Install KVM, QEMU, and Virt-Manager on Linux

Chris Titus — Wed, 12 Jan 2022 16:28:59 -0500

This guide installs KVM/QEMU, libvirt, and the Virt-Manager desktop app on Debian, Arch Linux, or Fedora. Pick your distribution, copy the commands, and then complete the shared setup steps.

Before You Install

KVM needs Intel VT-x or AMD-V hardware virtualization. Check whether your CPU exposes either feature:

grep -Eoc '(vmx|svm)' /proc/cpuinfo

Any number greater than 0 means the CPU virtualization extensions are available. If the result is 0, reboot into your BIOS/UEFI settings and enable Intel VT-x, Intel Virtualization Technology, AMD-V, or SVM Mode.

Debian

These commands install the QEMU/KVM hypervisor, libvirt, its command-line tools, and Virt-Manager:

sudo apt update
sudo apt install -y qemu-system-x86 qemu-utils libvirt-daemon-system libvirt-clients virt-manager

Start libvirt now and automatically at boot:

sudo systemctl enable --now libvirtd.service

Arch Linux

The qemu-desktop package is the practical choice for running x86 virtual machines with a graphical desktop. dnsmasq supplies DHCP and DNS for libvirt’s default NAT network.

sudo pacman -Syu --needed qemu-desktop libvirt virt-manager dnsmasq

Start libvirt now and automatically at boot:

sudo systemctl enable --now libvirtd.service

Fedora

Fedora’s virtualization package group installs QEMU/KVM, libvirt, Virt-Manager, and the default network configuration:

sudo dnf install -y @virtualization

Start libvirt now and automatically at boot:

sudo systemctl enable --now libvirtd.service

Allow Your User to Manage Virtual Machines

Add your current user to the libvirt group:

sudo usermod -aG libvirt "$USER"

Log out and back in so the new group membership takes effect. A reboot works too.

Membership in the libvirt group grants permission to manage system virtual machines. Do not add your account to broad device-access groups such as disk or input for this setup.

Enable the Default Virtual Network

First, check the available libvirt networks:

sudo virsh net-list --all

If default is listed as inactive, start it and configure it to start at boot:

sudo virsh net-start default
sudo virsh net-autostart default

Verify that default now shows active and yes under Autostart:

sudo virsh net-list --all

Verify KVM and Libvirt

Check that the KVM kernel modules are loaded. You should see kvm_intel or kvm_amd, plus the main kvm module:

lsmod | grep kvm

After logging back in, verify that your user can connect to the system libvirt service:

virsh --connect qemu:///system list --all

An empty virtual-machine list is normal on a new installation. If the command returns without a connection or permission error, the setup is working.

Create Your First Virtual Machine

Download the ISO for the operating system you want to install.
Open Virtual Machine Manager from your application menu, or run virt-manager.
Make sure the connection is QEMU/KVM - System.
Select Create a new virtual machine, choose your ISO, and follow the wizard.

Virt-Manager stores system VM disk images in /var/lib/libvirt/images/ by default.

Troubleshooting

The Virtualization Check Returns 0

Enable VT-x or AMD-V/SVM in BIOS/UEFI. On a VM host provided by a cloud service or another hypervisor, nested virtualization must also be enabled by that provider or parent hypervisor.

The Default Network Does Not Exist

Define it from libvirt’s packaged configuration, then start it:

sudo virsh net-define /usr/share/libvirt/networks/default.xml
sudo virsh net-autostart default
sudo virsh net-start default

Virt-Manager Cannot Connect

Confirm that libvirt is running:

systemctl status libvirtd.service

Then confirm that your login session has the libvirt group:

groups

If libvirt is missing, log out completely and log back in, or reboot.

Distribution Documentation

Walkthrough Video

The video below shows the original Debian-focused version of this setup. Package names and screens may differ from the updated commands above.

Arch Linux on Chris Titus Tech | Tech Content Creator

Install KVM, QEMU, and Virt-Manager on Linux

Before You Install

Debian

Arch Linux

Fedora

Allow Your User to Manage Virtual Machines

Enable the Default Virtual Network

Verify KVM and Libvirt

Create Your First Virtual Machine

Troubleshooting

The Virtualization Check Returns 0

The Default Network Does Not Exist

Virt-Manager Cannot Connect

Distribution Documentation

Walkthrough Video