drivers/iommu/io-pgtable-dart.c

   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
  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
  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
 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
 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_DART1_PTE_PROT_SP_DIS;
 139         pte |= APPLE_DART_PTE_VALID;
 140
 141         for (i = 0; i < num_entries; i++)
 142                 ptep[i] = pte | paddr_to_iopte(paddr + i * sz, data);
 143
 144         return 0;
 145 }
 146
 147 static dart_iopte dart_install_table(dart_iopte *table,
 148                                              dart_iopte *ptep,
 149                                              dart_iopte curr,
 150                                              struct dart_io_pgtable *data)
 151 {
 152         dart_iopte old, new;
 153
 154         new = paddr_to_iopte(__pa(table), data) | APPLE_DART_PTE_VALID;
 155
 156         /*
 157          * Ensure the table itself is visible before its PTE can be.
 158          * Whilst we could get away with cmpxchg64_release below, this
 159          * doesn't have any ordering semantics when !CONFIG_SMP.
 160          */
 161         dma_wmb();
 162
 163         old = cmpxchg64_relaxed(ptep, curr, new);
 164
 165         return old;
 166 }
 167
 168 static int dart_get_table(struct dart_io_pgtable *data, unsigned long iova)
 169 {
 170         return (iova >> (3 * data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
 171                 ((1 << data->tbl_bits) - 1);
 172 }
 173
 174 static int dart_get_l1_index(struct dart_io_pgtable *data, unsigned long iova)
 175 {
 176
 177         return (iova >> (2 * data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
 178                  ((1 << data->bits_per_level) - 1);
 179 }
 180
 181 static int dart_get_l2_index(struct dart_io_pgtable *data, unsigned long iova)
 182 {
 183
 184         return (iova >> (data->bits_per_level + ilog2(sizeof(dart_iopte)))) &
 185                  ((1 << data->bits_per_level) - 1);
 186 }
 187
 188 static  dart_iopte *dart_get_l2(struct dart_io_pgtable *data, unsigned long iova)
 189 {
 190         dart_iopte pte, *ptep;
 191         int tbl = dart_get_table(data, iova);
 192
 193         ptep = data->pgd[tbl];
 194         if (!ptep)
 195                 return NULL;
 196
 197         ptep += dart_get_l1_index(data, iova);
 198         pte = READ_ONCE(*ptep);
 199
 200         /* Valid entry? */
 201         if (!pte)
 202                 return NULL;
 203
 204         /* Deref to get level 2 table */
 205         return iopte_deref(pte, data);
 206 }
 207
 208 static dart_iopte dart_prot_to_pte(struct dart_io_pgtable *data,
 209                                            int prot)
 210 {
 211         dart_iopte pte = 0;
 212
 213         if (data->iop.fmt == APPLE_DART) {
 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
 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
 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
 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 *
 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 *
 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
 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 };