nova: Enable apic removal workaround for bug #1939108 when using QEMU

This change enables [workarounds]libvirt_disable_apic when devstack is
deployed using the libvirt virt driver and qemu virt type in an effort
to avoid issues outlined in bug #1939108 caused by the older kernel
currently used in Cirros 0.5.2.

Depends-On: https://review.opendev.org/c/openstack/nova/+/766043
Closes-Bug: #1939108
Change-Id: Ibb6c34133bb1c95ef11cc59d9b12a0f65502c61b

Author: lyarwood

lib/nova

@@ -926,6 +926,11 @@ function start_nova_compute {
         iniset $NOVA_CPU_CONF os_vif_ovs ovsdb_connection "tcp:$OVSDB_SERVER_LOCAL_HOST:6640"
     fi
 
+    # Workaround bug #1939108
+    if [[ "$VIRT_DRIVER" == "libvirt" && "$LIBVIRT_TYPE" == "qemu" ]]; then
+        iniset $NOVA_CPU_CONF workarounds libvirt_disable_apic True
+    fi
+
     if [[ "$VIRT_DRIVER" = 'libvirt' ]]; then
         # The group **$LIBVIRT_GROUP** is added to the current user in this script.
         # ``sg`` is used in run_process to execute nova-compute as a member of the