[S390] guest page hinting light
Use the existing arch_alloc_page/arch_free_page callbacks to do
the guest page state transitions between stable and unused.
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/page-states.c b/arch/s390/mm/page-states.c
new file mode 100644
index 0000000..fc0ad73
--- /dev/null
+++ b/arch/s390/mm/page-states.c
@@ -0,0 +1,79 @@
+/*
+ * arch/s390/mm/page-states.c
+ *
+ * Copyright IBM Corp. 2008
+ *
+ * Guest page hinting for unused pages.
+ *
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+
+#define ESSA_SET_STABLE 1
+#define ESSA_SET_UNUSED 2
+
+static int cmma_flag;
+
+static int __init cmma(char *str)
+{
+ char *parm;
+ parm = strstrip(str);
+ if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) {
+ cmma_flag = 1;
+ return 1;
+ }
+ cmma_flag = 0;
+ if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0)
+ return 1;
+ return 0;
+}
+
+__setup("cmma=", cmma);
+
+void __init cmma_init(void)
+{
+ register unsigned long tmp asm("0") = 0;
+ register int rc asm("1") = -EOPNOTSUPP;
+
+ if (!cmma_flag)
+ return;
+ asm volatile(
+ " .insn rrf,0xb9ab0000,%1,%1,0,0\n"
+ "0: la %0,0\n"
+ "1:\n"
+ EX_TABLE(0b,1b)
+ : "+&d" (rc), "+&d" (tmp));
+ if (rc)
+ cmma_flag = 0;
+}
+
+void arch_free_page(struct page *page, int order)
+{
+ int i, rc;
+
+ if (!cmma_flag)
+ return;
+ for (i = 0; i < (1 << order); i++)
+ asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
+ : "=&d" (rc)
+ : "a" ((page_to_pfn(page) + i) << PAGE_SHIFT),
+ "i" (ESSA_SET_UNUSED));
+}
+
+void arch_alloc_page(struct page *page, int order)
+{
+ int i, rc;
+
+ if (!cmma_flag)
+ return;
+ for (i = 0; i < (1 << order); i++)
+ asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
+ : "=&d" (rc)
+ : "a" ((page_to_pfn(page) + i) << PAGE_SHIFT),
+ "i" (ESSA_SET_STABLE));
+}