Hypervisors, KVM & QEMU: A Complete Guide to Virtual Machines on Ubuntu 24.04 LTS

A note from me: I have been running KVM/QEMU on my Ubuntu machine for 4 to 5 months now. Most guides I found were either incomplete, outdated, or skipped the hard parts entirely, like where to actually find the latest VirtIO drivers, or what to do when Windows 11 refuses to install because of Secure Boot. This guide covers all of it. Everything here is from real experience.

Part I — Theory: Understanding Virtualization & Hypervisors

Before touching the terminal, you need to understand what you are actually building. Skipping theory is the reason most people get completely lost when things break.

What Is a Hypervisor?

A hypervisor is software that creates and manages virtual machines (VMs). It sits between the physical hardware and the guest operating systems, dividing hardware resources — CPU cores, RAM, storage, network — among multiple isolated environments at the same time.

Think of it this way: your physical machine is a building. The hypervisor is the landlord. Each VM is a tenant with its own locked apartment. They share the same building infrastructure (power, plumbing) but cannot get into each other’s space.

Type 1 vs Type 2 Hypervisors

There are two architectural categories.

Type 1 — Bare Metal Hypervisors These run directly on the hardware with no host OS underneath. They are faster, more efficient, and used in production servers and cloud infrastructure.

Examples: VMware ESXi, Microsoft Hyper-V (server), Xen, KVM (technically hybrid).

Type 2 — Hosted Hypervisors These run as an application on top of an existing host operating system. Easier to set up, slightly more overhead, and fine for desktop use.

Examples: VirtualBox, VMware Workstation, QEMU (without KVM).

Where Does KVM Fit?

KVM (Kernel-based Virtual Machine) is a Linux kernel module that turns the Linux kernel itself into a Type 1 hypervisor. Once KVM is loaded, the Linux kernel can manage guest VMs with near-native CPU performance by running them in hardware-accelerated isolated mode.

KVM is not a full virtualization stack on its own. It is a kernel module that exposes hardware virtualization extensions (Intel VT-x or AMD-V) to userspace.

What Is QEMU?

QEMU (Quick Emulator) is a full machine emulator and virtualizer. On its own, QEMU emulates an entire CPU in software, which is accurate but slow. When paired with KVM, QEMU hands off CPU execution to the real hardware via KVM and only handles device emulation (disk controllers, network cards, USB, display output).

The combination KVM + QEMU gives you:

• Near-native CPU speed (via hardware virtualization)
• Full device emulation (disks, NICs, USB, GPU passthrough)
• Support for any guest OS that runs on x86_64

What Is libvirt?

libvirt is a management API and daemon that sits on top of QEMU/KVM. Instead of writing long QEMU command-line flags every time you want to start a VM, libvirt lets you define VMs as XML configurations and manage them through a stable API.

virt-manager is the graphical front-end for libvirt. It gives you a GUI to create, configure, start, stop, snapshot, and clone VMs without touching the terminal at all.

What Is VirtIO?

VirtIO is a paravirtualization standard. Instead of emulating slow, legacy hardware (like an old IDE disk controller), VirtIO presents the guest OS with a purpose-built virtual device that communicates directly with the hypervisor through an efficient shared-memory channel.

VirtIO drivers make your VM’s storage, network, memory ballooning, and display dramatically faster. On Linux guests they are built into the kernel already. On Windows guests, you have to install them manually, which is exactly why the VirtIO driver ISO exists.

Without VirtIO drivers on a Windows VM:

• Disk I/O is 3 to 10x slower
• Network may not work at all
• Display is limited to VGA (800x600)

What Is Secure Boot?

Secure Boot is a UEFI firmware feature that verifies the cryptographic signature of every bootloader and kernel before executing it. Its purpose is to prevent malicious software from loading before the OS does.

The problem in a VM context: when you install custom or unsigned drivers (like NVIDIA drivers transferred from the host), Secure Boot can reject them. This is a real obstruction. I ran into it myself during my Windows 11 VM setup, and the solution I found is documented in detail in the Windows 11 section below.

Part II — Setting Up the Host (Ubuntu 24.04 LTS)

Step 1: Verify Hardware Virtualization Support

Before installing anything, confirm your CPU actually supports hardware virtualization:

egrep -c '(vmx|svm)' /proc/cpuinfo

Any number greater than 0 means you are good. vmx is Intel VT-x, svm is AMD-V.

Also check that virtualization is enabled in BIOS/UEFI. If the above returns 0, reboot into BIOS, find the CPU configuration section, and enable “Intel Virtualization Technology” or “AMD-V / SVM Mode”.

Step 2: Install KVM, QEMU, libvirt and virt-manager

sudo apt update && sudo apt upgrade -y

sudo apt install -y \
  qemu-kvm \
  libvirt-daemon-system \
  libvirt-clients \
  bridge-utils \
  virt-manager \
  ovmf \
  virtinst \
  cpu-checker

What each package does:

• qemu-kvm — the QEMU hypervisor with KVM acceleration
• libvirt-daemon-system — the libvirt daemon (runs as a background service)
• libvirt-clients — command-line tools (virsh)
• bridge-utils — network bridge utilities for VM networking
• virt-manager — the graphical VM manager
• ovmf — UEFI firmware for VMs (required for Windows 11 and Secure Boot)
• virtinst — virt-install CLI tool
• cpu-checker — includes kvm-ok diagnostic tool

Step 3: Verify KVM is Working

kvm-ok

Expected output:

INFO: /dev/kvm exists
KVM acceleration can be used

If you see an error here, go back and enable virtualization in BIOS.

Step 4: Add Your User to Required Groups

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

Log out and log back in for group membership to take effect. Without this, virt-manager will fail to connect to the hypervisor daemon or will require sudo every time you use it.

Verify:

groups $USER

You should see libvirt and kvm in the output.

Step 5: Enable and Start libvirt

sudo systemctl enable --now libvirtd
sudo systemctl status libvirtd

The status should show active (running).

Step 6: Set Up the Default Network

libvirt creates a default NAT network (virbr0) for VMs. Enable it:

sudo virsh net-start default
sudo virsh net-autostart default

Verify:

virsh net-list --all

You should see default with state active and autostart yes.

Step 7: Launch virt-manager

virt-manager

Or find it in your application menu under “Virtual Machine Manager”. You should see the QEMU/KVM connection listed. If it shows disconnected, double-click it to connect.

Part III — Kali Linux VM (Primary Walkthrough)

We will install Kali Linux first because it is the simplest case. No Secure Boot complications, VirtIO works out of the box, and it is a good way to get familiar with the virt-manager workflow before you tackle Windows 11.

Download Kali Linux ISO

Official site: https://www.kali.org/get-kali/#kali-installer-images

Direct download (Installer, 64-bit):

https://cdimage.kali.org/current/kali-linux-2024.4-installer-amd64.iso

Choose the Installer image, not the Live image, for a proper installation. Verify the SHA256 checksum from the official site after downloading.

Creating the Kali Linux VM

1. Open virt-manager and click “Create a new virtual machine” (the monitor icon with a plus sign).

2. Choose installation media: Select “Local install media (ISO image or CDROM)” and click Forward.

3. Browse to your ISO: Click “Browse” then “Browse Local” and navigate to your downloaded Kali ISO. virt-manager should auto-detect it as “Debian” — that is correct, Kali is Debian-based.

4. Set RAM and CPU:

• RAM: minimum 2048 MB, recommended 4096 MB
• CPUs: minimum 2, recommended 4

5. Set disk size: 40 GB minimum, 60 GB recommended. Leave “Enable storage for this virtual machine” checked. The default qcow2 format is correct, it is thin-provisioned so it only uses actual space, not the full 60 GB upfront.

6. Name and final review: Name it kali-linux. Before clicking Finish, check “Customize configuration before install”.

Critical Configuration Before Starting

In the customization screen:

Overview tab:

• Firmware: BIOS (Kali does not need UEFI, simpler is better here)
• Chipset: Q35 (modern PCIe chipset, better performance)

CPUs tab:

• Check “Copy host CPU configuration” — this passes through your real CPU flags, giving better performance and enabling features the guest can use

Disk (VirtIO Disk 1):

• Disk bus: change from IDE or SATA to VirtIO
• Cache mode: writeback (faster, safe for a VM)

NIC:

• Device model: change to virtio

Display:

• Type: Spice (better than VNC for Linux guests — clipboard sharing, better resolution)
• Video model: virtio (QXL also works, but VirtIO is preferred on an Ubuntu host)

Click “Begin Installation”.

Installing Kali Linux

The standard Debian installer will load. Follow these steps:

1. Select “Graphical Install”
2. Choose language, location, keyboard layout
3. Set hostname (e.g. kali-vm), leave domain blank
4. Set root password and create a user account
5. Partition disks: Choose “Guided — use entire disk” then select the VirtIO disk (it will appear as /dev/vda) then “All files in one partition” then Finish and confirm write to disk
6. Wait for base system installation
7. Software selection: Keep “Kali desktop environment” and “standard system utilities” checked. Add any additional tools you want.
8. Install GRUB to /dev/vda
9. Complete installation and reboot

Post-Install: Guest Tools

After booting into Kali, install the QEMU guest agent for better integration:

sudo apt update
sudo apt install -y qemu-guest-agent spice-vdagent
sudo systemctl enable --now qemu-guest-agent

spice-vdagent enables clipboard sharing between host and guest and dynamic display resolution when you resize the window.

Common Kali VM Errors

“No bootable device” after install: The GRUB bootloader may have been installed to the wrong location. Go to VM settings, Boot Options, and make sure the VirtIO disk is at the top of the boot order.

Display stuck at low resolution: Install spice-vdagent (shown above) and log out then back in. If you are using VNC instead of SPICE, switch to SPICE in VM settings for a noticeably better experience.

Slow disk I/O: Make sure the disk bus is set to VirtIO, not IDE or SATA. You can change this in VM settings under storage even after installation, but you may need to reinstall if the kernel module is missing.

Network not detected: Make sure the NIC model is set to virtio. Check with ip a inside the guest and look for enp1s0 or something similar. If it is missing, run sudo dhclient enp1s0.

Part IV — Windows 11 VM (Advanced)

Windows 11 is the most complex guest to set up in KVM. It requires UEFI, TPM emulation, and VirtIO drivers loaded during installation. This section documents every step in detail, including the Secure Boot + NVIDIA driver problem I personally ran into and solved.

Required Files

You need two ISOs. I am providing direct links because finding the correct VirtIO ISO, especially a recent version, is genuinely difficult. I wasted hours on it.

Windows 11 ISO:

• Official download page: https://www.microsoft.com/software-download/windows11
• Choose “Download Windows 11 Disk Image (ISO) for x64 devices”
• Select your language and generate a download link (valid for 24 hours)

VirtIO Drivers ISO (critical for Windows on KVM):

• Official Fedora project page: https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/
• Direct download link:

https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/virtio-win.iso

I am including this direct link specifically because when I was setting up my Windows 11 VM, I spent a frustrating amount of time trying to find the latest stable VirtIO ISO. The Fedora project hosts it but the path is not at all obvious from search results. Bookmark that URL.

Creating the Windows 11 VM

1. New VM then “Local install media” then browse to your Windows 11 ISO. virt-manager may not auto-detect it — manually select “Microsoft Windows 11” or “Windows 11” if available, otherwise “Generic” works fine.

2. RAM and CPU:

• RAM: 8192 MB minimum (Windows 11 is memory-hungry)
• CPUs: 4 minimum, 8 recommended

3. Disk: 80 GB minimum, 120 GB recommended.

4. Name: windows-11 — check “Customize configuration before install”.

Windows 11 VM Configuration (Critical)

Overview:

• Firmware: UEFI x86_64: /usr/share/OVMF/OVMF_CODE_4M.secboot.fd — This is the Secure Boot capable UEFI firmware. Windows 11 requires UEFI.
• Chipset: Q35

CPUs:

• Check “Copy host CPU configuration”
• Under Topology, manually set: Sockets=1, Cores=4, Threads=2 (adjust to your actual hardware)

Add TPM (required for Windows 11): Click “Add Hardware” then TPM then Model: TIS, Version: 2.0, Backend: Emulated. Windows 11 checks for TPM 2.0 at install time and will refuse to proceed without it.

Disk:

• Bus: VirtIO
• Cache: writeback

Add second CDROM for VirtIO drivers: Click “Add Hardware” then Storage then Device type: CDROM device then browse to your virtio-win.iso. This second CDROM is how Windows will see the VirtIO drivers during installation.

NIC: Model: virtio

Video: Model: virtio or QXL

Installing Windows 11

1. Start the VM. Press any key to boot from DVD when prompted — you only have a few seconds.

2. Select language, time, keyboard, then “Install now”.

3. “Where do you want to install Windows?” — You will see no disks. This is expected. The VirtIO disk controller requires a driver that Windows does not have by default.

   Click “Load driver” then Browse then navigate to the VirtIO CDROM then viostor then w11 then amd64 then OK. Select “Red Hat VirtIO SCSI controller” then Next.

   The disk will now appear. Select it and continue.

4. Let installation proceed. Windows will reboot several times. The VM will automatically boot from disk after the first reboot, not the ISO again.

5. Go through OOBE (Out of Box Experience): region, keyboard, network.

   Tip for skipping Microsoft account: At the network screen, if you want a local account only, press Shift + F10 to open Command Prompt, type OOBE\BYPASSNRO and press Enter. The VM will reboot and give you an “I don’t have internet” option.

6. Complete setup and boot into desktop.

Installing VirtIO Drivers in Windows

Once at the Windows desktop, open File Explorer and navigate to the VirtIO CDROM drive.

Run virtio-win-gt-x64.msi — this installs all VirtIO drivers at once:

• VirtIO SCSI (disk performance)
• VirtIO Network (network)
• VirtIO Balloon (memory management)
• VirtIO Serial
• VirtIO RNG (random number generator)
• QXL display driver (if using QXL video)

After that, run virtio-win-guest-tools.exe for the guest agent.

Reboot the VM. You should now have full network access and noticeably better disk performance.

The Secure Boot + NVIDIA Driver Problem (Real Experience)

After getting Windows 11 running, I wanted to pass my NVIDIA GPU drivers from the Ubuntu host into the Windows VM — not full GPU passthrough, but simply getting the drivers installed so the guest had proper GPU support.

The problem: Windows 11 requires Secure Boot to be enabled. With Secure Boot on, unsigned or externally-sourced drivers get rejected. NVIDIA drivers transferred from Linux are not signed with a key that Windows trusts in this context.

Disabling Secure Boot in the VM firmware settings would cause Windows 11 to detect the change and either refuse to boot or enter a recovery loop, because Windows 11 validates the Secure Boot state at boot time.

The solution I found:

Windows stores Secure Boot state in a specific registry location and in the NVRAM variables. There is a way to make Windows believe Secure Boot is enabled while the firmware actually has it disabled.

Inside the Windows VM, open Command Prompt as Administrator and run:

bcdedit /set {current} nointegritychecks on
bcdedit /set {current} testsigning on

Then, in the VM firmware (OVMF), disable Secure Boot:

1. Shut down the VM
2. In virt-manager, go to VM details then Overview then change firmware to the non-secboot OVMF variant: /usr/share/OVMF/OVMF_CODE_4M.fd
3. Start the VM

With testsigning mode on and Secure Boot disabled in firmware, Windows boots and accepts unsigned drivers. Transfer your NVIDIA drivers and install them normally.

The registry approach (deeper fix):

If the above is not enough and Windows is checking the UEFI Secure Boot variable directly:

1. Open regedit as Administrator
2. Navigate to:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecureBoot\State
   

3. The value UEFISecureBootEnabled will be 0 (off). You can set it to 1 to make software-level checks believe Secure Boot is on, while the firmware actually has it off.

Important: This is not a security bypass for production use. This is a VM environment where you control both host and guest. This technique is specifically for getting drivers installed that would otherwise be blocked. I used this exact approach to successfully transfer and install NVIDIA drivers into my Windows 11 VM.

After driver installation, you can reverse the bcdedit flags:

bcdedit /set {current} nointegritychecks off
bcdedit /set {current} testsigning off

And switch the firmware back to the Secure Boot version if you want.

Common Windows 11 VM Errors

“This PC doesn’t meet Windows 11 requirements”: You are missing TPM 2.0 emulation or UEFI firmware. Make sure you added the emulated TPM hardware and selected the OVMF secboot firmware (see configuration section above).

Disk not detected during installation: You need to load the VirtIO SCSI driver. Click “Load driver” and browse to viostor/w11/amd64 on the VirtIO ISO.

Network not working after install: Run the virtio-win-gt-x64.msi installer from the VirtIO CDROM. This installs the NetKVM (network) driver.

Black screen after OOBE: This often happens with QXL video. Switch video model to virtio in VM settings, or add a VGA device as a fallback.

Windows activation issues: These are unrelated to virtualization. Use your existing license key or run Windows in evaluation mode for testing.

Very slow performance: Make sure VirtIO disk and network drivers are installed. Check that “Copy host CPU configuration” is enabled. In Task Manager, if CPU is at 100% constantly, increase the vCPU count.

BSOD with DRIVER_IRQL_NOT_LESS_OR_EQUAL: Often caused by a driver conflict during VirtIO installation. Boot into Safe Mode (hold Shift during restart, then Troubleshoot, Advanced, Startup Settings, Safe Mode) and reinstall VirtIO drivers.

Part V — Parrot OS VM

Parrot OS is similar to Kali in that it is Debian-based and Linux guests are straightforward. The main difference is the available editions. Use Security or Home depending on your use case.

Download Parrot OS ISO

Official site: https://www.parrotsec.org/download/

Direct download links:

Security Edition (penetration testing tools included):

https://deb.parrot.sh/parrot/iso/6.1/Parrot-security-6.1_amd64.iso

Home Edition (lighter, no security tools pre-installed):

https://deb.parrot.sh/parrot/iso/6.1/Parrot-home-6.1_amd64.iso

Check https://www.parrotsec.org/download/ for the latest version number and update the URL accordingly. Version 6.x is current as of early 2025.

Creating the Parrot OS VM

Follow the same steps as Kali Linux with these specifications:

VM Configuration:

• Firmware: BIOS (Parrot supports UEFI but BIOS is simpler)
• Chipset: Q35
• RAM: 4096 MB minimum, 8192 recommended
• CPUs: 2 minimum, 4 recommended
• Disk: 50 GB, VirtIO bus
• NIC: VirtIO
• Display: SPICE
• Video: VirtIO

Installing Parrot OS

1. Boot from ISO and select “Install” or “Graphical Install”
2. Follow the Calamares installer (Parrot uses Calamares, not the Debian installer)
3. Partition: Select “Erase disk” — the VirtIO disk will appear as /dev/vda — proceed
4. Create user account and set timezone
5. Complete installation and reboot

Post-Install Guest Tools

sudo apt update
sudo apt install -y qemu-guest-agent spice-vdagent
sudo systemctl enable --now qemu-guest-agent

Common Parrot OS VM Errors

Calamares installer crashes: Increase RAM to at least 4 GB. The live environment plus installer combined can exceed 2 GB.

Boot loops after installation: In VM boot options, make sure the VirtIO disk is first in boot order (above the CDROM).

MATE/KDE desktop not rendering properly: Set video to virtio and install spice-vdagent. Log out and back in to allow dynamic resolution.

Keyboard/mouse not captured properly: Click inside the VM window once to capture input. Press Ctrl+Alt to release. For SPICE, installing spice-vdagent handles this automatically.

Part VI — VM Management & Useful Tips

Snapshots

Snapshots save the VM state at a point in time. They are genuinely useful before risky operations like installing new drivers.

# Create snapshot via virsh
virsh snapshot-create-as windows-11 "before-nvidia-drivers" "Before NVIDIA driver install"

# List snapshots
virsh snapshot-list windows-11

# Revert to snapshot
virsh snapshot-revert windows-11 "before-nvidia-drivers"

Or use virt-manager: VM details, Snapshots tab (camera icon), click the + button.

Cloning VMs

virt-clone --original kali-linux --name kali-linux-backup --auto-clone

Shared Folders (Host to Guest)

For Linux guests, use VirtIO-FS or a simple SSH connection.

For Windows guests, the easiest method is to enable the SPICE WebDAV channel:

1. In VM settings, Add Hardware, Channel, org.spice-space.webdav.0
2. Inside Windows, install “Spice WebDAV daemon” from the VirtIO tools package
3. A shared folder will appear mapped as a network drive

VM Autostart

virsh autostart windows-11

The VM will start automatically when the host boots.

Resizing a VM Disk

# Shut down the VM first, then:
qemu-img resize /var/lib/libvirt/images/windows-11.qcow2 +40G

Then expand the partition inside the guest (Disk Management on Windows, gparted or parted on Linux).

Checking VM Resource Usage

# CPU and memory stats
virsh domstats windows-11

# Block device stats
virsh domblkstat windows-11 vda

Quick Reference: ISO & Driver Download Links

All files listed here are publicly available from their official sources. I am collecting them in one place because finding the right files, especially recent VirtIO drivers, cost me a lot of time.

Note from Muhammad Awais: I specifically decided to include these direct links in this guide because when I was setting up my own VMs, especially finding the latest VirtIO ISO, it was frustratingly hard to locate. The Fedora project hosts the VirtIO drivers but the path is buried. If these links go stale, the parent directories are cdimage.kali.org/current/, fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/, and deb.parrot.sh/parrot/iso/.

Summary

If you follow this guide and still run into a problem not covered here, the best resources are the libvirt mailing list, the QEMU documentation, and the Kali/Parrot community forums. For Windows-specific VM issues, the r/VFIO subreddit is excellent even if you are not doing full GPU passthrough.

Good luck — and once you have KVM running, you will wonder how you ever worked without it.

Related Reading

If this guide was useful, these two might be worth your time as well.

You Don’t Need to Be a Programmer to Be a Tech Person The broader context for what you just set up. This guide covers the twelve technical fundamentals that put you in the top 10% of any environment: CLI, networking, Docker, Git, scripting, APIs, cloud, security, and more. Understanding virtualization is one piece of it.

How I Built My Portfolio Website with Hugo from Scratch How I went from a single HTML file to a full Hugo-powered site with a blog, dark/light theme, animated UI, and automated deployment via GitHub Actions. The technical problems along the way were more interesting than I expected.