Re: [Xen-devel] Multi-Function PCI passthrough not implemented?

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Monday, September 16, 2013, 9:27:58 AM, you wrote:

>>>> On 13.09.13 at 23:52, Antonin Bas <antoninb@xxxxxxxxxxxxxxx> wrote:
>> There are several mentions of these features on the wiki
>> (http://wiki.xen.org/wiki/VTdHowTo,
>> http://wiki.xen.org/wiki/Bus:Device.Function_(BDF)_Notation). However,
>> this is definitely not working and I could not see it implemented
>> anywhere in libxl.
>> 
>> I actually even think there is a bug in the code:
>> 
>> xlu_pci_parse_bdf in libxlu_pci.c accepts inputs of the form
>> "domain:bus:dev.*" (* is really a star here), which is supposed to
>> designate all the functions for this PCI device.
>> In this case, pcidev->func will be set to an uninitiated value by
>> pcidev_struct_fill().
>> Later on, libxl__device_pci_add() and libxl_pcidev_assignable()
>> (libxl_pci.c) are called with pcidev as an argument. And because
>> pcidev->func is garbage, an error is thrown.

> You not mentioning the Xen version I'd assume you talk about
> -unstable, yet looking at the code I can't match things up with
> what you say above. In fact it looks to me as if multi-function
> support was properly dealt with by libxl{u,}_pci.c...

Hi Jan,

It is easy to trigger with unstable.

libxl__device_pci_add early on calls libxl_pcidev_assignable to verify the 
device func is assignable,
but this function isn't multifunction aware and tries to match the non-existant 
function number used
to to the assignable list which only contains the individual reserved device 
and function numbers.

So it returns false and xl gives an error like:
libxl: error: libxl_pci.c:1056:libxl__device_pci_add: PCI device 0:7:0.f0 is 
not assignable


So libxl_pcidev_assignable should check if it's multifunction is specified, and 
if so check if all 8 func's for this devices
are assignable.

--
Sander

> Jan





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