We have support for this attribute already inside the graphics libvirt_xml driver class.  If you pass around a ``vmxml`` instance, then you can get at the password value with one call:

     vmxml.devices().by_device_tag('graphics')[0].passwd

or with a more verbose approach:

     devices = vmxml.devices()
     first_graphics = devices.by_device_tag('graphics')[0]
     graphics_password = first_graphics.passwd

This will also automatically raise exceptions (IndexError, LibvirtXMLError) if the graphics device doesn't exist or there is no password set.