drivers/pci/iova.c

   1 /*
   2  * Copyright (c) 2006, Intel Corporation.
   3  *
   4  * This file is released under the GPLv2.
   5  *
   6  * Copyright (C) 2006-2008 Intel Corporation
   7  * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   8  */
   9
  10 #include "iova.h"
  11
  12 void
  13 init_iova_domain(struct iova_domain *iovad, unsigned long pfn_32bit)
  14 {
  15         spin_lock_init(&iovad->iova_alloc_lock);
  16         spin_lock_init(&iovad->iova_rbtree_lock);
  17         iovad->rbroot = RB_ROOT;
  18         iovad->cached32_node = NULL;
  19         iovad->dma_32bit_pfn = pfn_32bit;
  20 }
  21
  22 static struct rb_node *
  23 __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
  24 {
  25         if ((*limit_pfn != iovad->dma_32bit_pfn) ||
  26                 (iovad->cached32_node == NULL))
  27                 return rb_last(&iovad->rbroot);
  28         else {
  29                 struct rb_node *prev_node = rb_prev(iovad->cached32_node);
  30                 struct iova *curr_iova =
  31                         container_of(iovad->cached32_node, struct iova, node);
  32                 *limit_pfn = curr_iova->pfn_lo - 1;
  33                 return prev_node;
  34         }
  35 }
  36
  37 static void
  38 __cached_rbnode_insert_update(struct iova_domain *iovad,
  39         unsigned long limit_pfn, struct iova *new)
  40 {
  41         if (limit_pfn != iovad->dma_32bit_pfn)
  42                 return;
  43         iovad->cached32_node = &new->node;
  44 }
  45
  46 static void
  47 __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
  48 {
  49         struct iova *cached_iova;
  50         struct rb_node *curr;
  51
  52         if (!iovad->cached32_node)
  53                 return;
  54         curr = iovad->cached32_node;
  55         cached_iova = container_of(curr, struct iova, node);
  56
  57         if (free->pfn_lo >= cached_iova->pfn_lo)
  58                 iovad->cached32_node = rb_next(&free->node);
  59 }
  60
  61 /* Computes the padding size required, to make the
  62  * the start address naturally aligned on its size
  63  */
  64 static int
  65 iova_get_pad_size(int size, unsigned int limit_pfn)
  66 {
  67         unsigned int pad_size = 0;
  68         unsigned int order = ilog2(size);
  69
  70         if (order)
  71                 pad_size = (limit_pfn + 1) % (1 << order);
  72
  73         return pad_size;
  74 }
  75
  76 static int __alloc_iova_range(struct iova_domain *iovad, unsigned long size,
  77                 unsigned long limit_pfn, struct iova *new, bool size_aligned)
  78 {
  79         struct rb_node *curr = NULL;
  80         unsigned long flags;
  81         unsigned long saved_pfn;
  82         unsigned int pad_size = 0;
  83
  84         /* Walk the tree backwards */
  85         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  86         saved_pfn = limit_pfn;
  87         curr = __get_cached_rbnode(iovad, &limit_pfn);
  88         while (curr) {
  89                 struct iova *curr_iova = container_of(curr, struct iova, node);
  90                 if (limit_pfn < curr_iova->pfn_lo)
  91                         goto move_left;
  92                 else if (limit_pfn < curr_iova->pfn_hi)
  93                         goto adjust_limit_pfn;
  94                 else {
  95                         if (size_aligned)
  96                                 pad_size = iova_get_pad_size(size, limit_pfn);
  97                         if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
  98                                 break;  /* found a free slot */
  99                 }
 100 adjust_limit_pfn:
 101                 limit_pfn = curr_iova->pfn_lo - 1;
 102 move_left:
 103                 curr = rb_prev(curr);
 104         }
 105
 106         if (!curr) {
 107                 if (size_aligned)
 108                         pad_size = iova_get_pad_size(size, limit_pfn);
 109                 if ((IOVA_START_PFN + size + pad_size) > limit_pfn) {
 110                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 111                         return -ENOMEM;
 112                 }
 113         }
 114
 115         /* pfn_lo will point to size aligned address if size_aligned is set */
 116         new->pfn_lo = limit_pfn - (size + pad_size) + 1;
 117         new->pfn_hi = new->pfn_lo + size - 1;
 118
 119         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 120         return 0;
 121 }
 122
 123 static void
 124 iova_insert_rbtree(struct rb_root *root, struct iova *iova)
 125 {
 126         struct rb_node **new = &(root->rb_node), *parent = NULL;
 127         /* Figure out where to put new node */
 128         while (*new) {
 129                 struct iova *this = container_of(*new, struct iova, node);
 130                 parent = *new;
 131
 132                 if (iova->pfn_lo < this->pfn_lo)
 133                         new = &((*new)->rb_left);
 134                 else if (iova->pfn_lo > this->pfn_lo)
 135                         new = &((*new)->rb_right);
 136                 else
 137                         BUG(); /* this should not happen */
 138         }
 139         /* Add new node and rebalance tree. */
 140         rb_link_node(&iova->node, parent, new);
 141         rb_insert_color(&iova->node, root);
 142 }
 143
 144 /**
 145  * alloc_iova - allocates an iova
 146  * @iovad - iova domain in question
 147  * @size - size of page frames to allocate
 148  * @limit_pfn - max limit address
 149  * @size_aligned - set if size_aligned address range is required
 150  * This function allocates an iova in the range limit_pfn to IOVA_START_PFN
 151  * looking from limit_pfn instead from IOVA_START_PFN. If the size_aligned
 152  * flag is set then the allocated address iova->pfn_lo will be naturally
 153  * aligned on roundup_power_of_two(size).
 154  */
 155 struct iova *
 156 alloc_iova(struct iova_domain *iovad, unsigned long size,
 157         unsigned long limit_pfn,
 158         bool size_aligned)
 159 {
 160         unsigned long flags;
 161         struct iova *new_iova;
 162         int ret;
 163
 164         new_iova = alloc_iova_mem();
 165         if (!new_iova)
 166                 return NULL;
 167
 168         /* If size aligned is set then round the size to
 169          * to next power of two.
 170          */
 171         if (size_aligned)
 172                 size = __roundup_pow_of_two(size);
 173
 174         spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
 175         ret = __alloc_iova_range(iovad, size, limit_pfn, new_iova,
 176                         size_aligned);
 177
 178         if (ret) {
 179                 spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
 180                 free_iova_mem(new_iova);
 181                 return NULL;
 182         }
 183
 184         /* Insert the new_iova into domain rbtree by holding writer lock */
 185         spin_lock(&iovad->iova_rbtree_lock);
 186         iova_insert_rbtree(&iovad->rbroot, new_iova);
 187         __cached_rbnode_insert_update(iovad, limit_pfn, new_iova);
 188         spin_unlock(&iovad->iova_rbtree_lock);
 189
 190         spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
 191
 192         return new_iova;
 193 }
 194
 195 /**
 196  * find_iova - find's an iova for a given pfn
 197  * @iovad - iova domain in question.
 198  * pfn - page frame number
 199  * This function finds and returns an iova belonging to the
 200  * given doamin which matches the given pfn.
 201  */
 202 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
 203 {
 204         unsigned long flags;
 205         struct rb_node *node;
 206
 207         /* Take the lock so that no other thread is manipulating the rbtree */
 208         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 209         node = iovad->rbroot.rb_node;
 210         while (node) {
 211                 struct iova *iova = container_of(node, struct iova, node);
 212
 213                 /* If pfn falls within iova's range, return iova */
 214                 if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) {
 215                         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 216                         /* We are not holding the lock while this iova
 217                          * is referenced by the caller as the same thread
 218                          * which called this function also calls __free_iova()
 219                          * and it is by desing that only one thread can possibly
 220                          * reference a particular iova and hence no conflict.
 221                          */
 222                         return iova;
 223                 }
 224
 225                 if (pfn < iova->pfn_lo)
 226                         node = node->rb_left;
 227                 else if (pfn > iova->pfn_lo)
 228                         node = node->rb_right;
 229         }
 230
 231         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 232         return NULL;
 233 }
 234
 235 /**
 236  * __free_iova - frees the given iova
 237  * @iovad: iova domain in question.
 238  * @iova: iova in question.
 239  * Frees the given iova belonging to the giving domain
 240  */
 241 void
 242 __free_iova(struct iova_domain *iovad, struct iova *iova)
 243 {
 244         unsigned long flags;
 245
 246         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 247         __cached_rbnode_delete_update(iovad, iova);
 248         rb_erase(&iova->node, &iovad->rbroot);
 249         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 250         free_iova_mem(iova);
 251 }
 252
 253 /**
 254  * free_iova - finds and frees the iova for a given pfn
 255  * @iovad: - iova domain in question.
 256  * @pfn: - pfn that is allocated previously
 257  * This functions finds an iova for a given pfn and then
 258  * frees the iova from that domain.
 259  */
 260 void
 261 free_iova(struct iova_domain *iovad, unsigned long pfn)
 262 {
 263         struct iova *iova = find_iova(iovad, pfn);
 264         if (iova)
 265                 __free_iova(iovad, iova);
 266
 267 }
 268
 269 /**
 270  * put_iova_domain - destroys the iova doamin
 271  * @iovad: - iova domain in question.
 272  * All the iova's in that domain are destroyed.
 273  */
 274 void put_iova_domain(struct iova_domain *iovad)
 275 {
 276         struct rb_node *node;
 277         unsigned long flags;
 278
 279         spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 280         node = rb_first(&iovad->rbroot);
 281         while (node) {
 282                 struct iova *iova = container_of(node, struct iova, node);
 283                 rb_erase(node, &iovad->rbroot);
 284                 free_iova_mem(iova);
 285                 node = rb_first(&iovad->rbroot);
 286         }
 287         spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 288 }
 289
 290 static int
 291 __is_range_overlap(struct rb_node *node,
 292         unsigned long pfn_lo, unsigned long pfn_hi)
 293 {
 294         struct iova *iova = container_of(node, struct iova, node);
 295
 296         if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
 297                 return 1;
 298         return 0;
 299 }
 300
 301 static struct iova *
 302 __insert_new_range(struct iova_domain *iovad,
 303         unsigned long pfn_lo, unsigned long pfn_hi)
 304 {
 305         struct iova *iova;
 306
 307         iova = alloc_iova_mem();
 308         if (!iova)
 309                 return iova;
 310
 311         iova->pfn_hi = pfn_hi;
 312         iova->pfn_lo = pfn_lo;
 313         iova_insert_rbtree(&iovad->rbroot, iova);
 314         return iova;
 315 }
 316
 317 static void
 318 __adjust_overlap_range(struct iova *iova,
 319         unsigned long *pfn_lo, unsigned long *pfn_hi)
 320 {
 321         if (*pfn_lo < iova->pfn_lo)
 322                 iova->pfn_lo = *pfn_lo;
 323         if (*pfn_hi > iova->pfn_hi)
 324                 *pfn_lo = iova->pfn_hi + 1;
 325 }
 326
 327 /**
 328  * reserve_iova - reserves an iova in the given range
 329  * @iovad: - iova domain pointer
 330  * @pfn_lo: - lower page frame address
 331  * @pfn_hi:- higher pfn adderss
 332  * This function allocates reserves the address range from pfn_lo to pfn_hi so
 333  * that this address is not dished out as part of alloc_iova.
 334  */
 335 struct iova *
 336 reserve_iova(struct iova_domain *iovad,
 337         unsigned long pfn_lo, unsigned long pfn_hi)
 338 {
 339         struct rb_node *node;
 340         unsigned long flags;
 341         struct iova *iova;
 342         unsigned int overlap = 0;
 343
 344         spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
 345         spin_lock(&iovad->iova_rbtree_lock);
 346         for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
 347                 if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
 348                         iova = container_of(node, struct iova, node);
 349                         __adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
 350                         if ((pfn_lo >= iova->pfn_lo) &&
 351                                 (pfn_hi <= iova->pfn_hi))
 352                                 goto finish;
 353                         overlap = 1;
 354
 355                 } else if (overlap)
 356                                 break;
 357         }
 358
 359         /* We are here either becasue this is the first reserver node
 360          * or need to insert remaining non overlap addr range
 361          */
 362         iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
 363 finish:
 364
 365         spin_unlock(&iovad->iova_rbtree_lock);
 366         spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
 367         return iova;
 368 }
 369
 370 /**
 371  * copy_reserved_iova - copies the reserved between domains
 372  * @from: - source doamin from where to copy
 373  * @to: - destination domin where to copy
 374  * This function copies reserved iova's from one doamin to
 375  * other.
 376  */
 377 void
 378 copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
 379 {
 380         unsigned long flags;
 381         struct rb_node *node;
 382
 383         spin_lock_irqsave(&from->iova_alloc_lock, flags);
 384         spin_lock(&from->iova_rbtree_lock);
 385         for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
 386                 struct iova *iova = container_of(node, struct iova, node);
 387                 struct iova *new_iova;
 388                 new_iova = reserve_iova(to, iova->pfn_lo, iova->pfn_hi);
 389                 if (!new_iova)
 390                         printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
 391                                 iova->pfn_lo, iova->pfn_lo);
 392         }
 393         spin_unlock(&from->iova_rbtree_lock);
 394         spin_unlock_irqrestore(&from->iova_alloc_lock, flags);
 395 }