From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: Xen pci-passthrough problem with pci-detach and pci-assignable-remove Date: Tue, 1 Apr 2014 12:13:09 -0400 Message-ID: <20140401161309.GA10072@phenom.dumpdata.com> References: <1447395332.20140110155157@eikelenboom.it> <20140110151218.GA20152@phenom.dumpdata.com> <1087166993.20140110165729@eikelenboom.it> <20140110161248.GE21360@phenom.dumpdata.com> <1010658460.20140110171623@eikelenboom.it> <20140110173809.GA19423@pegasus.dumpdata.com> <1889333978.20140124143602@eikelenboom.it> <20140124174806.GA15571@phenom.dumpdata.com> <1142136480.20140220095359@eikelenboom.it> <929649832.20140220171846@eikelenboom.it> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WV1JR-0002OQ-KJ for xen-devel@lists.xenproject.org; Tue, 01 Apr 2014 16:13:21 +0000 Content-Disposition: inline In-Reply-To: <929649832.20140220171846@eikelenboom.it> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Sander Eikelenboom Cc: xen-devel , Ian Campbell List-Id: xen-devel@lists.xenproject.org On Thu, Feb 20, 2014 at 05:18:46PM +0100, Sander Eikelenboom wrote: > > Thursday, February 20, 2014, 9:53:59 AM, you wrote: > > > > Friday, January 24, 2014, 6:48:06 PM, you wrote: > > >> On Fri, Jan 24, 2014 at 02:36:02PM +0100, Sander Eikelenboom wrote: > >>> > >>> Friday, January 10, 2014, 6:38:10 PM, you wrote: > >>> > >>> >> > Wow. You just walked in a pile of bugs didn't you? And on Friday > >>> >> > nonethless. > >>> >> > >>> >> As usual ;-) > >>> > >>> > Ha! > >>> > ..snip.. > >>> >> >> [ 489.082358] [] ? mutex_spin_on_owner+0x38/0x45 > >>> >> >> [ 489.106272] [] ? schedule_preempt_disabled+0x6/0x9 > >>> >> >> [ 489.130158] [] ? __mutex_lock_slowpath+0x159/0x1b5 > >>> >> >> [ 489.154147] [] ? mutex_lock+0x16/0x25 > >>> >> >> [ 489.177890] [] ? pci_reset_function+0x26/0x4e > >>> >> > >>> >> > Yeah, that bug my RFC patchset (the one that does the slot/bus reset) should also fix. > >>> >> > I totally forgot about it ! > >>> >> > >>> >> Got a link to that patchset ? > >>> > >>> > https://lkml.org/lkml/2013/12/13/315 > >>> > >>> >> I at least could give it a spin .. you never know when fortune is on your side :-) > >>> > >>> > It is also at this git tree: > >>> > >>> > git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git and the > >>> > branch name is "devel/xen-pciback.slot_and_bus.v0". You will likely > >>> > want to merge it in your current Linus tree. > >>> > >>> > Thank you! > >>> > >>> > >>> Hi Konrad, > >>> > >>> Just got time to test this some more, when merging this branch *except* the last commit (9599a5ad38a3bb250e996ccb2cdaab6fb68aaacd) > >>> seems to help with my problem,i'm no capable of using: > >>> - xl pci-detach > >>> - xl pci-assignable-remove > >>> - echo "BDF" > /sys/bus/pci/drivers//bind > >>> > >>> to remove a pci device from a running HVM guest and rebinding it to a driver in dom0 without those nasty stacktraces :-) > >>> So the first 4 seem to be an improvement. > >>> > >>> That last commit (9599a5ad38a3bb250e996ccb2cdaab6fb68aaacd) seems to give troubles of it's own. > > >> Could you email me your lspci output and also which devices you move/switch etc? > > > Hi Konrad, > > > At the moment i found some time to figure out what goes wrong with the xl pci-detach and xl pci-assignable-remove, i have been > > able to narrow it down a bit: > > > The problem only occurs when you: > > - passthrough 2 (or more?) pci devices assigned to a guest .. > > - and only remove 1 of those devices with "xl pci-detach" followed by a "xl pci-assignable-remove" > > - when you first detach both devices with "xl pci-detach" before doing the "xl pci-assignable-remove" it works ok. > > > In my case i'm passingthrough 2 devices (02:00.0 and 00:19.0) > > > I added some printk's and what i found out is that: > > - after doing the pci-detach of 02:00.0, it doesn't call pcistub_put_pci_dev for that device ... > > - but when i subsequently pci-detach the second (and last) device 00:19.0 .. it does call it for both 02:00.0 and 00:19.0 ... > > - so somehow that call for the first detached device gets deferred .. but since it are different devices and not functions of the same device i don't > > see any reason for it to wait until all other devices would have been detached ... > > > > I tried to capture the console output but some how that didn't work out, so i attached a screenshot of what happens when: > > - doing a xl pci-list for the guest > > - doing a xl pci-assignable-list > > > - doing the xl pci-detach for 02:00.0 > > > - doing a xl pci-list for the guest > > - doing a xl pci-assignable-list > > > - waiting some time ... > > > - doing the xl pci-detach for 00:19.0 > > > - doing a xl pci-list for the guest > > - doing a xl pci-assignable-list > > > There you can see this strange sequence of events :-) > > > But i haven't been able to spot the culprit > > Enabled some extra debugging and added some more printk's .. (see new screenshot) > > From what it seems .. the frontend state for the first device isn't changed on the first pci-detach .. > > Is the signaling on pci-detach the guests (pcifront) responsibility or the toolstacks (libxl) ? It usually is pcifront. And in the screenshot I see: .. frontend is gone! unregister device which should trigger the process. And it does look to do that. Hm, I am wondering what the toolstack is waiting for. Time to debug. > > > > > attached: screenshot.jpg and thanks for the screenshot (didn't have copy-n-paste option handy :-))