Re: PCI passthrough problems after legacy update of xen 4.1

[Gordan Bobic <gordan@bobich.net>]

I stand corrected! Jan's patch does in fact fix the problem. I have no 
idea what I was doing wrong, but I just tried it again (for the 4th 
time) just to make sure, uninstalled the old packages, installed the new 
ones - and now it works! There must have been a stale file somewhere 
that was breaking it.

Thanks Jan, most appreciated. :)

Gordan

On 05/19/2013 03:56 PM, Andreas Falck wrote:
> Now I'm happy to inform that Jan's patch solves the problem for me. I
> patched the source version of the xen package under ubuntu12.10,
> currently 4.1.3-3ubuntu1.5_amd64. Now I can add pci devices any order I
> like.
>
> After installing the full xen suite from the source (not knowing exactly
> which packages were affected) and seeing it working, I replaced the
> hypervisor package with a version with the debug changes I made earlier,
> to produce the attached logs. These are xend.log and xm dmesg from the
> working case, when I pass pci = [04:00.0, 41:00.0, 41:00.1] which didn't
> work before with the pre-patch code.
>
> Thanks for this! Let me know if I should provide some more info,
> especially given that this change does not yet seem to work for Gordan
> on 4.2.
>
> Regards,
> Andreas
>
>
>
> 2013/5/16 Andreas Falck <falck.andreas.lists@gmail.com
> <mailto:falck.andreas.lists@gmail.com>>
>
>     Thanks! I'll give it a try in the weekend. I have been travelling,
>     that's why I haven't pursued this further yet.
>
>     Regards,
>     Andreas
>
>
>     2013/5/14 Jan Beulich <JBeulich@suse.com <mailto:JBeulich@suse.com>>
>
>          >>> On 05.05.13 at 21:33, Andreas Falck
>         <falck.andreas.lists@gmail.com
>         <mailto:falck.andreas.lists@gmail.com>> wrote:
>          > I tried adding some debugging statements in physdev_map_pirq.
>         I have
>          > attached the physdev.c with my debug statements, a hypervisor
>         log from
>          > testing, and the output of lspci -vv for my three devices.
>
>         Since I didn't hear anything from either of you anymore, I went
>         through the (not very familiar to me) tool stack code again, and
>         found that qemu and xend/libxl fundamentally disagree about the
>         model to be used. Qemu wants to allocate PIRQs while xend/libxl
>         want a 1:1 mapping. Allocating after having created a 1:1 mapping
>         works by returning the 1:1 mapping as allocation result, so as long
>         as libxl completes its setup before launching qemu, it would be
>         obvious why things work there. Consequently I assume that xend
>         launches qemu quite a bit earlier in the process of creating a new
>         domain, and the result of an attempt to establish a 1:1 mapping
>         when a different mapping was already established is dependent on
>         the specific interrupt numbers (i.e. also explains the observations
>         one of you made).
>
>         Since the tool stack as a whole really ought to use a consistent
>         model, and since the 1:1 mapping model for non-MSI IRQs seems
>         quite natural, the below/attached patch takes care of enforcing
>         a 1:1 mapping in libxc when allocation is being requested by the
>         caller. Ian, Ian - do you foresee any problem with this?
>
>         Please both of you give this a try and let us know of the results
>         (patch applies cleanly to all of -unstable, 4.2, and 4.1).
>
>         Jan
>
>         --- a/tools/libxc/xc_physdev.c
>         +++ b/tools/libxc/xc_physdev.c
>         @@ -49,7 +49,7 @@ int xc_physdev_map_pirq(xc_interface *xc
>               map.domid = domid;
>               map.type = MAP_PIRQ_TYPE_GSI;
>               map.index = index;
>         -    map.pirq = *pirq;
>         +    map.pirq = *pirq < 0 ? index : *pirq;
>
>               rc = do_physdev_op(xch, PHYSDEVOP_map_pirq, &map,
>         sizeof(map));
>
>         --- a/tools/python/xen/xend/server/pciif.py
>         +++ b/tools/python/xen/xend/server/pciif.py
>         @@ -340,7 +340,7 @@ class PciController(DevController):
>                           raise VmError(('pci: failed to configure I/O
>         memory on device '+
>                                       '%s - errno=%d')%(dev.name
>         <http://dev.name>,rc))
>
>         -        if not self.vm.info.is_hvm() and dev.irq:
>         +        if dev.irq > 0:
>                       rc = xc.physdev_map_pirq(domid = fe_domid,
>                                              index = dev.irq,
>                                              pirq  = dev.irq)
>
>
>
>