1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Apple DART page table allocator. 4 * 5 * Copyright (C) 2022 The Asahi Linux Contributors 6 * 7 * Based on io-pgtable-arm. 8 * 9 * Copyright (C) 2014 ARM Limited 10 * 11 * Author: Will Deacon <will.deacon@arm.com> 12 */ 13 14 #define pr_fmt(fmt) "dart io-pgtable: " fmt 15 16 #include <linux/atomic.h> 17 #include <linux/bitfield.h> 18 #include <linux/bitops.h> 19 #include <linux/io-pgtable.h> 20 #include <linux/kernel.h> 21 #include <linux/sizes.h> 22 #include <linux/slab.h> 23 #include <linux/types.h> 24 25 #include <asm/barrier.h> 26 #include "iommu-pages.h" 27 28 #define DART1_MAX_ADDR_BITS 36 29 30 #define DART_MAX_TABLES 4 31 #define DART_LEVELS 2 32 33 /* Struct accessors */ 34 #define io_pgtable_to_data(x) \ 35 container_of((x), struct dart_io_pgtable, iop) 36 37 #define io_pgtable_ops_to_data(x) \ 38 io_pgtable_to_data(io_pgtable_ops_to_pgtable(x)) 39 40 #define DART_GRANULE(d) \ 41 (sizeof(dart_iopte) << (d)->bits_per_level) 42 #define DART_PTES_PER_TABLE(d) \ 43 (DART_GRANULE(d) >> ilog2(sizeof(dart_iopte))) 44 45 #define APPLE_DART_PTE_SUBPAGE_START GENMASK_ULL(63, 52) 46 #define APPLE_DART_PTE_SUBPAGE_END GENMASK_ULL(51, 40) 47 48 #define APPLE_DART1_PADDR_MASK GENMASK_ULL(35, 12) 49 #define APPLE_DART2_PADDR_MASK GENMASK_ULL(37, 10) 50 #define APPLE_DART2_PADDR_SHIFT (4) 51 52 /* Apple DART1 protection bits */ 53 #define APPLE_DART1_PTE_PROT_NO_READ BIT(8) 54 #define APPLE_DART1_PTE_PROT_NO_WRITE BIT(7) 55 #define APPLE_DART1_PTE_PROT_SP_DIS BIT(1) 56 57 /* Apple DART2 protection bits */ 58 #define APPLE_DART2_PTE_PROT_NO_READ BIT(3) 59 #define APPLE_DART2_PTE_PROT_NO_WRITE BIT(2) 60 #define APPLE_DART2_PTE_PROT_NO_CACHE BIT(1) 61 62 /* marks PTE as valid */ 63 #define APPLE_DART_PTE_VALID BIT(0) 64 65 /* IOPTE accessors */ 66 #define iopte_deref(pte, d) __va(iopte_to_paddr(pte, d)) 67 68 struct dart_io_pgtable { 69 struct io_pgtable iop; 70 71 int tbl_bits; 72 int bits_per_level; 73 74 void *pgd[DART_MAX_TABLES]; 75 }; 76 77 typedef u64 dart_iopte; 78 79 paddr_to_iopte(phys_addr_t paddr,struct dart_io_pgtable * data)80 static dart_iopte paddr_to_iopte(phys_addr_t paddr, 81 struct dart_io_pgtable *data) 82 { 83 dart_iopte pte; 84 85 if (data->iop.fmt == APPLE_DART) 86 return paddr & APPLE_DART1_PADDR_MASK; 87 88 /* format is APPLE_DART2 */ 89 pte = paddr >> APPLE_DART2_PADDR_SHIFT; 90 pte &= APPLE_DART2_PADDR_MASK; 91 92 return pte; 93 } 94 iopte_to_paddr(dart_iopte pte,struct dart_io_pgtable * data)95 static phys_addr_t iopte_to_paddr(dart_iopte pte, 96 struct dart_io_pgtable *data) 97 { 98 u64 paddr; 99 100 if (data->iop.fmt == APPLE_DART) 101 return pte & APPLE_DART1_PADDR_MASK; 102 103 /* format is APPLE_DART2 */ 104 paddr = pte & APPLE_DART2_PADDR_MASK; 105 paddr <<= APPLE_DART2_PADDR_SHIFT; 106 107 return paddr; 108 } 109 __dart_alloc_pages(size_t size,gfp_t gfp)110 static void *__dart_alloc_pages(size_t size, gfp_t gfp) 111 { 112 int order = get_order(size); 113 114 VM_BUG_ON((gfp & __GFP_HIGHMEM)); 115 return iommu_alloc_pages(gfp, order); 116 } 117 dart_init_pte(struct dart_io_pgtable * data,unsigned long iova,phys_addr_t paddr,dart_iopte prot,int num_entries,dart_iopte * ptep)118 static int dart_init_pte(struct dart_io_pgtable *data, 119 unsigned long iova, phys_addr_t paddr, 120 dart_iopte prot, int num_entries, 121 dart_iopte *ptep) 122 { 123 int i; 124 dart_iopte pte = prot; 125 size_t sz = data->iop.cfg.pgsize_bitmap; 126 127 for (i = 0; i < num_entries; i++) 128 if (ptep[i] & APPLE_DART_PTE_VALID) { 129 /* We require an unmap first */ 130 WARN_ON(ptep[i] & APPLE_DART_PTE_VALID); 131 return -EEXIST; 132 } 133 134 /* subpage protection: always allow access to the entire page */ 135 pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_START, 0); 136 pte |= FIELD_PREP(APPLE_DART_PTE_SUBPAGE_END, 0xfff); 137 138 pte |= APPLE_DART_PTE_VALID; 139 140 for (i = 0; i < num_entries; i++) 141 ptep[i] = pte | paddr_to_iopte(paddr + i * sz, data); 142 143 return 0; 144 } 145 dart_install_table(dart_iopte * table,dart_iopte * ptep,dart_iopte curr,struct dart_io_pgtable * data)146 static dart_iopte dart_install_table(dart_iopte *table, 147 dart_iopte *ptep, 148 dart_iopte curr, 149 struct dart_io_pgtable *data) 150 { 151 dart_iopte old, new; 152 153 new = paddr_to_iopte(__pa(table), data) | APPLE_DART_PTE_VALID; 154 155 /* 156 * Ensure the table itself is visible before its PTE can be. 157 * Whilst we could get away with cmpxchg64_release below, this 158 * doesn't have any ordering semantics when !CONFIG_SMP. 159 */ 160 dma_wmb(); 161 162 old = cmpxchg64_relaxed(ptep, curr, new); 163 164 return old; 165 } 166 dart_get_table(struct dart_io_pgtable * data,unsigned long iova)167 static int dart_get_table(struct dart_io_pgtable *data, unsigned long iova) 168 { 169 return (iova >> (3 * data->bits_per_level + ilog2(sizeof(dart_iopte)))) & 170 ((1 << data->tbl_bits) - 1); 171 } 172 dart_get_l1_index(struct dart_io_pgtable * data,unsigned long iova)173 static int dart_get_l1_index(struct dart_io_pgtable *data, unsigned long iova) 174 { 175 176 return (iova >> (2 * data->bits_per_level + ilog2(sizeof(dart_iopte)))) & 177 ((1 << data->bits_per_level) - 1); 178 } 179 dart_get_l2_index(struct dart_io_pgtable * data,unsigned long iova)180 static int dart_get_l2_index(struct dart_io_pgtable *data, unsigned long iova) 181 { 182 183 return (iova >> (data->bits_per_level + ilog2(sizeof(dart_iopte)))) & 184 ((1 << data->bits_per_level) - 1); 185 } 186 dart_get_l2(struct dart_io_pgtable * data,unsigned long iova)187 static dart_iopte *dart_get_l2(struct dart_io_pgtable *data, unsigned long iova) 188 { 189 dart_iopte pte, *ptep; 190 int tbl = dart_get_table(data, iova); 191 192 ptep = data->pgd[tbl]; 193 if (!ptep) 194 return NULL; 195 196 ptep += dart_get_l1_index(data, iova); 197 pte = READ_ONCE(*ptep); 198 199 /* Valid entry? */ 200 if (!pte) 201 return NULL; 202 203 /* Deref to get level 2 table */ 204 return iopte_deref(pte, data); 205 } 206 dart_prot_to_pte(struct dart_io_pgtable * data,int prot)207 static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data, 208 int prot) 209 { 210 dart_iopte pte = 0; 211 212 if (data->iop.fmt == APPLE_DART) { 213 pte |= APPLE_DART1_PTE_PROT_SP_DIS; 214 if (!(prot & IOMMU_WRITE)) 215 pte |= APPLE_DART1_PTE_PROT_NO_WRITE; 216 if (!(prot & IOMMU_READ)) 217 pte |= APPLE_DART1_PTE_PROT_NO_READ; 218 } 219 if (data->iop.fmt == APPLE_DART2) { 220 if (!(prot & IOMMU_WRITE)) 221 pte |= APPLE_DART2_PTE_PROT_NO_WRITE; 222 if (!(prot & IOMMU_READ)) 223 pte |= APPLE_DART2_PTE_PROT_NO_READ; 224 if (!(prot & IOMMU_CACHE)) 225 pte |= APPLE_DART2_PTE_PROT_NO_CACHE; 226 } 227 228 return pte; 229 } 230 dart_map_pages(struct io_pgtable_ops * ops,unsigned long iova,phys_addr_t paddr,size_t pgsize,size_t pgcount,int iommu_prot,gfp_t gfp,size_t * mapped)231 static int dart_map_pages(struct io_pgtable_ops *ops, unsigned long iova, 232 phys_addr_t paddr, size_t pgsize, size_t pgcount, 233 int iommu_prot, gfp_t gfp, size_t *mapped) 234 { 235 struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops); 236 struct io_pgtable_cfg *cfg = &data->iop.cfg; 237 size_t tblsz = DART_GRANULE(data); 238 int ret = 0, tbl, num_entries, max_entries, map_idx_start; 239 dart_iopte pte, *cptep, *ptep; 240 dart_iopte prot; 241 242 if (WARN_ON(pgsize != cfg->pgsize_bitmap)) 243 return -EINVAL; 244 245 if (WARN_ON(paddr >> cfg->oas)) 246 return -ERANGE; 247 248 if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE))) 249 return -EINVAL; 250 251 tbl = dart_get_table(data, iova); 252 253 ptep = data->pgd[tbl]; 254 ptep += dart_get_l1_index(data, iova); 255 pte = READ_ONCE(*ptep); 256 257 /* no L2 table present */ 258 if (!pte) { 259 cptep = __dart_alloc_pages(tblsz, gfp); 260 if (!cptep) 261 return -ENOMEM; 262 263 pte = dart_install_table(cptep, ptep, 0, data); 264 if (pte) 265 iommu_free_pages(cptep, get_order(tblsz)); 266 267 /* L2 table is present (now) */ 268 pte = READ_ONCE(*ptep); 269 } 270 271 ptep = iopte_deref(pte, data); 272 273 /* install a leaf entries into L2 table */ 274 prot = dart_prot_to_pte(data, iommu_prot); 275 map_idx_start = dart_get_l2_index(data, iova); 276 max_entries = DART_PTES_PER_TABLE(data) - map_idx_start; 277 num_entries = min_t(int, pgcount, max_entries); 278 ptep += map_idx_start; 279 ret = dart_init_pte(data, iova, paddr, prot, num_entries, ptep); 280 if (!ret && mapped) 281 *mapped += num_entries * pgsize; 282 283 /* 284 * Synchronise all PTE updates for the new mapping before there's 285 * a chance for anything to kick off a table walk for the new iova. 286 */ 287 wmb(); 288 289 return ret; 290 } 291 dart_unmap_pages(struct io_pgtable_ops * ops,unsigned long iova,size_t pgsize,size_t pgcount,struct iommu_iotlb_gather * gather)292 static size_t dart_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova, 293 size_t pgsize, size_t pgcount, 294 struct iommu_iotlb_gather *gather) 295 { 296 struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops); 297 struct io_pgtable_cfg *cfg = &data->iop.cfg; 298 int i = 0, num_entries, max_entries, unmap_idx_start; 299 dart_iopte pte, *ptep; 300 301 if (WARN_ON(pgsize != cfg->pgsize_bitmap || !pgcount)) 302 return 0; 303 304 ptep = dart_get_l2(data, iova); 305 306 /* Valid L2 IOPTE pointer? */ 307 if (WARN_ON(!ptep)) 308 return 0; 309 310 unmap_idx_start = dart_get_l2_index(data, iova); 311 ptep += unmap_idx_start; 312 313 max_entries = DART_PTES_PER_TABLE(data) - unmap_idx_start; 314 num_entries = min_t(int, pgcount, max_entries); 315 316 while (i < num_entries) { 317 pte = READ_ONCE(*ptep); 318 if (WARN_ON(!pte)) 319 break; 320 321 /* clear pte */ 322 *ptep = 0; 323 324 if (!iommu_iotlb_gather_queued(gather)) 325 io_pgtable_tlb_add_page(&data->iop, gather, 326 iova + i * pgsize, pgsize); 327 328 ptep++; 329 i++; 330 } 331 332 return i * pgsize; 333 } 334 dart_iova_to_phys(struct io_pgtable_ops * ops,unsigned long iova)335 static phys_addr_t dart_iova_to_phys(struct io_pgtable_ops *ops, 336 unsigned long iova) 337 { 338 struct dart_io_pgtable *data = io_pgtable_ops_to_data(ops); 339 dart_iopte pte, *ptep; 340 341 ptep = dart_get_l2(data, iova); 342 343 /* Valid L2 IOPTE pointer? */ 344 if (!ptep) 345 return 0; 346 347 ptep += dart_get_l2_index(data, iova); 348 349 pte = READ_ONCE(*ptep); 350 /* Found translation */ 351 if (pte) { 352 iova &= (data->iop.cfg.pgsize_bitmap - 1); 353 return iopte_to_paddr(pte, data) | iova; 354 } 355 356 /* Ran out of page tables to walk */ 357 return 0; 358 } 359 360 static struct dart_io_pgtable * dart_alloc_pgtable(struct io_pgtable_cfg * cfg)361 dart_alloc_pgtable(struct io_pgtable_cfg *cfg) 362 { 363 struct dart_io_pgtable *data; 364 int tbl_bits, bits_per_level, va_bits, pg_shift; 365 366 pg_shift = __ffs(cfg->pgsize_bitmap); 367 bits_per_level = pg_shift - ilog2(sizeof(dart_iopte)); 368 369 va_bits = cfg->ias - pg_shift; 370 371 tbl_bits = max_t(int, 0, va_bits - (bits_per_level * DART_LEVELS)); 372 if ((1 << tbl_bits) > DART_MAX_TABLES) 373 return NULL; 374 375 data = kzalloc(sizeof(*data), GFP_KERNEL); 376 if (!data) 377 return NULL; 378 379 data->tbl_bits = tbl_bits; 380 data->bits_per_level = bits_per_level; 381 382 data->iop.ops = (struct io_pgtable_ops) { 383 .map_pages = dart_map_pages, 384 .unmap_pages = dart_unmap_pages, 385 .iova_to_phys = dart_iova_to_phys, 386 }; 387 388 return data; 389 } 390 391 static struct io_pgtable * apple_dart_alloc_pgtable(struct io_pgtable_cfg * cfg,void * cookie)392 apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie) 393 { 394 struct dart_io_pgtable *data; 395 int i; 396 397 if (!cfg->coherent_walk) 398 return NULL; 399 400 if (cfg->oas != 36 && cfg->oas != 42) 401 return NULL; 402 403 if (cfg->ias > cfg->oas) 404 return NULL; 405 406 if (!(cfg->pgsize_bitmap == SZ_4K || cfg->pgsize_bitmap == SZ_16K)) 407 return NULL; 408 409 data = dart_alloc_pgtable(cfg); 410 if (!data) 411 return NULL; 412 413 cfg->apple_dart_cfg.n_ttbrs = 1 << data->tbl_bits; 414 415 for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i) { 416 data->pgd[i] = __dart_alloc_pages(DART_GRANULE(data), GFP_KERNEL); 417 if (!data->pgd[i]) 418 goto out_free_data; 419 cfg->apple_dart_cfg.ttbr[i] = virt_to_phys(data->pgd[i]); 420 } 421 422 return &data->iop; 423 424 out_free_data: 425 while (--i >= 0) { 426 iommu_free_pages(data->pgd[i], 427 get_order(DART_GRANULE(data))); 428 } 429 kfree(data); 430 return NULL; 431 } 432 apple_dart_free_pgtable(struct io_pgtable * iop)433 static void apple_dart_free_pgtable(struct io_pgtable *iop) 434 { 435 struct dart_io_pgtable *data = io_pgtable_to_data(iop); 436 int order = get_order(DART_GRANULE(data)); 437 dart_iopte *ptep, *end; 438 int i; 439 440 for (i = 0; i < (1 << data->tbl_bits) && data->pgd[i]; ++i) { 441 ptep = data->pgd[i]; 442 end = (void *)ptep + DART_GRANULE(data); 443 444 while (ptep != end) { 445 dart_iopte pte = *ptep++; 446 447 if (pte) 448 iommu_free_pages(iopte_deref(pte, data), order); 449 } 450 iommu_free_pages(data->pgd[i], order); 451 } 452 453 kfree(data); 454 } 455 456 struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = { 457 .alloc = apple_dart_alloc_pgtable, 458 .free = apple_dart_free_pgtable, 459 }; 460