drivers/pci/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                 iovad->cached32_node = rb_next(&free->node);
  68 }
  69
  70 /* Computes the padding size required, to make the
  71  * the start address naturally aligned on its size
  72  */
  73 static int
  74 iova_get_pad_size(int size, unsigned int limit_pfn)
  75 {
  76         unsigned int pad_size = 0;
  77         unsigned int order = ilog2(size);
  78
  79         if (order)
  80                 pad_size = (limit_pfn + 1) % (1 << order);
  81
  82         return pad_size;
  83 }
  84
  85 static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
  86                 unsigned long size, unsigned long limit_pfn,
  87                         struct iova *new, bool size_aligned)
  88 {
  89         struct rb_node *prev, *curr = NULL;
  90         unsigned long flags;
  91         unsigned long saved_pfn;
  92         unsigned int pad_size = 0;
  93
  94         /* Walk the tree backwards */
  95         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  96         saved_pfn = limit_pfn;
  97         curr = __get_cached_rbnode(iovad, &limit_pfn);
  98         prev = curr;
  99         while (curr) {
 100                 struct iova *curr_iova = container_of(curr, struct iova, node);
 101
 102                 if (limit_pfn < curr_iova->pfn_lo)
 103                         goto move_left;
 104                 else if (limit_pfn < curr_iova->pfn_hi)
 105                         goto adjust_limit_pfn;
 106                 else {
 107                         if (size_aligned)
 108                                 pad_size = iova_get_pad_size(size, limit_pfn);
 109                         if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
 110                                 break;  /* found a free slot */
 111                 }
 112 adjust_limit_pfn:
 113                 limit_pfn = curr_iova->pfn_lo - 1;
 114 move_left:
 115                 prev = curr;
 116                 curr = rb_prev(curr);
 117         }
 118
 119         if (!curr) {
 120                 if (size_aligned)
 121                         pad_size = iova_get_pad_size(size, limit_pfn);
 122                 if ((IOVA_START_PFN + size + pad_size) > limit_pfn) {
 123                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 124                         return -ENOMEM;
 125                 }
 126         }
 127
 128         /* pfn_lo will point to size aligned address if size_aligned is set */
 129         new->pfn_lo = limit_pfn - (size + pad_size) + 1;
 130         new->pfn_hi = new->pfn_lo + size - 1;
 131
 132         /* Insert the new_iova into domain rbtree by holding writer lock */
 133         /* Add new node and rebalance tree. */
 134         {
 135                 struct rb_node **entry, *parent = NULL;
 136
 137                 /* If we have 'prev', it's a valid place to start the
 138                    insertion. Otherwise, start from the root. */
 139                 if (prev)
 140                         entry = &prev;
 141                 else
 142                         entry = &iovad->rbroot.rb_node;
 143
 144                 /* Figure out where to put new node */
 145                 while (*entry) {
 146                         struct iova *this = container_of(*entry,
 147                                                         struct iova, node);
 148                         parent = *entry;
 149
 150                         if (new->pfn_lo < this->pfn_lo)
 151                                 entry = &((*entry)->rb_left);
 152                         else if (new->pfn_lo > this->pfn_lo)
 153                                 entry = &((*entry)->rb_right);
 154                         else
 155                                 BUG(); /* this should not happen */
 156                 }
 157
 158                 /* Add new node and rebalance tree. */
 159                 rb_link_node(&new->node, parent, entry);
 160                 rb_insert_color(&new->node, &iovad->rbroot);
 161         }
 162         __cached_rbnode_insert_update(iovad, saved_pfn, new);
 163
 164         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 165
 166
 167         return 0;
 168 }
 169
 170 static void
 171 iova_insert_rbtree(struct rb_root *root, struct iova *iova)
 172 {
 173         struct rb_node **new = &(root->rb_node), *parent = NULL;
 174         /* Figure out where to put new node */
 175         while (*new) {
 176                 struct iova *this = container_of(*new, struct iova, node);
 177                 parent = *new;
 178
 179                 if (iova->pfn_lo < this->pfn_lo)
 180                         new = &((*new)->rb_left);
 181                 else if (iova->pfn_lo > this->pfn_lo)
 182                         new = &((*new)->rb_right);
 183                 else
 184                         BUG(); /* this should not happen */
 185         }
 186         /* Add new node and rebalance tree. */
 187         rb_link_node(&iova->node, parent, new);
 188         rb_insert_color(&iova->node, root);
 189 }
 190
 191 /**
 192  * alloc_iova - allocates an iova
 193  * @iovad - iova domain in question
 194  * @size - size of page frames to allocate
 195  * @limit_pfn - max limit address
 196  * @size_aligned - set if size_aligned address range is required
 197  * This function allocates an iova in the range limit_pfn to IOVA_START_PFN
 198  * looking from limit_pfn instead from IOVA_START_PFN. If the size_aligned
 199  * flag is set then the allocated address iova->pfn_lo will be naturally
 200  * aligned on roundup_power_of_two(size).
 201  */
 202 struct iova *
 203 alloc_iova(struct iova_domain *iovad, unsigned long size,
 204         unsigned long limit_pfn,
 205         bool size_aligned)
 206 {
 207         struct iova *new_iova;
 208         int ret;
 209
 210         new_iova = alloc_iova_mem();
 211         if (!new_iova)
 212                 return NULL;
 213
 214         /* If size aligned is set then round the size to
 215          * to next power of two.
 216          */
 217         if (size_aligned)
 218                 size = __roundup_pow_of_two(size);
 219
 220         ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn,
 221                         new_iova, size_aligned);
 222
 223         if (ret) {
 224                 free_iova_mem(new_iova);
 225                 return NULL;
 226         }
 227
 228         return new_iova;
 229 }
 230
 231 /**
 232  * find_iova - find's an iova for a given pfn
 233  * @iovad - iova domain in question.
 234  * pfn - page frame number
 235  * This function finds and returns an iova belonging to the
 236  * given doamin which matches the given pfn.
 237  */
 238 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 239 {
 240         unsigned long flags;
 241         struct rb_node *node;
 242
 243         /* Take the lock so that no other thread is manipulating the rbtree */
 244         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 245         node = iovad->rbroot.rb_node;
 246         while (node) {
 247                 struct iova *iova = container_of(node, struct iova, node);
 248
 249                 /* If pfn falls within iova's range, return iova */
 250                 if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) {
 251                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 252                         /* We are not holding the lock while this iova
 253                          * is referenced by the caller as the same thread
 254                          * which called this function also calls __free_iova()
 255                          * and it is by desing that only one thread can possibly
 256                          * reference a particular iova and hence no conflict.
 257                          */
 258                         return iova;
 259                 }
 260
 261                 if (pfn < iova->pfn_lo)
 262                         node = node->rb_left;
 263                 else if (pfn > iova->pfn_lo)
 264                         node = node->rb_right;
 265         }
 266
 267         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 268         return NULL;
 269 }
 270
 271 /**
 272  * __free_iova - frees the given iova
 273  * @iovad: iova domain in question.
 274  * @iova: iova in question.
 275  * Frees the given iova belonging to the giving domain
 276  */
 277 void
 278 __free_iova(struct iova_domain *iovad, struct iova *iova)
 279 {
 280         unsigned long flags;
 281
 282         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 283         __cached_rbnode_delete_update(iovad, iova);
 284         rb_erase(&iova->node, &iovad->rbroot);
 285         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 286         free_iova_mem(iova);
 287 }
 288
 289 /**
 290  * free_iova - finds and frees the iova for a given pfn
 291  * @iovad: - iova domain in question.
 292  * @pfn: - pfn that is allocated previously
 293  * This functions finds an iova for a given pfn and then
 294  * frees the iova from that domain.
 295  */
 296 void
 297 free_iova(struct iova_domain *iovad, unsigned long pfn)
 298 {
 299         struct iova *iova = find_iova(iovad, pfn);
 300         if (iova)
 301                 __free_iova(iovad, iova);
 302
 303 }
 304
 305 /**
 306  * put_iova_domain - destroys the iova doamin
 307  * @iovad: - iova domain in question.
 308  * All the iova's in that domain are destroyed.
 309  */
 310 void put_iova_domain(struct iova_domain *iovad)
 311 {
 312         struct rb_node *node;
 313         unsigned long flags;
 314
 315         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 316         node = rb_first(&iovad->rbroot);
 317         while (node) {
 318                 struct iova *iova = container_of(node, struct iova, node);
 319                 rb_erase(node, &iovad->rbroot);
 320                 free_iova_mem(iova);
 321                 node = rb_first(&iovad->rbroot);
 322         }
 323         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 324 }
 325
 326 static int
 327 __is_range_overlap(struct rb_node *node,
 328         unsigned long pfn_lo, unsigned long pfn_hi)
 329 {
 330         struct iova *iova = container_of(node, struct iova, node);
 331
 332         if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
 333                 return 1;
 334         return 0;
 335 }
 336
 337 static struct iova *
 338 __insert_new_range(struct iova_domain *iovad,
 339         unsigned long pfn_lo, unsigned long pfn_hi)
 340 {
 341         struct iova *iova;
 342
 343         iova = alloc_iova_mem();
 344         if (!iova)
 345                 return iova;
 346
 347         iova->pfn_hi = pfn_hi;
 348         iova->pfn_lo = pfn_lo;
 349         iova_insert_rbtree(&iovad->rbroot, iova);
 350         return iova;
 351 }
 352
 353 static void
 354 __adjust_overlap_range(struct iova *iova,
 355         unsigned long *pfn_lo, unsigned long *pfn_hi)
 356 {
 357         if (*pfn_lo < iova->pfn_lo)
 358                 iova->pfn_lo = *pfn_lo;
 359         if (*pfn_hi > iova->pfn_hi)
 360                 *pfn_lo = iova->pfn_hi + 1;
 361 }
 362
 363 /**
 364  * reserve_iova - reserves an iova in the given range
 365  * @iovad: - iova domain pointer
 366  * @pfn_lo: - lower page frame address
 367  * @pfn_hi:- higher pfn adderss
 368  * This function allocates reserves the address range from pfn_lo to pfn_hi so
 369  * that this address is not dished out as part of alloc_iova.
 370  */
 371 struct iova *
 372 reserve_iova(struct iova_domain *iovad,
 373         unsigned long pfn_lo, unsigned long pfn_hi)
 374 {
 375         struct rb_node *node;
 376         unsigned long flags;
 377         struct iova *iova;
 378         unsigned int overlap = 0;
 379
 380         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 381         for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
 382                 if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
 383                         iova = container_of(node, struct iova, node);
 384                         __adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
 385                         if ((pfn_lo >= iova->pfn_lo) &&
 386                                 (pfn_hi <= iova->pfn_hi))
 387                                 goto finish;
 388                         overlap = 1;
 389
 390                 } else if (overlap)
 391                                 break;
 392         }
 393
 394         /* We are here either becasue this is the first reserver node
 395          * or need to insert remaining non overlap addr range
 396          */
 397         iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
 398 finish:
 399
 400         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 401         return iova;
 402 }
 403
 404 /**
 405  * copy_reserved_iova - copies the reserved between domains
 406  * @from: - source doamin from where to copy
 407  * @to: - destination domin where to copy
 408  * This function copies reserved iova's from one doamin to
 409  * other.
 410  */
 411 void
 412 copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
 413 {
 414         unsigned long flags;
 415         struct rb_node *node;
 416
 417         spin_lock_irqsave(&from->iova_rbtree_lock, flags);
 418         for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
 419                 struct iova *iova = container_of(node, struct iova, node);
 420                 struct iova *new_iova;
 421                 new_iova = reserve_iova(to, iova->pfn_lo, iova->pfn_hi);
 422                 if (!new_iova)
 423                         printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
 424                                 iova->pfn_lo, iova->pfn_lo);
 425         }
 426         spin_unlock_irqrestore(&from->iova_rbtree_lock, flags);
 427 }