qemu-kvm und libvirt


Running anything as root always has security implications and so has libvirt. Therefor make sure you have your user set in /etc/libvirt/qemu.conf:

which implies, that your virtual machines are accessable by the defined user and group as well. They usually live under /var/lib/libvirt/images when using libvirtd, where you can mount anything.

manually call qemu with kvm

You can use this script to start virtual machines manually and with many features enabled.


Read things like $(: enable usb2.0 support) as comment (bash does!)


virsh does not start virutal machine with “Error: Machine ‘XYZ’ already exists”

This has been a bug, but in case your machine went into this trouble and you want to avoid a reboot, you can force the shutdown of the not-running process causing this issue by machinectl terminate qemu-xyz. The naming scheme differs slightly from the one we know from virsh and it can be looked up with machinectl list.

USB-Redirection not possible: Permission denied

That might be a polkit issue. I fixed it by creating a file: