Virtualization is an old technology that still finds high use in this era of cloud computing. It can be defined as dividing the computer resources logically. By doing so, it helps create software-based or virtual versions of computer resources such as networks, storage, servers, and applications. Moreso, organizations are able to partition a single server into different Virtual Machines that interact independently
To facilitate virtualization, a hypervisor is used either on top of the operating system or directly installed on the hardware. This brings the two major Hypervisor types:
- Bare Metal/Type 1 Hypervisors: These hypervisors are installed directly on top of the physical machine. They are considered secure hypervisors when compared to Type2 Hypervisors. They include Microsoft Hyper-V, open-source Kernel-based VMs (KVMs), VMware ESXi
- Hosted/Type 2 Hypervisors: These are installed on top of an existing operating system. They have more latency as compared to Type 1 due to their hosted nature. These include VMware Workstation and Oracle VirtualBox
Kernel-based Virtual Machine abbreviated as KVM is an open-source hypervisor that allows your Linux system to host and run multiple isolated virtual environments. It works by converting the Linux system into a Type1/bare-metal hypervisor. It avails the host resources including Memory, CPUs, and virtual devices to the virtual machine instances.
KVM offers a lot of features that include high performance, scalability, scheduling, and resource control, lower latency, live migration, memory management e.t.c Amongst the amazing feature is the ability to automate deployments on KVM using Ansible and other automation tools. This makes it easy to run several deployments at once.
In this guide, we will take a walk through how to install and use KVM Virtualization on Rocky Linux 9.
You need to confirm if the required virtualization extensions are available. These are Intel VT for Intel or AMD-V for AMD processors. If not enabled, you may be required to make the configuration in BIOS.
cat /proc/cpuinfo | egrep --color "vmx|svm"
Alternatively, you can use the command:
$ lscpu | grep Virtualization Virtualization: VT-x Virtualization type: full
1. Install KVM tools on Rocky Linux 9
The KVM packages reside in the default Rocky Linux 9 repositories and can be installed using the command:
sudo dnf install qemu-kvm libvirt virt-manager virt-install
Install other managements tools:
sudo dnf install epel-release -y sudo dnf -y install bridge-utils virt-top libguestfs-tools bridge-utils virt-viewer
Once complete, check if the kernel modules are loaded:
$ lsmod | grep kvm kvm_intel 364544 0 kvm 1056768 1 kvm_intel irqbypass 16384 1 kvm
Start and enable the service:
sudo systemctl start libvirtd sudo systemctl enable libvirtd
Verify if the service is running:
$ systemctl status libvirtd libvirtd.service - Virtualization daemon Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; enabled; vendor preset: disabled) Active: active (running) since Fri 2022-07-22 14:28:15 CEST; 8s ago TriggeredBy: ● libvirtd.socket ● libvirtd-ro.socket ● libvirtd-admin.socket ○ libvirtd-tcp.socket ○ libvirtd-tls.socket Docs: man:libvirtd(8) https://libvirt.org Main PID: 35007 (libvirtd) Tasks: 21 (limit: 32768) Memory: 14.6M CPU: 293ms CGroup: /system.slice/libvirtd.service ├─35007 /usr/sbin/libvirtd --timeout 120 ├─35119 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_> └─35120 /usr/sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/libexec/libvirt_
To execute commands, you need to add your system user to the KVM group:
sudo usermod -aG libvirt $USER newgrp libvirt
2. Create a Network Bridge for KVM instances
By default, a network bridge with the name virbr0 is created to provide NAT. The VMs using this bridge do not have external connectivity.
The available bridge networks can be checked using the command:
$ brctl show bridge name bridge id STP enabled interfaces virbr0 8000.5254002f2d76 yes
For external connections, you need to create a network bridge. In this guide, I will show you how to create a network bridge using NMCLI.
Begin by identifying the available connections:
$ sudo nmcli connection show NAME UUID TYPE DEVICE enp6s18 f546038c-74f7-359d-849b-c7be2f0bd125 ethernet enp6s18 virbr0 221e4b7d-ebef-4acb-b3e5-b729338f0d1d bridge virbr0
After identifying the device, export the related variables for the bridge:
BR_NAME="br0" BR_INT="enp6s18" SUBNET_IP="192.168.205.10/24" GW="192.168.205.1" DNS1="126.96.36.199" DNS2="188.8.131.52"
- BR_NAME: The name of the bridge to be created.
- BR_INT: the physical network device to be used as bridge slave.
- SUBNET_IP: IP address and subnet assigned to the bridge created.
- GW: The IP address of the default gateway
- DNS1 and DNS2: IP addresses of the DNS servers to be used.
Proceed and define the bridge network:
sudo nmcli connection add type bridge autoconnect yes con-name $BR_NAME ifname $BR_NAME
Now add the IP, gateway, and DNS to the bridge:
sudo nmcli connection modify $BR_NAME ipv4.addresses $SUBNET_IP ipv4.method manual sudo nmcli connection modify $BR_NAME ipv4.gateway $GW sudo nmcli connection modify $BR_NAME ipv4.dns $DNS1 +ipv4.dns $DNS2
Add the identified network device as a slave to the bridge:
sudo nmcli connection delete $BR_INT sudo nmcli connection add type bridge-slave autoconnect yes con-name $BR_INT ifname $BR_INT master $BR_NAME
Verify the creation:
sudo nmcli connection show
Start the network bridge:
sudo nmcli connection up br0
Verify if the network is running:
sudo nmcli connection show br0
You can also use the command:
$ ip ad 1: lo:
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: enp6s18: mtu 1500 qdisc fq_codel master br0 state UP group default qlen 1000 link/ether 72:b2:b9:a5:70:7c brd ff:ff:ff:ff:ff:ff 3: br0: mtu 1500 qdisc noqueue state UP group default qlen 1000 link/ether 72:b2:b9:a5:70:7c brd ff:ff:ff:ff:ff:ff inet 192.168.205.10/24 brd 192.168.205.255 scope global noprefixroute br0 valid_lft forever preferred_lft forever
For the bridge to be used by KVM, edit the below file:
sudo vim /etc/qemu-kvm/bridge.conf
Add the line:
Then restart KVM:
sudo systemctl restart libvirtd
3. Create Virtual Machines on KVM
There are two ways how to create VMs on KVM. These are:
- Using the CLI
- Using Virtual Machine Manager
To proceed, you need an ISO file required for the OS installation.
Option 1 – Using virt-install CLI tool
Spinning a VM from the CLI is simple especially if you are familiar with the KVM concepts, all you need to do is run a command with the following variables captured. But first, set the right ownership of the
sudo chown -R $USER:libvirt /var/lib/libvirt/
Then proceed as shown:
virt-install \ --name Rocky9 \ --ram 2048 \ --vcpus 1 \ --disk path=/var/lib/libvirt/images/rocky-9.img,size=20 \ --os-variant centos-stream9 \ --os-type linux \ --network bridge=br0,model=virtio \ --graphics vnc,listen=0.0.0.0 \ --console pty,target_type=serial \ --location /home/rocky9/Downloads/Rocky-9.0-x86_64-minimal.iso
- –disk path=/var/lib/libvirt/images/rocky-9.img,size=20 is the path to create the disk and disk size in GBs
- –vcpus 1 is the number of CPUs to be used
- –ram 2048 is the allocated memory.
- –network bridge=br0 flag specifies the network bridge to use.
- –graphics vnc,listen=0.0.0.0 specifies the VNC listen address. You can also set a password by editing the line to be –graphics vnc,listen=0.0.0.0,password=password
- –location /home/rocky9/Downloads/Rocky-9.0-x86_64-minimal.iso is the path of your ISO file.
Once the command is executed, VNC will be launched as shown.
You can view available VMs using the command:
$ virsh list --all Id Name State --------------------------------- 1 centos-stream-9 running 2 Rocky9 running
Option 2 – Using the Virtual Machine Manager GUI tool
The GUI tool provides an easy-to-understand method. Here, all the activities performed above are done in a GUI tool launched as shown:
To create a VM, click on the highlighted icon.
Load the ISO file
Browse and load the ISO file:
Configure the CPU and Memory for the VM.
Create and set the hard disk size.
Allow customization before installation by checking the box as shown below. You can also configure the VM network and select the network bridge.
On the overview windows, you can configure the system chipset and Firmware(whether BIOS or UEFI).
Add/configure a VNC server. You can as well set a password and port.
You can also add the required hardware such as TPM required for some Operating systems such as Windows 11
Once desired configurations have been made, click finish and apply the changes. On the overview page, click Begin Installation and proceed:
More demonstration of how to enable create a VM on KVM and enable TPM 2.0, UEFI, and many other VM configurations has been captured in the guide on how to:
That is it!
We have triumphantly walked through how to install and use KVM Virtualization on Rocky Linux 9. I hope this was important to you.