Comment 1 for bug 1422342

John, looking on the reboot() function:

def reboot(self, context, instance, network_info, reboot_type,
                      block_device_info=None, bad_volumes_callback=None)

There is a reboot_type parameter. For XenAPI this param is properly passed to underlying
VMOps class in nova/virt/xenapi/vmops.py which implements the reboot() for Xen.
So you can have, either proper SOFT or HARD reboot and this looks fine for me.

While in the nova/virt/libvirt/driver.py, if reboot_type=='SOFT' fails nova unconditionally
does the hard reboot what can be sometimes unexpected but at the end of the day we
want to reboot the VM.