[S390] Add support for memory hot-add.

Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -313,6 +313,10 @@ config ARCH_SPARSEMEM_DEFAULT
 config ARCH_SELECT_MEMORY_MODEL
        def_bool y
 
+config ARCH_ENABLE_MEMORY_HOTPLUG
+	def_bool y
+	depends on SPARSEMEM
+
 source "mm/Kconfig"
 
 comment "I/O subsystem configuration"

arch/s390/mm/init.c

@@ -202,3 +202,22 @@ void free_initrd_mem(unsigned long start, unsigned long end)
         }
 }
 #endif
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+int arch_add_memory(int nid, u64 start, u64 size)
+{
+	struct pglist_data *pgdat;
+	struct zone *zone;
+	int rc;
+
+	pgdat = NODE_DATA(nid);
+	zone = pgdat->node_zones + ZONE_NORMAL;
+	rc = vmem_add_mapping(start, size);
+	if (rc)
+		return rc;
+	rc = __add_pages(zone, PFN_DOWN(start), PFN_DOWN(size));
+	if (rc)
+		vmem_remove_mapping(start, size);
+	return rc;
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */

include/asm-s390/sparsemem.h

@@ -1,15 +1,15 @@
 #ifndef _ASM_S390_SPARSEMEM_H
 #define _ASM_S390_SPARSEMEM_H
 
-#define SECTION_SIZE_BITS	25
-
 #ifdef CONFIG_64BIT
 
+#define SECTION_SIZE_BITS	28
 #define MAX_PHYSADDR_BITS	42
 #define MAX_PHYSMEM_BITS	42
 
 #else
 
+#define SECTION_SIZE_BITS	25
 #define MAX_PHYSADDR_BITS	31
 #define MAX_PHYSMEM_BITS	31
 

mm/Kconfig

@@ -129,7 +129,7 @@ config MEMORY_HOTPLUG
 	bool "Allow for memory hot-add"
 	depends on SPARSEMEM || X86_64_ACPI_NUMA
 	depends on HOTPLUG && !HIBERNATION && ARCH_ENABLE_MEMORY_HOTPLUG
-	depends on (IA64 || X86 || PPC64 || SUPERH)
+	depends on (IA64 || X86 || PPC64 || SUPERH || S390)
 
 comment "Memory hotplug is currently incompatible with Software Suspend"
 	depends on SPARSEMEM && HOTPLUG && HIBERNATION