s390/mm: do not initialize storage keys

With dirty and referenced bits implemented in software it is unnecessary
to initialize the storage key for every page. With this patch not a single
storage key operation is done for a system that does not use KVM.
For KVM set_pte_at/pgste_set_key will do the initialization for the guest
view of the storage key when the mapping for the page is established in
the host.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/page.h

@@ -30,7 +30,12 @@
 #include <asm/setup.h>
 #ifndef __ASSEMBLY__
 
-void storage_key_init_range(unsigned long start, unsigned long end);
+static inline void storage_key_init_range(unsigned long start, unsigned long end)
+{
+#if PAGE_DEFAULT_KEY
+	__storage_key_init_range(start, end);
+#endif
+}
 
 static inline void clear_page(void *page)
 {

arch/s390/kernel/early.c

@@ -206,13 +206,15 @@ static noinline __init void clear_bss_section(void)
  */
 static noinline __init void init_kernel_storage_key(void)
 {
+#if PAGE_DEFAULT_KEY
 	unsigned long end_pfn, init_pfn;
 
 	end_pfn = PFN_UP(__pa(&_end));
 
 	for (init_pfn = 0 ; init_pfn < end_pfn; init_pfn++)
 		page_set_storage_key(init_pfn << PAGE_SHIFT,
 				     PAGE_DEFAULT_KEY, 0);
+#endif
 }
 
 static __initdata char sysinfo_page[PAGE_SIZE] __aligned(PAGE_SIZE);

arch/s390/mm/pageattr.c

@@ -9,14 +9,15 @@
 #include <asm/pgtable.h>
 #include <asm/page.h>
 
+#if PAGE_DEFAULT_KEY
 static inline unsigned long sske_frame(unsigned long addr, unsigned char skey)
 {
 	asm volatile(".insn rrf,0xb22b0000,%[skey],%[addr],9,0"
 		     : [addr] "+a" (addr) : [skey] "d" (skey));
 	return addr;
 }
 
-void storage_key_init_range(unsigned long start, unsigned long end)
+void __storage_key_init_range(unsigned long start, unsigned long end)
 {
 	unsigned long boundary, size;
 
@@ -36,6 +37,7 @@ void storage_key_init_range(unsigned long start, unsigned long end)
 		start += PAGE_SIZE;
 	}
 }
+#endif
 
 static pte_t *walk_page_table(unsigned long addr)
 {