# Libvirt

This is a devlog about getting libvirt up and running on NixOS to use Windows.

I started getting odd errors from VirtualBox related to KVM modules loaded by the kernel. This motivated me to evaluate libvirt as an option for running virtual machines.

My primary need is having quick access to windows only software, primarily for work purposes. This means I need the setup to be reliable, performant and easy to access. Currently, I have a Windows 10 VM managed by VirtualBox and so long as it starts I have no issues with it.

To get started, I headed over to the official wiki for nixos and looked at the libvirt page. And added the below snippet to hosts/othalan/virt.nix. If this works well, I’ll abstract the config to a nixosModule.

{
  pkgs,
  enabled,
  ...
}:
{
  programs.virt-manager = enabled;

  virtualisation.libvirtd = enabled // {

    # Enable TPM emulation (optional)
    libvirtd.qemu = {
      swtpn = enabled;
      ovmf.packages = [ pkgs.OVMFFull.fd ];
    };

    # Enable USB redirection (optional)
    spiceUSBRedirection = enabled;
  };

  users.users.daylin = {
    extraGroups = [ "libvirtd" ];
  };
}

## Setting up a Windows 11

Installation was originally based on this blog post,

But as it turns out just using a regular Windows 11 iso solved most of my setup hiccups.

General VM settings:

• Memory: 16384 MiB
• CPUs: 4
• Storage: 80GiB

Under “SATA Disk 1” open the Advanced options and changed Disk bus to VirtIO. Under “NIC” change device model to virtio.

I downloaded a pre-built iso for win-virtio from following a link in this repo. I then used “add hardware” to add this iso to the VM.

I booted up windows and used the win-virtio iso to ensure networking and needed storage drivers were installed.

I also used this tutorial to get file share up and running though.

virtualisation.libvirtd = {
  enable = true;
  qemu.vhostUserPackages = with pkgs; [ virtiofsd ];
};

Perhaps, I can now take this domain and instantiate it using NixVirt. Without going into any detail, this worked so now the xml/config for the VM is instantiated with NixVirt.