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
init_iova_domain(struct iova_domain * iovad,unsigned long pfn_32bit)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 *
__get_cached_rbnode(struct iova_domain * iovad,unsigned long * limit_pfn)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
__cached_rbnode_insert_update(struct iova_domain * iovad,unsigned long limit_pfn,struct iova * new)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
__cached_rbnode_delete_update(struct iova_domain * iovad,struct iova * free)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
iova_get_pad_size(int size,unsigned int limit_pfn)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
__alloc_and_insert_iova_range(struct iova_domain * iovad,unsigned long size,unsigned long limit_pfn,struct iova * new,bool size_aligned)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
iova_insert_rbtree(struct rb_root * root,struct iova * iova)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 *
alloc_iova(struct iova_domain * iovad,unsigned long size,unsigned long limit_pfn,bool size_aligned)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 */
find_iova(struct iova_domain * iovad,unsigned long pfn)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 desing 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
__free_iova(struct iova_domain * iovad,struct iova * iova)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
free_iova(struct iova_domain * iovad,unsigned long pfn)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 */
put_iova_domain(struct iova_domain * iovad)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
__is_range_overlap(struct rb_node * node,unsigned long pfn_lo,unsigned long pfn_hi)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 *
__insert_new_range(struct iova_domain * iovad,unsigned long pfn_lo,unsigned long pfn_hi)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
__adjust_overlap_range(struct iova * iova,unsigned long * pfn_lo,unsigned long * pfn_hi)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 *
reserve_iova(struct iova_domain * iovad,unsigned long pfn_lo,unsigned long pfn_hi)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
copy_reserved_iova(struct iova_domain * from,struct iova_domain * to)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