1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright IBM Corp. 2008
4 *
5 * Guest page hinting for unused pages.
6 *
7 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/types.h>
13 #include <linux/mm.h>
14 #include <linux/memblock.h>
15 #include <linux/gfp.h>
16 #include <linux/init.h>
17 #include <asm/asm-extable.h>
18 #include <asm/facility.h>
19 #include <asm/page-states.h>
20
21 static int cmma_flag = 1;
22
cmma(char * str)23 static int __init cmma(char *str)
24 {
25 bool enabled;
26
27 if (!kstrtobool(str, &enabled))
28 cmma_flag = enabled;
29 return 1;
30 }
31 __setup("cmma=", cmma);
32
cmma_test_essa(void)33 static inline int cmma_test_essa(void)
34 {
35 unsigned long tmp = 0;
36 int rc = -EOPNOTSUPP;
37
38 /* test ESSA_GET_STATE */
39 asm volatile(
40 " .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n"
41 "0: la %[rc],0\n"
42 "1:\n"
43 EX_TABLE(0b,1b)
44 : [rc] "+&d" (rc), [tmp] "+&d" (tmp)
45 : [cmd] "i" (ESSA_GET_STATE));
46 return rc;
47 }
48
cmma_init(void)49 void __init cmma_init(void)
50 {
51 if (!cmma_flag)
52 return;
53 if (cmma_test_essa()) {
54 cmma_flag = 0;
55 return;
56 }
57 if (test_facility(147))
58 cmma_flag = 2;
59 }
60
get_page_state(struct page * page)61 static inline unsigned char get_page_state(struct page *page)
62 {
63 unsigned char state;
64
65 asm volatile(" .insn rrf,0xb9ab0000,%0,%1,%2,0"
66 : "=&d" (state)
67 : "a" (page_to_phys(page)),
68 "i" (ESSA_GET_STATE));
69 return state & 0x3f;
70 }
71
set_page_unused(struct page * page,int order)72 static inline void set_page_unused(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_UNUSED));
81 }
82
set_page_stable_dat(struct page * page,int order)83 static inline void set_page_stable_dat(struct page *page, int order)
84 {
85 int i, rc;
86
87 for (i = 0; i < (1 << order); i++)
88 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
89 : "=&d" (rc)
90 : "a" (page_to_phys(page + i)),
91 "i" (ESSA_SET_STABLE));
92 }
93
set_page_stable_nodat(struct page * page,int order)94 static inline void set_page_stable_nodat(struct page *page, int order)
95 {
96 int i, rc;
97
98 for (i = 0; i < (1 << order); i++)
99 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
100 : "=&d" (rc)
101 : "a" (page_to_phys(page + i)),
102 "i" (ESSA_SET_STABLE_NODAT));
103 }
104
mark_kernel_pmd(pud_t * pud,unsigned long addr,unsigned long end)105 static void mark_kernel_pmd(pud_t *pud, unsigned long addr, unsigned long end)
106 {
107 unsigned long next;
108 struct page *page;
109 pmd_t *pmd;
110
111 pmd = pmd_offset(pud, addr);
112 do {
113 next = pmd_addr_end(addr, end);
114 if (pmd_none(*pmd) || pmd_large(*pmd))
115 continue;
116 page = phys_to_page(pmd_val(*pmd));
117 set_bit(PG_arch_1, &page->flags);
118 } while (pmd++, addr = next, addr != end);
119 }
120
mark_kernel_pud(p4d_t * p4d,unsigned long addr,unsigned long end)121 static void mark_kernel_pud(p4d_t *p4d, unsigned long addr, unsigned long end)
122 {
123 unsigned long next;
124 struct page *page;
125 pud_t *pud;
126 int i;
127
128 pud = pud_offset(p4d, addr);
129 do {
130 next = pud_addr_end(addr, end);
131 if (pud_none(*pud) || pud_large(*pud))
132 continue;
133 if (!pud_folded(*pud)) {
134 page = phys_to_page(pud_val(*pud));
135 for (i = 0; i < 3; i++)
136 set_bit(PG_arch_1, &page[i].flags);
137 }
138 mark_kernel_pmd(pud, addr, next);
139 } while (pud++, addr = next, addr != end);
140 }
141
mark_kernel_p4d(pgd_t * pgd,unsigned long addr,unsigned long end)142 static void mark_kernel_p4d(pgd_t *pgd, unsigned long addr, unsigned long end)
143 {
144 unsigned long next;
145 struct page *page;
146 p4d_t *p4d;
147 int i;
148
149 p4d = p4d_offset(pgd, addr);
150 do {
151 next = p4d_addr_end(addr, end);
152 if (p4d_none(*p4d))
153 continue;
154 if (!p4d_folded(*p4d)) {
155 page = phys_to_page(p4d_val(*p4d));
156 for (i = 0; i < 3; i++)
157 set_bit(PG_arch_1, &page[i].flags);
158 }
159 mark_kernel_pud(p4d, addr, next);
160 } while (p4d++, addr = next, addr != end);
161 }
162
mark_kernel_pgd(void)163 static void mark_kernel_pgd(void)
164 {
165 unsigned long addr, next;
166 struct page *page;
167 pgd_t *pgd;
168 int i;
169
170 addr = 0;
171 pgd = pgd_offset_k(addr);
172 do {
173 next = pgd_addr_end(addr, MODULES_END);
174 if (pgd_none(*pgd))
175 continue;
176 if (!pgd_folded(*pgd)) {
177 page = phys_to_page(pgd_val(*pgd));
178 for (i = 0; i < 3; i++)
179 set_bit(PG_arch_1, &page[i].flags);
180 }
181 mark_kernel_p4d(pgd, addr, next);
182 } while (pgd++, addr = next, addr != MODULES_END);
183 }
184
cmma_init_nodat(void)185 void __init cmma_init_nodat(void)
186 {
187 struct page *page;
188 unsigned long start, end, ix;
189 int i;
190
191 if (cmma_flag < 2)
192 return;
193 /* Mark pages used in kernel page tables */
194 mark_kernel_pgd();
195
196 /* Set all kernel pages not used for page tables to stable/no-dat */
197 for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, NULL) {
198 page = pfn_to_page(start);
199 for (ix = start; ix < end; ix++, page++) {
200 if (__test_and_clear_bit(PG_arch_1, &page->flags))
201 continue; /* skip page table pages */
202 if (!list_empty(&page->lru))
203 continue; /* skip free pages */
204 set_page_stable_nodat(page, 0);
205 }
206 }
207 }
208
arch_free_page(struct page * page,int order)209 void arch_free_page(struct page *page, int order)
210 {
211 if (!cmma_flag)
212 return;
213 set_page_unused(page, order);
214 }
215
arch_alloc_page(struct page * page,int order)216 void arch_alloc_page(struct page *page, int order)
217 {
218 if (!cmma_flag)
219 return;
220 if (cmma_flag < 2)
221 set_page_stable_dat(page, order);
222 else
223 set_page_stable_nodat(page, order);
224 }
225
arch_set_page_dat(struct page * page,int order)226 void arch_set_page_dat(struct page *page, int order)
227 {
228 if (!cmma_flag)
229 return;
230 set_page_stable_dat(page, order);
231 }
232