# Xen hypervisor (Dom0) support. { config, lib, pkgs, ... }: with lib; let cfg = config.virtualisation.xen; in { imports = [ (mkRemovedOptionModule [ "virtualisation" "xen" "qemu" ] "You don't need this option anymore, it will work without it.") (mkRenamedOptionModule [ "virtualisation" "xen" "qemu-package" ] [ "virtualisation" "xen" "package-qemu" ]) ]; ###### interface options = { virtualisation.xen.enable = mkOption { default = false; type = types.bool; description = mdDoc '' Setting this option enables the Xen hypervisor, a virtualisation technology that allows multiple virtual machines, known as *domains*, to run concurrently on the physical machine. NixOS runs as the privileged *Domain 0*. This option requires a reboot to take effect. ''; }; virtualisation.xen.package = mkOption { type = types.package; defaultText = literalExpression "pkgs.xen"; example = literalExpression "pkgs.xen-light"; description = lib.mdDoc '' The package used for Xen binary. ''; relatedPackages = [ "xen" "xen-light" ]; }; virtualisation.xen.package-qemu = mkOption { type = types.package; defaultText = literalExpression "pkgs.xen"; example = literalExpression "pkgs.qemu_xen-light"; description = lib.mdDoc '' The package with qemu binaries for dom0 qemu and xendomains. ''; relatedPackages = [ "xen" { name = "qemu_xen-light"; comment = "For use with pkgs.xen-light."; } ]; }; virtualisation.xen.bootParams = mkOption { default = []; type = types.listOf types.str; description = lib.mdDoc '' Parameters passed to the Xen hypervisor at boot time. ''; }; virtualisation.xen.domain0MemorySize = mkOption { default = 0; example = 512; type = types.addCheck types.int (n: n >= 0); description = lib.mdDoc '' Amount of memory (in MiB) allocated to Domain 0 on boot. If set to 0, all memory is assigned to Domain 0. ''; }; virtualisation.xen.bridge = { name = mkOption { default = "xenbr0"; type = types.str; description = lib.mdDoc '' Name of bridge the Xen domUs connect to. ''; }; address = mkOption { type = types.str; default = "172.16.0.1"; description = lib.mdDoc '' IPv4 address of the bridge. ''; }; prefixLength = mkOption { type = types.addCheck types.int (n: n >= 0 && n <= 32); default = 16; description = lib.mdDoc '' Subnet mask of the bridge interface, specified as the number of bits in the prefix (`24`). A DHCP server will provide IP addresses for the whole, remaining subnet. ''; }; forwardDns = mkOption { type = types.bool; default = false; description = lib.mdDoc '' If set to `true`, the DNS queries from the hosts connected to the bridge will be forwarded to the DNS servers specified in /etc/resolv.conf . ''; }; }; virtualisation.xen.stored = mkOption { type = types.path; description = lib.mdDoc '' Xen Store daemon to use. Defaults to oxenstored of the xen package. ''; }; virtualisation.xen.domains = { extraConfig = mkOption { type = types.lines; default = ""; description = lib.mdDoc '' Options defined here will override the defaults for xendomains. The default options can be seen in the file included from /etc/default/xendomains. ''; }; }; virtualisation.xen.trace = mkEnableOption "Xen tracing"; }; ###### implementation config = mkIf cfg.enable { assertions = [ { assertion = pkgs.stdenv.isx86_64; message = "Xen currently not supported on ${pkgs.stdenv.hostPlatform.system}"; } { assertion = config.boot.loader.grub.enable && (config.boot.loader.grub.efiSupport == false); message = "Xen currently does not support EFI boot"; } ]; virtualisation.xen.package = mkDefault pkgs.xen; virtualisation.xen.package-qemu = mkDefault pkgs.xen; virtualisation.xen.stored = mkDefault "${cfg.package}/bin/oxenstored"; environment.systemPackages = [ cfg.package ]; boot.kernelModules = [ "xen-evtchn" "xen-gntdev" "xen-gntalloc" "xen-blkback" "xen-netback" "xen-pciback" "evtchn" "gntdev" "netbk" "blkbk" "xen-scsibk" "usbbk" "pciback" "xen-acpi-processor" "blktap2" "tun" "netxen_nic" "xen_wdt" "xen-acpi-processor" "xen-privcmd" "xen-scsiback" "xenfs" ]; # The xenfs module is needed in system.activationScripts.xen, but # the modprobe command there fails silently. Include xenfs in the # initrd as a work around. boot.initrd.kernelModules = [ "xenfs" ]; # The radeonfb kernel module causes the screen to go black as soon # as it's loaded, so don't load it. boot.blacklistedKernelModules = [ "radeonfb" ]; # Increase the number of loopback devices from the default (8), # which is way too small because every VM virtual disk requires a # loopback device. boot.extraModprobeConfig = '' options loop max_loop=64 ''; virtualisation.xen.bootParams = [] ++ optionals cfg.trace [ "loglvl=all" "guest_loglvl=all" ] ++ optional (cfg.domain0MemorySize != 0) "dom0_mem=${toString cfg.domain0MemorySize}M"; system.extraSystemBuilderCmds = '' ln -s ${cfg.package}/boot/xen.gz $out/xen.gz echo "${toString cfg.bootParams}" > $out/xen-params ''; # Mount the /proc/xen pseudo-filesystem. system.activationScripts.xen = '' if [ -d /proc/xen ]; then ${pkgs.kmod}/bin/modprobe xenfs 2> /dev/null ${pkgs.util-linux}/bin/mountpoint -q /proc/xen || \ ${pkgs.util-linux}/bin/mount -t xenfs none /proc/xen fi ''; # Domain 0 requires a pvops-enabled kernel. system.requiredKernelConfig = with config.lib.kernelConfig; [ (isYes "XEN") (isYes "X86_IO_APIC") (isYes "ACPI") (isYes "XEN_DOM0") (isYes "PCI_XEN") (isYes "XEN_DEV_EVTCHN") (isYes "XENFS") (isYes "XEN_COMPAT_XENFS") (isYes "XEN_SYS_HYPERVISOR") (isYes "XEN_GNTDEV") (isYes "XEN_BACKEND") (isModule "XEN_NETDEV_BACKEND") (isModule "XEN_BLKDEV_BACKEND") (isModule "XEN_PCIDEV_BACKEND") (isYes "XEN_BALLOON") (isYes "XEN_SCRUB_PAGES") ]; environment.etc = { "xen/xl.conf".source = "${cfg.package}/etc/xen/xl.conf"; "xen/scripts".source = "${cfg.package}/etc/xen/scripts"; "default/xendomains".text = '' source ${cfg.package}/etc/default/xendomains ${cfg.domains.extraConfig} ''; } // optionalAttrs (builtins.compareVersions cfg.package.version "4.10" >= 0) { # in V 4.10 oxenstored requires /etc/xen/oxenstored.conf to start "xen/oxenstored.conf".source = "${cfg.package}/etc/xen/oxenstored.conf"; }; # Xen provides udev rules. services.udev.packages = [ cfg.package ]; services.udev.path = [ pkgs.bridge-utils pkgs.iproute2 ]; systemd.services.xen-store = { description = "Xen Store Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "network.target" "xen-store.socket" ]; requires = [ "xen-store.socket" ]; preStart = '' export XENSTORED_ROOTDIR="/var/lib/xenstored" rm -f "$XENSTORED_ROOTDIR"/tdb* &>/dev/null mkdir -p /var/run mkdir -p /var/log/xen # Running xl requires /var/log/xen and /var/lib/xen, mkdir -p /var/lib/xen # so we create them here unconditionally. grep -q control_d /proc/xen/capabilities ''; serviceConfig = if (builtins.compareVersions cfg.package.version "4.8" < 0) then { ExecStart = '' ${cfg.stored}${optionalString cfg.trace " -T /var/log/xen/xenstored-trace.log"} --no-fork ''; } else { ExecStart = '' ${cfg.package}/etc/xen/scripts/launch-xenstore ''; Type = "notify"; RemainAfterExit = true; NotifyAccess = "all"; }; postStart = '' ${optionalString (builtins.compareVersions cfg.package.version "4.8" < 0) '' time=0 timeout=30 # Wait for xenstored to actually come up, timing out after 30 seconds while [ $time -lt $timeout ] && ! `${cfg.package}/bin/xenstore-read -s / >/dev/null 2>&1` ; do time=$(($time+1)) sleep 1 done # Exit if we timed out if ! [ $time -lt $timeout ] ; then echo "Could not start Xenstore Daemon" exit 1 fi ''} echo "executing xen-init-dom0" ${cfg.package}/lib/xen/bin/xen-init-dom0 ''; }; systemd.sockets.xen-store = { description = "XenStore Socket for userspace API"; wantedBy = [ "sockets.target" ]; socketConfig = { ListenStream = [ "/var/run/xenstored/socket" "/var/run/xenstored/socket_ro" ]; SocketMode = "0660"; SocketUser = "root"; SocketGroup = "root"; }; }; systemd.services.xen-console = { description = "Xen Console Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "xen-store.service" ]; requires = [ "xen-store.service" ]; preStart = '' mkdir -p /var/run/xen ${optionalString cfg.trace "mkdir -p /var/log/xen"} grep -q control_d /proc/xen/capabilities ''; serviceConfig = { ExecStart = '' ${cfg.package}/bin/xenconsoled\ ${optionalString ((builtins.compareVersions cfg.package.version "4.8" >= 0)) " -i"}\ ${optionalString cfg.trace " --log=all --log-dir=/var/log/xen"} ''; }; }; systemd.services.xen-qemu = { description = "Xen Qemu Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "xen-console.service" ]; requires = [ "xen-store.service" ]; serviceConfig.ExecStart = '' ${cfg.package-qemu}/${cfg.package-qemu.qemu-system-i386} \ -xen-attach -xen-domid 0 -name dom0 -M xenpv \ -nographic -monitor /dev/null -serial /dev/null -parallel /dev/null ''; }; systemd.services.xen-watchdog = { description = "Xen Watchdog Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "xen-qemu.service" "xen-domains.service" ]; serviceConfig.ExecStart = "${cfg.package}/bin/xenwatchdogd 30 15"; serviceConfig.Type = "forking"; serviceConfig.RestartSec = "1"; serviceConfig.Restart = "on-failure"; }; systemd.services.xen-bridge = { description = "Xen bridge"; wantedBy = [ "multi-user.target" ]; before = [ "xen-domains.service" ]; preStart = '' mkdir -p /var/run/xen touch /var/run/xen/dnsmasq.pid touch /var/run/xen/dnsmasq.etherfile touch /var/run/xen/dnsmasq.leasefile IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Usable\ range` export XEN_BRIDGE_IP_RANGE_START="${"\${data[1]//[[:blank:]]/}"}" export XEN_BRIDGE_IP_RANGE_END="${"\${data[2]//[[:blank:]]/}"}" IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Network\ address` export XEN_BRIDGE_NETWORK_ADDRESS="${"\${data[1]//[[:blank:]]/}"}" IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Network\ mask` export XEN_BRIDGE_NETMASK="${"\${data[1]//[[:blank:]]/}"}" echo "${cfg.bridge.address} host gw dns" > /var/run/xen/dnsmasq.hostsfile cat < /var/run/xen/dnsmasq.conf no-daemon pid-file=/var/run/xen/dnsmasq.pid interface=${cfg.bridge.name} except-interface=lo bind-interfaces auth-zone=xen.local,$XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} domain=xen.local addn-hosts=/var/run/xen/dnsmasq.hostsfile expand-hosts strict-order no-hosts bogus-priv ${optionalString (!cfg.bridge.forwardDns) '' no-resolv no-poll auth-server=dns.xen.local,${cfg.bridge.name} ''} filterwin2k clear-on-reload domain-needed dhcp-hostsfile=/var/run/xen/dnsmasq.etherfile dhcp-authoritative dhcp-range=$XEN_BRIDGE_IP_RANGE_START,$XEN_BRIDGE_IP_RANGE_END dhcp-no-override no-ping dhcp-leasefile=/var/run/xen/dnsmasq.leasefile EOF # DHCP ${pkgs.iptables}/bin/iptables -w -I INPUT -i ${cfg.bridge.name} -p tcp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT ${pkgs.iptables}/bin/iptables -w -I INPUT -i ${cfg.bridge.name} -p udp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT # DNS ${pkgs.iptables}/bin/iptables -w -I INPUT -i ${cfg.bridge.name} -p tcp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT ${pkgs.iptables}/bin/iptables -w -I INPUT -i ${cfg.bridge.name} -p udp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT ${pkgs.bridge-utils}/bin/brctl addbr ${cfg.bridge.name} ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} ${cfg.bridge.address} ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} netmask $XEN_BRIDGE_NETMASK ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} up ''; serviceConfig.ExecStart = "${pkgs.dnsmasq}/bin/dnsmasq --conf-file=/var/run/xen/dnsmasq.conf"; postStop = '' IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Network\ address` export XEN_BRIDGE_NETWORK_ADDRESS="${"\${data[1]//[[:blank:]]/}"}" ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} down ${pkgs.bridge-utils}/bin/brctl delbr ${cfg.bridge.name} # DNS ${pkgs.iptables}/bin/iptables -w -D INPUT -i ${cfg.bridge.name} -p udp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT ${pkgs.iptables}/bin/iptables -w -D INPUT -i ${cfg.bridge.name} -p tcp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT # DHCP ${pkgs.iptables}/bin/iptables -w -D INPUT -i ${cfg.bridge.name} -p udp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT ${pkgs.iptables}/bin/iptables -w -D INPUT -i ${cfg.bridge.name} -p tcp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT ''; }; systemd.services.xen-domains = { description = "Xen domains - automatically starts, saves and restores Xen domains"; wantedBy = [ "multi-user.target" ]; after = [ "xen-bridge.service" "xen-qemu.service" ]; requires = [ "xen-bridge.service" "xen-qemu.service" ]; ## To prevent a race between dhcpcd and xend's bridge setup script ## (which renames eth* to peth* and recreates eth* as a virtual ## device), start dhcpcd after xend. before = [ "dhcpd.service" ]; restartIfChanged = false; serviceConfig.RemainAfterExit = "yes"; path = [ cfg.package cfg.package-qemu ]; environment.XENDOM_CONFIG = "${cfg.package}/etc/sysconfig/xendomains"; preStart = "mkdir -p /var/lock/subsys -m 755"; serviceConfig.ExecStart = "${cfg.package}/etc/init.d/xendomains start"; serviceConfig.ExecStop = "${cfg.package}/etc/init.d/xendomains stop"; }; }; }