Virt-manager: Difference between revisions

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m Added note to explain dconf, numerous issues were created on nixpkgs were related to this
Unable to find 'efi' firmware
 
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[https://virt-manager.org/ Virt-manager] (a.k.a. Virtual Machine Manager) is a GUI application for managing local and remote virtual machines through [[libvirt]]. It primarily targets KVM VMs, but also manages Xen and LXC (Linux Containers).
== Prequisites ==
Though Virt-manager (using the KVM hypervisor) is able to take advantage of virtualisation capabilities without any UEFI/BIOS configuration, best performance demands that the host have Vt-x and Vt-d (Intel) or AMD-V and AMD-Vi (AMD) enabled.
These settings can usually be found under the UEFI/BIOS settings.
== Installation ==
== Installation ==
In your configuration file add:
{{File|3=virtualisation.libvirtd.enable = true;
programs.virt-manager.enable = true;|name=/etc/nixos/configuration.nix|lang=nix}}{{Note|<br/><br /><code>authentication unavailable: no polkit agent available to authenticate action 'org.libvirt.unix.manage'</code>


=== NixOS ===
To resolve, add your user to the libvirtd group:
<syntaxhighlight lang="nix">
virtualisation.libvirtd.enable = true;
programs.dconf.enable = true; # virt-manager requires dconf to remember settings
environment.systemPackages = with pkgs; [ virt-manager ];
</syntaxhighlight>


You will get a warning when you open it for the first time
{{File|3={
  users.users.<myuser>.extraGroups = [ "libvirtd" ];
}|name=/etc/nixos/configuration.nix|lang=nix}}|leading=After rebuild, you may get the following error:}}


<code>Could not detect a default hypervisor. Make sure the appropriate QEMU/KVM virtualization packages are installed to manage virtualization on this host.
=== Networking ===
To use the default libvirt network, you will need to install the <code>dnsmasq</code> package. This is required for DNS and DCHP functionality within the network:


A virtualization connection can be manually added via File->Add Connection</code>
{{File|3=environment.systemPackages = with pkgs; [
  dnsmasq
];|name=/etc/nixos/configuration.nix|lang=nix}}


To resolve
The default network starts off inactive, you must enable it before it is accessible. This can be done by running the following command: <syntaxhighlight lang="console"># virsh net-start default</syntaxhighlight>And if you would like to enable it automatically at boot:<syntaxhighlight lang="console">
# virsh net-autostart default
</syntaxhighlight>By default, this will enable a virtual network bridge under the name <code>virbr0</code>. You may need to allow it through your firewall filter like so:
{{File|3=networking.firewall.trustedInterfaces = [ "virbr0" ];|name=/etc/nixos/configuration.nix|lang=nix}}


<pre>
=== Display ===
File (in the menu bar) -> Add connection
The default video may not allow different resolutions and is limited. It is recommended to use Virtio instead.


HyperVisor = QEMU/KVM
For information on how to use Virtio with your VM's, [https://wiki.libvirt.org/Virtio.html you can read up on Virtio on the libvirt wiki].
Autoconnect = checkmark


Connect
=== Shared folders ===
</pre>
To be able to share a folder with a guest, you will need 'virtiofsd'. The recommended way to solve this problem is now to add <code>pkgs.virtiofsd</code> to <code>virtualisation.libvirtd.qemu.vhostUserPackages</code>:


The same can also be achieved decoratively by setting the corresponding dconf settings with home-manager. If you want to do this instead of the imperative configuration described above, add the following snippet to your home-manager configuration:
<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
dconf.settings = {
virtualisation.libvirtd = {
   "org/virt-manager/virt-manager/connections" = {
   enable = true;
    autoconnect = ["qemu:///system"];
  qemu.vhostUserPackages = with pkgs; [ virtiofsd ];
    uris = ["qemu:///system"];
  };
};
};
</syntaxhighlight>
</syntaxhighlight>


You can get the following error :  
===Windows Guest===
See [https://github.com/virtio-win/virtio-win-guest-tools-installer Virtio-win guest tools] for additional drivers for both paravirtual and emulated hardware


<code>authentication unavailable: no polkit agent available to authenticate action 'org.libvirt.unix.manage'</code>
===Guest Agent===
 
When running NixOS as a guest, enable the [https://wiki.qemu.org/Features/GuestAgent QEMU guest agent] with:
To resolve, add the user to the <code>libvirtd</code> group.


<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
{
{
   users.users.<myuser>.extraGroups = [ "libvirtd" ];
   services.qemuGuest.enable = true;
  services.spice-vdagentd.enable = true; # enable copy and paste between host and guest
}
}
</syntaxhighlight>
</syntaxhighlight>
The host must [https://wiki.libvirt.org/Qemu_guest_agent.html#setting-qemu-ga-up provide the needed virtio serial port] under the special name <code>org.qemu.guest_agent.0</code>.
=== Wayland ===
In order to run on Wayland, virt-manager must be ran under XWayland with `$ GDK_BACKEND=x11 virt-manager` or a gdk cursor must be set. An example of setting a gdk cursor with home-manager is as follows:
  home.pointerCursor = {
    gtk.enable = true;
    package = pkgs.vanilla-dmz;
    name = "Vanilla-DMZ";
  };
== Troubleshooting ==
=== Unable to find 'efi' firmware ===
The following guide is to fix the following error which will occur when starting a virtual machine after NixOS upgrade:
<code>Error:  Error starting domain: operation failed: Unable to find 'efi' firmware that is compatible with the current configuration</code>
Solution:
# Delete old generations:  <code>nix-collect-garbage -d</code>
# Find where the EFI boot loaded file is located:  <code>find /nix/store/ -maxdepth 1 -type d -name "*qemu*"  |  xargs -I {} find "{}" -type f -name "edk2-x86_64-secure-code.fd"</code>  Find the dir holding the latest qemu.  The directory should be something like: <code>xbfjilai721rzd9rf9dhhpv03xza4xp4-qemu-9.1.3</code>.  Take a note of this directory name.
# Open VM in virt-manager, go to XML and within the <code><os ...></code> tag:
## Edit <code><loader ...></code> with the above directory name
## Edit <code><nvram ...></code> with the above directory name.


[[Category:Virtualization]]
[[Category:Virtualization]]