Virtual machines on linux using QEMU/KVM and virt-manager

A guide for Arch Linux

Install QEMU/KVM and virt-manager

Installing all the packages we need.

sudo pacman -S qemu virt-manager archlinux-keyring virt-viewer dnsmasq vde2 bridge-utils openbsd-netcat ebtables iptables libguestfs

Now lets start the KVM libvirt service

sudo systemctl enable --now libvirtd.service

Make sure libvirtd is running

sudo systemctl status libvirtd.service

Now lets give permissions for our standard user to manage KVM.

sudo vim /etc/libvirt/libvirtd.conf

Now uncomment unix_sock_group = "libvirt" and unix_sock_rw_perms = "0770". Now add your user to the libvirt group and restart the libvirt service.

sudo usermod -a -G libvirt $(whoami)
newgrp libvirt
sudo systemctl restart libvirtd.service

Enabling Nested Virtualization

This allows you to run virtual machines inside virtual machines.

# Intel CPU
sudo modprobe -r kvm_intel
sudo modprobe kvm_intel nested=1
# AMD CPU
sudo modprobe -r kvm_amd
sudo modprobe kvm_amd nested=1

To make this configuration persistant:

echo "options kvm-intel nested=1" | sudo tee /etc/modprobe.d/kvm-intel.conf

# Intel CPU
systool -m kvm_intel -v | grep nested
cat /sys/module/kvm_intel/parameters/nested
 
# AMD CPU
systool -m kvm_amd -v | grep nested
cat /sys/module/kvm_amd/parameters/nested

If your network `default` is not enabled run `sudo virsh net-start default`

Conclusion

Now you can install your virtual machines using virt-manager