Update: I haven't been able to figure out how to tell qemu to use a USB1.x interface instead of USB2.x (EHCI) which would let me pass the device through, but I've found a different work around. The device I'm trying to pass through appears as a USB serial device. After I stumbled upon a page mentioning that you could tie an emulated serial port to a TCP socket I dug further and found that you can do

xe vm-param-add uuid=<uuid> param-name=platform hvm_serial=/dev/ttyACM0

and hey presto your /dev/ttyS0 in the guest is now tied to the device on the hypervisor

I may still poke around and try and find a better solution but for now my needs appear to be satisfied.

A slightly less hacky work around for USB v1 passthrough based on the issue I created:

--- /opt/xensource/libexec/usb_scan.py     2019-11-04 10:03:02.000000000 +0000
+++ /tmp/usb_scan.py    2020-03-01 17:32:29.266317478 +0000
@@ -152,10 +152,11 @@
     _CLASS = "bDeviceClass"
     _CONF_VALUE = "bConfigurationValue"
     _NUM_INTERFACES = "bNumInterfaces"
+    _USB_SPEED = "speed"
 
     _PRODUCT_DESC = [_DESC_VENDOR, _DESC_PRODUCT]
     _PRODUCT_DETAILS = [_VERSION, _ID_VENDOR, _ID_PRODUCT, _BCD_DEVICE, _SERIAL,
-                        _CLASS, _CONF_VALUE, _NUM_INTERFACES]
+                        _CLASS, _CONF_VALUE, _NUM_INTERFACES, _USB_SPEED]
     _PROPS = _PRODUCT_DESC + _PRODUCT_DETAILS
     _PROPS_NONABLE = _PRODUCT_DESC + [_SERIAL]
 
@@ -590,7 +591,10 @@
 
     pusb["path"] = device.get_node()
     # strip the leading space of "version"
-    pusb["version"] = device[UsbDevice._VERSION].strip()
+    if int(device[UsbDevice._USB_SPEED]) <= 12:
+        pusb["version"] = "1.00"
+    else:
+        pusb["version"] = device[UsbDevice._VERSION].strip()
     pusb["vendor-id"] = device[UsbDevice._ID_VENDOR]
     pusb["product-id"] = device[UsbDevice._ID_PRODUCT]
     pusb["vendor-desc"] = device[UsbDevice._DESC_VENDOR]

in theory any deice which is "low" or "full" speed (i.e. USB1) will have it's version number changed to 1.00 which forces xenopsd to use a USB1 bus. It may have side effects if the driver in the guest relies on the version number so caveat emptor.

@olivierlambert created https://github.com/xcp-ng/xcp/issues/342 under xcp project. Thanks!

ScottyGuy created this issue in xcp-ng/xcp

closed Please create test packages to help with USB support (related to CA-328130 ) #342