xen64: defer setting pagetable alloc/release ops

We need to wait until the page structure is available to use the
proper pagetable page alloc/release operations, since they use struct
page to determine if a pagetable is pinned.

This happened to work in 32bit because nobody allocated new pagetable
pages in the interim between xen_pagetable_setup_done and
xen_post_allocator_init, but the 64-bit kenrel needs to allocate more
pagetable levels.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/xen/enlighten.c

@@ -878,30 +878,29 @@ void xen_setup_shared_info(void)
 
 static __init void xen_pagetable_setup_done(pgd_t *base)
 {
-	/* This will work as long as patching hasn't happened yet
-	   (which it hasn't) */
-	pv_mmu_ops.alloc_pte = xen_alloc_pte;
-	pv_mmu_ops.alloc_pmd = xen_alloc_pmd;
-	pv_mmu_ops.release_pte = xen_release_pte;
-	pv_mmu_ops.release_pmd = xen_release_pmd;
-#if PAGETABLE_LEVELS == 4
-	pv_mmu_ops.alloc_pud = xen_alloc_pud;
-	pv_mmu_ops.release_pud = xen_release_pud;
-#endif
-
-	pv_mmu_ops.set_pte = xen_set_pte;
-
 	xen_setup_shared_info();
 }
 
 static __init void xen_post_allocator_init(void)
 {
+	pv_mmu_ops.set_pte = xen_set_pte;
 	pv_mmu_ops.set_pmd = xen_set_pmd;
 	pv_mmu_ops.set_pud = xen_set_pud;
 #if PAGETABLE_LEVELS == 4
 	pv_mmu_ops.set_pgd = xen_set_pgd;
 #endif
 
+	/* This will work as long as patching hasn't happened yet
+	   (which it hasn't) */
+	pv_mmu_ops.alloc_pte = xen_alloc_pte;
+	pv_mmu_ops.alloc_pmd = xen_alloc_pmd;
+	pv_mmu_ops.release_pte = xen_release_pte;
+	pv_mmu_ops.release_pmd = xen_release_pmd;
+#if PAGETABLE_LEVELS == 4
+	pv_mmu_ops.alloc_pud = xen_alloc_pud;
+	pv_mmu_ops.release_pud = xen_release_pud;
+#endif
+
 	xen_mark_init_mm_pinned();
 }