Re: [Xen-devel] USB passthrough with Xen on ARM

[Julien Grall <julien.grall@xxxxxxx>]

Hello,

On 12/09/17 12:22, Roger Quadros wrote:
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>
> On 12/09/17 13:57, Julien Grall wrote:
> > Hi,
> >
> > On 12/09/17 11:00, Juergen Gross wrote:
> > > On 12/09/17 10:13, Roger Quadros wrote:
> > > > Hi,
> > > >
> > > > I'm running Xen v4.9 on DRA7 (OMAP5/ArmV7) with Linux kernel v3.14 (yikes!!) on 
> > > > dom0 and domU.
> > > > I'm struggling to get USB passthrough working using pvUSB.
> > > >
> > > > My domU config file contains
> > > >      usb = 1
> > > >      usbctrl = ['type=qusb,version=2,ports=4', 'type=qusb,version=1, ports=4', ]
> > > >
> > > > I can see the vusb-0 and vusb-1 platform devices in /sys/devices
> > > >
> > > > And the following message on domU kernel log
> > > > [    1.849572] xenbus_probe_frontend: Device with no driver: device/vusb/0
> > > > [    1.849627] xenbus_probe_frontend: Device with no driver: device/vusb/1
> > > >
> > > > This means that there is no device driver for the vusb host controllers.
> > > >
> > > > What is the way forward? Do I need to apply some patches to the domU kernel to
> > > > add support for the USB frontend HCD drivers?
> > > This is one mandatory step, yes. You'll need:
> > >
> > > https://lkml.org/lkml/2015/6/23/34
> > > https://lkml.org/lkml/2015/6/23/36
> OK, after applying the above 2 patches to v4.12 kernel for domU I'm able to see 
> the xen HCD driver
> enumerate, but it times out most likely due to the missing pvusb backend.
>
> [    0.510149] vusb vusb-0: Xen USB2.0 Virtual Host Controller
> [    0.510192] vusb vusb-0: new USB bus registered, assigned bus number 1
> [    0.510811] hub 1-0:1.0: USB hub found
> [    0.510865] hub 1-0:1.0: 4 ports detected
> [    0.812721] vusb vusb-1: Xen USB1.1 Virtual Host Controller
> [    0.812760] vusb vusb-1: new USB bus registered, assigned bus number 2
> [    0.813356] hub 2-0:1.0: USB hub found
> [    0.813410] hub 2-0:1.0: 4 ports detected
>
> ...
>
> [    5.888997] xenbus_probe_frontend: Waiting for devices to initialise: 
> 25s...20s...15s...10s...5s...0s...
> [   35.919000] 
> 235s...230s...225s...220s...215s...210s...205s...200s...195s...190s...185s...180s...175s...170s...165s...160s...155s...150s...145s...140s...135s...130s...125s...120s...115s...110s...105s...100s...95s...90s...85s...80s...75s...70s...65s...60s...55s...50s...45s...40s...35s...30s...25s...20s...15s...10s...5s...0s...
> [  270.879130]
> [  270.884161] xenbus_probe_frontend: Timeout connecting to device: 
> device/vusb/0 (local state 1, remote state 1)
> [  270.887059] xenbus_probe_frontend: Timeout connecting to device: 
> device/vusb/1 (local state 1, remote state 1)
>
> > > The question is whether this will be enough for you to make it work: the
> > > pvusb backend is qemu based. I'm not sure this will just work on ARM.
> > Backends in QEMU should just work with ARM. Although, I haven't tried the PVUSB 
> > one.
> Newbie question now. How do I start the QEMU pvusb backend on dom0?
If I am not mistaken, the backend should be started by 
"/etc/init.d/xencommons start" which also start xenstore and all the 
userspace components for Xen.
So you should have a QEMU running in Dom0. Can you check if it is the case?

Also, I would check that QEMU has been built with the PV USB backend. It 
depends on libusb. I am not entirely sure if the build system will 
require it and will therefore fault if it is not installed.
Juergen, do you have other idea why it would timeout?

Cheers,

--
Julien Grall

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