feat: working gpu passthrough \o/

nixos/vm.nix

@@ -0,0 +1,72 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: 
+let
+  gpuIDs = [
+    "1002:7480" # Graphics
+    "1002:ab30" # Audio
+    "1022:15c0" # Top Right physical USB C port
+  ];
+in {
+  options.vfio.enable = with lib;
+    mkEnableOption "Configure the machine for VFIO";
+
+  options.vfio.earlyKMS = with lib;
+    mkEnableOption "Configure the machine to load the GPU driver during initramfs";
+
+  options.vfio.applyACSpatch = with lib;
+    mkEnableOption
+      ''If set, the following things will happen:
+          - The ACS override patch is applied
+          - Applies the i915-vga-arbiter patch
+          - Adds pcie_acs_override=downstream to the command line
+      '';
+
+  config = let cfg = config.vfio;
+  in {
+    networking.bridges = {
+      "winvm0" = {
+        interfaces = [ "eth0" ];
+      };
+    };
+    networking.interfaces.eth0.useDHCP = true;
+    networking.interfaces.winvm0.useDHCP = true;
+
+    programs.virt-manager.enable = true;
+    users.groups.libvirtd.members = ["evar"];
+    hardware.graphics.enable = true;
+    virtualisation.libvirtd.enable = true;
+    virtualisation.libvirtd.qemu.swtpm.enable = true; # for TPM 2.0 support
+    virtualisation.spiceUSBRedirection.enable = true;
+  
+    boot = {
+      initrd.kernelModules = [
+        "vfio_pci"
+        "vfio"
+        "vfio_iommu_type1"
+        # "vfio_virqfd" # This is apparently a part of the kernel now
+      ] ++ lib.optional cfg.earlyKMS "amdgpu";
+
+      # kernelPatches = [] ++ lib.optional cfg.applyACSpatch
+      #   {
+      #     name = "add-acs-overrides";
+      #     patch = pkgs.fetchurl {
+      #       name = "add-acs-overrides.patch";
+      #       url = "https://aur.archlinux.org/cgit/aur.git/plain/1001-6.8.0-add-acs-overrides.patch?h=linux-vfio";
+      #       sha256 = "1qd68s9r0ppynksbffqn2qbp1whqpbfp93dpccp9griwhx5srx6v";
+      #     };
+      #   };
+
+      kernelParams = [
+        # enable IOMMU
+        "amd_iommu=on"
+      ] ++ lib.optional cfg.enable
+        # isolate the GPU
+        ("vfio-pci.ids=" + lib.concatStringsSep "," gpuIDs);
+        # ++ lib.optional cfg.applyACSpatch "pcie_acs_override=downstream,multifunction";
+    };
+  };
+}