nixos-config/modules/virtualisation/gaming.nix

{ pkgs, ... }:

{
  environment.etc = {
    "evdev-proxy/config.toml".source = pkgs.writeText "config.toml" ''
        log_level = "INFO"

        [[device]]
          [device.Simple]
            name = "EvdevProxyMouse"
            vendor = 0x1337
            model = 0x1337
            class = "Mouse"
            [[device.Simple.selector]]
              USBIDClass = {vendor=0x046d, model=0xc531, class="Mouse"}
            [[device.Simple.selector]]
              USBIDClass = {vendor=0x046d, model=0xc07c, class="Mouse"}
        [[device]]
          [device.Simple]
            name = "EvdevProxyTartarus"
            vendor = 0x1337
            model = 0x1338
            class = "Keyboard"
            # This is to give a deterministic /dev/input/by-id/ path to
            # the mapped version of the Tartarus evdev node.
            # (Useful for qemu)
            [[device.Simple.selector]]
              EVDEVClass = {phys="\"key-mapper\""}
      '';
    "libvirt/hooks/qemu".source = let
      vfio-isolate-state = "/tmp/vfio-isolate-state";
    in pkgs.writeScript "qemu" ''
        #!${pkgs.stdenv.shell}
        guest=$1
        action=$2
        phase=$3
        extra=$4

        if [[ "$guest" = "win10" ]]; then
            case "$action" in
                prepare)
                # Only do this while in preparation
                [[ ! "$phase" = "prepare" ]] && exit 0

                sudo -u alexander systemctl --user start evdev-proxy.service
                sudo -u alexander systemctl --user start scream.service
                sleep 2

                ${pkgs.vfio-isolate}/bin/vfio-isolate \
                  -u ${vfio-isolate-state} \
                 	cpu-governor performance "$GUEST_CORES" \
                  cpuset-create --cpus "$GUEST_CORES" /guest.slice \
                  cpuset-create --cpus C0,4 /host.slice \
                  move-tasks / /host.slice \
                  irq-affinity mask "$GUEST_CORES"
                ;;
                stopped)
                # Only run when the VM is fully stopped
                [[ ! "$phase" = "end" ]] && exit 0
                sudo -u alexander systemctl --user stop evdev-proxy.service
                sudo -u alexander systemctl --user stop scream.service

                ${pkgs.vfio-isolate}/bin/vfio-isolate \
                  restore ${vfio-isolate-state}
            esac
        fi
      '';
  };

  virtualisation.libvirtd = {
    enable = true;
    #qemuRunAsRoot = false;
    qemuOvmf = true;
    qemuPackage = pkgs.unstable.qemu;
    qemuVerbatimConfig = ''
      seccomp_sandbox = 0
      cgroup_device_acl = [
      	"/dev/null", "/dev/full", "/dev/zero", 
      	"/dev/random", "/dev/urandom",
      	"/dev/ptmx", "/dev/kvm", "/dev/kqemu",
      	"/dev/rtc","/dev/hpet",
        "/dev/input/by-id/usb-Logitech_USB_Receiver-if02-event-mouse",
        "/dev/input/by-id/usb-Razer_Razer_Tartarus_V2-event-kbd",
        "/dev/input/by-id/virtual-event-EvdevProxyMouse",
        "/dev/input/by-id/virtual-event-EvdevProxyTartarus",
        "/dev/input/by-id/usb-Razer_Razer_BlackWidow_Ultimate-event-kbd"
      ]
    '';
  };

  # NOTE: Workaround for libvirt's SYSCONFDIR being set to /var/lib
  # (See https://github.com/NixOS/nixpkgs/issues/51152#issuecomment-899374407)
  system.activationScripts.libvirt-hooks.text = ''
    ln -Tfs /etc/libvirt/hooks /var/lib/libvirt/hooks
  '';

  #services.udev.packages = with pkgs; [ evdev-proxy ];
  
  systemd = {
    services.libvirtd.path = with pkgs; [ vfio-isolate systemd bash ];
   #user.services.evdev-proxy = {
   #  description = "Creates virtual device to proxy evdev devices events";
   #  #wantedBy = [ "default.target" ];
   #  serviceConfig = {
   #    Type = "simple";
   #    ExecStart = "${pkgs.evdev-proxy}/bin/evdev-proxy";
   #    Restart = "always";
   #  };
   #};
  };
}