diff options
Diffstat (limited to 'nixpkgs/nixos/modules/virtualisation/qemu-vm.nix')
| -rw-r--r-- | nixpkgs/nixos/modules/virtualisation/qemu-vm.nix | 672 |
1 files changed, 672 insertions, 0 deletions
diff --git a/nixpkgs/nixos/modules/virtualisation/qemu-vm.nix b/nixpkgs/nixos/modules/virtualisation/qemu-vm.nix new file mode 100644 index 000000000000..be06d6feb11f --- /dev/null +++ b/nixpkgs/nixos/modules/virtualisation/qemu-vm.nix @@ -0,0 +1,672 @@ +# This module creates a virtual machine from the NixOS configuration. +# Building the `config.system.build.vm' attribute gives you a command +# that starts a KVM/QEMU VM running the NixOS configuration defined in +# `config'. The Nix store is shared read-only with the host, which +# makes (re)building VMs very efficient. However, it also means you +# can't reconfigure the guest inside the guest - you need to rebuild +# the VM in the host. On the other hand, the root filesystem is a +# read/writable disk image persistent across VM reboots. + +{ config, lib, pkgs, ... }: + +with lib; +with import ../../lib/qemu-flags.nix { inherit pkgs; }; + +let + + qemu = config.system.build.qemu or pkgs.qemu_test; + + vmName = + if config.networking.hostName == "" + then "noname" + else config.networking.hostName; + + cfg = config.virtualisation; + + consoles = lib.concatMapStringsSep " " (c: "console=${c}") cfg.qemu.consoles; + + driveOpts = { ... }: { + + options = { + + file = mkOption { + type = types.str; + description = "The file image used for this drive."; + }; + + driveExtraOpts = mkOption { + type = types.attrsOf types.str; + default = {}; + description = "Extra options passed to drive flag."; + }; + + deviceExtraOpts = mkOption { + type = types.attrsOf types.str; + default = {}; + description = "Extra options passed to device flag."; + }; + + }; + + }; + + driveCmdline = idx: { file, driveExtraOpts, deviceExtraOpts, ... }: + let + drvId = "drive${toString idx}"; + mkKeyValue = generators.mkKeyValueDefault {} "="; + mkOpts = opts: concatStringsSep "," (mapAttrsToList mkKeyValue opts); + driveOpts = mkOpts (driveExtraOpts // { + index = idx; + id = drvId; + "if" = "none"; + inherit file; + }); + deviceOpts = mkOpts (deviceExtraOpts // { + drive = drvId; + }); + device = + if cfg.qemu.diskInterface == "scsi" then + "-device lsi53c895a -device scsi-hd,${deviceOpts}" + else + "-device virtio-blk-pci,${deviceOpts}"; + in + "-drive ${driveOpts} ${device}"; + + drivesCmdLine = drives: concatStringsSep " " (imap1 driveCmdline drives); + + # Shell script to start the VM. + startVM = + '' + #! ${pkgs.runtimeShell} + + NIX_DISK_IMAGE=$(readlink -f ''${NIX_DISK_IMAGE:-${config.virtualisation.diskImage}}) + + if ! test -e "$NIX_DISK_IMAGE"; then + ${qemu}/bin/qemu-img create -f qcow2 "$NIX_DISK_IMAGE" \ + ${toString config.virtualisation.diskSize}M || exit 1 + fi + + # Create a directory for storing temporary data of the running VM. + if [ -z "$TMPDIR" -o -z "$USE_TMPDIR" ]; then + TMPDIR=$(mktemp -d nix-vm.XXXXXXXXXX --tmpdir) + fi + + # Create a directory for exchanging data with the VM. + mkdir -p $TMPDIR/xchg + + ${if cfg.useBootLoader then '' + # Create a writable copy/snapshot of the boot disk. + # A writable boot disk can be booted from automatically. + ${qemu}/bin/qemu-img create -f qcow2 -b ${bootDisk}/disk.img $TMPDIR/disk.img || exit 1 + + ${if cfg.useEFIBoot then '' + # VM needs a writable flash BIOS. + cp ${bootDisk}/bios.bin $TMPDIR || exit 1 + chmod 0644 $TMPDIR/bios.bin || exit 1 + '' else '' + ''} + '' else '' + ''} + + cd $TMPDIR + idx=0 + ${flip concatMapStrings cfg.emptyDiskImages (size: '' + if ! test -e "empty$idx.qcow2"; then + ${qemu}/bin/qemu-img create -f qcow2 "empty$idx.qcow2" "${toString size}M" + fi + idx=$((idx + 1)) + '')} + + # Start QEMU. + exec ${qemuBinary qemu} \ + -name ${vmName} \ + -m ${toString config.virtualisation.memorySize} \ + -smp ${toString config.virtualisation.cores} \ + -device virtio-rng-pci \ + ${concatStringsSep " " config.virtualisation.qemu.networkingOptions} \ + -virtfs local,path=/nix/store,security_model=none,mount_tag=store \ + -virtfs local,path=$TMPDIR/xchg,security_model=none,mount_tag=xchg \ + -virtfs local,path=''${SHARED_DIR:-$TMPDIR/xchg},security_model=none,mount_tag=shared \ + ${drivesCmdLine config.virtualisation.qemu.drives} \ + ${toString config.virtualisation.qemu.options} \ + $QEMU_OPTS \ + "$@" + ''; + + + regInfo = pkgs.closureInfo { rootPaths = config.virtualisation.pathsInNixDB; }; + + + # Generate a hard disk image containing a /boot partition and GRUB + # in the MBR. Used when the `useBootLoader' option is set. + # FIXME: use nixos/lib/make-disk-image.nix. + bootDisk = + pkgs.vmTools.runInLinuxVM ( + pkgs.runCommand "nixos-boot-disk" + { preVM = + '' + mkdir $out + diskImage=$out/disk.img + bootFlash=$out/bios.bin + ${qemu}/bin/qemu-img create -f qcow2 $diskImage "40M" + ${if cfg.useEFIBoot then '' + cp ${pkgs.OVMF-CSM.fd}/FV/OVMF.fd $bootFlash + chmod 0644 $bootFlash + '' else '' + ''} + ''; + buildInputs = [ pkgs.utillinux ]; + QEMU_OPTS = if cfg.useEFIBoot + then "-pflash $out/bios.bin -nographic -serial pty" + else "-nographic -serial pty"; + } + '' + # Create a /boot EFI partition with 40M and arbitrary but fixed GUIDs for reproducibility + ${pkgs.gptfdisk}/bin/sgdisk \ + --set-alignment=1 --new=1:34:2047 --change-name=1:BIOSBootPartition --typecode=1:ef02 \ + --set-alignment=512 --largest-new=2 --change-name=2:EFISystem --typecode=2:ef00 \ + --attributes=1:set:1 \ + --attributes=2:set:2 \ + --disk-guid=97FD5997-D90B-4AA3-8D16-C1723AEA73C1 \ + --partition-guid=1:1C06F03B-704E-4657-B9CD-681A087A2FDC \ + --partition-guid=2:970C694F-AFD0-4B99-B750-CDB7A329AB6F \ + --hybrid 2 \ + --recompute-chs /dev/vda + ${pkgs.dosfstools}/bin/mkfs.fat -F16 /dev/vda2 + export MTOOLS_SKIP_CHECK=1 + ${pkgs.mtools}/bin/mlabel -i /dev/vda2 ::boot + + # Mount /boot; load necessary modules first. + ${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/nls/nls_cp437.ko.xz || true + ${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/nls/nls_iso8859-1.ko.xz || true + ${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/fat/fat.ko.xz || true + ${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/fat/vfat.ko.xz || true + ${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/efivarfs/efivarfs.ko.xz || true + mkdir /boot + mount /dev/vda2 /boot + + # This is needed for GRUB 0.97, which doesn't know about virtio devices. + mkdir /boot/grub + echo '(hd0) /dev/vda' > /boot/grub/device.map + + # This is needed for systemd-boot to find ESP, and udev is not available here to create this + mkdir -p /dev/block + ln -s /dev/vda2 /dev/block/254:2 + + # Set up system profile (normally done by nixos-rebuild / nix-env --set) + mkdir -p /nix/var/nix/profiles + ln -s ${config.system.build.toplevel} /nix/var/nix/profiles/system-1-link + ln -s /nix/var/nix/profiles/system-1-link /nix/var/nix/profiles/system + + # Install bootloader + touch /etc/NIXOS + export NIXOS_INSTALL_BOOTLOADER=1 + ${config.system.build.toplevel}/bin/switch-to-configuration boot + + umount /boot + '' # */ + ); + +in + +{ + imports = [ + ../profiles/qemu-guest.nix + ./docker-preloader.nix + ]; + + options = { + + virtualisation.memorySize = + mkOption { + default = 384; + description = + '' + Memory size (M) of virtual machine. + ''; + }; + + virtualisation.diskSize = + mkOption { + default = 512; + description = + '' + Disk size (M) of virtual machine. + ''; + }; + + virtualisation.diskImage = + mkOption { + default = "./${vmName}.qcow2"; + description = + '' + Path to the disk image containing the root filesystem. + The image will be created on startup if it does not + exist. + ''; + }; + + virtualisation.bootDevice = + mkOption { + type = types.str; + example = "/dev/vda"; + description = + '' + The disk to be used for the root filesystem. + ''; + }; + + virtualisation.emptyDiskImages = + mkOption { + default = []; + type = types.listOf types.int; + description = + '' + Additional disk images to provide to the VM. The value is + a list of size in megabytes of each disk. These disks are + writeable by the VM. + ''; + }; + + virtualisation.graphics = + mkOption { + default = true; + description = + '' + Whether to run QEMU with a graphics window, or in nographic mode. + Serial console will be enabled on both settings, but this will + change the preferred console. + ''; + }; + + virtualisation.cores = + mkOption { + default = 1; + type = types.int; + description = + '' + Specify the number of cores the guest is permitted to use. + The number can be higher than the available cores on the + host system. + ''; + }; + + virtualisation.pathsInNixDB = + mkOption { + default = []; + description = + '' + The list of paths whose closure is registered in the Nix + database in the VM. All other paths in the host Nix store + appear in the guest Nix store as well, but are considered + garbage (because they are not registered in the Nix + database in the guest). + ''; + }; + + virtualisation.vlans = + mkOption { + default = [ 1 ]; + example = [ 1 2 ]; + description = + '' + Virtual networks to which the VM is connected. Each + number <replaceable>N</replaceable> in this list causes + the VM to have a virtual Ethernet interface attached to a + separate virtual network on which it will be assigned IP + address + <literal>192.168.<replaceable>N</replaceable>.<replaceable>M</replaceable></literal>, + where <replaceable>M</replaceable> is the index of this VM + in the list of VMs. + ''; + }; + + virtualisation.writableStore = + mkOption { + default = true; # FIXME + description = + '' + If enabled, the Nix store in the VM is made writable by + layering an overlay filesystem on top of the host's Nix + store. + ''; + }; + + virtualisation.writableStoreUseTmpfs = + mkOption { + default = true; + description = + '' + Use a tmpfs for the writable store instead of writing to the VM's + own filesystem. + ''; + }; + + networking.primaryIPAddress = + mkOption { + default = ""; + internal = true; + description = "Primary IP address used in /etc/hosts."; + }; + + virtualisation.qemu = { + options = + mkOption { + type = types.listOf types.unspecified; + default = []; + example = [ "-vga std" ]; + description = "Options passed to QEMU."; + }; + + consoles = mkOption { + type = types.listOf types.str; + default = let + consoles = [ "${qemuSerialDevice},115200n8" "tty0" ]; + in if cfg.graphics then consoles else reverseList consoles; + example = [ "console=tty1" ]; + description = '' + The output console devices to pass to the kernel command line via the + <literal>console</literal> parameter, the primary console is the last + item of this list. + + By default it enables both serial console and + <literal>tty0</literal>. The preferred console (last one) is based on + the value of <option>virtualisation.graphics</option>. + ''; + }; + + networkingOptions = + mkOption { + default = [ + "-net nic,netdev=user.0,model=virtio" + "-netdev user,id=user.0\${QEMU_NET_OPTS:+,$QEMU_NET_OPTS}" + ]; + type = types.listOf types.str; + description = '' + Networking-related command-line options that should be passed to qemu. + The default is to use userspace networking (slirp). + + If you override this option, be advised to keep + ''${QEMU_NET_OPTS:+,$QEMU_NET_OPTS} (as seen in the default) + to keep the default runtime behaviour. + ''; + }; + + drives = + mkOption { + type = types.listOf (types.submodule driveOpts); + description = "Drives passed to qemu."; + }; + + diskInterface = + mkOption { + default = "virtio"; + example = "scsi"; + type = types.enum [ "virtio" "scsi" "ide" ]; + description = "The interface used for the virtual hard disks."; + }; + + guestAgent.enable = + mkOption { + default = true; + type = types.bool; + description = '' + Enable the Qemu guest agent. + ''; + }; + }; + + virtualisation.useBootLoader = + mkOption { + default = false; + description = + '' + If enabled, the virtual machine will be booted using the + regular boot loader (i.e., GRUB 1 or 2). This allows + testing of the boot loader. If + disabled (the default), the VM directly boots the NixOS + kernel and initial ramdisk, bypassing the boot loader + altogether. + ''; + }; + + virtualisation.useEFIBoot = + mkOption { + default = false; + description = + '' + If enabled, the virtual machine will provide a EFI boot + manager. + useEFIBoot is ignored if useBootLoader == false. + ''; + }; + + virtualisation.bios = + mkOption { + default = null; + type = types.nullOr types.package; + description = + '' + An alternate BIOS (such as <package>qboot</package>) with which to start the VM. + Should contain a file named <literal>bios.bin</literal>. + If <literal>null</literal>, QEMU's builtin SeaBIOS will be used. + ''; + }; + + }; + + config = { + + boot.loader.grub.device = mkVMOverride cfg.bootDevice; + + boot.initrd.extraUtilsCommands = + '' + # We need mke2fs in the initrd. + copy_bin_and_libs ${pkgs.e2fsprogs}/bin/mke2fs + ''; + + boot.initrd.postDeviceCommands = + '' + # If the disk image appears to be empty, run mke2fs to + # initialise. + FSTYPE=$(blkid -o value -s TYPE ${cfg.bootDevice} || true) + if test -z "$FSTYPE"; then + mke2fs -t ext4 ${cfg.bootDevice} + fi + ''; + + boot.initrd.postMountCommands = + '' + # Mark this as a NixOS machine. + mkdir -p $targetRoot/etc + echo -n > $targetRoot/etc/NIXOS + + # Fix the permissions on /tmp. + chmod 1777 $targetRoot/tmp + + mkdir -p $targetRoot/boot + + ${optionalString cfg.writableStore '' + echo "mounting overlay filesystem on /nix/store..." + mkdir -p 0755 $targetRoot/nix/.rw-store/store $targetRoot/nix/.rw-store/work $targetRoot/nix/store + mount -t overlay overlay $targetRoot/nix/store \ + -o lowerdir=$targetRoot/nix/.ro-store,upperdir=$targetRoot/nix/.rw-store/store,workdir=$targetRoot/nix/.rw-store/work || fail + ''} + ''; + + # After booting, register the closure of the paths in + # `virtualisation.pathsInNixDB' in the Nix database in the VM. This + # allows Nix operations to work in the VM. The path to the + # registration file is passed through the kernel command line to + # allow `system.build.toplevel' to be included. (If we had a direct + # reference to ${regInfo} here, then we would get a cyclic + # dependency.) + boot.postBootCommands = + '' + if [[ "$(cat /proc/cmdline)" =~ regInfo=([^ ]*) ]]; then + ${config.nix.package.out}/bin/nix-store --load-db < ''${BASH_REMATCH[1]} + fi + ''; + + boot.initrd.availableKernelModules = + optional cfg.writableStore "overlay" + ++ optional (cfg.qemu.diskInterface == "scsi") "sym53c8xx"; + + virtualisation.bootDevice = + mkDefault (if cfg.qemu.diskInterface == "scsi" then "/dev/sda" else "/dev/vda"); + + virtualisation.pathsInNixDB = [ config.system.build.toplevel ]; + + # FIXME: Consolidate this one day. + virtualisation.qemu.options = mkMerge [ + (mkIf (pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64) [ + "-usb" "-device usb-tablet,bus=usb-bus.0" + ]) + (mkIf (pkgs.stdenv.isAarch32 || pkgs.stdenv.isAarch64) [ + "-device virtio-gpu-pci" "-device usb-ehci,id=usb0" "-device usb-kbd" "-device usb-tablet" + ]) + (mkIf (!cfg.useBootLoader) [ + "-kernel ${config.system.build.toplevel}/kernel" + "-initrd ${config.system.build.toplevel}/initrd" + ''-append "$(cat ${config.system.build.toplevel}/kernel-params) init=${config.system.build.toplevel}/init regInfo=${regInfo}/registration ${consoles} $QEMU_KERNEL_PARAMS"'' + ]) + (mkIf cfg.useEFIBoot [ + "-pflash $TMPDIR/bios.bin" + ]) + (mkIf (cfg.bios != null) [ + "-bios ${cfg.bios}/bios.bin" + ]) + (mkIf (!cfg.graphics) [ + "-nographic" + ]) + ]; + + virtualisation.qemu.drives = mkMerge [ + (mkIf cfg.useBootLoader [ + { + file = "$NIX_DISK_IMAGE"; + driveExtraOpts.cache = "writeback"; + driveExtraOpts.werror = "report"; + } + { + file = "$TMPDIR/disk.img"; + driveExtraOpts.media = "disk"; + deviceExtraOpts.bootindex = "1"; + } + ]) + (mkIf (!cfg.useBootLoader) [ + { + file = "$NIX_DISK_IMAGE"; + driveExtraOpts.cache = "writeback"; + driveExtraOpts.werror = "report"; + } + ]) + (imap0 (idx: _: { + file = "$(pwd)/empty${toString idx}.qcow2"; + driveExtraOpts.werror = "report"; + }) cfg.emptyDiskImages) + ]; + + # Mount the host filesystem via 9P, and bind-mount the Nix store + # of the host into our own filesystem. We use mkVMOverride to + # allow this module to be applied to "normal" NixOS system + # configuration, where the regular value for the `fileSystems' + # attribute should be disregarded for the purpose of building a VM + # test image (since those filesystems don't exist in the VM). + fileSystems = mkVMOverride ( + { "/".device = cfg.bootDevice; + ${if cfg.writableStore then "/nix/.ro-store" else "/nix/store"} = + { device = "store"; + fsType = "9p"; + options = [ "trans=virtio" "version=9p2000.L" "cache=loose" ]; + neededForBoot = true; + }; + "/tmp" = mkIf config.boot.tmpOnTmpfs + { device = "tmpfs"; + fsType = "tmpfs"; + neededForBoot = true; + # Sync with systemd's tmp.mount; + options = [ "mode=1777" "strictatime" "nosuid" "nodev" ]; + }; + "/tmp/xchg" = + { device = "xchg"; + fsType = "9p"; + options = [ "trans=virtio" "version=9p2000.L" ]; + neededForBoot = true; + }; + "/tmp/shared" = + { device = "shared"; + fsType = "9p"; + options = [ "trans=virtio" "version=9p2000.L" ]; + neededForBoot = true; + }; + } // optionalAttrs (cfg.writableStore && cfg.writableStoreUseTmpfs) + { "/nix/.rw-store" = + { fsType = "tmpfs"; + options = [ "mode=0755" ]; + neededForBoot = true; + }; + } // optionalAttrs cfg.useBootLoader + { "/boot" = + { device = "/dev/vdb2"; + fsType = "vfat"; + options = [ "ro" ]; + noCheck = true; # fsck fails on a r/o filesystem + }; + }); + + swapDevices = mkVMOverride [ ]; + boot.initrd.luks.devices = mkVMOverride {}; + + # Don't run ntpd in the guest. It should get the correct time from KVM. + services.timesyncd.enable = false; + + services.qemuGuest.enable = cfg.qemu.guestAgent.enable; + + system.build.vm = pkgs.runCommand "nixos-vm" { preferLocalBuild = true; } + '' + mkdir -p $out/bin + ln -s ${config.system.build.toplevel} $out/system + ln -s ${pkgs.writeScript "run-nixos-vm" startVM} $out/bin/run-${vmName}-vm + ''; + + # When building a regular system configuration, override whatever + # video driver the host uses. + services.xserver.videoDrivers = mkVMOverride [ "modesetting" ]; + services.xserver.defaultDepth = mkVMOverride 0; + services.xserver.resolutions = mkVMOverride [ { x = 1024; y = 768; } ]; + services.xserver.monitorSection = + '' + # Set a higher refresh rate so that resolutions > 800x600 work. + HorizSync 30-140 + VertRefresh 50-160 + ''; + + # Wireless won't work in the VM. + networking.wireless.enable = mkVMOverride false; + services.connman.enable = mkVMOverride false; + + # Speed up booting by not waiting for ARP. + networking.dhcpcd.extraConfig = "noarp"; + + networking.usePredictableInterfaceNames = false; + + system.requiredKernelConfig = with config.lib.kernelConfig; + [ (isEnabled "VIRTIO_BLK") + (isEnabled "VIRTIO_PCI") + (isEnabled "VIRTIO_NET") + (isEnabled "EXT4_FS") + (isYes "BLK_DEV") + (isYes "PCI") + (isYes "EXPERIMENTAL") + (isYes "NETDEVICES") + (isYes "NET_CORE") + (isYes "INET") + (isYes "NETWORK_FILESYSTEMS") + ] ++ optional (!cfg.graphics) [ + (isYes "SERIAL_8250_CONSOLE") + (isYes "SERIAL_8250") + ]; + + }; +} |