drivers/iommu/iova.c

   1 /*
   2  * Copyright © 2006-2009, Intel Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  15  * Place - Suite 330, Boston, MA 02111-1307 USA.
  16  *
  17  * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
  18  */
  19
  20 #include <linux/iova.h>
  21
  22 void
  23 init_iova_domain(struct iova_domain *iovad, unsigned long pfn_32bit)
  24 {
  25         spin_lock_init(&iovad->iova_rbtree_lock);
  26         iovad->rbroot = RB_ROOT;
  27         iovad->cached32_node = NULL;
  28         iovad->dma_32bit_pfn = pfn_32bit;
  29 }
  30
  31 static struct rb_node *
  32 __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
  33 {
  34         if ((*limit_pfn != iovad->dma_32bit_pfn) ||
  35                 (iovad->cached32_node == NULL))
  36                 return rb_last(&iovad->rbroot);
  37         else {
  38                 struct rb_node *prev_node = rb_prev(iovad->cached32_node);
  39                 struct iova *curr_iova =
  40                         container_of(iovad->cached32_node, struct iova, node);
  41                 *limit_pfn = curr_iova->pfn_lo - 1;
  42                 return prev_node;
  43         }
  44 }
  45
  46 static void
  47 __cached_rbnode_insert_update(struct iova_domain *iovad,
  48         unsigned long limit_pfn, struct iova *new)
  49 {
  50         if (limit_pfn != iovad->dma_32bit_pfn)
  51                 return;
  52         iovad->cached32_node = &new->node;
  53 }
  54
  55 static void
  56 __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
  57 {
  58         struct iova *cached_iova;
  59         struct rb_node *curr;
  60
  61         if (!iovad->cached32_node)
  62                 return;
  63         curr = iovad->cached32_node;
  64         cached_iova = container_of(curr, struct iova, node);
  65
  66         if (free->pfn_lo >= cached_iova->pfn_lo) {
  67                 struct rb_node *node = rb_next(&free->node);
  68                 struct iova *iova = container_of(node, struct iova, node);
  69
  70                 /* only cache if it's below 32bit pfn */
  71                 if (node && iova->pfn_lo < iovad->dma_32bit_pfn)
  72                         iovad->cached32_node = node;
  73                 else
  74                         iovad->cached32_node = NULL;
  75         }
  76 }
  77
  78 /* Computes the padding size required, to make the
  79  * the start address naturally aligned on its size
  80  */
  81 static int
  82 iova_get_pad_size(int size, unsigned int limit_pfn)
  83 {
  84         unsigned int pad_size = 0;
  85         unsigned int order = ilog2(size);
  86
  87         if (order)
  88                 pad_size = (limit_pfn + 1) % (1 << order);
  89
  90         return pad_size;
  91 }
  92
  93 static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
  94                 unsigned long size, unsigned long limit_pfn,
  95                         struct iova *new, bool size_aligned)
  96 {
  97         struct rb_node *prev, *curr = NULL;
  98         unsigned long flags;
  99         unsigned long saved_pfn;
 100         unsigned int pad_size = 0;
 101
 102         /* Walk the tree backwards */
 103         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 104         saved_pfn = limit_pfn;
 105         curr = __get_cached_rbnode(iovad, &limit_pfn);
 106         prev = curr;
 107         while (curr) {
 108                 struct iova *curr_iova = container_of(curr, struct iova, node);
 109
 110                 if (limit_pfn < curr_iova->pfn_lo)
 111                         goto move_left;
 112                 else if (limit_pfn < curr_iova->pfn_hi)
 113                         goto adjust_limit_pfn;
 114                 else {
 115                         if (size_aligned)
 116                                 pad_size = iova_get_pad_size(size, limit_pfn);
 117                         if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
 118                                 break;  /* found a free slot */
 119                 }
 120 adjust_limit_pfn:
 121                 limit_pfn = curr_iova->pfn_lo - 1;
 122 move_left:
 123                 prev = curr;
 124                 curr = rb_prev(curr);
 125         }
 126
 127         if (!curr) {
 128                 if (size_aligned)
 129                         pad_size = iova_get_pad_size(size, limit_pfn);
 130                 if ((IOVA_START_PFN + size + pad_size) > limit_pfn) {
 131                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 132                         return -ENOMEM;
 133                 }
 134         }
 135
 136         /* pfn_lo will point to size aligned address if size_aligned is set */
 137         new->pfn_lo = limit_pfn - (size + pad_size) + 1;
 138         new->pfn_hi = new->pfn_lo + size - 1;
 139
 140         /* Insert the new_iova into domain rbtree by holding writer lock */
 141         /* Add new node and rebalance tree. */
 142         {
 143                 struct rb_node **entry, *parent = NULL;
 144
 145                 /* If we have 'prev', it's a valid place to start the
 146                    insertion. Otherwise, start from the root. */
 147                 if (prev)
 148                         entry = &prev;
 149                 else
 150                         entry = &iovad->rbroot.rb_node;
 151
 152                 /* Figure out where to put new node */
 153                 while (*entry) {
 154                         struct iova *this = container_of(*entry,
 155                                                         struct iova, node);
 156                         parent = *entry;
 157
 158                         if (new->pfn_lo < this->pfn_lo)
 159                                 entry = &((*entry)->rb_left);
 160                         else if (new->pfn_lo > this->pfn_lo)
 161                                 entry = &((*entry)->rb_right);
 162                         else
 163                                 BUG(); /* this should not happen */
 164                 }
 165
 166                 /* Add new node and rebalance tree. */
 167                 rb_link_node(&new->node, parent, entry);
 168                 rb_insert_color(&new->node, &iovad->rbroot);
 169         }
 170         __cached_rbnode_insert_update(iovad, saved_pfn, new);
 171
 172         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 173
 174
 175         return 0;
 176 }
 177
 178 static void
 179 iova_insert_rbtree(struct rb_root *root, struct iova *iova)
 180 {
 181         struct rb_node **new = &(root->rb_node), *parent = NULL;
 182         /* Figure out where to put new node */
 183         while (*new) {
 184                 struct iova *this = container_of(*new, struct iova, node);
 185                 parent = *new;
 186
 187                 if (iova->pfn_lo < this->pfn_lo)
 188                         new = &((*new)->rb_left);
 189                 else if (iova->pfn_lo > this->pfn_lo)
 190                         new = &((*new)->rb_right);
 191                 else
 192                         BUG(); /* this should not happen */
 193         }
 194         /* Add new node and rebalance tree. */
 195         rb_link_node(&iova->node, parent, new);
 196         rb_insert_color(&iova->node, root);
 197 }
 198
 199 /**
 200  * alloc_iova - allocates an iova
 201  * @iovad: - iova domain in question
 202  * @size: - size of page frames to allocate
 203  * @limit_pfn: - max limit address
 204  * @size_aligned: - set if size_aligned address range is required
 205  * This function allocates an iova in the range limit_pfn to IOVA_START_PFN
 206  * looking from limit_pfn instead from IOVA_START_PFN. If the size_aligned
 207  * flag is set then the allocated address iova->pfn_lo will be naturally
 208  * aligned on roundup_power_of_two(size).
 209  */
 210 struct iova *
 211 alloc_iova(struct iova_domain *iovad, unsigned long size,
 212         unsigned long limit_pfn,
 213         bool size_aligned)
 214 {
 215         struct iova *new_iova;
 216         int ret;
 217
 218         new_iova = alloc_iova_mem();
 219         if (!new_iova)
 220                 return NULL;
 221
 222         /* If size aligned is set then round the size to
 223          * to next power of two.
 224          */
 225         if (size_aligned)
 226                 size = __roundup_pow_of_two(size);
 227
 228         ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn,
 229                         new_iova, size_aligned);
 230
 231         if (ret) {
 232                 free_iova_mem(new_iova);
 233                 return NULL;
 234         }
 235
 236         return new_iova;
 237 }
 238
 239 /**
 240  * find_iova - find's an iova for a given pfn
 241  * @iovad: - iova domain in question.
 242  * @pfn: - page frame number
 243  * This function finds and returns an iova belonging to the
 244  * given doamin which matches the given pfn.
 245  */
 246 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 247 {
 248         unsigned long flags;
 249         struct rb_node *node;
 250
 251         /* Take the lock so that no other thread is manipulating the rbtree */
 252         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 253         node = iovad->rbroot.rb_node;
 254         while (node) {
 255                 struct iova *iova = container_of(node, struct iova, node);
 256
 257                 /* If pfn falls within iova's range, return iova */
 258                 if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) {
 259                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 260                         /* We are not holding the lock while this iova
 261                          * is referenced by the caller as the same thread
 262                          * which called this function also calls __free_iova()
 263                          * and it is by design that only one thread can possibly
 264                          * reference a particular iova and hence no conflict.
 265                          */
 266                         return iova;
 267                 }
 268
 269                 if (pfn < iova->pfn_lo)
 270                         node = node->rb_left;
 271                 else if (pfn > iova->pfn_lo)
 272                         node = node->rb_right;
 273         }
 274
 275         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 276         return NULL;
 277 }
 278
 279 /**
 280  * __free_iova - frees the given iova
 281  * @iovad: iova domain in question.
 282  * @iova: iova in question.
 283  * Frees the given iova belonging to the giving domain
 284  */
 285 void
 286 __free_iova(struct iova_domain *iovad, struct iova *iova)
 287 {
 288         unsigned long flags;
 289
 290         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 291         __cached_rbnode_delete_update(iovad, iova);
 292         rb_erase(&iova->node, &iovad->rbroot);
 293         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 294         free_iova_mem(iova);
 295 }
 296
 297 /**
 298  * free_iova - finds and frees the iova for a given pfn
 299  * @iovad: - iova domain in question.
 300  * @pfn: - pfn that is allocated previously
 301  * This functions finds an iova for a given pfn and then
 302  * frees the iova from that domain.
 303  */
 304 void
 305 free_iova(struct iova_domain *iovad, unsigned long pfn)
 306 {
 307         struct iova *iova = find_iova(iovad, pfn);
 308         if (iova)
 309                 __free_iova(iovad, iova);
 310
 311 }
 312
 313 /**
 314  * put_iova_domain - destroys the iova doamin
 315  * @iovad: - iova domain in question.
 316  * All the iova's in that domain are destroyed.
 317  */
 318 void put_iova_domain(struct iova_domain *iovad)
 319 {
 320         struct rb_node *node;
 321         unsigned long flags;
 322
 323         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 324         node = rb_first(&iovad->rbroot);
 325         while (node) {
 326                 struct iova *iova = container_of(node, struct iova, node);
 327                 rb_erase(node, &iovad->rbroot);
 328                 free_iova_mem(iova);
 329                 node = rb_first(&iovad->rbroot);
 330         }
 331         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 332 }
 333
 334 static int
 335 __is_range_overlap(struct rb_node *node,
 336         unsigned long pfn_lo, unsigned long pfn_hi)
 337 {
 338         struct iova *iova = container_of(node, struct iova, node);
 339
 340         if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
 341                 return 1;
 342         return 0;
 343 }
 344
 345 static struct iova *
 346 __insert_new_range(struct iova_domain *iovad,
 347         unsigned long pfn_lo, unsigned long pfn_hi)
 348 {
 349         struct iova *iova;
 350
 351         iova = alloc_iova_mem();
 352         if (!iova)
 353                 return iova;
 354
 355         iova->pfn_hi = pfn_hi;
 356         iova->pfn_lo = pfn_lo;
 357         iova_insert_rbtree(&iovad->rbroot, iova);
 358         return iova;
 359 }
 360
 361 static void
 362 __adjust_overlap_range(struct iova *iova,
 363         unsigned long *pfn_lo, unsigned long *pfn_hi)
 364 {
 365         if (*pfn_lo < iova->pfn_lo)
 366                 iova->pfn_lo = *pfn_lo;
 367         if (*pfn_hi > iova->pfn_hi)
 368                 *pfn_lo = iova->pfn_hi + 1;
 369 }
 370
 371 /**
 372  * reserve_iova - reserves an iova in the given range
 373  * @iovad: - iova domain pointer
 374  * @pfn_lo: - lower page frame address
 375  * @pfn_hi:- higher pfn adderss
 376  * This function allocates reserves the address range from pfn_lo to pfn_hi so
 377  * that this address is not dished out as part of alloc_iova.
 378  */
 379 struct iova *
 380 reserve_iova(struct iova_domain *iovad,
 381         unsigned long pfn_lo, unsigned long pfn_hi)
 382 {
 383         struct rb_node *node;
 384         unsigned long flags;
 385         struct iova *iova;
 386         unsigned int overlap = 0;
 387
 388         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 389         for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
 390                 if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
 391                         iova = container_of(node, struct iova, node);
 392                         __adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
 393                         if ((pfn_lo >= iova->pfn_lo) &&
 394                                 (pfn_hi <= iova->pfn_hi))
 395                                 goto finish;
 396                         overlap = 1;
 397
 398                 } else if (overlap)
 399                                 break;
 400         }
 401
 402         /* We are here either because this is the first reserver node
 403          * or need to insert remaining non overlap addr range
 404          */
 405         iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
 406 finish:
 407
 408         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 409         return iova;
 410 }
 411
 412 /**
 413  * copy_reserved_iova - copies the reserved between domains
 414  * @from: - source doamin from where to copy
 415  * @to: - destination domin where to copy
 416  * This function copies reserved iova's from one doamin to
 417  * other.
 418  */
 419 void
 420 copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
 421 {
 422         unsigned long flags;
 423         struct rb_node *node;
 424
 425         spin_lock_irqsave(&from->iova_rbtree_lock, flags);
 426         for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
 427                 struct iova *iova = container_of(node, struct iova, node);
 428                 struct iova *new_iova;
 429                 new_iova = reserve_iova(to, iova->pfn_lo, iova->pfn_hi);
 430                 if (!new_iova)
 431                         printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
 432                                 iova->pfn_lo, iova->pfn_lo);
 433         }
 434         spin_unlock_irqrestore(&from->iova_rbtree_lock, flags);
 435 }