xen: add p2m mfn_list_list

When saving a domain, the Xen tools need to remap all our mfns to
portable pfns.  In order to remap our p2m table, it needs to know
where all its pages are, so maintain the references to the p2m table
for it to use.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/xen/enlighten.c

@@ -880,6 +880,8 @@ static __init void setup_shared_info(void)
 	/* In UP this is as good a place as any to set up shared info */
 	xen_setup_vcpu_info_placement();
 #endif
+
+	xen_setup_mfn_list_list();
 }
 
 static __init void xen_pagetable_setup_done(pgd_t *base)