Use arbitrary_virt_to_machine() to deal with ioremapped pud updates.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index c03101e..083b835 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -518,7 +518,7 @@
 	xen_mc_batch();
 
 	/* ptr may be ioremapped for 64-bit pagetable setup */
-	u.ptr = virt_to_machine(ptr).maddr;
+	u.ptr = arbitrary_virt_to_machine(ptr).maddr;
 	u.val = pud_val_ma(val);
 	xen_extend_mmu_update(&u);