nixos/kvmgt: init

nixos/modules/module-list.nix

@@ -787,6 +787,7 @@
   ./virtualisation/lxd.nix
   ./virtualisation/amazon-options.nix
   ./virtualisation/hyperv-guest.nix
+  ./virtualisation/kvmgt.nix
   ./virtualisation/openvswitch.nix
   ./virtualisation/parallels-guest.nix
   ./virtualisation/qemu-guest-agent.nix

nixos/modules/virtualisation/kvmgt.nix

@@ -0,0 +1,64 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.virtualisation.kvmgt;
+  kernelPackages = config.boot.kernelPackages;
+  vgpuOptions = {
+    uuid = mkOption {
+      type = types.string;
+      description = "UUID of VGPU device. You can generate one with <package>libossp_uuid</package>.";
+    };
+  };
+in {
+  options = {
+    virtualisation.kvmgt = {
+      enable = mkEnableOption ''
+        KVMGT (iGVT-g) VGPU support. Allows Qemu/KVM guests to share host's Intel integrated graphics card.
+        Currently only one graphical device can be shared
+      '';
+      # multi GPU support is under the question
+      device = mkOption {
+        type = types.string;
+        default = "0000:00:02.0";
+        description = "PCI ID of graphics card. You can figure it with <command>ls /sys/class/mdev_bus</command>.";
+      };
+      vgpus = mkOption {
+        default = {};
+        type = with types; attrsOf (submodule [ { options = vgpuOptions; } ]);
+        description = ''
+          Virtual GPUs to be used in Qemu. You can find devices via <command>ls /sys/bus/pci/devices/*/mdev_supported_types</command>
+          and find info about device via <command>cat /sys/bus/pci/devices/*/mdev_supported_types/i915-GVTg_V5_4/description</command>
+        '';
+        example = {
+          "i915-GVTg_V5_8" = {
+            uuid = "a297db4a-f4c2-11e6-90f6-d3b88d6c9525";
+          };
+        };
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = singleton {
+      assertion = versionAtLeast kernelPackages.kernel.version "4.16";
+      message = "KVMGT is not properly supported for kernels older than 4.16";
+    };
+    boot.kernelParams = [ "i915.enable_gvt=1" ];
+    systemd.services = mapAttrs' (name: value:
+      nameValuePair "kvmgt-${name}" {
+        description = "KVMGT VGPU ${name}";
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+          ExecStart = "${pkgs.runtimeShell} -c 'echo ${value.uuid} > /sys/bus/pci/devices/${cfg.device}/mdev_supported_types/${name}/create'";
+          ExecStop = "${pkgs.runtimeShell} -c 'echo 1 > /sys/bus/pci/devices/${cfg.device}/${value.uuid}/remove'";
+        };
+        wantedBy = [ "multi-user.target" ];
+      }
+    ) cfg.vgpus;
+  };
+
+  meta.maintainers = with maintainers; [ gnidorah ];
+}