drivers/pci/iova.c

   1 /*
   2  * Copyright (c) 2006, Intel Corporation.
   3  *
   4  * This file is released under the GPLv2.
   5  *
   6  * Copyright (C) 2006 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   7  */
   8
   9 #include "iova.h"
  10
  11 void
  12 init_iova_domain(struct iova_domain *iovad)
  13 {
  14         spin_lock_init(&iovad->iova_alloc_lock);
  15         spin_lock_init(&iovad->iova_rbtree_lock);
  16         iovad->rbroot = RB_ROOT;
  17         iovad->cached32_node = NULL;
  18
  19 }
  20
  21 static struct rb_node *
  22 __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
  23 {
  24         if ((*limit_pfn != DMA_32BIT_PFN) ||
  25                 (iovad->cached32_node == NULL))
  26                 return rb_last(&iovad->rbroot);
  27         else {
  28                 struct rb_node *prev_node = rb_prev(iovad->cached32_node);
  29                 struct iova *curr_iova =
  30                         container_of(iovad->cached32_node, struct iova, node);
  31                 *limit_pfn = curr_iova->pfn_lo - 1;
  32                 return prev_node;
  33         }
  34 }
  35
  36 static void
  37 __cached_rbnode_insert_update(struct iova_domain *iovad,
  38         unsigned long limit_pfn, struct iova *new)
  39 {
  40         if (limit_pfn != DMA_32BIT_PFN)
  41                 return;
  42         iovad->cached32_node = &new->node;
  43 }
  44
  45 static void
  46 __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
  47 {
  48         struct iova *cached_iova;
  49         struct rb_node *curr;
  50
  51         if (!iovad->cached32_node)
  52                 return;
  53         curr = iovad->cached32_node;
  54         cached_iova = container_of(curr, struct iova, node);
  55
  56         if (free->pfn_lo >= cached_iova->pfn_lo)
  57                 iovad->cached32_node = rb_next(&free->node);
  58 }
  59
  60 /* Computes the padding size required, to make the
  61  * the start address naturally aligned on its size
  62  */
  63 static int
  64 iova_get_pad_size(int size, unsigned int limit_pfn)
  65 {
  66         unsigned int pad_size = 0;
  67         unsigned int order = ilog2(size);
  68
  69         if (order)
  70                 pad_size = (limit_pfn + 1) % (1 << order);
  71
  72         return pad_size;
  73 }
  74
  75 static int __alloc_iova_range(struct iova_domain *iovad, unsigned long size,
  76                 unsigned long limit_pfn, struct iova *new, bool size_aligned)
  77 {
  78         struct rb_node *curr = NULL;
  79         unsigned long flags;
  80         unsigned long saved_pfn;
  81         unsigned int pad_size = 0;
  82
  83         /* Walk the tree backwards */
  84         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  85         saved_pfn = limit_pfn;
  86         curr = __get_cached_rbnode(iovad, &limit_pfn);
  87         while (curr) {
  88                 struct iova *curr_iova = container_of(curr, struct iova, node);
  89                 if (limit_pfn < curr_iova->pfn_lo)
  90                         goto move_left;
  91                 else if (limit_pfn < curr_iova->pfn_hi)
  92                         goto adjust_limit_pfn;
  93                 else {
  94                         if (size_aligned)
  95                                 pad_size = iova_get_pad_size(size, limit_pfn);
  96                         if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
  97                                 break;  /* found a free slot */
  98                 }
  99 adjust_limit_pfn:
 100                 limit_pfn = curr_iova->pfn_lo - 1;
 101 move_left:
 102                 curr = rb_prev(curr);
 103         }
 104
 105         if (!curr) {
 106                 if (size_aligned)
 107                         pad_size = iova_get_pad_size(size, limit_pfn);
 108                 if ((IOVA_START_PFN + size + pad_size) > limit_pfn) {
 109                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 110                         return -ENOMEM;
 111                 }
 112         }
 113
 114         /* pfn_lo will point to size aligned address if size_aligned is set */
 115         new->pfn_lo = limit_pfn - (size + pad_size) + 1;
 116         new->pfn_hi = new->pfn_lo + size - 1;
 117
 118         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 119         return 0;
 120 }
 121
 122 static void
 123 iova_insert_rbtree(struct rb_root *root, struct iova *iova)
 124 {
 125         struct rb_node **new = &(root->rb_node), *parent = NULL;
 126         /* Figure out where to put new node */
 127         while (*new) {
 128                 struct iova *this = container_of(*new, struct iova, node);
 129                 parent = *new;
 130
 131                 if (iova->pfn_lo < this->pfn_lo)
 132                         new = &((*new)->rb_left);
 133                 else if (iova->pfn_lo > this->pfn_lo)
 134                         new = &((*new)->rb_right);
 135                 else
 136                         BUG(); /* this should not happen */
 137         }
 138         /* Add new node and rebalance tree. */
 139         rb_link_node(&iova->node, parent, new);
 140         rb_insert_color(&iova->node, root);
 141 }
 142
 143 /**
 144  * alloc_iova - allocates an iova
 145  * @iovad - iova domain in question
 146  * @size - size of page frames to allocate
 147  * @limit_pfn - max limit address
 148  * @size_aligned - set if size_aligned address range is required
 149  * This function allocates an iova in the range limit_pfn to IOVA_START_PFN
 150  * looking from limit_pfn instead from IOVA_START_PFN. If the size_aligned
 151  * flag is set then the allocated address iova->pfn_lo will be naturally
 152  * aligned on roundup_power_of_two(size).
 153  */
 154 struct iova *
 155 alloc_iova(struct iova_domain *iovad, unsigned long size,
 156         unsigned long limit_pfn,
 157         bool size_aligned)
 158 {
 159         unsigned long flags;
 160         struct iova *new_iova;
 161         int ret;
 162
 163         new_iova = alloc_iova_mem();
 164         if (!new_iova)
 165                 return NULL;
 166
 167         /* If size aligned is set then round the size to
 168          * to next power of two.
 169          */
 170         if (size_aligned)
 171                 size = __roundup_pow_of_two(size);
 172
 173         spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
 174         ret = __alloc_iova_range(iovad, size, limit_pfn, new_iova,
 175                         size_aligned);
 176
 177         if (ret) {
 178                 spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
 179                 free_iova_mem(new_iova);
 180                 return NULL;
 181         }
 182
 183         /* Insert the new_iova into domain rbtree by holding writer lock */
 184         spin_lock(&iovad->iova_rbtree_lock);
 185         iova_insert_rbtree(&iovad->rbroot, new_iova);
 186         __cached_rbnode_insert_update(iovad, limit_pfn, new_iova);
 187         spin_unlock(&iovad->iova_rbtree_lock);
 188
 189         spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
 190
 191         return new_iova;
 192 }
 193
 194 /**
 195  * find_iova - find's an iova for a given pfn
 196  * @iovad - iova domain in question.
 197  * pfn - page frame number
 198  * This function finds and returns an iova belonging to the
 199  * given doamin which matches the given pfn.
 200  */
 201 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 202 {
 203         unsigned long flags;
 204         struct rb_node *node;
 205
 206         /* Take the lock so that no other thread is manipulating the rbtree */
 207         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 208         node = iovad->rbroot.rb_node;
 209         while (node) {
 210                 struct iova *iova = container_of(node, struct iova, node);
 211
 212                 /* If pfn falls within iova's range, return iova */
 213                 if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) {
 214                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 215                         /* We are not holding the lock while this iova
 216                          * is referenced by the caller as the same thread
 217                          * which called this function also calls __free_iova()
 218                          * and it is by desing that only one thread can possibly
 219                          * reference a particular iova and hence no conflict.
 220                          */
 221                         return iova;
 222                 }
 223
 224                 if (pfn < iova->pfn_lo)
 225                         node = node->rb_left;
 226                 else if (pfn > iova->pfn_lo)
 227                         node = node->rb_right;
 228         }
 229
 230         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 231         return NULL;
 232 }
 233
 234 /**
 235  * __free_iova - frees the given iova
 236  * @iovad: iova domain in question.
 237  * @iova: iova in question.
 238  * Frees the given iova belonging to the giving domain
 239  */
 240 void
 241 __free_iova(struct iova_domain *iovad, struct iova *iova)
 242 {
 243         unsigned long flags;
 244
 245         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 246         __cached_rbnode_delete_update(iovad, iova);
 247         rb_erase(&iova->node, &iovad->rbroot);
 248         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 249         free_iova_mem(iova);
 250 }
 251
 252 /**
 253  * free_iova - finds and frees the iova for a given pfn
 254  * @iovad: - iova domain in question.
 255  * @pfn: - pfn that is allocated previously
 256  * This functions finds an iova for a given pfn and then
 257  * frees the iova from that domain.
 258  */
 259 void
 260 free_iova(struct iova_domain *iovad, unsigned long pfn)
 261 {
 262         struct iova *iova = find_iova(iovad, pfn);
 263         if (iova)
 264                 __free_iova(iovad, iova);
 265
 266 }
 267
 268 /**
 269  * put_iova_domain - destroys the iova doamin
 270  * @iovad: - iova domain in question.
 271  * All the iova's in that domain are destroyed.
 272  */
 273 void put_iova_domain(struct iova_domain *iovad)
 274 {
 275         struct rb_node *node;
 276         unsigned long flags;
 277
 278         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 279         node = rb_first(&iovad->rbroot);
 280         while (node) {
 281                 struct iova *iova = container_of(node, struct iova, node);
 282                 rb_erase(node, &iovad->rbroot);
 283                 free_iova_mem(iova);
 284                 node = rb_first(&iovad->rbroot);
 285         }
 286         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 287 }
 288
 289 static int
 290 __is_range_overlap(struct rb_node *node,
 291         unsigned long pfn_lo, unsigned long pfn_hi)
 292 {
 293         struct iova *iova = container_of(node, struct iova, node);
 294
 295         if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
 296                 return 1;
 297         return 0;
 298 }
 299
 300 static struct iova *
 301 __insert_new_range(struct iova_domain *iovad,
 302         unsigned long pfn_lo, unsigned long pfn_hi)
 303 {
 304         struct iova *iova;
 305
 306         iova = alloc_iova_mem();
 307         if (!iova)
 308                 return iova;
 309
 310         iova->pfn_hi = pfn_hi;
 311         iova->pfn_lo = pfn_lo;
 312         iova_insert_rbtree(&iovad->rbroot, iova);
 313         return iova;
 314 }
 315
 316 static void
 317 __adjust_overlap_range(struct iova *iova,
 318         unsigned long *pfn_lo, unsigned long *pfn_hi)
 319 {
 320         if (*pfn_lo < iova->pfn_lo)
 321                 iova->pfn_lo = *pfn_lo;
 322         if (*pfn_hi > iova->pfn_hi)
 323                 *pfn_lo = iova->pfn_hi + 1;
 324 }
 325
 326 /**
 327  * reserve_iova - reserves an iova in the given range
 328  * @iovad: - iova domain pointer
 329  * @pfn_lo: - lower page frame address
 330  * @pfn_hi:- higher pfn adderss
 331  * This function allocates reserves the address range from pfn_lo to pfn_hi so
 332  * that this address is not dished out as part of alloc_iova.
 333  */
 334 struct iova *
 335 reserve_iova(struct iova_domain *iovad,
 336         unsigned long pfn_lo, unsigned long pfn_hi)
 337 {
 338         struct rb_node *node;
 339         unsigned long flags;
 340         struct iova *iova;
 341         unsigned int overlap = 0;
 342
 343         spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
 344         spin_lock(&iovad->iova_rbtree_lock);
 345         for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
 346                 if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
 347                         iova = container_of(node, struct iova, node);
 348                         __adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
 349                         if ((pfn_lo >= iova->pfn_lo) &&
 350                                 (pfn_hi <= iova->pfn_hi))
 351                                 goto finish;
 352                         overlap = 1;
 353
 354                 } else if (overlap)
 355                                 break;
 356         }
 357
 358         /* We are here either becasue this is the first reserver node
 359          * or need to insert remaining non overlap addr range
 360          */
 361         iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
 362 finish:
 363
 364         spin_unlock(&iovad->iova_rbtree_lock);
 365         spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
 366         return iova;
 367 }
 368
 369 /**
 370  * copy_reserved_iova - copies the reserved between domains
 371  * @from: - source doamin from where to copy
 372  * @to: - destination domin where to copy
 373  * This function copies reserved iova's from one doamin to
 374  * other.
 375  */
 376 void
 377 copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
 378 {
 379         unsigned long flags;
 380         struct rb_node *node;
 381
 382         spin_lock_irqsave(&from->iova_alloc_lock, flags);
 383         spin_lock(&from->iova_rbtree_lock);
 384         for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
 385                 struct iova *iova = container_of(node, struct iova, node);
 386                 struct iova *new_iova;
 387                 new_iova = reserve_iova(to, iova->pfn_lo, iova->pfn_hi);
 388                 if (!new_iova)
 389                         printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
 390                                 iova->pfn_lo, iova->pfn_lo);
 391         }
 392         spin_unlock(&from->iova_rbtree_lock);
 393         spin_unlock_irqrestore(&from->iova_alloc_lock, flags);
 394 }