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 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 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 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 61 static inline void set_page_unused(struct page *page, int order) 62 { 63 int i, rc; 64 65 for (i = 0; i < (1 << order); i++) 66 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0" 67 : "=&d" (rc) 68 : "a" (page_to_phys(page + i)), 69 "i" (ESSA_SET_UNUSED)); 70 } 71 72 static inline void set_page_stable_dat(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 83 static inline void set_page_stable_nodat(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_NODAT)); 92 } 93 94 static void mark_kernel_pmd(pud_t *pud, unsigned long addr, unsigned long end) 95 { 96 unsigned long next; 97 struct page *page; 98 pmd_t *pmd; 99 100 pmd = pmd_offset(pud, addr); 101 do { 102 next = pmd_addr_end(addr, end); 103 if (pmd_none(*pmd) || pmd_large(*pmd)) 104 continue; 105 page = phys_to_page(pmd_val(*pmd)); 106 set_bit(PG_arch_1, &page->flags); 107 } while (pmd++, addr = next, addr != end); 108 } 109 110 static void mark_kernel_pud(p4d_t *p4d, unsigned long addr, unsigned long end) 111 { 112 unsigned long next; 113 struct page *page; 114 pud_t *pud; 115 int i; 116 117 pud = pud_offset(p4d, addr); 118 do { 119 next = pud_addr_end(addr, end); 120 if (pud_none(*pud) || pud_large(*pud)) 121 continue; 122 if (!pud_folded(*pud)) { 123 page = phys_to_page(pud_val(*pud)); 124 for (i = 0; i < 4; i++) 125 set_bit(PG_arch_1, &page[i].flags); 126 } 127 mark_kernel_pmd(pud, addr, next); 128 } while (pud++, addr = next, addr != end); 129 } 130 131 static void mark_kernel_p4d(pgd_t *pgd, unsigned long addr, unsigned long end) 132 { 133 unsigned long next; 134 struct page *page; 135 p4d_t *p4d; 136 int i; 137 138 p4d = p4d_offset(pgd, addr); 139 do { 140 next = p4d_addr_end(addr, end); 141 if (p4d_none(*p4d)) 142 continue; 143 if (!p4d_folded(*p4d)) { 144 page = phys_to_page(p4d_val(*p4d)); 145 for (i = 0; i < 4; i++) 146 set_bit(PG_arch_1, &page[i].flags); 147 } 148 mark_kernel_pud(p4d, addr, next); 149 } while (p4d++, addr = next, addr != end); 150 } 151 152 static void mark_kernel_pgd(void) 153 { 154 unsigned long addr, next; 155 struct page *page; 156 pgd_t *pgd; 157 int i; 158 159 addr = 0; 160 pgd = pgd_offset_k(addr); 161 do { 162 next = pgd_addr_end(addr, MODULES_END); 163 if (pgd_none(*pgd)) 164 continue; 165 if (!pgd_folded(*pgd)) { 166 page = phys_to_page(pgd_val(*pgd)); 167 for (i = 0; i < 4; i++) 168 set_bit(PG_arch_1, &page[i].flags); 169 } 170 mark_kernel_p4d(pgd, addr, next); 171 } while (pgd++, addr = next, addr != MODULES_END); 172 } 173 174 void __init cmma_init_nodat(void) 175 { 176 struct page *page; 177 unsigned long start, end, ix; 178 int i; 179 180 if (cmma_flag < 2) 181 return; 182 /* Mark pages used in kernel page tables */ 183 mark_kernel_pgd(); 184 185 /* Set all kernel pages not used for page tables to stable/no-dat */ 186 for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, NULL) { 187 page = pfn_to_page(start); 188 for (ix = start; ix < end; ix++, page++) { 189 if (__test_and_clear_bit(PG_arch_1, &page->flags)) 190 continue; /* skip page table pages */ 191 if (!list_empty(&page->lru)) 192 continue; /* skip free pages */ 193 set_page_stable_nodat(page, 0); 194 } 195 } 196 } 197 198 void arch_free_page(struct page *page, int order) 199 { 200 if (!cmma_flag) 201 return; 202 set_page_unused(page, order); 203 } 204 205 void arch_alloc_page(struct page *page, int order) 206 { 207 if (!cmma_flag) 208 return; 209 if (cmma_flag < 2) 210 set_page_stable_dat(page, order); 211 else 212 set_page_stable_nodat(page, order); 213 } 214 215 void arch_set_page_dat(struct page *page, int order) 216 { 217 if (!cmma_flag) 218 return; 219 set_page_stable_dat(page, order); 220 } 221