1 /* 2 * Copyright IBM Corporation, 2015 3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms of version 2 of the GNU Lesser General Public License 7 * as published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it would be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 12 * 13 */ 14 15 #include <linux/mm.h> 16 #include <asm/machdep.h> 17 #include <asm/mmu.h> 18 19 #include "internal.h" 20 21 /* 22 * Return true, if the entry has a slot value which 23 * the software considers as invalid. 24 */ 25 static inline bool hpte_soft_invalid(unsigned long hidx) 26 { 27 return ((hidx & 0xfUL) == 0xfUL); 28 } 29 30 /* 31 * index from 0 - 15 32 */ 33 bool __rpte_sub_valid(real_pte_t rpte, unsigned long index) 34 { 35 return !(hpte_soft_invalid(__rpte_to_hidx(rpte, index))); 36 } 37 38 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid, 39 pte_t *ptep, unsigned long trap, unsigned long flags, 40 int ssize, int subpg_prot) 41 { 42 real_pte_t rpte; 43 unsigned long hpte_group; 44 unsigned int subpg_index; 45 unsigned long rflags, pa; 46 unsigned long old_pte, new_pte, subpg_pte; 47 unsigned long vpn, hash, slot, gslot; 48 unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift; 49 50 /* 51 * atomically mark the linux large page PTE busy and dirty 52 */ 53 do { 54 pte_t pte = READ_ONCE(*ptep); 55 56 old_pte = pte_val(pte); 57 /* If PTE busy, retry the access */ 58 if (unlikely(old_pte & H_PAGE_BUSY)) 59 return 0; 60 /* If PTE permissions don't match, take page fault */ 61 if (unlikely(!check_pte_access(access, old_pte))) 62 return 1; 63 /* 64 * Try to lock the PTE, add ACCESSED and DIRTY if it was 65 * a write access. Since this is 4K insert of 64K page size 66 * also add H_PAGE_COMBO 67 */ 68 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED | H_PAGE_COMBO; 69 if (access & _PAGE_WRITE) 70 new_pte |= _PAGE_DIRTY; 71 } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte))); 72 73 /* 74 * Handle the subpage protection bits 75 */ 76 subpg_pte = new_pte & ~subpg_prot; 77 rflags = htab_convert_pte_flags(subpg_pte, flags); 78 79 if (cpu_has_feature(CPU_FTR_NOEXECUTE) && 80 !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) { 81 82 /* 83 * No CPU has hugepages but lacks no execute, so we 84 * don't need to worry about that case 85 */ 86 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap); 87 } 88 89 subpg_index = (ea & (PAGE_SIZE - 1)) >> shift; 90 vpn = hpt_vpn(ea, vsid, ssize); 91 rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE); 92 /* 93 *None of the sub 4k page is hashed 94 */ 95 if (!(old_pte & H_PAGE_HASHPTE)) 96 goto htab_insert_hpte; 97 /* 98 * Check if the pte was already inserted into the hash table 99 * as a 64k HW page, and invalidate the 64k HPTE if so. 100 */ 101 if (!(old_pte & H_PAGE_COMBO)) { 102 flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags); 103 /* 104 * clear the old slot details from the old and new pte. 105 * On hash insert failure we use old pte value and we don't 106 * want slot information there if we have a insert failure. 107 */ 108 old_pte &= ~H_PAGE_HASHPTE; 109 new_pte &= ~H_PAGE_HASHPTE; 110 goto htab_insert_hpte; 111 } 112 /* 113 * Check for sub page valid and update 114 */ 115 if (__rpte_sub_valid(rpte, subpg_index)) { 116 int ret; 117 118 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 119 subpg_index); 120 ret = mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, 121 MMU_PAGE_4K, MMU_PAGE_4K, 122 ssize, flags); 123 124 /* 125 * If we failed because typically the HPTE wasn't really here 126 * we try an insertion. 127 */ 128 if (ret == -1) 129 goto htab_insert_hpte; 130 131 *ptep = __pte(new_pte & ~H_PAGE_BUSY); 132 return 0; 133 } 134 135 htab_insert_hpte: 136 137 /* 138 * Initialize all hidx entries to invalid value, the first time 139 * the PTE is about to allocate a 4K HPTE. 140 */ 141 if (!(old_pte & H_PAGE_COMBO)) 142 rpte.hidx = INVALID_RPTE_HIDX; 143 144 /* 145 * handle H_PAGE_4K_PFN case 146 */ 147 if (old_pte & H_PAGE_4K_PFN) { 148 /* 149 * All the sub 4k page have the same 150 * physical address. 151 */ 152 pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT; 153 } else { 154 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT; 155 pa += (subpg_index << shift); 156 } 157 hash = hpt_hash(vpn, shift, ssize); 158 repeat: 159 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP; 160 161 /* Insert into the hash table, primary slot */ 162 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0, 163 MMU_PAGE_4K, MMU_PAGE_4K, ssize); 164 /* 165 * Primary is full, try the secondary 166 */ 167 if (unlikely(slot == -1)) { 168 bool soft_invalid; 169 170 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP; 171 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, 172 rflags, HPTE_V_SECONDARY, 173 MMU_PAGE_4K, MMU_PAGE_4K, 174 ssize); 175 176 soft_invalid = hpte_soft_invalid(slot); 177 if (unlikely(soft_invalid)) { 178 /* 179 * We got a valid slot from a hardware point of view. 180 * but we cannot use it, because we use this special 181 * value; as defined by hpte_soft_invalid(), to track 182 * invalid slots. We cannot use it. So invalidate it. 183 */ 184 gslot = slot & _PTEIDX_GROUP_IX; 185 mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn, 186 MMU_PAGE_4K, MMU_PAGE_4K, 187 ssize, 0); 188 } 189 190 if (unlikely(slot == -1 || soft_invalid)) { 191 /* 192 * For soft invalid slot, let's ensure that we release a 193 * slot from the primary, with the hope that we will 194 * acquire that slot next time we try. This will ensure 195 * that we do not get the same soft-invalid slot. 196 */ 197 if (soft_invalid || (mftb() & 0x1)) 198 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP; 199 200 mmu_hash_ops.hpte_remove(hpte_group); 201 /* 202 * FIXME!! Should be try the group from which we removed ? 203 */ 204 goto repeat; 205 } 206 } 207 /* 208 * Hypervisor failure. Restore old pte and return -1 209 * similar to __hash_page_* 210 */ 211 if (unlikely(slot == -2)) { 212 *ptep = __pte(old_pte); 213 hash_failure_debug(ea, access, vsid, trap, ssize, 214 MMU_PAGE_4K, MMU_PAGE_4K, old_pte); 215 return -1; 216 } 217 218 new_pte |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE); 219 new_pte |= H_PAGE_HASHPTE; 220 221 if (stress_hpt()) 222 hpt_do_stress(ea, hpte_group); 223 224 *ptep = __pte(new_pte & ~H_PAGE_BUSY); 225 return 0; 226 } 227 228 int __hash_page_64K(unsigned long ea, unsigned long access, 229 unsigned long vsid, pte_t *ptep, unsigned long trap, 230 unsigned long flags, int ssize) 231 { 232 real_pte_t rpte; 233 unsigned long hpte_group; 234 unsigned long rflags, pa; 235 unsigned long old_pte, new_pte; 236 unsigned long vpn, hash, slot; 237 unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift; 238 239 /* 240 * atomically mark the linux large page PTE busy and dirty 241 */ 242 do { 243 pte_t pte = READ_ONCE(*ptep); 244 245 old_pte = pte_val(pte); 246 /* If PTE busy, retry the access */ 247 if (unlikely(old_pte & H_PAGE_BUSY)) 248 return 0; 249 /* If PTE permissions don't match, take page fault */ 250 if (unlikely(!check_pte_access(access, old_pte))) 251 return 1; 252 /* 253 * Check if PTE has the cache-inhibit bit set 254 * If so, bail out and refault as a 4k page 255 */ 256 if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) && 257 unlikely(pte_ci(pte))) 258 return 0; 259 /* 260 * Try to lock the PTE, add ACCESSED and DIRTY if it was 261 * a write access. 262 */ 263 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED; 264 if (access & _PAGE_WRITE) 265 new_pte |= _PAGE_DIRTY; 266 } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte))); 267 268 rflags = htab_convert_pte_flags(new_pte, flags); 269 rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE); 270 271 if (cpu_has_feature(CPU_FTR_NOEXECUTE) && 272 !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) 273 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap); 274 275 vpn = hpt_vpn(ea, vsid, ssize); 276 if (unlikely(old_pte & H_PAGE_HASHPTE)) { 277 unsigned long gslot; 278 279 /* 280 * There MIGHT be an HPTE for this pte 281 */ 282 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0); 283 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K, 284 MMU_PAGE_64K, ssize, 285 flags) == -1) 286 old_pte &= ~_PAGE_HPTEFLAGS; 287 } 288 289 if (likely(!(old_pte & H_PAGE_HASHPTE))) { 290 291 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT; 292 hash = hpt_hash(vpn, shift, ssize); 293 294 repeat: 295 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP; 296 297 /* Insert into the hash table, primary slot */ 298 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0, 299 MMU_PAGE_64K, MMU_PAGE_64K, 300 ssize); 301 /* 302 * Primary is full, try the secondary 303 */ 304 if (unlikely(slot == -1)) { 305 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP; 306 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, 307 rflags, 308 HPTE_V_SECONDARY, 309 MMU_PAGE_64K, 310 MMU_PAGE_64K, ssize); 311 if (slot == -1) { 312 if (mftb() & 0x1) 313 hpte_group = (hash & htab_hash_mask) * 314 HPTES_PER_GROUP; 315 mmu_hash_ops.hpte_remove(hpte_group); 316 /* 317 * FIXME!! Should be try the group from which we removed ? 318 */ 319 goto repeat; 320 } 321 } 322 /* 323 * Hypervisor failure. Restore old pte and return -1 324 * similar to __hash_page_* 325 */ 326 if (unlikely(slot == -2)) { 327 *ptep = __pte(old_pte); 328 hash_failure_debug(ea, access, vsid, trap, ssize, 329 MMU_PAGE_64K, MMU_PAGE_64K, old_pte); 330 return -1; 331 } 332 333 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE; 334 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE); 335 336 if (stress_hpt()) 337 hpt_do_stress(ea, hpte_group); 338 } 339 340 *ptep = __pte(new_pte & ~H_PAGE_BUSY); 341 342 return 0; 343 } 344