A domain could just be dying when live updating Xenstore, so the case
of not being able to map the ring page or to connect to the event
channel must be handled gracefully.
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Wei Liu <wl@xen.org>