initial commit

modules/nixos/virtualisation/kvmfr.nix

@@ -0,0 +1,157 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.virtualisation.kvmfr;
+
+  sizeFromResolution =
+    resolution:
+    let
+      ceilToPowerOf2 =
+        let
+          findNextPower = target: power: if power >= target then power else findNextPower target (power * 2);
+        in
+        n: if n <= 1 then 1 else findNextPower n 1;
+      pixelSize = if resolution.pixelFormat == "rgb24" then 3 else 4;
+      bytes = resolution.width * resolution.height * pixelSize * 2;
+    in
+    ceilToPowerOf2 (bytes / 1024 / 1024 + 10);
+
+  deviceSizes = map (device: device.size) cfg.devices;
+
+  devices = imap (index: _deviceConfig: "/dev/kvmfr${toString index}") cfg.devices;
+
+  udevPackage = pkgs.writeTextDir "/lib/udev/rules.d/99-kvmfr.rules" (
+    concatStringsSep "\n" (
+      imap0 (index: deviceConfig: ''
+        SUBSYSTEM=="kvmfr", KERNEL=="kvmfr${toString index}", OWNER="${deviceConfig.permissions.user}", GROUP="${deviceConfig.permissions.group}", MODE="${deviceConfig.permissions.mode}", TAG+="systemd"
+      '') cfg.devices
+    )
+  );
+
+  apparmorAbstraction = concatStringsSep "\n" (map (device: "${device} rw") devices);
+
+  permissionsType = types.submodule {
+    options = {
+      user = mkOption {
+        type = types.str;
+        default = "root";
+        description = "Owner of the shared memory device.";
+      };
+      group = mkOption {
+        type = types.str;
+        default = "root";
+        description = "Group of the shared memory device.";
+      };
+      mode = mkOption {
+        type = types.str;
+        default = "0600";
+        description = "Mode of the shared memory device.";
+      };
+    };
+  };
+
+  resolutionType = types.submodule {
+    options = {
+      width = mkOption {
+        type = types.number;
+        description = "Maximum horizontal video size that should be supported by this device.";
+      };
+
+      height = mkOption {
+        type = types.number;
+        description = "Maximum vertical video size that should be supported by this device.";
+      };
+
+      pixelFormat = mkOption {
+        type = types.enum [
+          "rgba32"
+          "rgb24"
+        ];
+        description = "Pixel format to use.";
+        default = "rgba32";
+      };
+    };
+  };
+
+  deviceType = (
+    types.submodule (
+      { config, options, ... }:
+      {
+        options = {
+          resolution = mkOption {
+            type = types.nullOr resolutionType;
+            default = null;
+            description = "Automatically calculate the minimum device size for a specific resolution. Overrides `size` if set.";
+          };
+
+          size = mkOption {
+            type = types.number;
+            description = "Size for the kvmfr device in megabytes.";
+          };
+
+          permissions = mkOption {
+            type = permissionsType;
+            default = { };
+            description = "Permissions of the kvmfr device.";
+          };
+        };
+
+        config = {
+          size = mkIf (config.resolution != null) (sizeFromResolution config.resolution);
+        };
+      }
+    )
+  );
+
+  inherit (lib)
+    concatStringsSep
+    imap
+    imap0
+    mkIf
+    mkOption
+    optionals
+    types
+    ;
+in
+{
+  options.virtualisation.kvmfr = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Whether to enable the kvmfr kernel module.";
+    };
+
+    devices = mkOption {
+      type = types.listOf deviceType;
+      default = [ ];
+      description = "List of devices to create.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    boot.extraModulePackages = with config.boot.kernelPackages; [ kvmfr ];
+    services.udev.packages = optionals (cfg.devices != [ ]) [ udevPackage ];
+
+    environment.systemPackages = with pkgs; [ looking-glass-client ];
+    environment.etc = {
+      "modules-load.d/kvmfr.conf".text = ''
+        kvmfr
+      '';
+
+      "modprobe.d/kvmfr.conf".text = ''
+        options kvmfr static_size_mb=${concatStringsSep "," (map (size: toString size) deviceSizes)}
+      '';
+
+      "apparmor.d/local/abstractions/libvirt-qemu" = mkIf config.security.apparmor.enable {
+        text = apparmorAbstraction;
+      };
+    };
+
+    virtualisation.libvirtd.deviceACL = devices;
+  };
+}