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}
115