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.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->pid,
  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(void)
  70 {
  71         if (!current || !current->mm)
  72                 return false;
  73
  74         return !list_empty(&current->mm->context.iommu_group_mem_list);
  75 }
  76 EXPORT_SYMBOL_GPL(mm_iommu_preregistered);
  77
  78 /*
  79  * Taken from alloc_migrate_target with changes to remove CMA allocations
  80  */
  81 struct page *new_iommu_non_cma_page(struct page *page, unsigned long private,
  82                                         int **resultp)
  83 {
  84         gfp_t gfp_mask = GFP_USER;
  85         struct page *new_page;
  86
  87         if (PageHuge(page) || PageTransHuge(page) || PageCompound(page))
  88                 return NULL;
  89
  90         if (PageHighMem(page))
  91                 gfp_mask |= __GFP_HIGHMEM;
  92
  93         /*
  94          * We don't want the allocation to force an OOM if possibe
  95          */
  96         new_page = alloc_page(gfp_mask | __GFP_NORETRY | __GFP_NOWARN);
  97         return new_page;
  98 }
  99
 100 static int mm_iommu_move_page_from_cma(struct page *page)
 101 {
 102         int ret = 0;
 103         LIST_HEAD(cma_migrate_pages);
 104
 105         /* Ignore huge pages for now */
 106         if (PageHuge(page) || PageTransHuge(page) || PageCompound(page))
 107                 return -EBUSY;
 108
 109         lru_add_drain();
 110         ret = isolate_lru_page(page);
 111         if (ret)
 112                 return ret;
 113
 114         list_add(&page->lru, &cma_migrate_pages);
 115         put_page(page); /* Drop the gup reference */
 116
 117         ret = migrate_pages(&cma_migrate_pages, new_iommu_non_cma_page,
 118                                 NULL, 0, MIGRATE_SYNC, MR_CMA);
 119         if (ret) {
 120                 if (!list_empty(&cma_migrate_pages))
 121                         putback_movable_pages(&cma_migrate_pages);
 122         }
 123
 124         return 0;
 125 }
 126
 127 long mm_iommu_get(unsigned long ua, unsigned long entries,
 128                 struct mm_iommu_table_group_mem_t **pmem)
 129 {
 130         struct mm_iommu_table_group_mem_t *mem;
 131         long i, j, ret = 0, locked_entries = 0;
 132         struct page *page = NULL;
 133
 134         if (!current || !current->mm)
 135                 return -ESRCH; /* process exited */
 136
 137         mutex_lock(&mem_list_mutex);
 138
 139         list_for_each_entry_rcu(mem, &current->mm->context.iommu_group_mem_list,
 140                         next) {
 141                 if ((mem->ua == ua) && (mem->entries == entries)) {
 142                         ++mem->used;
 143                         *pmem = mem;
 144                         goto unlock_exit;
 145                 }
 146
 147                 /* Overlap? */
 148                 if ((mem->ua < (ua + (entries << PAGE_SHIFT))) &&
 149                                 (ua < (mem->ua +
 150                                        (mem->entries << PAGE_SHIFT)))) {
 151                         ret = -EINVAL;
 152                         goto unlock_exit;
 153                 }
 154
 155         }
 156
 157         ret = mm_iommu_adjust_locked_vm(current->mm, entries, true);
 158         if (ret)
 159                 goto unlock_exit;
 160
 161         locked_entries = entries;
 162
 163         mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 164         if (!mem) {
 165                 ret = -ENOMEM;
 166                 goto unlock_exit;
 167         }
 168
 169         mem->hpas = vzalloc(entries * sizeof(mem->hpas[0]));
 170         if (!mem->hpas) {
 171                 kfree(mem);
 172                 ret = -ENOMEM;
 173                 goto unlock_exit;
 174         }
 175
 176         for (i = 0; i < entries; ++i) {
 177                 if (1 != get_user_pages_fast(ua + (i << PAGE_SHIFT),
 178                                         1/* pages */, 1/* iswrite */, &page)) {
 179                         ret = -EFAULT;
 180                         for (j = 0; j < i; ++j)
 181                                 put_page(pfn_to_page(mem->hpas[j] >>
 182                                                 PAGE_SHIFT));
 183                         vfree(mem->hpas);
 184                         kfree(mem);
 185                         goto unlock_exit;
 186                 }
 187                 /*
 188                  * If we get a page from the CMA zone, since we are going to
 189                  * be pinning these entries, we might as well move them out
 190                  * of the CMA zone if possible. NOTE: faulting in + migration
 191                  * can be expensive. Batching can be considered later
 192                  */
 193                 if (get_pageblock_migratetype(page) == MIGRATE_CMA) {
 194                         if (mm_iommu_move_page_from_cma(page))
 195                                 goto populate;
 196                         if (1 != get_user_pages_fast(ua + (i << PAGE_SHIFT),
 197                                                 1/* pages */, 1/* iswrite */,
 198                                                 &page)) {
 199                                 ret = -EFAULT;
 200                                 for (j = 0; j < i; ++j)
 201                                         put_page(pfn_to_page(mem->hpas[j] >>
 202                                                                 PAGE_SHIFT));
 203                                 vfree(mem->hpas);
 204                                 kfree(mem);
 205                                 goto unlock_exit;
 206                         }
 207                 }
 208 populate:
 209                 mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
 210         }
 211
 212         atomic64_set(&mem->mapped, 1);
 213         mem->used = 1;
 214         mem->ua = ua;
 215         mem->entries = entries;
 216         *pmem = mem;
 217
 218         list_add_rcu(&mem->next, &current->mm->context.iommu_group_mem_list);
 219
 220 unlock_exit:
 221         if (locked_entries && ret)
 222                 mm_iommu_adjust_locked_vm(current->mm, locked_entries, false);
 223
 224         mutex_unlock(&mem_list_mutex);
 225
 226         return ret;
 227 }
 228 EXPORT_SYMBOL_GPL(mm_iommu_get);
 229
 230 static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 231 {
 232         long i;
 233         struct page *page = NULL;
 234
 235         for (i = 0; i < mem->entries; ++i) {
 236                 if (!mem->hpas[i])
 237                         continue;
 238
 239                 page = pfn_to_page(mem->hpas[i] >> PAGE_SHIFT);
 240                 if (!page)
 241                         continue;
 242
 243                 put_page(page);
 244                 mem->hpas[i] = 0;
 245         }
 246 }
 247
 248 static void mm_iommu_do_free(struct mm_iommu_table_group_mem_t *mem)
 249 {
 250
 251         mm_iommu_unpin(mem);
 252         vfree(mem->hpas);
 253         kfree(mem);
 254 }
 255
 256 static void mm_iommu_free(struct rcu_head *head)
 257 {
 258         struct mm_iommu_table_group_mem_t *mem = container_of(head,
 259                         struct mm_iommu_table_group_mem_t, rcu);
 260
 261         mm_iommu_do_free(mem);
 262 }
 263
 264 static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
 265 {
 266         list_del_rcu(&mem->next);
 267         mm_iommu_adjust_locked_vm(current->mm, mem->entries, false);
 268         call_rcu(&mem->rcu, mm_iommu_free);
 269 }
 270
 271 long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem)
 272 {
 273         long ret = 0;
 274
 275         if (!current || !current->mm)
 276                 return -ESRCH; /* process exited */
 277
 278         mutex_lock(&mem_list_mutex);
 279
 280         if (mem->used == 0) {
 281                 ret = -ENOENT;
 282                 goto unlock_exit;
 283         }
 284
 285         --mem->used;
 286         /* There are still users, exit */
 287         if (mem->used)
 288                 goto unlock_exit;
 289
 290         /* Are there still mappings? */
 291         if (atomic_cmpxchg(&mem->mapped, 1, 0) != 1) {
 292                 ++mem->used;
 293                 ret = -EBUSY;
 294                 goto unlock_exit;
 295         }
 296
 297         /* @mapped became 0 so now mappings are disabled, release the region */
 298         mm_iommu_release(mem);
 299
 300 unlock_exit:
 301         mutex_unlock(&mem_list_mutex);
 302
 303         return ret;
 304 }
 305 EXPORT_SYMBOL_GPL(mm_iommu_put);
 306
 307 struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua,
 308                 unsigned long size)
 309 {
 310         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 311
 312         list_for_each_entry_rcu(mem,
 313                         &current->mm->context.iommu_group_mem_list,
 314                         next) {
 315                 if ((mem->ua <= ua) &&
 316                                 (ua + size <= mem->ua +
 317                                  (mem->entries << PAGE_SHIFT))) {
 318                         ret = mem;
 319                         break;
 320                 }
 321         }
 322
 323         return ret;
 324 }
 325 EXPORT_SYMBOL_GPL(mm_iommu_lookup);
 326
 327 struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua,
 328                 unsigned long entries)
 329 {
 330         struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 331
 332         list_for_each_entry_rcu(mem,
 333                         &current->mm->context.iommu_group_mem_list,
 334                         next) {
 335                 if ((mem->ua == ua) && (mem->entries == entries)) {
 336                         ret = mem;
 337                         break;
 338                 }
 339         }
 340
 341         return ret;
 342 }
 343 EXPORT_SYMBOL_GPL(mm_iommu_find);
 344
 345 long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 346                 unsigned long ua, unsigned long *hpa)
 347 {
 348         const long entry = (ua - mem->ua) >> PAGE_SHIFT;
 349         u64 *va = &mem->hpas[entry];
 350
 351         if (entry >= mem->entries)
 352                 return -EFAULT;
 353
 354         *hpa = *va | (ua & ~PAGE_MASK);
 355
 356         return 0;
 357 }
 358 EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
 359
 360 long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
 361 {
 362         if (atomic64_inc_not_zero(&mem->mapped))
 363                 return 0;
 364
 365         /* Last mm_iommu_put() has been called, no more mappings allowed() */
 366         return -ENXIO;
 367 }
 368 EXPORT_SYMBOL_GPL(mm_iommu_mapped_inc);
 369
 370 void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem)
 371 {
 372         atomic64_add_unless(&mem->mapped, -1, 1);
 373 }
 374 EXPORT_SYMBOL_GPL(mm_iommu_mapped_dec);
 375
 376 void mm_iommu_init(struct mm_struct *mm)
 377 {
 378         INIT_LIST_HEAD_RCU(&mm->context.iommu_group_mem_list);
 379 }
 380
 381 void mm_iommu_cleanup(struct mm_struct *mm)
 382 {
 383         struct mm_iommu_table_group_mem_t *mem, *tmp;
 384
 385         list_for_each_entry_safe(mem, tmp, &mm->context.iommu_group_mem_list,
 386                         next) {
 387                 list_del_rcu(&mem->next);
 388                 mm_iommu_do_free(mem);
 389         }
 390 }