ia64/xen: xencomm conversion functions for hypercalls

On ia64/xen, pointer arguments for hypercall is passed
by pseudo physical address(guest physical address.)
So such hypercalls needs address conversion functions.
This patch implements concrete conversion functions for
such hypercalls.

Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/include/asm/xen/xencomm.h b/arch/ia64/include/asm/xen/xencomm.h
index 28732cd..cded677 100644
--- a/arch/ia64/include/asm/xen/xencomm.h
+++ b/arch/ia64/include/asm/xen/xencomm.h
@@ -24,6 +24,7 @@
 
 /* Must be called before any hypercall.  */
 extern void xencomm_initialize(void);
+extern int xencomm_is_initialized(void);
 
 /* Check if virtual contiguity means physical contiguity
  * where the passed address is a pointer value in virtual address.