A little utility to dynamically passthrough USB devices to running libvirt virtual machines.
libvirt supports permanently mapping a USB device to a VM, or dynamically attaching a device once during runtime. It does not have very good support for temporarily passing through USB devices that are frequently reconnected. qemu-stormcrow is for that case.
qemu-stormcrow should be launched as a daemon first. cargo run in a terminal, or write a systemd service, or spawn it in the background from a script, or whatever. It does not self-daemonize.
A USB device with a (Vendor ID, Product ID) pair is registered for a running libvirt VM via D-Bus:
$ dbus-send --type=method_call --print-reply --dest=com.stormcrow.device /device com.stormcrow.device.Add string:<VM> string:<VID> string:<PID>qemu-stormcrow monitors the udev subsystem for attach/remove events of the VID/PID pair. When one is attached, qemu-stormcrow generates a libvirt hostdev XML snippet for the device and attaches it to the running VM. Likewise, it detaches the hostdev device when removed.
When finished, the device can be unregistered. qemu-stormcrow will no longer monitor for such devices:
$ dbus-send --type=method_call --print-reply --dest=com.stormcrow.device /device com.stormcrow.device.Remove string:<VM> string:<VID> string:<PID>qemu-stormcrow can be shutdown via D-Bus as well:
$ dbus-send --type=method_call --print-reply --dest=com.stormcrow.device /device com.stormcrow.device.QuitNo. It's a hacky little script for personal use.