add vm host (closes #13)

hosts/vm/default.nix

@@ -0,0 +1,26 @@
+{ pkgs, config, lib, ... }: 
+{
+  imports = [
+    ./hardware-configuration.nix
+    ./../../modules/core
+  ];
+
+  # kvm/qemu doesn't use UEFI firmware mode by default.
+  # so we force-override the setting here 
+  # and configure GRUB instead.
+  boot.loader.systemd-boot.enable = lib.mkForce false;
+  boot.loader.grub.enable = true;
+  boot.loader.grub.device = "/dev/vda";
+  boot.loader.grub.useOSProber = false;
+
+  # allow local remote access to make it easier to toy around with the system
+  services.openssh = {
+    enable = true;
+    ports = [22];
+    settings = {
+      PasswordAuthentication = true;
+      AllowUsers = null;
+      PermitRootLogin = "yes";
+    };
+  };
+}

hosts/vm/hardware-configuration.nix

@@ -0,0 +1,31 @@
+# Do not modify this file!  It was generated by ‘nixos-generate-config’
+# and may be overwritten by future invocations.  Please make changes
+# to /etc/nixos/configuration.nix instead.
+{ config, lib, pkgs, modulesPath, ... }:
+
+{
+  imports =
+    [ (modulesPath + "/profiles/qemu-guest.nix")
+    ];
+
+  boot.initrd.availableKernelModules = [ "ahci" "xhci_pci" "virtio_pci" "sr_mod" "virtio_blk" ];
+  boot.initrd.kernelModules = [ ];
+  boot.kernelModules = [ "kvm-intel" ];
+  boot.extraModulePackages = [ ];
+
+  fileSystems."/" =
+    { device = "/dev/disk/by-uuid/631775ef-6851-4fe7-997f-189372f87437";
+      fsType = "ext4";
+    };
+
+  swapDevices = [ ];
+
+  # Enables DHCP on each ethernet and wireless interface. In case of scripted networking
+  # (the default) this is the recommended approach. When using systemd-networkd it's
+  # still possible to use this option, but it's recommended to use it in conjunction
+  # with explicit per-interface declarations with `networking.interfaces.<interface>.useDHCP`.
+  networking.useDHCP = lib.mkDefault true;
+  # networking.interfaces.enp1s0.useDHCP = lib.mkDefault true;
+
+  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
+}