Ensure cur_pgd per-cpu variables are initialised early.

Secondary VCPUs can take page faults immediately after
booting, because of writable pagetable logic.

Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/arch/xen/i386/mm/init.c

@@ -348,9 +348,12 @@ static void __init pagetable_init (void)
 {
 	unsigned long vaddr;
 	pgd_t *pgd_base = (pgd_t *)xen_start_info.pt_base;
+	int i;
 
 	swapper_pg_dir = pgd_base;
 	init_mm.pgd    = pgd_base;
+	for (i = 0; i < NR_CPUS; i++)
+		per_cpu(cur_pgd, i) = pgd_base;
 
 	/* Enable PSE if available */
 	if (cpu_has_pse) {

linux-2.6-xen-sparse/arch/xen/x86_64/mm/init.c

@@ -559,6 +559,11 @@ static void xen_copy_pt(void)
 
 void __init xen_init_pt(void)
 {
+	int i;
+
+	for (i = 0; i < NR_CPUS; i++)
+		per_cpu(cur_pgd, i) = init_mm.pgd;
+
 	memcpy((void *)init_level4_pgt, 
 	       (void *)xen_start_info.pt_base, PAGE_SIZE);