Notes on how to install KVM on Ubuntu 20.04 or 22.04
- Installing KVM on Ubuntu 20.04 or 22.04
- Pre-Req's
- Install Tooling for KVM Management
- Check that virt-manager was installed and can talk to your libvirt daemon
- Setup a network bridge to enable communication between the host and your VMS
- Setup Bridge Network on KVM
- Use Virtual Machine Manager to check Network Bridge
- Use Virtual Machine Manager to Create a VM
- Conclusion and Next Steps
Install Ubuntu 20.04 or 22.04, we will use Desktop version for this guide.
During install choose "Normal installation",
"Download updates while installing Ubuntu", and
"Install third-party software for graphics and Wi-Fi
hardware and additional media formats" to make sure we have all the necessary drivers.
This takes about 15 minutes, but depends on your Computer and Network Speed.
Once Ubuntu Install has completed, it will ask you to restart.
Follow the prompts and then login to the fresh install.
Open a terminal and update your packages to the latest version, this step may take a while. Follow the prompts from the command line tooling.
sudo apt update && sudo apt dist-upgradeYou don't need SSH access to the machine, but it makes it easier to administer it remotely.
Install OpenSSH, follow the prompts:
sudo apt install openssh-serverOnce Openssh is installed, you can get your IP with:
ip a | grep inetlook for the line that says something like:
inet 192.168.X.Ywhere X and Y are dependent on your network setup.
The 192.168. part could also be different,
but it is usually 192.168.X.Y for smaller networks.
You can then ssh to your machine with:
ssh <username>@192.168.X.Yyou will be presented with something like:
The authenticity of host '192.168.X.Y (192.168.X.Y)' can't be established.
ECDSA key fingerprint is SHA256:SOME_SHA_KEY_GOES_HERE.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yestype yes and it should ask you for your password.
The intricacies of SSH and SSH keys are beyond the scope of this guide.
When remotely administering a machine, it is helpful to have a shell always running that you can re-connect to. Byobu enables you to do just that, learn more at byobu.org
it can be installed with:
sudo apt install byobuNow that our machine is up to date, we can Install cpu-checker package:
sudo apt install cpu-checkerFollow the prompts, and you should now have the kvm-ok application from the cpu-checker package. Run the kvm-ok application:
sudo kvm-okIf everything is setup properly, you should get something like:
daniel@kvmdemo:~$ sudo kvm-ok
INFO: /dev/kvm exists
KVM acceleration can be usedNote: in the example above, my user name is
danieland my machine name iskvmdemo
The important bit is that it responded with:
KVM acceleration can be usedIf you don't see that message, you may need to edit your BIOS settings. Unfortunately, each device is a little different in how you change that setting.
Since we know that the current machine supports KVM, we can now install some tooling to make our life easier.
sudo apt install qemu-kvm bridge-utils virt-managerThe above command installs the following, and supporting tooling:
-
qemu-kvm: provides machine emulation, learn more at qemu.org -
bridge-utils: tools to enable your host machine to network with the VMs -
virt-manager: a simple UI for creating VMs
Follow the prompts, a few packages will be installed to support using qemu, bridge-utils and virt-manager.
reboot the host machine. There are many ways to make sure everything is setup and started properly, but the easiest way is to just reboot the machine.
On the host machine, open your application view and look for "Virtual Machine Manager"
In order to communicate between your host machine and the hosted VMs, you need to create a bridge.
In order to setup a bridge, we need to figure out which ethernet adapter
to use, for this we can use the ip command:
ip -c linkHere the -c will provide you with a nice colorized output and the link will show you network device status
the output should look similar to this:
daniel@kvmdemo:~$ ip -c link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master breno1 state UP mode DEFAULT group default qlen 1000
link/ether <SOME ADDRESS HERE> brd ff:ff:ff:ff:ff:ffin the above example, the ethernet adapter of interest is eno1.
In case we need to get back to a default install
sudo cp /etc/netplan/01-network-manager-all.yaml /etc/netplan/01-network-manager-all.yaml.bakEdit Netplan config file with your editor of choice (here we use nano):
sudo nano /etc/netplan/01-network-manager-all.yamlnano should show something like:
# Let NetworkManager manage all devices on this system
network:
version: 2
renderer: NetworkManagerWe want to change it to:
network:
version: 2
renderer: networkd
ethernets:
# here eno1 is the ethernet adapter for the host machine
# we found this name in a previous step
eno1:
dhcp4: no
dhcp6: no
bridges:
# breno1 will be the name of our bridge
# it will use DHCP to get an IP address
breno1:
dhcp4: yes
dhcp6: no
interfaces: [ eno1 ]Note: The netplan file is in
yamlformat - Spaces matter
In order to make sure that our network bridge is created successfully, we can run the netplan try command on the host machine:
Note: Do this while connected directly to the host machine, not remotely since the DHCP lease may give you a new IP address.
sudo netplan tryThis command will try to parse the config file and apply it to the host system, if an error is detected it will roll back after 120 seconds.
If everything is working as expected, reboot the machine to make sure the new configuration is applied.
Once the machine comes back online, you should have a new entry on your networking stack showing the bridge:
ip ashould show something similar to:
daniel@kvmdemo:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master breno1 state UP group default qlen 1000
link/ether <SOME ADDRESS HERE>
altname <SOME NAME HERE>
3: breno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether <SOME ADDRESS HERE> brd ff:ff:ff:ff:ff:ff
inet 192.168.5.197/24 brd 192.168.5.255 scope global dynamic breno1
valid_lft 86172sec preferred_lft 86172secIn the above example, eno1 is the ethernet device and breno1 is the bridge. The bridge has been assigned the inet 192.168.5.197/24 address.
In order to use the bridge with KVM, we must configure the bridge with KVM.
Create a file called hostbridge.xml, in the example we are creating it in the user's home folder
nano ~/hostbridge.xmlthe contents should be:
<network>
<name>hostbridge</name>
<forward mode='bridge'/>
<bridge name='breno1'/>
</network>Note: The
namecan be anything you want, but thebridge name=should match what we setup in the netplan config file. In this example it isbreno1
We can now feed that configuration into virsh:
sudo virsh net-define hostbridge.xmlit should respond with:
Network hostbridge defined from hostbridge.xmlNow we can tell virsh to auto start the bridge and to start it up right now:
sudo virsh net-autostart hostbridge && sudo virsh net-start hostbridgeit should respond with something like:
Network hostbridge marked as autostarted
Network hostbridge startedWe can check the status of the KVM network with:
sudo virsh net-list --allit should respond with something like:
Name State Autostart Persistent
-----------------------------------------------
default active yes yes
hostbridge active yes yesNow back on the host machine, look for the "Virtual Machine Manager" application. The icon should look like this:
The main window for Virtual Machine Manager should open:
Right-click on "QEMU/KVM" and choose "Details":
A new window will open showing you "Qemu/KVM Connection Details"
Click on "Virtual Networks" and you should see the bridge "hostbridge"
There are command line tools to create VMs such as virt-install, but Virtual Machine Manager provides a way of doing it through a GUI.
We can now create a VM, we will use Ubuntu Desktop as a sample and thus need the ISO.
On the main Virtual Machine Manager Window, click on the "Create a new virtual machine":
A new window will open, choose "Local install media (ISO image or CDRom)"
Click Forward, it will now let you choose the ISO by clicking on Browse:
A new window will open, "Choose Storage Volume", click on Browse Local and
use the File chooser dialog to browse for the Ubuntu ISO.
In my case I had the ISO in the Downloads folder
Click Forward which will take you to the Memory and CPU Settings.
The values used here are up to you and your particular use case,
but I would recommend a minimum of 4GB of RAM and 2 CPUs:
Click Forward which will take you to the Storage specification.
The values used here are up to you and your particular use case:
Click Forward which will take you to the Final configuration screen.
Here you can specify a name for the VM (here I chose ubuntutest), see the OS KVM thinks you are installing,
Memory, CPU, and Storage specified.
Before finishing, we want to make our new VM use the bridge network rather than
the internal NAT network. We can change this by clicking on "Network selection"
and choosing "Virtual network 'hostbridge': Bridge network":
Click Finish and a new window called "ubuntutest on QEMU/KVM" will open. The VM will be initialized and act
just like a physical machine. In this example, the ubuntu installer will start:
From this point forward it is pretty much equivalent to installing on a bare metal machine. For this example, I chose "Try Ubuntu" to get a "live" session.
Note: I opened a terminal once the "live" session started in order to verify that I was on the correct network. In the screenshot below you can see that the machine has an IP of
192.168.5.190, meaning it reached out through the network bridge to the network and got a DHCP lease from my local network router.
That's it! You now have a machine that can host VMs.
Let me know if you have any questions. I can be reached at @IAmDanielV or @iamdanielv.bsky.social.
The performance of your VMs will vary depending on the host machine resources and number of VMs running.