1/*
  2 * Copyright IBM Corp. 2008
  3 *
  4 * Guest page hinting for unused pages.
  5 *
  6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/errno.h>
 11#include <linux/types.h>
 12#include <linux/mm.h>
 13#include <linux/gfp.h>
 14#include <linux/init.h>
 15
 16#define ESSA_SET_STABLE		1
 17#define ESSA_SET_UNUSED		2
 18
 19static int cmma_flag = 1;
 20
 21static int __init cmma(char *str)
 22{
 23	char *parm;
 24
 25	parm = strstrip(str);
 26	if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) {
 27		cmma_flag = 1;
 28		return 1;
 29	}
 30	cmma_flag = 0;
 31	if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0)
 32		return 1;
 33	return 0;
 34}
 35__setup("cmma=", cmma);
 36
 37void __init cmma_init(void)
 38{
 39	register unsigned long tmp asm("0") = 0;
 40	register int rc asm("1") = -EOPNOTSUPP;
 41
 42	if (!cmma_flag)
 43		return;
 44	asm volatile(
 45		"       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
 46		"0:     la      %0,0\n"
 47		"1:\n"
 48		EX_TABLE(0b,1b)
 49		: "+&d" (rc), "+&d" (tmp));
 50	if (rc)
 51		cmma_flag = 0;
 52}
 53
 54static inline void set_page_unstable(struct page *page, int order)
 55{
 56	int i, rc;
 57
 58	for (i = 0; i < (1 << order); i++)
 59		asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
 60			     : "=&d" (rc)
 61			     : "a" (page_to_phys(page + i)),
 62			       "i" (ESSA_SET_UNUSED));
 63}
 64
 65void arch_free_page(struct page *page, int order)
 66{
 67	if (!cmma_flag)
 68		return;
 69	set_page_unstable(page, order);
 70}
 71
 72static inline void set_page_stable(struct page *page, int order)
 73{
 74	int i, rc;
 75
 76	for (i = 0; i < (1 << order); i++)
 77		asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
 78			     : "=&d" (rc)
 79			     : "a" (page_to_phys(page + i)),
 80			       "i" (ESSA_SET_STABLE));
 81}
 82
 83void arch_alloc_page(struct page *page, int order)
 84{
 85	if (!cmma_flag)
 86		return;
 87	set_page_stable(page, order);
 88}
 89
 90void arch_set_page_states(int make_stable)
 91{
 92	unsigned long flags, order, t;
 93	struct list_head *l;
 94	struct page *page;
 95	struct zone *zone;
 96
 97	if (!cmma_flag)
 98		return;
 99	if (make_stable)
100		drain_local_pages(NULL);
101	for_each_populated_zone(zone) {
102		spin_lock_irqsave(&zone->lock, flags);
103		for_each_migratetype_order(order, t) {
104			list_for_each(l, &zone->free_area[order].free_list[t]) {
105				page = list_entry(l, struct page, lru);
106				if (make_stable)
107					set_page_stable(page, order);
108				else
109					set_page_unstable(page, order);
110			}
111		}
112		spin_unlock_irqrestore(&zone->lock, flags);
113	}
114}