[Xen-devel] Xen pci-passthrough problem with pci-detach and pci-assignable-remove

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Hi Konrad,

Normally i'm never reattaching pci devices to dom0, but at the moment i have 
some use for it.

But it seems pci-detach isn't completely detaching the device from the guest.

- Say i have a guest (HVM) with domid=2 and a pci device passedthrough with bdf 
00:19.0, the device is hidden on boot with xen-pciback.hide=(00:19.0) in grub.

- Now i do a "xl pci-assignable-list"
  This returns nothing, which is correct since all hidden devices have already 
been assigned to guests.

- Then i do "xl -v pci-detach 2 00:19.0"
  Which also returns nothing ...

- Now i do a "xl pci-assignable-list" again ..
  This returns:
  "0000:00:19.0"
  So the pci-detach does seem to have done *something* :-)

- But when now trying to remove the device from pciback to dom0 with "xl 
pci-assignable-remove 00:19.0" it gives an error
  and later it give some stacktraces ..

  xen_pciback: ****** removing device 0000:00:19.0 while still in-use! ******
  xen_pciback: ****** driver domain may still access this device's i/o 
resources!
  xen_pciback: ****** shutdown driver domain before binding device
  xen_pciback: ****** to other drivers of domains


When i shut the guest down instead of using pci-detach, the "xl 
pci-assignable-remove" works fine and i can rebind the device to it's driver in 
dom0.

So am i misreading the wiki .. and is it not possible to detach a device from a 
running domain or ... ?

Oh yes running xen-unstable and a 3.13-rc7 kernel

--
Sander



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