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 } 436