[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>
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index af650fb..a8729ea 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -108,9 +108,13 @@
 #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)
 {
-	asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));
+	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));
 }
 
 static inline unsigned int
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 85cd4b0..f79e7bb 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -590,7 +590,7 @@
 }
 
 /* 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 @@
 	}
 	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 @@
 }
 
 #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);
 }
 
 /*