[S390] add support for nonquiescing sske

Improve performance of the sske operation by using the nonquiescing
variant if the affected page has no mappings established. On machines
with no support for the new sske variant the mask bit will be ignored.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/page.h

@@ -108,8 +108,12 @@ typedef pte_t *pgtable_t;
 #define __pgprot(x)     ((pgprot_t) { (x) } )
 
 static inline void
-page_set_storage_key(unsigned long addr, unsigned int skey)
+page_set_storage_key(unsigned long addr, unsigned int skey, int mapped)
 {
+	if (!mapped)
+		asm volatile(".insn rrf,0xb22b0000,%0,%1,8,0"
+			     : : "d" (skey), "a" (addr));
+	else
 		asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));
 }
 

arch/s390/include/asm/pgtable.h

@@ -590,7 +590,7 @@ static inline void rcp_unlock(pte_t *ptep)
 }
 
 /* forward declaration for SetPageUptodate in page-flags.h*/
-static inline void page_clear_dirty(struct page *page);
+static inline void page_clear_dirty(struct page *page, int mapped);
 #include <linux/page-flags.h>
 
 static inline void ptep_rcp_copy(pte_t *ptep)
@@ -800,7 +800,7 @@ static inline int kvm_s390_test_and_clear_page_dirty(struct mm_struct *mm,
 	}
 	dirty = test_and_clear_bit_simple(KVM_UD_BIT, pgste);
 	if (skey & _PAGE_CHANGED)
-		page_clear_dirty(page);
+		page_clear_dirty(page, 1);
 	rcp_unlock(ptep);
 	return dirty;
 }
@@ -975,9 +975,9 @@ static inline int page_test_dirty(struct page *page)
 }
 
 #define __HAVE_ARCH_PAGE_CLEAR_DIRTY
-static inline void page_clear_dirty(struct page *page)
+static inline void page_clear_dirty(struct page *page, int mapped)
 {
-	page_set_storage_key(page_to_phys(page), PAGE_DEFAULT_KEY);
+	page_set_storage_key(page_to_phys(page), PAGE_DEFAULT_KEY, mapped);
 }
 
 /*

arch/s390/kernel/early.c

@@ -208,7 +208,8 @@ static noinline __init void init_kernel_storage_key(void)
 	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);
+		page_set_storage_key(init_pfn << PAGE_SHIFT,
+				     PAGE_DEFAULT_KEY, 0);
 }
 
 static __initdata struct sysinfo_3_2_2 vmms __aligned(PAGE_SIZE);

arch/s390/kernel/setup.c

@@ -627,7 +627,8 @@ setup_memory(void)
 		add_active_range(0, start_chunk, end_chunk);
 		pfn = max(start_chunk, start_pfn);
 		for (; pfn < end_chunk; pfn++)
-			page_set_storage_key(PFN_PHYS(pfn), PAGE_DEFAULT_KEY);
+			page_set_storage_key(PFN_PHYS(pfn),
+					     PAGE_DEFAULT_KEY, 0);
 	}
 
 	psw_set_key(PAGE_DEFAULT_KEY);

include/asm-generic/pgtable.h

@@ -108,7 +108,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
 #endif
 
 #ifndef __HAVE_ARCH_PAGE_CLEAR_DIRTY
-#define page_clear_dirty(page)		do { } while (0)
+#define page_clear_dirty(page, mapped)	do { } while (0)
 #endif
 
 #ifndef __HAVE_ARCH_PAGE_TEST_DIRTY

include/linux/page-flags.h

@@ -310,7 +310,7 @@ static inline void SetPageUptodate(struct page *page)
 {
 #ifdef CONFIG_S390
 	if (!test_and_set_bit(PG_uptodate, &page->flags))
-		page_clear_dirty(page);
+		page_clear_dirty(page, 0);
 #else
 	/*
 	 * Memory barrier must be issued before setting the PG_uptodate bit,

mm/rmap.c

@@ -745,7 +745,7 @@ int page_mkclean(struct page *page)
 		if (mapping) {
 			ret = page_mkclean_file(mapping, page);
 			if (page_test_dirty(page)) {
-				page_clear_dirty(page);
+				page_clear_dirty(page, 1);
 				ret = 1;
 			}
 		}
@@ -942,7 +942,7 @@ void page_remove_rmap(struct page *page)
 	 * containing the swap entry, but page not yet written to swap.
 	 */
 	if ((!PageAnon(page) || PageSwapCache(page)) && page_test_dirty(page)) {
-		page_clear_dirty(page);
+		page_clear_dirty(page, 1);
 		set_page_dirty(page);
 	}
 	/*