#!/bin/bash

kvm_setup_powerpc () {

    isPowerNV=no

    isPOWER8=no

    grep -q '^platform[[:space:]]*:[[:space:]]*PowerNV' /proc/cpuinfo && isPowerNV=yes

    grep -q '^cpu[[:space:]]*:[[:space:]]*POWER8' /proc/cpuinfo && isPOWER8=yes

    if [ "$isPowerNV" = "yes" ] ; then

	# PowerNV platform, which is KVM HV capable

	if [ -z "$SUBCORES" ]; then

	    SUBCORES=1

	fi

	# Step 1. Load the KVM HVmodule

	if ! modprobe -b kvm_hv; then

	    return

	fi

	# On POWER8 a host core can only run threads of a single

	# guest, meaning that SMT must be disabled on the host in

	# order to run KVM guests. (Also applieds to POWER7, but we

	# don't support that).

	#

	# Additionally, POWER8 guests can't benefit from transparent

	# hugepages used to back them, and THPs allocated by any app

	# can potentially interfere with HPT allocation (if they

	# become locked, they can fragment the CMA).  So, also disable

	# THPs system wide.

	#

	# POWER9 doesn't have this limitation (though it will for hash

	# guests on radix host when that's implemented).  So, only set

	# up subcores and disable SMT for POWER*.

	if [ "$isPOWER8" = "yes" ] ; then

	    # Step 2. Configure subcore mode

	    /usr/sbin/ppc64_cpu --subcores-per-core=$SUBCORES

	    # Step 3. Disable SMT (multithreading)

	    /usr/sbin/ppc64_cpu --smt=off

	    # Step 4. Disable transparent hugepages (THP)

	    echo never > /sys/kernel/mm/transparent_hugepage/enabled

	fi

    fi

}

case $(uname -m) in

    ppc64|ppc64le)

	kvm_setup_powerpc

	;;

esac

exit 0