arch/powerpc/mm/mmu_context_iommu.c

   1 /*
   2  *  IOMMU helpers in MMU context.
   3  *
   4  *  Copyright (C) 2015 IBM Corp. <aik@ozlabs.ru>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/sched/signal.h>
  14 #include <linux/slab.h>
  15 #include <linux/rculist.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/mutex.h>
  18 #include <linux/migrate.h>
  19 #include <linux/hugetlb.h>
  20 #include <linux/swap.h>
  21 #include <asm/mmu_context.h>
  22
  23 static DEFINE_MUTEX(mem_list_mutex);
  24
  25 struct mm_iommu_table_group_mem_t {
  26         struct list_head next;
  27         struct rcu_head rcu;
  28         unsigned long used;
  29         atomic64_t mapped;
  30         u64 ua;                 /* userspace address */
  31         u64 entries;            /* number of entries in hpas[] */
  32         u64 *hpas;              /* vmalloc'ed */
  33 };
  34
  35 static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
  36                 unsigned long npages, bool incr)
  37 {
  38         long ret = 0, locked, lock_limit;
  39
  40         if (!npages)
  41                 return 0;
  42
  43         down_write(&mm->mmap_sem);
  44
  45         if (incr) {
  46                 locked = mm->locked_vm + npages;
  47                 lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  48                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
  49                         ret = -ENOMEM;
  50                 else
  51                         mm->locked_vm += npages;
  52         } else {
  53                 if (WARN_ON_ONCE(npages > mm->locked_vm))
  54                         npages = mm->locked_vm;
  55                 mm->locked_vm -= npages;
  56         }
  57
  58         pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
  59                         current ? current->pid : 0,
  60                         incr ? '+' : '-',
  61                         npages << PAGE_SHIFT,
  62                         mm->locked_vm << PAGE_SHIFT,
  63                         rlimit(RLIMIT_MEMLOCK));
  64         up_write(&mm->mmap_sem);
  65
  66         return ret;
  67 }
  68
  69 bool mm_iommu_preregistered(struct mm_struct *mm)
  70 {
  71         return !list_empty(&mm->context.iommu_group_mem_list);
  72 }
  73 EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
  74
  75 /*
  76  * Taken from alloc_migrate_target with changes to remove CMA allocations
  77  */
  78 struct page *new_iommu_non_cma_page(struct page *page, unsigned long private,
  79                                         int **resultp)
  80 {
  81         gfp_t gfp_mask = GFP_USER;
  82         struct page *new_page;
  83
  84         if (PageCompound(page))
  85                 return NULL;
  86
  87         if (PageHighMem(page))
  88                 gfp_mask |= __GFP_HIGHMEM;
  89
  90         /*
  91          * We don't want the allocation to force an OOM if possibe
  92          */
  93         new_page = alloc_page(gfp_mask | __GFP_NORETRY | __GFP_NOWARN);
  94         return new_page;
  95 }
  96
  97 static int mm_iommu_move_page_from_cma(struct page *page)
  98 {
  99         int ret = 0;
 100         LIST_HEAD(cma_migrate_pages);
 101
 102         /* Ignore huge pages for now */
 103         if (PageCompound(page))
 104                 return -EBUSY;
 105
 106         lru_add_drain();
 107         ret = isolate_lru_page(page);
 108         if (ret)
 109                 return ret;
 110
 111         list_add(&page->lru, &cma_migrate_pages);
 112         put_page(page); /* Drop the gup reference */
 113
 114         ret = migrate_pages(&cma_migrate_pages, new_iommu_non_cma_page,
 115                                 NULL, 0, MIGRATE_SYNC, MR_CMA);
 116         if (ret) {
 117                 if (!list_empty(&cma_migrate_pages))
 118                         putback_movable_pages(&cma_migrate_pages);
 119         }
 120
 121         return 0;
 122 }
 123
 124 long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 125                 struct mm_iommu_table_group_mem_t **pmem)
 126 {
 127         struct mm_iommu_table_group_mem_t *mem;
 128         long i, j, ret = 0, locked_entries = 0;
 129         struct page *page = NULL;
 130
 131         mutex_lock(&mem_list_mutex);
 132
 133         list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
 134                         next) {
 135                 if ((mem->ua == ua) && (mem->entries == entries)) {
 136                         ++mem->used;
 137                         *pmem = mem;
 138                         goto unlock_exit;
 139                 }
 140
 141                 /* Overlap? */
 142                 if ((mem->ua < (ua + (entries << PAGE_SHIFT))) &&
 143                                 (ua < (mem->ua +
 144                                        (mem->entries << PAGE_SHIFT)))) {
 145                         ret = -EINVAL;
 146                         goto unlock_exit;
 147                 }
 148
 149         }
 150
 151         ret = mm_iommu_adjust_locked_vm(mm, entries, true);
 152         if (ret)
 153                 goto unlock_exit;
 154
 155         locked_entries = entries;
 156
 157         mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 158         if (!mem) {
 159                 ret = -ENOMEM;
 160                 goto unlock_exit;
 161         }
 162
 163         mem->hpas = vzalloc(entries * sizeof(mem->hpas[0]));
 164         if (!mem->hpas) {
 165                 kfree(mem);
 166                 ret = -ENOMEM;
 167                 goto unlock_exit;
 168         }
 169
 170         for (i = 0; i < entries; ++i) {
 171                 if (1 != get_user_pages_fast(ua + (i << PAGE_SHIFT),
 172                                         1/* pages */, 1/* iswrite */, &page)) {
 173                         ret = -EFAULT;
 174                         for (j = 0; j < i; ++j)
 175                                 put_page(pfn_to_page(mem->hpas[j] >>
 176                                                 PAGE_SHIFT));
 177                         vfree(mem->hpas);
 178                         kfree(mem);
 179                         goto unlock_exit;
 180                 }
 181                 /*
 182                  * If we get a page from the CMA zone, since we are going to
 183                  * be pinning these entries, we might as well move them out
 184                  * of the CMA zone if possible. NOTE: faulting in + migration
 185                  * can be expensive. Batching can be considered later
 186                  */
 187                 if (is_migrate_cma_page(page)) {
 188                         if (mm_iommu_move_page_from_cma(page))
 189                                 goto populate;
 190                         if (1 != get_user_pages_fast(ua + (i << PAGE_SHIFT),
 191                                                 1/* pages */, 1/* iswrite */,
 192                                                 &page)) {
 193                                 ret = -EFAULT;
 194                                 for (j = 0; j < i; ++j)
 195                                         put_page(pfn_to_page(mem->hpas[j] >>
 196                                                                 PAGE_SHIFT));
 197                                 vfree(mem->hpas);
 198                                 kfree(mem);
 199                                 goto unlock_exit;
 200                         }
 201                 }
 202 populate:
 203                 mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
 204         }
 205
 206         atomic64_set(&mem->mapped, 1);
 207         mem->used = 1;
 208         mem->ua = ua;
 209         mem->entries = entries;
 210         *pmem = mem;
 211
 212         list_add_rcu(&mem->next, &mm->context.iommu_group_mem_list);
 213
 214 unlock_exit:
 215         if (locked_entries && ret)
 216                 mm_iommu_adjust_locked_vm(mm, locked_entries, false);
 217
 218         mutex_unlock(&mem_list_mutex);
 219
 220         return ret;
 221 }
 222 EXPORT_SYMBOL_GPL(mm_iommu_get);
 223
 224 static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 225 {
 226         long i;
 227         struct page *page = NULL;
 228
 229         for (i = 0; i < mem->entries; ++i) {
 230                 if (!mem->hpas[i])
 231                         continue;
 232
 233                 page = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
 234                 if (!page)
 235                         continue;
 236
 237                 put_page(page);
 238                 mem->hpas[i] = 0;
 239         }
 240 }
 241
 242 static void mm_iommu_do_free(struct mm_iommu_table_group_mem_t *mem)
 243 {
 244
 245         mm_iommu_unpin(mem);
 246         vfree(mem->hpas);
 247         kfree(mem);
 248 }
 249
 250 static void mm_iommu_free(struct rcu_head *head)
 251 {
 252         struct mm_iommu_table_group_mem_t *mem = container_of(head,
 253                         struct mm_iommu_table_group_mem_t, rcu);
 254
 255         mm_iommu_do_free(mem);
 256 }
 257
 258 static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
 259 {
 260         list_del_rcu(&mem->next);
 261         call_rcu(&mem->rcu, mm_iommu_free);
 262 }
 263
 264 long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
 265 {
 266         long ret = 0;
 267
 268         mutex_lock(&mem_list_mutex);
 269
 270         if (mem->used == 0) {
 271                 ret = -ENOENT;
 272                 goto unlock_exit;
 273         }
 274
 275         --mem->used;
 276         /* There are still users, exit */
 277         if (mem->used)
 278                 goto unlock_exit;
 279
 280         /* Are there still mappings? */
 281         if (atomic_cmpxchg(&mem->mapped, 1, 0) != 1) {
 282                 ++mem->used;
 283                 ret = -EBUSY;
 284                 goto unlock_exit;
 285         }
 286
 287         /* @mapped became 0 so now mappings are disabled, release the region */
 288         mm_iommu_release(mem);
 289
 290         mm_iommu_adjust_locked_vm(mm, mem->entries, false);
 291
 292 unlock_exit:
 293         mutex_unlock(&mem_list_mutex);
 294
 295         return ret;
 296 }
 297 EXPORT_SYMBOL_GPL(mm_iommu_put);
 298
 299 struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
 300                 unsigned long ua, unsigned long size)
 301 {
 302         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 303
 304         list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
 305                 if ((mem->ua <= ua) &&
 306                                 (ua + size <= mem->ua +
 307                                  (mem->entries << PAGE_SHIFT))) {
 308                         ret = mem;
 309                         break;
 310                 }
 311         }
 312
 313         return ret;
 314 }
 315 EXPORT_SYMBOL_GPL(mm_iommu_lookup);
 316
 317 struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
 318                 unsigned long ua, unsigned long size)
 319 {
 320         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 321
 322         list_for_each_entry_lockless(mem, &mm->context.iommu_group_mem_list,
 323                         next) {
 324                 if ((mem->ua <= ua) &&
 325                                 (ua + size <= mem->ua +
 326                                  (mem->entries << PAGE_SHIFT))) {
 327                         ret = mem;
 328                         break;
 329                 }
 330         }
 331
 332         return ret;
 333 }
 334 EXPORT_SYMBOL_GPL(mm_iommu_lookup_rm);
 335
 336 struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
 337                 unsigned long ua, unsigned long entries)
 338 {
 339         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 340
 341         list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
 342                 if ((mem->ua == ua) && (mem->entries == entries)) {
 343                         ret = mem;
 344                         break;
 345                 }
 346         }
 347
 348         return ret;
 349 }
 350 EXPORT_SYMBOL_GPL(mm_iommu_find);
 351
 352 long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 353                 unsigned long ua, unsigned long *hpa)
 354 {
 355         const long entry = (ua - mem->ua) >> PAGE_SHIFT;
 356         u64 *va = &mem->hpas[entry];
 357
 358         if (entry >= mem->entries)
 359                 return -EFAULT;
 360
 361         *hpa = *va | (ua & ~PAGE_MASK);
 362
 363         return 0;
 364 }
 365 EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
 366
 367 long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
 368                 unsigned long ua, unsigned long *hpa)
 369 {
 370         const long entry = (ua - mem->ua) >> PAGE_SHIFT;
 371         void *va = &mem->hpas[entry];
 372         unsigned long *pa;
 373
 374         if (entry >= mem->entries)
 375                 return -EFAULT;
 376
 377         pa = (void *) vmalloc_to_phys(va);
 378         if (!pa)
 379                 return -EFAULT;
 380
 381         *hpa = *pa | (ua & ~PAGE_MASK);
 382
 383         return 0;
 384 }
 385 EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa_rm);
 386
 387 long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
 388 {
 389         if (atomic64_inc_not_zero(&mem->mapped))
 390                 return 0;
 391
 392         /* Last mm_iommu_put() has been called, no more mappings allowed() */
 393         return -ENXIO;
 394 }
 395 EXPORT_SYMBOL_GPL(mm_iommu_mapped_inc);
 396
 397 void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem)
 398 {
 399         atomic64_add_unless(&mem->mapped, -1, 1);
 400 }
 401 EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
 402
 403 void mm_iommu_init(struct mm_struct *mm)
 404 {
 405         INIT_LIST_HEAD_RCU(&mm->context.iommu_group_mem_list);
 406 }