Technology Tales

Windows 11 virtualisation on Linux using KVM and QEMU

Published on 5^th March 2026 Estimated Reading Time: 10 minutes

Windows 11 arrived in October 2021 with a requirement that posed a challenge to many virtualisation users: TPM 2.0 was mandatory, not optional. For anyone running Windows in a virtual machine, that meant their hypervisor needed to emulate a Trusted Platform Module convincingly enough to satisfy the installer.

VirtualBox, which had been my go-to choice for desktop virtualisation for years, could not do this in its 6.1.x series. Support arrived only with VirtualBox 7.0 in October 2022, meaning anyone who needed Windows 11 in a VM faced roughly a year with no straightforward path through their existing tool.

That gap prompted a look at KVM (Kernel-based Virtual Machine), which could handle the TPM requirement through software emulation. This article documents what that investigation found, what the rough edges were at the time, and how the situation has developed in the years since.

What KVM Actually Is

KVM is not a standalone application. It is a virtualisation infrastructure built directly into the Linux kernel, and has been since the module was merged between 2006 and 2007. Rather than sitting on top of the operating system as a separate layer, it turns the Linux kernel itself into a hypervisor. This makes KVM a type-1 hypervisor in practice, even when running on a desktop machine, which is part of why its performance characteristics compare favourably with hosted solutions.

In use, KVM operates alongside QEMU for hardware emulation, libvirt for virtual machine management and virt-manager as a graphical front end. The distinction matters because problems and improvements tend to originate in different parts of that stack. KVM itself is rarely the issue; QEMU and libvirt are where the day-to-day configuration lives.

To confirm that the host CPU supports hardware virtualisation before beginning, the following command checks for the relevant flags:

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

Any result above zero means the hardware is capable. Intel processors expose the vmx flag and AMD processors expose svm.

Installing the Required Packages

The installation is straightforward on any major distribution.

On Debian and Ubuntu:

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

On Fedora:

sudo dnf install @virtualization

On Arch Linux:

sudo pacman -S qemu libvirt virt-manager bridge-utils

After installation, the current user needs to be added to the libvirt and kvm groups before the tools will work without root privileges:

sudo usermod -aG libvirt,kvm $(whoami)

Logging out and back in instates the group membership.

Configuring Network Bridging

The default network configuration in libvirt uses NAT, which is sufficient for most purposes and requires no additional setup. The VM can reach the internet and the host, but the host cannot initiate connections to the VM. For a Windows 11 guest used primarily for application compatibility, NAT works without complaint.

A bridged network, which places the VM on the same network segment as the host, requires a wired Ethernet connection. Wireless interfaces do not support bridging in the standard Linux networking stack due to how 802.11 handles MAC addresses. For those on a wired connection, a bridge can be defined with a file named bridge.xml:

<network>
  <name>br0</name>
  <forward mode="bridge"/>
  <bridge name="br0"/>
</network>

The bridge is then activated with:

sudo virsh net-define bridge.xml
sudo virsh net-start br0
sudo virsh net-autostart br0

Installing Windows 11

Windows 11 requires TPM 2.0 and Secure Boot. Neither is present in a default KVM configuration, and both need to be added explicitly.

The swtpm package provides software TPM emulation:

sudo apt install swtpm swtpm-tools   # Debian/Ubuntu
sudo dnf install swtpm swtpm-tools   # Fedora

UEFI firmware is provided by the ovmf package, which supplies the file that virt-manager needs for Secure Boot:

sudo apt install ovmf   # Debian/Ubuntu
sudo dnf install edk2-ovmf   # Fedora

In virt-manager, when creating the VM, the firmware should be set to UEFI x86_64: /usr/share/OVMF/OVMF_CODE.fd rather than the default BIOS option. A TPM 2.0 device should be added in the hardware configuration before the VM is started. With those two elements in place, the Windows 11 installer proceeds without complaint about the hardware requirements.

The VirtIO drivers ISO should be attached as a second virtual CD-ROM drive during installation. The installer will not find the storage device otherwise because the VirtIO disk controller is not a standard device that Windows recognises without a driver. When prompted to select an installation location and no disks appear, clicking "Load driver" and browsing to the VirtIO ISO resolves it.

During the out-of-box experience, Windows 11 requires a Microsoft account and an internet connection by default. To bypass this and create a local account instead, opening a command prompt with Shift+F10 and running the following works on the Home edition:

oobebypassNRO

The machine restarts and presents an option to proceed without internet access.

Performance Considerations

KVM performance for a Windows 11 guest is generally good, but one factor specific to Windows 11 is worth understanding. Memory Integrity, also referred to as Hypervisor-Protected Code Integrity (HVCI), is a Windows security feature that uses virtualisation to protect the kernel. Running it inside a virtual machine creates nested virtualisation overhead because the guest is attempting to run its own virtualisation layer inside the host's. The performance impact is more pronounced on processors predating Intel Kaby Lake or AMD Zen 2, where the hardware support for nested virtualisation is less capable.

The CPU type selection in virt-manager also matters more than it might appear. Setting the CPU model to host-passthrough exposes the actual host CPU flags to the guest, which improves performance compared to emulated CPU models, at the cost of reduced portability if the VM image is ever moved to a different machine.

Host File System Access and Clipboard Sharing

This was where the experience diverged most noticeably from VirtualBox. VirtualBox Guest Additions handle shared folders and clipboard integration as a single installation, and the result works reliably with minimal configuration. KVM requires separate solutions for each, and in 2022 neither was as seamless as it has since become.

Clipboard Sharing via SPICE

Clipboard sharing uses the SPICE display protocol rather than VNC. The VM needs a SPICE display and a virtio-serial controller, which virt-manager adds automatically when SPICE is selected. Within the Windows guest, the installer for SPICE guest tools provides the clipboard agent. Once installed, clipboard text passes between host and guest in both directions.

The critical dependency that caused problems in 2022 was the virtio-serial channel. Without a com.redhat.spice.0 character device present in the VM configuration, the clipboard agent installs successfully but does nothing. Virt-manager now adds this automatically when SPICE is selected, which removes one of the more common failure points.

Host Directory Sharing via Virtiofs

At the time of this investigation, the practical option for sharing files between the Linux host and a Windows guest was WebDAV, which worked but felt like a workaround. The proper solution, virtiofs, existed but was not yet well-supported on Windows guests. The situation has since improved to the point where virtiofs is now the standard recommended approach.

It requires three components: the virtiofsd daemon on the host (included in recent QEMU packages), the virtiofs driver from the VirtIO Windows drivers package and WinFsp, which is the Windows equivalent of FUSE. Once configured through virt-manager's file system hardware settings, the shared directory appears as a mapped drive in Windows Explorer. The virtiofsd daemon was also rewritten in Rust in the intervening period, improving both its reliability and performance.

To configure a shared directory, shared memory must first be enabled in the VM's memory settings, then a file system device added with the driver set to virtiofs, a source path on the host and an arbitrary mount tag. The corresponding libvirt XML looks like this:

<memoryBacking>
  <source type='memfd'/>
  <access mode='shared'/>
</memoryBacking>

<filesystem type='mount' accessmode='passthrough'>
  <driver type='virtiofs' queue='1024'/>
  <source dir='/home/user/shared'/>
  <target dir='host_share'/>
</filesystem>

This was the area where VirtualBox held a clear practical advantage in 2022. The gap has since narrowed considerably.

Migrating from VirtualBox

Moving existing VirtualBox VMs to KVM is possible using qemu-img, which converts between disk image formats. The straightforward conversion from VDI to QCOW2 is:

qemu-img convert -f vdi -O qcow2 windows11.vdi windows11.qcow2

For large images or where reliability is a concern, converting via an intermediate RAW format reduces the risk of issues:

qemu-img convert -f vdi -O raw windows11.vdi windows11.raw
qemu-img convert -f raw -O qcow2 windows11.raw windows11.qcow2

The resulting QCOW2 file can then be used when creating a new VM in virt-manager, selecting "Import existing disk image" rather than creating a new one.

How the Landscape Has Shifted Since

The investigation described here took place during a specific window: VirtualBox 6.1.x was the current release, Windows 11 had just launched, and KVM was the most practical route to TPM emulation on Linux. That context has changed in several ways worth noting for anyone reading this in 2026.

VirtualBox 7.0 arrived in October 2022 with TPM 1.2 and 2.0 support, Secure Boot and a number of additional improvements. The original reason for investigating KVM was resolved, and for those who had moved across during the gap period, returning to VirtualBox for Windows guests made sense given its more straightforward Guest Additions integration.

QEMU reached version 10.0 in April 2025, a significant milestone reflecting years of accumulated improvements to hardware emulation, storage performance and x86 guest support. Libvirt has kept pace, adding reliable internal snapshots for UEFI-based VMs, evdev input device hot plug and improved unprivileged user support. The virtiofs situation for Windows guests has moved from "technically possible but awkward" to "the recommended approach with good documentation and a rewritten daemon", which addresses the most significant practical shortcoming from 2022 directly.

The broader desktop virtualisation landscape shifted when VMware Workstation Pro became free for all users, including commercial ones, in November 2024. VMware Workstation Player was discontinued as a separate product at the same time, having become redundant once Workstation Pro was available at no cost. This gave desktop users a third credible option alongside VirtualBox and KVM, with VMware's historically strong Windows guest integration now accessible without a licence fee, though users of the free version are not entitled to support through the global support team.

The miniature PC market also expanded considerably from 2023 onwards, with Intel N100-based and AMD Ryzen Embedded systems offering enough performance to run Windows natively at modest cost. For many people, that proves a cleaner solution than any hypervisor, eliminating the integration limitations entirely by giving Windows its own dedicated hardware.

Final Assessment

KVM handled Windows 11 competently during a period when the alternatives could not, and the platform has continued to improve in the years since. The two areas that fell short in 2022, host file sharing and clipboard integration, have been addressed by developments in virtiofs and the SPICE tooling, and a new user starting today may find the experience noticeably smoother.

Whether KVM is the right choice in 2026 depends on the use case. For Linux-native workloads and server-style VM management, it remains the strongest option on Linux. For a Windows desktop guest where ease of integration matters most, VirtualBox 7.x and VMware Workstation Pro are both strong alternatives, with the latter now free to use for both commercial and personal purposes. The question that drove this investigation was answered by VirtualBox itself in October 2022. KVM provided a workable solution in the meantime, and the platform has only become more capable since then.

Additional Reading

How To Convert VirtualBox Disk Image (VDI) to Qcow2 format

How to enable TPM and secure boot on KVM?

Windows 11 on KVM – How to Install Step by Step?

Enable Virtualization-based Protection of Code Integrity in Microsoft Windows