#!/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