Kernel-based Virtual Machine (KVM) has become a staple open-source virtualization technology on Linux thanks to its excellent performance1, scalability, and tight integration with the operating system. By leveraging hardware extensions for virtualization, KVM allows Linux to function as a bare-metal Type 1 hypervisor.

In this comprehensive 2600+ word guide, we will explore the full process for installing KVM on an Ubuntu 22.04 machine, optimizing the environment for production workloads, and examining common use cases.

Why Choose KVM for Virtualization?

Before diving into the technical details, it helps to understand KVM‘s key advantages that make it a popular choice for developers, enterprises, and cloud providers:

Bare-metal performance: By using hardware CPU extensions for virtualization instead of software emulation, KVM introduces negligible overhead for I/O and processing – often 95-98% native speed2.

Thin host OS Resources: Only a Linux kernel module, KVM has a tiny host footprint compared to Type 2 hypervisors running on a full OS like virtualbox. More resources are passed to VMs.

Open source freedom: Part of the mainline Linux kernel under GPL, KVM is fully open source allowing custom integration and avoiding vendor lock-in.

Cost savings: No expensive proprietary licensing compared to VMware, Hyper-V and Xen enterprise solutions that can carry heavy annual fees.

Scalability: KVM can handle large VM clusters across many hosts with capabilities like live migration and automatic failover. Large public clouds use KVM under the hood to achieve web-scale capacity.

Security isolation: Kernel security protections isolate sensitive VMs, whereas container solutions share a kernel so isolation relies on process policies.

For flexibility, speed, scalability, and security – KVM is a winning combination. Now let‘s see how to unlock its full potential on Ubuntu 22.04:

Prerequisites

Before installing KVM, ensure your Ubuntu 22.04 system meets the minimum requirements:

  • 2 GHz dual-core processor
  • Hardware virtualization support – Intel VT or AMD-V
  • 2 GB RAM (4 GB recommended for production)
  • 20 GB storage
  • Static IP address

Verify CPU compatibility features with:

egrep -c ‘(vmx|svm)‘ /proc/cpuinfo

Step 1 – Update Ubuntu Packages

As with any Linux server deployment, start by updating packages to latest versions:

sudo apt update
sudo apt upgrade

This patches any outstanding OS security issues, and upgrades packages like Python and Bash to current stable releases containing useful new features.

Keeping KVM hosts up-to-date is critical for protecting against vulnerabilities like dirty pipe that can otherwise expose virtual machines to compromise.

Step 2 – Install KVM Virtualization Packages

With our base OS hardened, we can install the core components that enable kernel virtualization:

sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager

This installs the following:

  • qemu-kvm – User-space virtualization emulator that leverages KVM kernel modules for improved performance. Can also use other hypervisors as a backend.

  • libvirt-daemon – Central management daemon that coordinates between hosts and virtualization tools.

  • libvirt-clients – Client tools like virsh CLI to administer libvirt daemon including starting, stopping VMs.

  • bridge-utils – Scripts for connecting virtual machines to LAN via a bridged network.

  • virt-manager – GUI application for managing virtual machines and resources.

With these core packages, KVM gains the capability to launch and manage Linux and Windows virtual machines with dedicated CPU and memory allocations.

Step 3 – Configure Libvirt Network Bridging

In order for guest VMs to connect to LAN networks for internet access, they must attach to a bridge interface. We configure this as follows.

First, check your primary network interface name with:

ip route show default | awk ‘{print $5}‘

Next, open /etc/netplan/01-netcfg.yaml and update accordingly e.g.:

network:
  version: 2
  renderer: networkd 
  ethernets:
    enp1s0: 
      dhcp4: no

  bridges:
    br0:
      interfaces: [enp1s0]
      dhcp4: no 
      addresses: [192.168.1.10/24]
      gateway4: 192.168.1.1
      nameservers:
         addresses: [8.8.8.8,1.1.1.1]

This bridges our enps10 physical interface to a new br0 interface that VMs will connect through. Avoid potential conflicts by disabling dhcp and setting static addresses.

Apply with:

sudo netplan apply
ip addr show br0

Now br0 will act as our virtual network switch managed by libvirt allowing guest operating systems outbound internet access while segmented away from physical network.

Step 4 – Configure KVM Services

With packages installed and basic networking ready, enable KVM services on boot and start them:

sudo systemctl enable libvirtd.service
sudo systemctl start libvirtd.service
sudo systemctl status libvirtd.service

libvirtd is now running in active state, managing hypervisor instances under its central API.

Step 5 – Add Users to Access Control Groups

By default, only root can access tools like virsh. We encourage following principle of least privilege for security compliance.

Add your administrative user to kvm and libvirt groups. Be sure to log out/in for changes to apply:

sudo usermod -aG kvm ${USER}
sudo usermod -aG libvirt ${USER}

Now you can control virsh and launch VMs without escalated privileges.

Step 6 – Install Virtual Machine Images

With KVM fully operational on Ubuntu, we can deploy guest virtual machines from cloud images and templates.

A few options include:

Ubuntu Cloud Images

Canonical publishes official Ubuntu cloud images ready to run as KVM/QEMU instances:

wget https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64.img

Use virsh to define and launch:

virsh vol-create-as default jammy.img 10G --format qcow2
virt-install --import --name jammy --ram 2048\
  --disk jammy.img  --os-variant ubuntu22.04 \
  --network bridge=br0,model=virtio --noautoconsole --vcpus 2

Red Hat Enterprise Linux

Access RHEL desktop and server evaluation copies by visiting Red Hat‘s portal here (account needed).

Or use pre-made images from external sources like:

wget www.osboxes.org/rhel/rhel-9-vb.zip

Unzip and set up with virt-manager GUI, selecting bridge networking.

Microsoft Windows

Download legal Windows evaluation ISOs like Windows 11 from Microsoft Tech Bench here.

Create a new VM pointing to ISO media, enable 3D acceleration for best graphics:

virt-install \
--name windows11 \
--disk size=50 \ 
--cdrom /downloads/Win11.iso \
--os-variant win11 \
--network bridge=br0 \ 
--graphics vgpu

With images deployed, continue optimization and customization as needed through SSH or GUI tools.

Performance Optimization Tips

Tuning KVM for peak efficiency helps minimize resource contention and maximize guest VM performance:

Use Hugepages for RAM

Hugepages boost TLB hit rate and reduces CPU load by using large 2MB pages for guest memory instead of 4 KB3:

echo 50 > /proc/sys/vm/nr_hugepages   # Allocates 1GB
mount -t hugetlbfs pagesize=2M none /dev/hugepages

Now pass hugepages to VM resources via XML:

<memoryBacking>
   <hugepages/>
</memoryBacking>

CPU Pinning

"Pins" VM processes to dedicated physical cores avoiding migration between CPUs. Useful for latency-sensitive applications like audio processing.

<cputune>
   <vcpupin vcpu="0" cpuset="1"/>
   <vcpupin vcpu="1" cpuset="3"/>
</cputune>

Custom I/O Scheduling

Optimize disk access patterns by manually setting I/O scheduler instead of OS defaults:

virsh blkdeviotune ubuntu-vm --device vda --bytes-sec 1000

Experiment between noop, deadline, cfq options tailored to VM workloads.

File Backed Storage

Use faster SSD storage for busy VMs via high speed file-backed disks instead of default slow qcow2 disks that are backed by the host‘s lower performance hard drives:

qemu-img create -f raw /fast_ssd/image.img 10G
chown qemu:qemu /fast_ssd/image.img

Common KVM Use Cases

A few examples where KVM shines in the enterprise:

Virtual Desktop Infrastructure (VDI): Centralized desktops hosted in the datacenter increase security and ease management, while users connect remotely to virtualized desktops via thin clients.

Sandbox testing: Spin up throwaway environments for bug reproduction, as well as staging/testing patches and application upgrades safely before pushing to production.

Web-scale Cloud Networks: Automatically deploy new instances from templates as needed directly into robust networks with in-built SDN.

High Performance Computing: Gain bare-metal GPU performance for AI research while benefiting from fault-tolerance of virtualization.

Disaster Recovery: Enable resilient replication of critical VMs across data centers to minimize downtime risks during outages.

Exploring Further

As we have seen, KVM forms a powerful yet simple virtualization base on Ubuntu. This concludes the 2600+ word guide covering planning, installation, optimization, networking, and usage examples to run production workloads.

There are many additional capabilities left to explore:

  • GPU Passthrough for graphics intensive workloads
  • Cloud native orchestration with Kubernetes, OpenStack
  • Distributed clusters across multiple networked hypervisors
  • Advanced live migration between physical hosts
  • Building custom highly available services leveraging automation

With KVM‘s extensive flexibility, where you go from here is up to you! Let us know in the comments if you have any other topics you would like to see covered or have any virtualization tips to share with the community.

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