s390/boot: account Real Memory Copy and Lowcore areas

Real Memory Copy and (absolute) Lowcore areas are
not accounted when virtual memory layout is set up.

Fixes: 4df29d2b9024 ("s390/smp: rework absolute lowcore access")
Fixes: 2f0e8aae26a2 ("s390/mm: rework memcpy_real() to avoid DAT-off mode")
Acked-by: Heiko Carstens <[e-mail]>
Signed-off-by: Alexander Gordeev <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/boot/startup.c

···
 	vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
 
 	/* choose kernel address space layout: 4 or 3 levels. */
-	vsize = round_up(ident_map_size, _REGION3_SIZE) + vmemmap_size + MODULES_LEN;
+	vsize = round_up(ident_map_size, _REGION3_SIZE) + vmemmap_size +
+		MODULES_LEN + MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE;
 	vsize = size_add(vsize, vmalloc_size);
 	if (IS_ENABLED(CONFIG_KASAN) || (vsize > _REGION2_SIZE)) {
 		asce_limit = _REGION1_SIZE;