From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ch1ehsobe005.messaging.microsoft.com ([216.32.181.185]:54625 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751642Ab2JENI7 (ORCPT ); Fri, 5 Oct 2012 09:08:59 -0400 Date: Fri, 5 Oct 2012 15:08:57 +0200 From: "Roedel, Joerg" To: Alex Williamson CC: Andreas Hartmann , , Bjorn Helgaas , linux-pci Subject: Re: vfio: missing patch in linux 3.6 Message-ID: <20121005130857.GX4009@amd.com> References: <506DA799.5090603@01019freenet.de> <1349364399.2759.42.camel@ul30vt.home> <20121004161421.GV4009@amd.com> <1349368080.2759.52.camel@ul30vt.home> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <1349368080.2759.52.camel@ul30vt.home> Sender: linux-pci-owner@vger.kernel.org List-ID: On Thu, Oct 04, 2012 at 10:28:00AM -0600, Alex Williamson wrote: > There are a couple questions in the link above. Since the devices don't > expose a PCIe capability, we probably need to add a check to look at the > upstream device and verify we're not on a legacy bus where ACS can't be > enforced. You can certainly do that, but for existing hardware (with an AMD IOMMU) this check would never be true. These devices are always on a seperate south-bridge chip which is connected to the north-bridge via PCIe. So the topology where you find these devices is always the same in an AMD IOMMU system. > Then there's the general question of whether the confirmation > of no peer-to-peer applies to every case where we might see this device > (some of them seem to have history that pre-dates this specific package > implementation) or do we need to try to identify specific package > properties in addition to just a device ID? The device ids are kept the same to maintain compatability with older software. Besides that, my statement about the peer-2-peer safety is true for all south-bridges that you can find in an AMD IOMMU capable system. Regards, Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632