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# Xen hypervisor (Dom0) support.
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.virtualisation.xen;
in
{
###### interface
options = {
virtualisation.xen.enable =
mkOption {
default = false;
type = types.bool;
description =
''
Setting this option enables the Xen hypervisor, a
virtualisation technology that allows multiple virtual
machines, known as <emphasis>domains</emphasis>, to run
concurrently on the physical machine. NixOS runs as the
privileged <emphasis>Domain 0</emphasis>. This option
requires a reboot to take effect.
'';
};
virtualisation.xen.package = mkOption {
type = types.package;
defaultText = "pkgs.xen";
example = literalExample "pkgs.xen-light";
description = ''
The package used for Xen binary.
'';
relatedPackages = [ "xen" "xen-light" ];
};
virtualisation.xen.package-qemu = mkOption {
type = types.package;
defaultText = "pkgs.xen";
example = literalExample "pkgs.qemu_xen-light";
description = ''
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 = "";
description =
''
Parameters passed to the Xen hypervisor at boot time.
'';
};
virtualisation.xen.domain0MemorySize =
mkOption {
default = 0;
example = 512;
description =
''
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";
description = ''
Name of bridge the Xen domUs connect to.
'';
};
address = mkOption {
type = types.str;
default = "172.16.0.1";
description = ''
IPv4 address of the bridge.
'';
};
prefixLength = mkOption {
type = types.addCheck types.int (n: n >= 0 && n <= 32);
default = 16;
description = ''
Subnet mask of the bridge interface, specified as the number of
bits in the prefix (<literal>24</literal>).
A DHCP server will provide IP addresses for the whole, remaining
subnet.
'';
};
forwardDns = mkOption {
default = false;
description = ''
If set to <literal>true</literal>, 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 =
''
Xen Store daemon to use. Defaults to oxenstored of the xen package.
'';
};
virtualisation.xen.domains = {
extraConfig = mkOption {
type = types.string;
default = "";
description =
''
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 =
mkOption {
default = false;
description =
''
Enable 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 ];
# Make sure Domain 0 gets the required configuration
#boot.kernelPackages = pkgs.boot.kernelPackages.override { features={xen_dom0=true;}; };
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.utillinux}/bin/mountpoint -q /proc/xen || \
${pkgs.utillinux}/bin/mount -t xenfs none /proc/xen
fi
'';
# Domain 0 requires a pvops-enabled kernel.
system.requiredKernelConfig = with config.lib.kernelConfig;
[ (isYes "XEN")
(isYes "X86_IO_APIC")
(isYes "ACPI")
(isYes "XEN_DOM0")
(isYes "PCI_XEN")
(isYes "XEN_DEV_EVTCHN")
(isYes "XENFS")
(isYes "XEN_COMPAT_XENFS")
(isYes "XEN_SYS_HYPERVISOR")
(isYes "XEN_GNTDEV")
(isYes "XEN_BACKEND")
(isModule "XEN_NETDEV_BACKEND")
(isModule "XEN_BLKDEV_BACKEND")
(isModule "XEN_PCIDEV_BACKEND")
(isYes "XEN_BALLOON")
(isYes "XEN_SCRUB_PAGES")
];
environment.etc =
[ { source = "${cfg.package}/etc/xen/xl.conf";
target = "xen/xl.conf";
}
{ source = "${cfg.package}/etc/xen/scripts";
target = "xen/scripts";
}
{ text = ''
source ${cfg.package}/etc/default/xendomains
${cfg.domains.extraConfig}
'';
target = "default/xendomains";
}
]
++ lib.optionals (builtins.compareVersions cfg.package.version "4.10" >= 0) [
# in V 4.10 oxenstored requires /etc/xen/oxenstored.conf to start
{ source = "${cfg.package}/etc/xen/oxenstored.conf";
target = "xen/oxenstored.conf";
}
];
# Xen provides udev rules.
services.udev.packages = [ cfg.package ];
services.udev.path = [ pkgs.bridge-utils pkgs.iproute ];
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 <<EOF > /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";
};
};
}
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