1 /* 2 * Copyright IBM Corporation, 2013 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 2.1 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 /* 16 * PPC64 THP Support for hash based MMUs 17 */ 18 #include <linux/mm.h> 19 #include <asm/machdep.h> 20 21 int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid, 22 pmd_t *pmdp, unsigned long trap, unsigned long flags, 23 int ssize, unsigned int psize) 24 { 25 unsigned int index, valid; 26 unsigned char *hpte_slot_array; 27 unsigned long rflags, pa, hidx; 28 unsigned long old_pmd, new_pmd; 29 int ret, lpsize = MMU_PAGE_16M; 30 unsigned long vpn, hash, shift, slot; 31 32 /* 33 * atomically mark the linux large page PMD busy and dirty 34 */ 35 do { 36 pmd_t pmd = READ_ONCE(*pmdp); 37 38 old_pmd = pmd_val(pmd); 39 /* If PMD busy, retry the access */ 40 if (unlikely(old_pmd & H_PAGE_BUSY)) 41 return 0; 42 /* If PMD permissions don't match, take page fault */ 43 if (unlikely(!check_pte_access(access, old_pmd))) 44 return 1; 45 /* 46 * Try to lock the PTE, add ACCESSED and DIRTY if it was 47 * a write access 48 */ 49 new_pmd = old_pmd | H_PAGE_BUSY | _PAGE_ACCESSED; 50 if (access & _PAGE_WRITE) 51 new_pmd |= _PAGE_DIRTY; 52 } while (!pmd_xchg(pmdp, __pmd(old_pmd), __pmd(new_pmd))); 53 54 /* 55 * Make sure this is thp or devmap entry 56 */ 57 if (!(old_pmd & (H_PAGE_THP_HUGE | _PAGE_DEVMAP))) 58 return 0; 59 60 rflags = htab_convert_pte_flags(new_pmd, flags); 61 62 #if 0 63 if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) { 64 65 /* 66 * No CPU has hugepages but lacks no execute, so we 67 * don't need to worry about that case 68 */ 69 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap); 70 } 71 #endif 72 /* 73 * Find the slot index details for this ea, using base page size. 74 */ 75 shift = mmu_psize_defs[psize].shift; 76 index = (ea & ~HPAGE_PMD_MASK) >> shift; 77 BUG_ON(index >= PTE_FRAG_SIZE); 78 79 vpn = hpt_vpn(ea, vsid, ssize); 80 hpte_slot_array = get_hpte_slot_array(pmdp); 81 if (psize == MMU_PAGE_4K) { 82 /* 83 * invalidate the old hpte entry if we have that mapped via 64K 84 * base page size. This is because demote_segment won't flush 85 * hash page table entries. 86 */ 87 if ((old_pmd & H_PAGE_HASHPTE) && !(old_pmd & H_PAGE_COMBO)) { 88 flush_hash_hugepage(vsid, ea, pmdp, MMU_PAGE_64K, 89 ssize, flags); 90 /* 91 * With THP, we also clear the slot information with 92 * respect to all the 64K hash pte mapping the 16MB 93 * page. They are all invalid now. This make sure we 94 * don't find the slot valid when we fault with 4k 95 * base page size. 96 * 97 */ 98 memset(hpte_slot_array, 0, PTE_FRAG_SIZE); 99 } 100 } 101 102 valid = hpte_valid(hpte_slot_array, index); 103 if (valid) { 104 /* update the hpte bits */ 105 hash = hpt_hash(vpn, shift, ssize); 106 hidx = hpte_hash_index(hpte_slot_array, index); 107 if (hidx & _PTEIDX_SECONDARY) 108 hash = ~hash; 109 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP; 110 slot += hidx & _PTEIDX_GROUP_IX; 111 112 ret = mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, 113 psize, lpsize, ssize, flags); 114 /* 115 * We failed to update, try to insert a new entry. 116 */ 117 if (ret == -1) { 118 /* 119 * large pte is marked busy, so we can be sure 120 * nobody is looking at hpte_slot_array. hence we can 121 * safely update this here. 122 */ 123 valid = 0; 124 hpte_slot_array[index] = 0; 125 } 126 } 127 128 if (!valid) { 129 unsigned long hpte_group; 130 131 hash = hpt_hash(vpn, shift, ssize); 132 /* insert new entry */ 133 pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT; 134 new_pmd |= H_PAGE_HASHPTE; 135 136 repeat: 137 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP; 138 139 /* Insert into the hash table, primary slot */ 140 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0, 141 psize, lpsize, ssize); 142 /* 143 * Primary is full, try the secondary 144 */ 145 if (unlikely(slot == -1)) { 146 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP; 147 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, 148 rflags, 149 HPTE_V_SECONDARY, 150 psize, lpsize, ssize); 151 if (slot == -1) { 152 if (mftb() & 0x1) 153 hpte_group = (hash & htab_hash_mask) * 154 HPTES_PER_GROUP; 155 156 mmu_hash_ops.hpte_remove(hpte_group); 157 goto repeat; 158 } 159 } 160 /* 161 * Hypervisor failure. Restore old pmd and return -1 162 * similar to __hash_page_* 163 */ 164 if (unlikely(slot == -2)) { 165 *pmdp = __pmd(old_pmd); 166 hash_failure_debug(ea, access, vsid, trap, ssize, 167 psize, lpsize, old_pmd); 168 return -1; 169 } 170 /* 171 * large pte is marked busy, so we can be sure 172 * nobody is looking at hpte_slot_array. hence we can 173 * safely update this here. 174 */ 175 mark_hpte_slot_valid(hpte_slot_array, index, slot); 176 } 177 /* 178 * Mark the pte with H_PAGE_COMBO, if we are trying to hash it with 179 * base page size 4k. 180 */ 181 if (psize == MMU_PAGE_4K) 182 new_pmd |= H_PAGE_COMBO; 183 /* 184 * The hpte valid is stored in the pgtable whose address is in the 185 * second half of the PMD. Order this against clearing of the busy bit in 186 * huge pmd. 187 */ 188 smp_wmb(); 189 *pmdp = __pmd(new_pmd & ~H_PAGE_BUSY); 190 return 0; 191 } 192