[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/Kconfig b/arch/s390/Kconfig
index 29a7940f284f62fa1f9e27508bc7d55f9b50aca4..1d035082e78eb15fc73f8f3b7b939af19eaa23ba 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -430,6 +430,13 @@ config CMM_IUCV
          Select this option to enable the special message interface to
          the cooperative memory management.
 
+config PAGE_STATES
+       bool "Unused page notification"
+       help
+         This enables the notification of unused pages to the
+         hypervisor. The ESSA instruction is used to do the states
+         changes between a page that has content and the unused state.
+
 config VIRT_TIMER
        bool "Virtual CPU timer support"
        help

diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index fb988a48a754ff541d161ba341a108e10a2a15e1..2a745813454410cb35ff525e837efc9f29c0dd95 100644 (file)
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -5,3 +5,4 @@
 obj-y   := init.o fault.o extmem.o mmap.o vmem.o pgtable.o
 obj-$(CONFIG_CMM) += cmm.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
+obj-$(CONFIG_PAGE_STATES) += page-states.o

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index fa31de6ae97aef1577b99d0f9afb04cf257334ce..29f3a63806b976ee8847dd3efd84292697ba53db 100644 (file)
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -126,6 +126,9 @@ void __init mem_init(void)
         /* clear the zero-page */
         memset(empty_zero_page, 0, PAGE_SIZE);
 
+       /* Setup guest page hinting */
+       cmma_init();
+
        /* this will put all low memory onto the freelists */
        totalram_pages += free_all_bootmem();
 

diff --git a/arch/s390/mm/page-states.c b/arch/s390/mm/page-states.c
new file mode 100644 (file)
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));
+}

diff --git a/include/asm-s390/page.h b/include/asm-s390/page.h
index f0f4579eac13144b01f43eaf401428dfb2d8c5db..12fd9c4f0f154fe86baaed66c71103d24b15f65a 100644 (file)
--- a/include/asm-s390/page.h
+++ b/include/asm-s390/page.h
@@ -125,6 +125,17 @@ page_get_storage_key(unsigned long addr)
        return skey;
 }
 
+#ifdef CONFIG_PAGE_STATES
+
+struct page;
+void arch_free_page(struct page *page, int order);
+void arch_alloc_page(struct page *page, int order);
+
+#define HAVE_ARCH_FREE_PAGE
+#define HAVE_ARCH_ALLOC_PAGE
+
+#endif
+
 #endif /* !__ASSEMBLY__ */
 
 /* to align the pointer to the (next) page boundary */

diff --git a/include/asm-s390/system.h b/include/asm-s390/system.h
index c819ae25a8425ddfd72136dda4d674bf0f8b0ac1..e0d4500d5f95c14478205c60269849a8d5852ace 100644 (file)
--- a/include/asm-s390/system.h
+++ b/include/asm-s390/system.h
@@ -116,6 +116,12 @@ extern void pfault_fini(void);
 #define pfault_fini()          do { } while (0)
 #endif /* CONFIG_PFAULT */
 
+#ifdef CONFIG_PAGE_STATES
+extern void cmma_init(void);
+#else
+static inline void cmma_init(void) { }
+#endif
+
 #define finish_arch_switch(prev) do {                                       \
        set_fs(current->thread.mm_segment);                                  \
        account_vtime(prev);                                                 \