libvirt for Windows (unofficial port)

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libvirt 12.9.0 built natively for Windows x64: virsh, the daemons (virtqemud, virtnetworkd, virtsecretd, libvirtd…) and QEMU guests accelerated by the Windows Hypervisor Platform (WHPX). This is libvirt's own code with its platform layers ported, not a rewrite: the same API, domain and network XML, virsh commands and RPC protocol.

Important

Not an official libvirt release, and not affiliated with the libvirt project. The Windows changes were written with an AI assistant; libvirt declines contributions that include AI-generated content (docs/hacking.rst), so nothing here is to be submitted upstream. Experimental software: try it on machines you can afford to break.

The history shows the port as a diff: the first commit is libvirt as downloaded, the second one is the Windows port.

Status

Tested on Windows 11 (build 26300) with Ubuntu 24.04 guests.

Area	Works and tested	Not done or not tested
Daemons	libvirtd and the modular daemons, --daemon, reload and stop (signals as named events), reconnection to running guests after a restart	Windows services
Remote	UNIX sockets, ext transport	ssh transport (implemented, untested), TLS
Secrets	define, set, get, undefine, persistence
QEMU	whpx domain type; define, start, destroy, suspend, resume; screenshot; qemu-monitor-command; virsh console (serial on a UNIX socket); NIC hotplug; setmem (balloon, memory given back to the host with the QEMU patch); dommemstat	save/restore, migration, snapshots, SMBIOS sysinfo
Guest networking	type='user' (libslirp); type='network' and type='bridge' to a libvirt network	type='ethernet' and bridges to the host LAN (TAP, planned)
Virtual networks	forward mode nat and isolated; DHCP and DHCPv6 (ranges, hosts by MAC, DUID or name); DNS (hosts, TXT, SRV, PTR, forwarders, local domain); IPv6 (SLAAC or DHCPv6); net-update; net-dhcp-leases; domifaddr; autostart; QoS (domiftune, floors, network bandwidth); domifstat	forward modes route and open (written, need Wintun, untested)
Other drivers		storage, nodedev, interface, nwfilter, LXC, VirtualBox

How it works

On Linux	On this port
fork + exec	CreateProcess suspended, resumed after the handshake
Signals	named events Local\libvirt-signal-PID-SIG, console control handlers
UNIX sockets	AF_UNIX sockets of Windows 10 1803 and later
/run emptied at boot	autostart marks older than the boot ignored
Symbolic links	symbolic links, or without the privilege system files as Cygwin/MSYS2 make them
PTY consoles	QEMU serial on a UNIX socket, virsh console through the Windows console
KVM	WHPX (<domain type='whpx'>), TCG otherwise
Bridge, TAP, dnsmasq, iptables	libvirt_netswitch: one process per network, an Ethernet switch on a UNIX socket that QEMU joins with -netdev stream, libslirp for NAT, its own DHCP/DHCPv6/DNS, QoS by token buckets
tc	the switch shapes what a guest receives and polices what it sends
Replacing running binaries	renamed NAME.busy-STAMP by the install, removed by the next one

Requirements

• Windows 10 1803 or later, x64. For hardware acceleration, the Windows Hypervisor Platform optional feature.
• MSYS2, UCRT64 environment.
• QEMU for Windows with the patch in windows/qemu: without it WHPX crashes while libvirt probes QEMU.

Build

From an MSYS2 UCRT64 shell:

git clone --recurse-submodules https://github.com/EGKrb/libvirt-windows
cd libvirt-windows
windows/build.sh deps     # MSYS2 packages
windows/build.sh          # configure, build, install into install/

BUILD and PREFIX change the build and install directories. The install can run while daemons and networks run, and keeps edited configuration files (the new version goes beside them as NAME.new).

Run

The DLLs come from MSYS2: put install\bin, C:\msys64\ucrt64\bin and QEMU on PATH, then from PowerShell:

install\sbin\virtnetworkd.exe --daemon
install\sbin\virtqemud.exe --daemon
install\bin\virsh.exe -c qemu:///system net-list --all
install\bin\virsh.exe -c qemu:///system define guest.xml
install\bin\virsh.exe -c qemu:///system start guest
install\bin\virsh.exe -c qemu:///system console guest

A guest with WHPX, the default network and a serial console:

<domain type='whpx'>
  <name>guest</name>
  <memory unit='MiB'>2048</memory>
  <vcpu>2</vcpu>
  <os><type arch='x86_64' machine='q35'>hvm</type></os>
  <features><acpi/><apic/></features>
  <cpu mode='host-passthrough'/>
  <devices>
    <emulator>C:\Program Files\qemu\qemu-system-x86_64.exe</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='C:/vms/guest.qcow2'/>
      <target dev='vda' bus='virtio'/>
    </disk>
    <interface type='network'>
      <source network='default'/>
      <model type='virtio'/>
    </interface>
    <serial type='unix'>
      <source mode='bind' path='C:/vms/guest-serial0.sock'/>
    </serial>
    <console type='unix'>
      <source mode='bind' path='C:/vms/guest-serial0.sock'/>
      <target type='serial'/>
    </console>
    <graphics type='vnc' port='-1' listen='127.0.0.1'/>
  </devices>
</domain>

A daemon is stopped by its SIGTERM event:

$p = (Get-Content install\var\run\virtqemud.pid).Trim()
[System.Threading.EventWaitHandle]::OpenExisting("Local\libvirt-signal-$p-15").Set()

Configuration is in install\etc\libvirt, logs in install\var\log\libvirt (a network's switch logs to network\NAME.log), run state in install\var\run\libvirt.

Networks

• nat and isolated networks work out of the box, as the default network. Guests reach the host's services by the gateway address (192.168.122.1).
• route and open need Wintun: wintun.dll (amd64) beside install\libexec\libvirt_netswitch.exe, and administrator rights. The host then has a virbr0 interface with the gateway address, as on Linux.

Layout

• windows/build.sh: build script; windows/qemu: the QEMU patch; windows/site: the GitHub Pages site.
• scripts/windows-install.py: install over a running libvirt.
• src/network/netswitch.c: the switch of a virtual network.
• The rest is libvirt, with the Windows changes in place. Every change since upstream: git diff $(git rev-list --max-parents=0 HEAD).

License

As libvirt: the library under the LGPL 2.1 or later, some tools under the GPL 2.0 or later; see COPYING and COPYING.LESSER. libvirt is a project of the libvirt developers: https://libvirt.org.