[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>

4 files changed, 14 insertions, 8 deletions

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 @@ 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)
 {
-	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 @@ 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);
 }
 
 /*
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index c00856a..0badc63 100644
--- a/arch/s390/kernel/early.c
+++ b/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);
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index c8e8e13..9071e98 100644
--- a/arch/s390/kernel/setup.c
+++ b/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);