paravirt: add a hook for once the allocator is ready

Add a hook so that the paravirt backend knows when the allocator is
ready.  This is useful for the obvious reason that the allocator is
available, but the other side-effect of having the bootmem allocator
available is that each page now has an associated "struct page".

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index 99bf661..7868569 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -52,6 +52,8 @@
 	/* Basic arch-specific setup */
 	void (*arch_setup)(void);
 	char *(*memory_setup)(void);
+	void (*post_allocator_init)(void);
+
 	void (*init_IRQ)(void);
 	void (*time_init)(void);
 
@@ -669,6 +671,12 @@
 }
 #endif
 
+static inline void paravirt_post_allocator_init(void)
+{
+	if (paravirt_ops.post_allocator_init)
+		(*paravirt_ops.post_allocator_init)();
+}
+
 static inline void paravirt_pagetable_setup_start(pgd_t *base)
 {
 	if (paravirt_ops.pagetable_setup_start)