Use kvm for ironic VMs when possible

Nova pick KVM as preferred virtualization type when possible and
fallback to qemu [0].
This patch introduce devstack IRONIC_VM_ENGINE option that allows to
set libvirt type explicitly. If not set pick it dynamically,
kvm is preffered.

[0] https://review.openstack.org/#/c/31177/4/lib/nova@240

Change-Id: I05859974c312cb5df1d4b96dc3b98fbc1006359e

devstack/lib/ironic

@@ -119,7 +119,8 @@ IRONIC_VM_SPECS_CPU_ARCH=${IRONIC_VM_SPECS_CPU_ARCH:-'x86_64'}
 IRONIC_VM_SPECS_DISK=${IRONIC_VM_SPECS_DISK:-10}
 IRONIC_VM_SPECS_DISK_FORMAT=${IRONIC_VM_SPECS_DISK_FORMAT:-qcow2}
 IRONIC_VM_EPHEMERAL_DISK=${IRONIC_VM_EPHEMERAL_DISK:-0}
-IRONIC_VM_EMULATOR=${IRONIC_VM_EMULATOR:-/usr/bin/qemu-system-x86_64}
+IRONIC_VM_EMULATOR=${IRONIC_VM_EMULATOR:-}
+IRONIC_VM_ENGINE=${IRONIC_VM_ENGINE:-}
 IRONIC_VM_NETWORK_BRIDGE=${IRONIC_VM_NETWORK_BRIDGE:-brbm}
 IRONIC_VM_NETWORK_RANGE=${IRONIC_VM_NETWORK_RANGE:-192.0.2.0/24}
 IRONIC_VM_MACS_CSV_FILE=${IRONIC_VM_MACS_CSV_FILE:-$IRONIC_DATA_DIR/ironic_macs.csv}
@@ -128,6 +129,22 @@ IRONIC_CLEAN_NET_NAME=${IRONIC_CLEAN_NET_NAME:-${IRONIC_PROVISION_NETWORK_NAME:-
 IRONIC_EXTRA_PXE_PARAMS=${IRONIC_EXTRA_PXE_PARAMS:-}
 IRONIC_TTY_DEV=${IRONIC_TTY_DEV:-ttyS0}
 
+# NOTE(vsaienko) nova already pick right libvirt type at
+# https://review.openstack.org/#/c/31177/4/lib/nova@240
+# pick hardware virtualization if possible while it is not set explicitly
+if [[ -z "$IRONIC_VM_ENGINE" ]]; then
+    sudo modprobe kvm || true
+    if [ ! -e /dev/kvm ]; then
+        echo "WARNING: Switching to QEMU"
+        IRONIC_VM_ENGINE=qemu
+        if [[ -z "$IRONIC_VM_EMULATOR" ]]; then
+            IRONIC_VM_EMULATOR='/usr/bin/qemu-system-x86_64'
+        fi
+    else
+        IRONIC_VM_ENGINE=kvm
+    fi
+fi
+
 # By default, baremetal VMs will console output to file.
 IRONIC_VM_LOG_CONSOLE=$(trueorfalse True IRONIC_VM_LOG_CONSOLE)
 IRONIC_VM_LOG_DIR=${IRONIC_VM_LOG_DIR:-$IRONIC_DATA_DIR/logs/}
@@ -971,10 +988,16 @@ function create_bridge_and_vms {
 
     local vbmc_port=$IRONIC_VBMC_PORT_RANGE_START
     local vm_name
+    local vm_opts=""
+    if [[ -n "$IRONIC_VM_EMULATOR" ]]; then
+        vm_opts+=" -e $IRONIC_VM_EMULATOR"
+    fi
+    vm_opts+=" -E $IRONIC_VM_ENGINE"
+
     for vm_name in $(_ironic_bm_vm_names); do
         sudo -E su $STACK_USER -c "$IRONIC_SCRIPTS_DIR/create-node.sh -n $vm_name \
             -c $IRONIC_VM_SPECS_CPU -m $IRONIC_VM_SPECS_RAM -d $IRONIC_VM_SPECS_DISK \
-            -a $IRONIC_VM_SPECS_CPU_ARCH -b $IRONIC_VM_NETWORK_BRIDGE -e $IRONIC_VM_EMULATOR \
+            -a $IRONIC_VM_SPECS_CPU_ARCH -b $IRONIC_VM_NETWORK_BRIDGE $vm_opts \
             -p $vbmc_port -f $IRONIC_VM_SPECS_DISK_FORMAT $log_arg" >> $IRONIC_VM_MACS_CSV_FILE
         vbmc_port=$((vbmc_port+1))
     done

devstack/tools/ironic/scripts/create-node.sh

@@ -9,7 +9,7 @@ set -ex
 # Keep track of the DevStack directory
 TOP_DIR=$(cd $(dirname "$0")/.. && pwd)
 
-while getopts "n:c:m:d:a:b:e:p:f:l:" arg; do
+while getopts "n:c:m:d:a:b:e:E:p:f:l:" arg; do
     case $arg in
         n) NAME=$OPTARG;;
         c) CPU=$OPTARG;;
@@ -20,6 +20,7 @@ while getopts "n:c:m:d:a:b:e:p:f:l:" arg; do
         a) ARCH=$OPTARG;;
         b) BRIDGE=$OPTARG;;
         e) EMULATOR=$OPTARG;;
+        E) ENGINE=$OPTARG;;
         p) VBMC_PORT=$OPTARG;;
         f) DISK_FORMAT=$OPTARG;;
         l) LOGDIR=$OPTARG;;
@@ -82,10 +83,14 @@ if ! virsh list --all | grep -q $NAME; then
     # Pre-touch the VM to set +C, as it can only be set on empty files.
     sudo touch "$volume_path"
     sudo chattr +C "$volume_path" || true
+    vm_opts=""
+    if [[ -n "$EMULATOR" ]]; then
+        vm_opts+="--emulator $EMULATOR "
+    fi
     $TOP_DIR/scripts/configure-vm.py \
         --bootdev network --name $NAME --image "$volume_path" \
         --arch $ARCH --cpus $CPU --memory $MEM --libvirt-nic-driver $LIBVIRT_NIC_DRIVER \
-        --emulator $EMULATOR --bridge br-$NAME --disk-format $DISK_FORMAT $VM_LOGGING >&2
+        --bridge br-$NAME --disk-format $DISK_FORMAT $VM_LOGGING --engine $ENGINE $vm_opts >&2
 
     # Createa Virtual BMC for the node if IPMI is used
     if [[ $(type -P vbmc) != "" ]]; then

devstack/tools/ironic/templates/vm.xml

@@ -8,6 +8,9 @@
     <bootmenu enable='no'/>
     <bios useserial='yes'/>
   </os>
+  {% if engine == 'kvm' %}
+    <cpu mode='host-passthrough'/>
+  {% endif %}
   <features>
     <acpi/>
     <apic/>