.8.3 used for Xen PCI pass through for PV guests. From: Alex Williamson To: Konrad Rzeszutek Wilk Cc: linux-kernel@vger.kernel.org, fujita.tomonori@lab.ntt.co.jp, iommu@lists.linux-foundation.org, albert_herranz@yahoo.es, x86@kernel.org In-Reply-To: <1277235772-26757-1-git-send-email-konrad.wilk@oracle.com> References: <1277235772-26757-1-git-send-email-konrad.wilk@oracle.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 22 Jun 2010 15:23:25 -0600 Message-ID: <1277241805.4669.691.camel@x201> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-06-22 at 15:42 -0400, Konrad Rzeszutek Wilk wrote: > These nineteen patches lay the groundwork for Xen Paravirtualized (PV) > domains to access PCI pass-through devices. These patches utilize the > SWIOTLB library modifications (http://lkml.org/lkml/2010/6/4/272). > > The end user of this is the Xen PCI frontend and Xen PCI [1] which > require a DMA API "backend" that understands Xen's MMU. This allows the > PV domains to use PCI devices. Hi Konrad, Sorry if I missed it, but I didn't see any mention or apparent requirement of a hardware iommu in xen for this code. Is that true? If so, is there anything to stop a PV guest with ownership of a DMA capable PCI device from reading all sorts of memory that the domain wouldn't otherwise have access to? I was under the impression that the old PCI front/back for PV guests was mainly an interesting hack with limited applications due to security. Thanks, Alex