From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: xsa46-4.2.patch breaks PCI passthrough? Date: Wed, 1 May 2013 17:07:56 +0100 Message-ID: <51813DDC.6010608@citrix.com> References: <5180A825.4050108@crc.id.au> <51813412.9070104@crc.id.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51813412.9070104@crc.id.au> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Steven Haigh , George Dunlap Cc: "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 01/05/13 16:26, Steven Haigh wrote: > On 2/05/2013 1:18 AM, George Dunlap wrote: >> On Wed, May 1, 2013 at 6:29 AM, Steven Haigh wrote: >>> Hi all, >>> >>> I've had a report lodged against my packages that the patch provided for >>> XSA46 against Xen 4.2.1 causes PCI passthru to break. >>> >>> It seems that 4.2.1 *without* the XSA46 patch works perfectly. 4.2.2 does >>> not work. >> Have you tried this with xen-unstable tip? That would be a blocker >> bug for the 4.3 release. > Hi George, > > It hasn't been tried it against anything other than 4.2.1 & 4.2.2 as > yet. As I'm not the end user with the problem here, I need to wait for > feedback. > > I have passed the patch provided by Andrew to the bug author - when I've > got feedback on this I'll be able to provide more information. I think > when we've got a root cause for this then it should be simple to verify > it on 4.3. > I have been investigating this issue on XenServer. On XenServer, PCIPassthrough to a SLES11SP1 guest is working correctly, even with the XSA-46 patch applied. When passing through physical devices, my hypervisor debugging is being triggered, but the actions of XEN_DOMCTL_irq_permission appear to be correct, given sensible input from the Xapi toolstack. When passing through an SRIOV virtual function, no hypervisor debugging is being triggered. At a preliminary guess, I would say that XM looks to be doing something stupid which it used to be getting away with, but is not now given the changed in the hypervisor. I suspect that it will be hard to progress this issue until Gordan applied my debugging patch and gets back with the results. ~Andrew