1 files changed, 86 insertions, 0 deletions
diff --git a/nixos/modules/virtualisation/kvmgt.nix b/nixos/modules/virtualisation/kvmgt.nix
new file mode 100644
index 00000000000..5e7a73bec90
--- /dev/null
+++ b/nixos/modules/virtualisation/kvmgt.nix
@@ -0,0 +1,86 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.virtualisation.kvmgt;
+
+  kernelPackages = config.boot.kernelPackages;
+
+  vgpuOptions = {
+    uuid = mkOption {
+      type = with types; listOf str;
+      description = "UUID(s) 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. To allow users to access the device without root add them
+        to the kvm group: <literal>users.extraUsers.&lt;yourusername&gt;.extraGroups = [ "kvm" ];</literal>
+      '';
+      # multi GPU support is under the question
+      device = mkOption {
+        type = types.str;
+        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.kernelModules = [ "kvmgt" ];
+    boot.kernelParams = [ "i915.enable_gvt=1" ];
+
+    services.udev.extraRules = ''
+      SUBSYSTEM=="vfio", OWNER="root", GROUP="kvm"
+    '';
+
+    systemd = let
+      vgpus = listToAttrs (flatten (mapAttrsToList
+        (mdev: opt: map (id: nameValuePair "kvmgt-${id}" { inherit mdev; uuid = id; }) opt.uuid)
+        cfg.vgpus));
+    in {
+      paths = mapAttrs (_: opt:
+        {
+          description = "KVMGT VGPU ${opt.uuid} path";
+          wantedBy = [ "multi-user.target" ];
+          pathConfig = {
+            PathExists = "/sys/bus/pci/devices/${cfg.device}/mdev_supported_types/${opt.mdev}/create";
+          };
+        }) vgpus;
+
+      services = mapAttrs (_: opt:
+        {
+          description = "KVMGT VGPU ${opt.uuid}";
+          serviceConfig = {
+            Type = "oneshot";
+            RemainAfterExit = true;
+            ExecStart = "${pkgs.runtimeShell} -c 'echo ${opt.uuid} > /sys/bus/pci/devices/${cfg.device}/mdev_supported_types/${opt.mdev}/create'";
+            ExecStop = "${pkgs.runtimeShell} -c 'echo 1 > /sys/bus/pci/devices/${cfg.device}/${opt.uuid}/remove'";
+          };
+        }) vgpus;
+    };
+  };
+
+  meta.maintainers = with maintainers; [ patryk27 ];
+}