6cfb3b6364
The reason to patch QEMU is that with latest Nix, tests like "printing" or "misc" fail because they expect the store paths to be owned by uid 0 and gid 0. Starting with NixOS/nix@5e51ffb1c2, Nix builds inside of a new user namespace. Unfortunately this also means that bind-mounted store paths that are part of the derivation's inputs are no longer owned by uid 0 and gid 0 but by uid 65534 and gid 65534. This in turn causes things like sudo or cups to fail with errors about insecure file permissions. So in order to avoid that, let's make sure the VM always gets files owned by uid 0 and gid 0 and does a no-op when doing a chmod on a store path. In addition, this adds a virtualisation.qemu.program option so that we can make sure that we only use the patched version if we're *really* running NixOS VM tests (that is, whenever we have imported test-instrumentation.nix). Tested against the "misc" and "printing" tests. Signed-off-by: aszlig <aszlig@redmoonstudios.org>
530 lines
18 KiB
Nix
530 lines
18 KiB
Nix
# This module creates a virtual machine from the NixOS configuration.
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# Building the `config.system.build.vm' attribute gives you a command
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# that starts a KVM/QEMU VM running the NixOS configuration defined in
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# `config'. The Nix store is shared read-only with the host, which
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# makes (re)building VMs very efficient. However, it also means you
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# can't reconfigure the guest inside the guest - you need to rebuild
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# the VM in the host. On the other hand, the root filesystem is a
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# read/writable disk image persistent across VM reboots.
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{ config, lib, pkgs, ... }:
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with lib;
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let
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vmName =
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if config.networking.hostName == ""
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then "noname"
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else config.networking.hostName;
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cfg = config.virtualisation;
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qemuGraphics = if cfg.graphics then "" else "-nographic";
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kernelConsole = if cfg.graphics then "" else "console=ttyS0";
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ttys = [ "tty1" "tty2" "tty3" "tty4" "tty5" "tty6" ];
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# Shell script to start the VM.
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startVM =
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''
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#! ${pkgs.stdenv.shell}
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NIX_DISK_IMAGE=$(readlink -f ''${NIX_DISK_IMAGE:-${config.virtualisation.diskImage}})
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if ! test -e "$NIX_DISK_IMAGE"; then
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${pkgs.qemu_kvm}/bin/qemu-img create -f qcow2 "$NIX_DISK_IMAGE" \
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${toString config.virtualisation.diskSize}M || exit 1
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fi
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# Create a directory for storing temporary data of the running VM.
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if [ -z "$TMPDIR" -o -z "$USE_TMPDIR" ]; then
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TMPDIR=$(mktemp -d nix-vm.XXXXXXXXXX --tmpdir)
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fi
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# Create a directory for exchanging data with the VM.
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mkdir -p $TMPDIR/xchg
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${if cfg.useBootLoader then ''
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# Create a writable copy/snapshot of the boot disk.
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# A writable boot disk can be booted from automatically.
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${pkgs.qemu_kvm}/bin/qemu-img create -f qcow2 -b ${bootDisk}/disk.img $TMPDIR/disk.img || exit 1
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${if cfg.useEFIBoot then ''
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# VM needs a writable flash BIOS.
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cp ${bootDisk}/bios.bin $TMPDIR || exit 1
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chmod 0644 $TMPDIR/bios.bin || exit 1
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'' else ''
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''}
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'' else ''
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''}
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cd $TMPDIR
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idx=2
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extraDisks=""
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${flip concatMapStrings cfg.emptyDiskImages (size: ''
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if ! test -e "empty$idx.qcow2"; then
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${pkgs.qemu_kvm}/bin/qemu-img create -f qcow2 "empty$idx.qcow2" "${toString size}M"
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fi
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extraDisks="$extraDisks -drive index=$idx,file=$(pwd)/empty$idx.qcow2,if=${cfg.qemu.diskInterface},werror=report"
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idx=$((idx + 1))
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'')}
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# Start QEMU.
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exec ${cfg.qemu.program} \
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-name ${vmName} \
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-m ${toString config.virtualisation.memorySize} \
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${optionalString (pkgs.stdenv.system == "x86_64-linux") "-cpu kvm64"} \
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${concatStringsSep " " config.virtualisation.qemu.networkingOptions} \
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-virtfs local,path=/nix/store,security_model=none,mount_tag=store \
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-virtfs local,path=$TMPDIR/xchg,security_model=none,mount_tag=xchg \
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-virtfs local,path=''${SHARED_DIR:-$TMPDIR/xchg},security_model=none,mount_tag=shared \
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${if cfg.useBootLoader then ''
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-drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=${cfg.qemu.diskInterface},cache=writeback,werror=report \
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-drive index=1,id=drive2,file=$TMPDIR/disk.img,media=disk \
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${if cfg.useEFIBoot then ''
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-pflash $TMPDIR/bios.bin \
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'' else ''
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''}
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'' else ''
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-drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=${cfg.qemu.diskInterface},cache=writeback,werror=report \
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-kernel ${config.system.build.toplevel}/kernel \
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-initrd ${config.system.build.toplevel}/initrd \
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-append "$(cat ${config.system.build.toplevel}/kernel-params) init=${config.system.build.toplevel}/init regInfo=${regInfo} ${kernelConsole} $QEMU_KERNEL_PARAMS" \
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''} \
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$extraDisks \
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${qemuGraphics} \
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${toString config.virtualisation.qemu.options} \
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$QEMU_OPTS \
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$@
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'';
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regInfo = pkgs.runCommand "reginfo"
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{ exportReferencesGraph =
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map (x: [("closure-" + baseNameOf x) x]) config.virtualisation.pathsInNixDB;
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buildInputs = [ pkgs.perl ];
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preferLocalBuild = true;
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}
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''
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printRegistration=1 perl ${pkgs.pathsFromGraph} closure-* > $out
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'';
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# Generate a hard disk image containing a /boot partition and GRUB
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# in the MBR. Used when the `useBootLoader' option is set.
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# FIXME: use nixos/lib/make-disk-image.nix.
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bootDisk =
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pkgs.vmTools.runInLinuxVM (
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pkgs.runCommand "nixos-boot-disk"
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{ preVM =
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''
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mkdir $out
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diskImage=$out/disk.img
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bootFlash=$out/bios.bin
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${pkgs.qemu_kvm}/bin/qemu-img create -f qcow2 $diskImage "40M"
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${if cfg.useEFIBoot then ''
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cp ${pkgs.OVMF-CSM}/FV/OVMF.fd $bootFlash
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chmod 0644 $bootFlash
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'' else ''
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''}
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'';
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buildInputs = [ pkgs.utillinux ];
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QEMU_OPTS = if cfg.useEFIBoot
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then "-pflash $out/bios.bin -nographic -serial pty"
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else "-nographic -serial pty";
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}
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''
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# Create a /boot EFI partition with 40M
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${pkgs.gptfdisk}/bin/sgdisk -G /dev/vda
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${pkgs.gptfdisk}/bin/sgdisk -a 1 -n 1:34:2047 -c 1:"BIOS Boot Partition" -t 1:ef02 /dev/vda
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${pkgs.gptfdisk}/bin/sgdisk -a 512 -N 2 -c 2:"EFI System" -t 2:ef00 /dev/vda
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${pkgs.gptfdisk}/bin/sgdisk -A 1:set:1 /dev/vda
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${pkgs.gptfdisk}/bin/sgdisk -A 2:set:2 /dev/vda
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${pkgs.gptfdisk}/bin/sgdisk -h 2 /dev/vda
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${pkgs.gptfdisk}/bin/sgdisk -C /dev/vda
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${pkgs.utillinux}/bin/sfdisk /dev/vda -A 2
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. /sys/class/block/vda2/uevent
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mknod /dev/vda2 b $MAJOR $MINOR
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. /sys/class/block/vda/uevent
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${pkgs.dosfstools}/bin/mkfs.fat -F16 /dev/vda2
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export MTOOLS_SKIP_CHECK=1
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${pkgs.mtools}/bin/mlabel -i /dev/vda2 ::boot
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# Mount /boot; load necessary modules first.
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/nls/nls_cp437.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/nls/nls_iso8859-1.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/fat/fat.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/fat/vfat.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/efivarfs/efivarfs.ko.xz || true
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mkdir /boot
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mount /dev/vda2 /boot
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# This is needed for GRUB 0.97, which doesn't know about virtio devices.
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mkdir /boot/grub
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echo '(hd0) /dev/vda' > /boot/grub/device.map
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# Install GRUB and generate the GRUB boot menu.
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touch /etc/NIXOS
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mkdir -p /nix/var/nix/profiles
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${config.system.build.toplevel}/bin/switch-to-configuration boot
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umount /boot
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'' # */
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);
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in
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{
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imports = [ ../profiles/qemu-guest.nix ];
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options = {
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virtualisation.memorySize =
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mkOption {
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default = 384;
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description =
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''
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Memory size (M) of virtual machine.
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'';
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};
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virtualisation.diskSize =
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mkOption {
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default = 512;
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description =
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''
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Disk size (M) of virtual machine.
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'';
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};
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virtualisation.diskImage =
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mkOption {
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default = "./${vmName}.qcow2";
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description =
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''
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Path to the disk image containing the root filesystem.
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The image will be created on startup if it does not
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exist.
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'';
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};
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virtualisation.bootDevice =
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mkOption {
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type = types.str;
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example = "/dev/vda";
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description =
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''
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The disk to be used for the root filesystem.
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'';
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};
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virtualisation.emptyDiskImages =
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mkOption {
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default = [];
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type = types.listOf types.int;
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description =
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''
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Additional disk images to provide to the VM. The value is
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a list of size in megabytes of each disk. These disks are
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writeable by the VM.
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'';
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};
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virtualisation.graphics =
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mkOption {
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default = true;
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description =
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''
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Whether to run QEMU with a graphics window, or access
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the guest computer serial port through the host tty.
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'';
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};
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virtualisation.pathsInNixDB =
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mkOption {
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default = [];
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description =
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''
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The list of paths whose closure is registered in the Nix
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database in the VM. All other paths in the host Nix store
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appear in the guest Nix store as well, but are considered
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garbage (because they are not registered in the Nix
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database in the guest).
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'';
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};
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virtualisation.vlans =
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mkOption {
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default = [ 1 ];
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example = [ 1 2 ];
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description =
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''
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Virtual networks to which the VM is connected. Each
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number <replaceable>N</replaceable> in this list causes
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the VM to have a virtual Ethernet interface attached to a
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separate virtual network on which it will be assigned IP
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address
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<literal>192.168.<replaceable>N</replaceable>.<replaceable>M</replaceable></literal>,
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where <replaceable>M</replaceable> is the index of this VM
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in the list of VMs.
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'';
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};
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virtualisation.writableStore =
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mkOption {
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default = false;
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description =
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''
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If enabled, the Nix store in the VM is made writable by
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layering a unionfs-fuse/tmpfs filesystem on top of the host's Nix
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store.
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'';
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};
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virtualisation.writableStoreUseTmpfs =
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mkOption {
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default = true;
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description =
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''
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Use a tmpfs for the writable store instead of writing to the VM's
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own filesystem.
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'';
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};
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networking.primaryIPAddress =
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mkOption {
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default = "";
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internal = true;
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description = "Primary IP address used in /etc/hosts.";
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};
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virtualisation.qemu = {
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program = mkOption {
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type = types.path;
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default = "${pkgs.qemu_kvm}/bin/qemu-kvm";
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defaultText = "\${pkgs.qemu_kvm}/bin/qemu-kvm";
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example = literalExample "\${pkgs.qemu_test}/bin/qemu-kvm";
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description = "The QEMU variant used to start the VM.";
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};
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options =
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mkOption {
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type = types.listOf types.unspecified;
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default = [];
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example = [ "-vga std" ];
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description = "Options passed to QEMU.";
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};
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networkingOptions =
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mkOption {
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default = [
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"-net nic,vlan=0,model=virtio"
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"-net user,vlan=0\${QEMU_NET_OPTS:+,$QEMU_NET_OPTS}"
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];
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type = types.listOf types.str;
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description = ''
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Networking-related command-line options that should be passed to qemu.
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The default is to use userspace networking (slirp).
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If you override this option, be advised to keep
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''${QEMU_NET_OPTS:+,$QEMU_NET_OPTS} (as seen in the default)
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to keep the default runtime behaviour.
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'';
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};
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diskInterface =
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mkOption {
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default = "virtio";
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example = "scsi";
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type = types.str;
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description = ''
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The interface used for the virtual hard disks
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(<literal>virtio</literal> or <literal>scsi</literal>).
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'';
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};
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};
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virtualisation.useBootLoader =
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mkOption {
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default = false;
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description =
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''
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If enabled, the virtual machine will be booted using the
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regular boot loader (i.e., GRUB 1 or 2). This allows
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testing of the boot loader. If
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disabled (the default), the VM directly boots the NixOS
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kernel and initial ramdisk, bypassing the boot loader
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altogether.
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'';
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};
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virtualisation.useEFIBoot =
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mkOption {
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default = false;
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description =
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''
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If enabled, the virtual machine will provide a EFI boot
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manager.
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useEFIBoot is ignored if useBootLoader == false.
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'';
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};
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};
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config = {
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boot.loader.grub.device = mkVMOverride cfg.bootDevice;
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boot.initrd.extraUtilsCommands =
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''
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# We need mke2fs in the initrd.
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copy_bin_and_libs ${pkgs.e2fsprogs}/bin/mke2fs
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'';
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boot.initrd.postDeviceCommands =
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''
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# If the disk image appears to be empty, run mke2fs to
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# initialise.
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FSTYPE=$(blkid -o value -s TYPE ${cfg.bootDevice} || true)
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if test -z "$FSTYPE"; then
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mke2fs -t ext4 ${cfg.bootDevice}
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fi
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'';
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boot.initrd.postMountCommands =
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''
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# Mark this as a NixOS machine.
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mkdir -p $targetRoot/etc
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echo -n > $targetRoot/etc/NIXOS
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# Fix the permissions on /tmp.
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chmod 1777 $targetRoot/tmp
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mkdir -p $targetRoot/boot
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'';
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# After booting, register the closure of the paths in
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# `virtualisation.pathsInNixDB' in the Nix database in the VM. This
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# allows Nix operations to work in the VM. The path to the
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# registration file is passed through the kernel command line to
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# allow `system.build.toplevel' to be included. (If we had a direct
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# reference to ${regInfo} here, then we would get a cyclic
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# dependency.)
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boot.postBootCommands =
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''
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if [[ "$(cat /proc/cmdline)" =~ regInfo=([^ ]*) ]]; then
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${config.nix.package.out}/bin/nix-store --load-db < ''${BASH_REMATCH[1]}
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fi
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'';
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boot.initrd.availableKernelModules =
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optional (cfg.qemu.diskInterface == "scsi") "sym53c8xx";
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virtualisation.bootDevice =
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mkDefault (if cfg.qemu.diskInterface == "scsi" then "/dev/sda" else "/dev/vda");
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virtualisation.pathsInNixDB = [ config.system.build.toplevel ];
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virtualisation.qemu.options = [ "-vga std" "-usbdevice tablet" ];
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# Mount the host filesystem via 9P, and bind-mount the Nix store
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# of the host into our own filesystem. We use mkVMOverride to
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# allow this module to be applied to "normal" NixOS system
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# configuration, where the regular value for the `fileSystems'
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# attribute should be disregarded for the purpose of building a VM
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# test image (since those filesystems don't exist in the VM).
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fileSystems = mkVMOverride (
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{ "/".device = cfg.bootDevice;
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${if cfg.writableStore then "/nix/.ro-store" else "/nix/store"} =
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{ device = "store";
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fsType = "9p";
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options = [ "trans=virtio" "version=9p2000.L" "cache=loose" ];
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neededForBoot = true;
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};
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"/tmp/xchg" =
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{ device = "xchg";
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fsType = "9p";
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options = [ "trans=virtio" "version=9p2000.L" "cache=loose" ];
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neededForBoot = true;
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};
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"/tmp/shared" =
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{ device = "shared";
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fsType = "9p";
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options = [ "trans=virtio" "version=9p2000.L" ];
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neededForBoot = true;
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};
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} // optionalAttrs cfg.writableStore
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{ "/nix/store" =
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{ fsType = "unionfs-fuse";
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device = "unionfs";
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options = [ "allow_other" "cow" "nonempty" "chroot=/mnt-root" "max_files=32768" "hide_meta_files" "dirs=/nix/.rw-store=rw:/nix/.ro-store=ro" ];
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};
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} // optionalAttrs (cfg.writableStore && cfg.writableStoreUseTmpfs)
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{ "/nix/.rw-store" =
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{ fsType = "tmpfs";
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options = [ "mode=0755" ];
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neededForBoot = true;
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};
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} // optionalAttrs cfg.useBootLoader
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{ "/boot" =
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{ device = "/dev/vdb2";
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fsType = "vfat";
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options = [ "ro" ];
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noCheck = true; # fsck fails on a r/o filesystem
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};
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});
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swapDevices = mkVMOverride [ ];
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boot.initrd.luks.devices = mkVMOverride {};
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# Don't run ntpd in the guest. It should get the correct time from KVM.
|
|
services.ntp.enable = false;
|
|
|
|
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;
|
|
networking.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")
|
|
];
|
|
|
|
};
|
|
}
|