smt: Do not disable SMT in virtual machines

[people/pmueller/ipfire-2.x.git] / src / initscripts / system / smt

#!/bin/sh
########################################################################
# Begin $rc_base/init.d/smt
########################################################################

. /etc/sysconfig/rc
. ${rc_functions}

eval $(/usr/local/bin/readhash /var/ipfire/main/security)

case "${1}" in
	start)
		# Nothing to do here when SMT is forced on
		if [ "${ENABLE_SMT}" = "on" ]; then
			exit 0
		fi

		# Nothing to do when SMT is not enabled or not supported anyways
		if [ "$(</sys/devices/system/cpu/smt/control)" != "on" ]; then
			exit 0
		fi 2>/dev/null

		# Do not disable SMT inside virtual machines
		if [ -d "/sys/hypervisor" ]; then
			exit 0
		fi

		# Disable SMT when the processor is vulnerable to Foreshadow or Fallout/ZombieLoad/RIDL
		for vuln in l1tf mds; do
			if [ -r "/sys/devices/system/cpu/vulnerabilities/${vuln}" ] && \
					[[ "$(</sys/devices/system/cpu/vulnerabilities/${vuln})" =~ "SMT vulnerable" ]]; then
				# Disable SMT
				boot_mesg "Disabling Simultaneous Multi-Threading (SMT)..."
				echo "forceoff" > /sys/devices/system/cpu/smt/control
				echo_ok

				# No need to check any further when we have disabled SMT already
				break
			fi
		done
		;;

	*)
		echo "Usage: ${0} {start}"
		exit 1
		;;
esac

# End $rc_base/init.d/smt