xen: make phys_to_machine structure dynamic

We now support the use of memory hotplug, so the physical to machine
page mapping structure must be dynamic.  This is implemented as a
two-level radix tree structure, which allows us to efficiently
incrementally allocate memory for the p2m table as new pages are
added.

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

arch/x86/xen/xen-ops.h

@@ -22,6 +22,8 @@ void __init xen_arch_setup(void);
 void __init xen_init_IRQ(void);
 void xen_enable_sysenter(void);
 
+void __init xen_build_dynamic_phys_to_machine(void);
+
 void xen_setup_timer(int cpu);
 void xen_setup_cpu_clockevents(void);
 unsigned long xen_cpu_khz(void);