Re: Usb passthrough with upstream qemu question

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

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