Re: Usb passthrough with upstream qemu question

[George Dunlap <george.dunlap@eu.citrix.com>]

On 04/10/13 15:00, Fabio Fantoni wrote:
> Il 04/10/2013 15:30, George Dunlap ha scritto:
>> On 04/10/13 14:16, Fabio Fantoni wrote:
>>> Il 04/10/2013 11:59, George Dunlap ha scritto:
>>>> On 25/09/13 15:11, Pasi Kärkkäinen wrote:
>>>>> On Tue, Sep 24, 2013 at 10:59:18AM +0100, George Dunlap wrote:
>>>>>> On 09/23/2013 03:46 PM, Fabio Fantoni wrote:
>>>>>>> I tested my latest patches about usb controllers (1-2-3) and usb
>>>>>>> redirection (from Spice client) support for upstream qemu and 
>>>>>>> are working.
>>>>>>> I also tested usb passthrough (from dom0) but seems that with older
>>>>>>> -usbdevice paraters is not working.
>>>>>>> I see the qemu docs/qdev-device-use.txt and based on this I 
>>>>>>> tried the
>>>>>>> new parameters, for example:
>>>>>>> device_model_args=["-device","usb-host,vendorid=0x058f,productid=0x6387"] 
>>>>>>>
>>>>>>> With new parameters usb passthrough is working, also with new usb
>>>>>>> controller and also with usb redirection enabled.
>>>>>>> I did all tests using latest xen and qemu version (1.6).
>>>>>>> I think should be good to change upstream qemu parameters for usb
>>>>>>> passthrough on libxl with the new ones.
>>>>>> Yes, I think it would be better.  The main difficulty is that the
>>>>>> libxl parameter is basically the old-style usbdevice parameter
>>>>>> passed straight through.  To support the current libxl parameter
>>>>>> with the new qemu would mean interpreting the usbdevice parameter
>>>>>> and translating it into the new-style parameter.
>>>>>>
>>>>>> My USB hot-plug series begins to introduce a more reasonable
>>>>>> interface for USB devices. Once that's in, we can think about
>>>>>> introducing a similar new interface for creating domains, that
>>>>>> should match the new way of specifying devices better. Then we
>>>>>> could just say, "If you're using spice, you have to use the new
>>>>>> interface."
>>>>>>
>>>>>> Unfortunately, it's looking like the USB hot-plug series may not
>>>>>> make it into 4.4 unless someone else can pick it up (or unless we
>>>>>> slip the feature freeze).
>>>>>>
>>>>> Hi,
>>>>>
>>>>> Is the latest version of the usb hotplug series posted to xen-devel,
>>>>> or are these not-yet-posted changes in your (private) tree?
>>>>>
>>>>> Just wondering if someone else wants to take a look at that.
>>>>
>>>> The latest patches I posted were version 6; the 1/2 can be found here:
>>>>
>>>> http://marc.info/?l=xen-devel&m=136638728928743
>>>>
>>>> I can't remember if I went through and made any changes as a result 
>>>> of comments or not; My latest local version can be found here:
>>>>
>>>> git://xenbits.xen.org/people/gdunlap/xen.git 
>>>> out/hvm-usb-hotplug.v6-plus
>>>>
>>>>  -George
>>>
>>> Thanks for reply, I see your patches but I didn't found changes on 
>>> "xl create" parts.
>>> Please could you keep an eye on my yesterday's mail about "xl 
>>> create" part changes?
>>> http://lists.xen.org/archives/html/xen-devel/2013-10/msg00157.html
>>> For now I'm trying to do patch for basic spice support to pv.
>>> After that I'll try to do a patch for changes usb qemu parameters to 
>>> make usb passthrough full working also with usb2,usb3 and usb 
>>> redirection enabled ifno one else can do.
>>
>> So at the moment, USB devices specified in the config file are added 
>> to the guest on the qemu command line.  However, most devices aren't 
>> like that: if you specify a PCI pass-through device, it will create 
>> the guest, and then the domain creation will call the pci add 
>> functions, just as it would if you were hot-plugging the device 
>> afterwards.
>>
>> So the idea would be that once the new USB hotplug interface was 
>> fully functional, then you'd do the same thing: just specify the USB 
>> controller on the qemu command line, and add in the other USB devices 
>> afterwards (i.e., after qemu had come up but before actually 
>> unpausing the guest).
>>
>>  -George
>
> If I'm not wrong on what you mean, usb controller definition should be 
> right with my patch "usbversion" while actual usbpassthrough part 
> should be
> replaced/remade in order to have devices passed by usbdevice and 
> usbdevice_list added after qemu launch with hotplug function you had 
> already did with your patches.
> Did you mean something else?

I thought the "usbpassthrough" stuff had to do with spice.

In any case, what you describe it sounds pretty close, with one caveat: 
Because usbdevice and usbdevice_list are basically just passing through 
strings that qemu understands on its command line, I don't think we can 
re-use them: I think we'd have to introduce another config option that 
would have a new interface which matches the new libxl interface 
better.  We'd have to keep the old ones around for backwards 
compatibility, but we can deprecate them.

  -George