From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gordan Bobic Subject: Nvidia GPU passthrough and Device IDs Date: Thu, 28 Nov 2013 11:21:28 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Vlzf1-0002dx-1J for xen-devel@lists.xenproject.org; Thu, 28 Nov 2013 11:21:31 +0000 Received: from mail.shatteredsilicon.net (localhost [127.0.0.1]) by external.sentinel2 (Postfix) with ESMTP id 66B70220294 for ; Thu, 28 Nov 2013 11:21:28 +0000 (GMT) List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org This has recently come to my attention: http://www.nvidia.com/object/user-selectable-machines.html along with this snippet of information: - Physical Function PCIid: 10ed:11bf - GK104GL [GRID K2] - Virtual Function selectable from PCIid: 10ed:118b - GK104 [GeForce K2 USM] PCIid: 10ed:118c - GK104 [NVS K2 USM] PCIid: 10ed: 11b0 - GK104GL [Quadro K2 USM] PCIid: 10ed:11b1 - GK104GL [Tesla K2 USM] The way this reads to me is that it means that a different device ID is exposed to domU than what runs on the host. Therefore, it must be possible to change the device ID visible to domU to something other than what is visible on the host. So, as per a question that has recently been asked, is there a way to apply a software shim to expose a different device ID to the domU when doing PCI passthrough? This might completely avoid the need to modify the GeForce cards in ways discussed here recently to make them work in PCI passthrough mode by simply faking the device ID exposed. Gordan