7:59 a.m.
Hi Maxime,
Quoting Maxime Accadia (2020-02-03 14:20:47)
Hi,
We have a VM with several USB devices attached. Everything works well,
but sometimes, after a reboot of the host, some usb device get a
different bus/device number and that prevent the reboot of the VM :
...
Any idea on how to handle this case ?
We were thinking about using udev, but it seems that libvirt only
supports vendor/id (not unique in our case) and bus/device (not
predictable) to identify usb devices.
I had a similar issue where I have to distribute some identical USB
devices across three VMs. On my setup, the key to the fix is that the
*PCI* topology of the USB buses doesn't change, the port in which the
device is attached doesn't change, and udev supports globbing.
Here's my udev rules. Note I've left in the non-globbed old rules, so
that you can see how a typical bus distribution can look in my OS under
/sys/devices.
/etc/udev/rules.d/99-libvirt-wireless-dongles.rules:
# This doesn't work for removal since ATTR{devpath} isn't available at
# that point.
#SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="148f",
ENV{ID_MODEL_ID}=="5370", ATTR{busnum}=="8",
ATTR{devpath}=="6", RUN+="/usr/local/bin/usb-libvirt-hotplug.sh
gromit"
SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="0cf3",
ENV{ID_MODEL_ID}=="9271",
ENV{DEVPATH}=="/devices/pci0000:00/0000:00:1d.7/usb?/?-5",
RUN+="/usr/local/bin/usb-libvirt-hotplug.sh gromit"
#SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="0cf3",
ENV{ID_MODEL_ID}=="9271",
ENV{DEVPATH}=="/devices/pci0000:00/0000:00:1d.7/usb8/8-5",
RUN+="/usr/local/bin/usb-libvirt-hotplug.sh gromit"
SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="148f",
ENV{ID_MODEL_ID}=="5370",
ENV{DEVPATH}=="/devices/pci0000:00/0000:00:1a.7/usb?/?-2",
RUN+="/usr/local/bin/usb-libvirt-hotplug.sh odie"
#SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="148f",
ENV{ID_MODEL_ID}=="5370",
ENV{DEVPATH}=="/devices/pci0000:00/0000:00:1a.7/usb7/7-2",
RUN+="/usr/local/bin/usb-libvirt-hotplug.sh odie"
SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="148f",
ENV{ID_MODEL_ID}=="5370",
ENV{DEVPATH}=="/devices/pci0000:00/0000:00:1a.7/usb?/?-6",
RUN+="/usr/local/bin/usb-libvirt-hotplug.sh snoopy"
#SUBSYSTEM=="usb", ENV{ID_VENDOR_ID}=="148f",
ENV{ID_MODEL_ID}=="5370",
ENV{DEVPATH}=="/devices/pci0000:00/0000:00:1a.7/usb7/7-6",
RUN+="/usr/local/bin/usb-libvirt-hotplug.sh snoopy"
===
Now, due to the globs, this *might* break down if you have two identical
devices on two USB buses that are attached to the same PCI address, but
I *think* every bus actually has a dedicated PCI sub-address that
doesn't change even though the bus number itself might (the .7 in 1d.7
and 1a.7 in the rules). So YMMV, but I'm highly confident it will just
work.
The script being called, usb-libvirt-hotlug.sh <vmname>, can be found at
<https://github.com/olavmrk/usb-libvirt-hotplug/blob/master/usb-libvirt-ho...
However, I made a minor edit so that it uses attach --live, so that
they're immediately forwarded even if the machine is already up. So line
101-102 becomes:
echo "Running virsh ${COMMAND} ${DOMAIN} --live for USB vendor=0x${ID_VENDOR_ID}
product=0x${ID_MODEL_ID} bus=${BUSNUM} device=${DEVNUM}:" >&2
virsh "${COMMAND}" "${DOMAIN}" /dev/stdin --live <<END
===
I'm including the entire script below for posterity's sake, it's
MIT-licensed.
And yes, I'm including the license as well because that's what you're
supposed
to do.
The MIT License (MIT)
Copyright (c) 2016 Olav Morken
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
===
/usr/local/bin/usb-libvirt-hotplug.sh:
!/bin/bash
#
# usb-libvirt-hotplug.sh
#
# This script can be used to hotplug USB devices to libvirt virtual
# machines from udev rules.
#
# This can be used to attach devices when they are plugged into a
# specific port on the host machine.
#
# See: https://github.com/olavmrk/usb-libvirt-hotplug
#
# Abort script execution on errors
set -e
PROG="$(basename "$0")"
if [ ! -t 1 ]; then
# stdout is not a tty. Send all output to syslog.
coproc logger --tag "${PROG}"
exec >&${COPROC[1]} 2>&1
fi
DOMAIN="$1"
if [ -z "${DOMAIN}" ]; then
echo "Missing libvirt domain parameter for ${PROG}." >&2
exit 1
fi
#
# Do some sanity checking of the udev environment variables.
#
if [ -z "${SUBSYSTEM}" ]; then
echo "Missing udev SUBSYSTEM environment variable." >&2
exit 1
fi
if [ "${SUBSYSTEM}" != "usb" ]; then
echo "Invalid udev SUBSYSTEM: ${SUBSYSTEM}" >&2
echo "You should probably add a SUBSYSTEM=\"USB\" match to your udev
rule." >&2
exit 1
fi
if [ -z "${DEVTYPE}" ]; then
echo "Missing udev DEVTYPE environment variable." >&2
exit 1
fi
if [ "${DEVTYPE}" == "usb_interface" ]; then
# This is normal -- sometimes the udev rule will match
# usb_interface events as well.
exit 0
fi
if [ "${DEVTYPE}" != "usb_device" ]; then
echo "Invalid udev DEVTYPE: ${DEVTYPE}" >&2
exit 1
fi
if [ -z "${ACTION}" ]; then
echo "Missing udev ACTION environment variable." >&2
exit 1
fi
if [ "${ACTION}" == 'add' ]; then
COMMAND='attach-device'
elif [ "${ACTION}" == 'remove' ]; then
COMMAND='detach-device'
else
echo "Invalid udev ACTION: ${ACTION}" >&2
exit 1
fi
if [ -z "${BUSNUM}" ]; then
echo "Missing udev BUSNUM environment variable." >&2
exit 1
fi
if [ -z "${DEVNUM}" ]; then
echo "Missing udev DEVNUM environment variable." >&2
exit 1
fi
#
# This is a bit ugly. udev passes us the USB bus number and
# device number with leading zeroes. E.g.:
# BUSNUM=001 DEVNUM=022
# This causes libvirt to assume that the numbers are octal.
# To work around this, we need to strip the leading zeroes.
# The easiest way is to ask bash to convert the numbers from
# base 10:
#
BUSNUM=$((10#$BUSNUM))
DEVNUM=$((10#$DEVNUM))
#
# Now we have all the information we need to update the VM.
# Run the appropriate virsh-command, and ask it to read the
# update XML from stdin.
#
echo "Running virsh ${COMMAND} ${DOMAIN} --live for USB vendor=0x${ID_VENDOR_ID}
product=0x${ID_MODEL_ID} bus=${BUSNUM} device=${DEVNUM}:" >&2
virsh "${COMMAND}" "${DOMAIN}" /dev/stdin --live <<END
<hostdev mode='subsystem' type='usb' managed='yes'>
<source startupPolicy='optional'>
<vendor id='0x${ID_VENDOR_ID}' />
<product id='0x${ID_MODEL_ID}' />
<address bus='${BUSNUM}' device='${DEVNUM}' />
</source>
</hostdev>
END
===