Install all the required for the installation of Qemu, KVM hypervisor, and Libvirt

# apt install qemu-system libvirt-daemon-system qemu-utils virt-manager

• qemu-system: is an open source virtualizer that provides hardware emulation for the KVM hypervisor. It acts as a virtual machine monitor together with the KVM kernel modules, and emulates the hardware for a full system such as a PC and its associated peripherals.
• virt-manager: Virt-Manager is a graphical user interface (GUI) tool for managing virtual machines through libvirt-daemon.
• libvirt-daemon-system: provides API libraries that enables GUI apps such as virt-manager to communicate with libvirtd daemon, a system service libvirtd , and a virsh CLI tool
• qemu-utils: Various utilities e.g. for manipulating disk images
• virtinst: Allows to create Virtual Machines (VMs) from the command-line.

Verify that the virtualization daemon, libvritd-daemon, is operating before moving on. Execute the command to achieve this.

#  systemctl status libvirtd

Output: 

● libvirtd.service - Virtualization daemon
     Loaded: loaded (/lib/systemd/system/libvirtd.service; enabled; preset: enabled)
     Active: active (running) since Sun 2023-08-06 10:57:02 CEST; 1min 30s ago
TriggeredBy: ● libvirtd-ro.socket
             ● libvirtd-admin.socket
             ● libvirtd.socket
       Docs: man:libvirtd(8)
             https://libvirt.org
   Main PID: 7999 (libvirtd)
      Tasks: 19 (limit: 32768)
     Memory: 15.7M
        CPU: 188ms
     CGroup: /system.slice/libvirtd.service
             └─7999 /usr/sbin/libvirtd --timeout 120
Aug 06 10:57:02 pcwerkkamer systemd[1]: Starting libvirtd.service - Virtualization daemon...
Aug 06 10:57:02 pcwerkkamer systemd[1]: Started libvirtd.service - Virtualization daemon.

Check if libvirtd service will start automatically at boot time.

# systemctl is-enabled libvirtd

Output: 
enabled

If disabled run the following command to have it boot automatically:

# systemctl enable --now libvirtd

Use the following command to determine whether the KVM modules are loaded:

$ lsmod | grep -i kvm
kvm_intel             380928  0
kvm                  1142784  1 kvm_intel
irqbypass              16384  1 kvm

In order to manage virtual machines as a regular user, that user needs to be added to the libvirt group:

# adduser <youruser> libvirt

By default, if virsh is run as a normal user it will connect to libvirt using qemu:/session URI string. This URI allows virsh to manage only the set of VMs belonging to this particular user. To manage the system set of VMs (i.e., VMs belonging to root) virsh should be run as root or with qemu:/system URI:

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

To avoid having to use the –connect flag on every command, the URI string can be set in the LIBVIRT_DEFAULT_URI environment variable:

$ export LIBVIRT_DEFAULT_URI='qemu:///system'