Having trouble with USB Passthrough to an HVM vm

[David Kowis <david@xxxxxx>]

Firstly the error,

root@nosgoth:/etc/xen/conf# xl create hass-hvm.cfg
Parsing config from hass-hvm.cfg
libxl: error: libxl_qmp.c:1813:qmp_ev_parse_error_messages: Domain 
24:failed to open host usb device 2:3
libxl: error: libxl_create.c:1701:domcreate_attach_devices: Domain 
24:unable to add vusb devices
libxl: error: libxl_domain.c:1177:libxl__destroy_domid: Domain 
24:Non-existant domain
libxl: error: libxl_domain.c:1131:domain_destroy_callback: Domain 
24:Unable to destroy guest
libxl: error: libxl_domain.c:1058:domain_destroy_cb: Domain 
24:Destruction of domain failed
from /var/log/xen/qemu-dm-hass.log:
Warning: speed mismatch trying to attach usb device "host:2.3" (full 
speed) to bus "xenusb-0.0", port "1" (high speed)
qemu-system-i386: terminating on signal 1 from pid 12738 (xl)
(that's all there is.)

And, my config:
<hass-hvm.cfg>
name="hass"
type="hvm"
vcpus=4
memory=2048
maxmem=4096
#device_model_version = "qemu-xen"
firmware = "seabios"

# Enable pv on hvm drivers
xen_platform_pci=1

vif = [ 'mac=00:16:3E:DE:AD:78, bridge=xenbr0' ]

boot='c'

disk = [
  
'phy:/dev/disk/by-path/ip-10.255.255.2:3260-iscsi-iqn.2005-10.org.freenas.ctl:xen-lun-35,xvda,w'
  
#'file:/mnt/systems/ubuntu/18.04/ubuntu-18.04.01-netboot.iso,hdc:cdrom,r'
  
#'file:/mnt/systems/ubuntu/18.04/ubuntu-18.04.4-live-server-amd64.iso,hdc:cdrom,r'
       ]


# usb passthrough for the zwave stick
usbctrl=['type=auto,version=2,ports=6']
usbdev=['hostbus=2,hostaddr=3']

#usb=1
#usbdevice=['host:658:200']

vnc=0

# Everything but qxl
vga = 'stdvga'

# Spice configuration?
spice = 1
spicehost = '10.10.220.111'
spiceport = 9701
spicepasswd = 'blerp'
spicevdagent = 1
spice_clipboard_sharing = 1
</hass-hvm.cfg>

Host lsusb:
<lsusb>
root@nosgoth:/etc/xen/conf# lsusb
Bus 002 Device 003: ID 0658:0200 Sigma Designs, Inc.
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching 
Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 004: ID 0624:0249 Avocent Corp. Virtual Keyboard/Mouse
Bus 001 Device 003: ID 0624:0248 Avocent Corp. Virtual Hub
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching 
Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
root@nosgoth:/etc/xen/conf# lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
        |__ Port 5: Dev 3, If 0, Class=Communications, Driver=cdc_acm, 
12M
        |__ Port 5: Dev 3, If 1, Class=CDC Data, Driver=cdc_acm, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
        |__ Port 1: Dev 3, If 0, Class=Hub, Driver=hub/5p, 480M
            |__ Port 1: Dev 4, If 0, Class=Human Interface Device, 
Driver=usbhid, 480M
            |__ Port 1: Dev 4, If 1, Class=Human Interface Device, 
Driver=usbhid, 480M
            |__ Port 1: Dev 4, If 2, Class=Human Interface Device, 
Driver=usbhid, 480M
</lsusb>


Next, I've built xen by hand from the upstream tarball, 4.13.1 using 
this docker image: 
https://gitlab.light.kow.is/kowis-projects/xen-builder
Configuration options are as in the readme:
./configure --enable-stubdom 
--with-extra-qemu-configure-args="--enable-spice --enable-libusb 
--enable-usb-redir" --with-xenstored=oxenstored --enable-systemd 
--enable-ovmf
I'm not sure why I can't get usb passthrough to work, I kinda need it to 
work, else I'll have to switch to some other virtualization 
infrastructure :( I'm hoping it's just something simple, and that ya'll 
will be able to point it out to me.
Thanks!