1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright © 2006-2009, Intel Corporation.
4  *
5  * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
6  */
7 
8 #include <linux/iova.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/smp.h>
12 #include <linux/bitops.h>
13 #include <linux/cpu.h>
14 #include <linux/workqueue.h>
15 
16 /* The anchor node sits above the top of the usable address space */
17 #define IOVA_ANCHOR	~0UL
18 
19 #define IOVA_RANGE_CACHE_MAX_SIZE 6	/* log of max cached IOVA range size (in pages) */
20 
21 static bool iova_rcache_insert(struct iova_domain *iovad,
22 			       unsigned long pfn,
23 			       unsigned long size);
24 static unsigned long iova_rcache_get(struct iova_domain *iovad,
25 				     unsigned long size,
26 				     unsigned long limit_pfn);
27 static void free_iova_rcaches(struct iova_domain *iovad);
28 static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
29 static void free_global_cached_iovas(struct iova_domain *iovad);
30 
to_iova(struct rb_node * node)31 static struct iova *to_iova(struct rb_node *node)
32 {
33 	return rb_entry(node, struct iova, node);
34 }
35 
36 void
init_iova_domain(struct iova_domain * iovad,unsigned long granule,unsigned long start_pfn)37 init_iova_domain(struct iova_domain *iovad, unsigned long granule,
38 	unsigned long start_pfn)
39 {
40 	/*
41 	 * IOVA granularity will normally be equal to the smallest
42 	 * supported IOMMU page size; both *must* be capable of
43 	 * representing individual CPU pages exactly.
44 	 */
45 	BUG_ON((granule > PAGE_SIZE) || !is_power_of_2(granule));
46 
47 	spin_lock_init(&iovad->iova_rbtree_lock);
48 	iovad->rbroot = RB_ROOT;
49 	iovad->cached_node = &iovad->anchor.node;
50 	iovad->cached32_node = &iovad->anchor.node;
51 	iovad->granule = granule;
52 	iovad->start_pfn = start_pfn;
53 	iovad->dma_32bit_pfn = 1UL << (32 - iova_shift(iovad));
54 	iovad->max32_alloc_size = iovad->dma_32bit_pfn;
55 	iovad->anchor.pfn_lo = iovad->anchor.pfn_hi = IOVA_ANCHOR;
56 	rb_link_node(&iovad->anchor.node, NULL, &iovad->rbroot.rb_node);
57 	rb_insert_color(&iovad->anchor.node, &iovad->rbroot);
58 }
59 EXPORT_SYMBOL_GPL(init_iova_domain);
60 
61 static struct rb_node *
__get_cached_rbnode(struct iova_domain * iovad,unsigned long limit_pfn)62 __get_cached_rbnode(struct iova_domain *iovad, unsigned long limit_pfn)
63 {
64 	if (limit_pfn <= iovad->dma_32bit_pfn)
65 		return iovad->cached32_node;
66 
67 	return iovad->cached_node;
68 }
69 
70 static void
__cached_rbnode_insert_update(struct iova_domain * iovad,struct iova * new)71 __cached_rbnode_insert_update(struct iova_domain *iovad, struct iova *new)
72 {
73 	if (new->pfn_hi < iovad->dma_32bit_pfn)
74 		iovad->cached32_node = &new->node;
75 	else
76 		iovad->cached_node = &new->node;
77 }
78 
79 static void
__cached_rbnode_delete_update(struct iova_domain * iovad,struct iova * free)80 __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
81 {
82 	struct iova *cached_iova;
83 
84 	cached_iova = to_iova(iovad->cached32_node);
85 	if (free == cached_iova ||
86 	    (free->pfn_hi < iovad->dma_32bit_pfn &&
87 	     free->pfn_lo >= cached_iova->pfn_lo))
88 		iovad->cached32_node = rb_next(&free->node);
89 
90 	if (free->pfn_lo < iovad->dma_32bit_pfn)
91 		iovad->max32_alloc_size = iovad->dma_32bit_pfn;
92 
93 	cached_iova = to_iova(iovad->cached_node);
94 	if (free->pfn_lo >= cached_iova->pfn_lo)
95 		iovad->cached_node = rb_next(&free->node);
96 }
97 
iova_find_limit(struct iova_domain * iovad,unsigned long limit_pfn)98 static struct rb_node *iova_find_limit(struct iova_domain *iovad, unsigned long limit_pfn)
99 {
100 	struct rb_node *node, *next;
101 	/*
102 	 * Ideally what we'd like to judge here is whether limit_pfn is close
103 	 * enough to the highest-allocated IOVA that starting the allocation
104 	 * walk from the anchor node will be quicker than this initial work to
105 	 * find an exact starting point (especially if that ends up being the
106 	 * anchor node anyway). This is an incredibly crude approximation which
107 	 * only really helps the most likely case, but is at least trivially easy.
108 	 */
109 	if (limit_pfn > iovad->dma_32bit_pfn)
110 		return &iovad->anchor.node;
111 
112 	node = iovad->rbroot.rb_node;
113 	while (to_iova(node)->pfn_hi < limit_pfn)
114 		node = node->rb_right;
115 
116 search_left:
117 	while (node->rb_left && to_iova(node->rb_left)->pfn_lo >= limit_pfn)
118 		node = node->rb_left;
119 
120 	if (!node->rb_left)
121 		return node;
122 
123 	next = node->rb_left;
124 	while (next->rb_right) {
125 		next = next->rb_right;
126 		if (to_iova(next)->pfn_lo >= limit_pfn) {
127 			node = next;
128 			goto search_left;
129 		}
130 	}
131 
132 	return node;
133 }
134 
135 /* Insert the iova into domain rbtree by holding writer lock */
136 static void
iova_insert_rbtree(struct rb_root * root,struct iova * iova,struct rb_node * start)137 iova_insert_rbtree(struct rb_root *root, struct iova *iova,
138 		   struct rb_node *start)
139 {
140 	struct rb_node **new, *parent = NULL;
141 
142 	new = (start) ? &start : &(root->rb_node);
143 	/* Figure out where to put new node */
144 	while (*new) {
145 		struct iova *this = to_iova(*new);
146 
147 		parent = *new;
148 
149 		if (iova->pfn_lo < this->pfn_lo)
150 			new = &((*new)->rb_left);
151 		else if (iova->pfn_lo > this->pfn_lo)
152 			new = &((*new)->rb_right);
153 		else {
154 			WARN_ON(1); /* this should not happen */
155 			return;
156 		}
157 	}
158 	/* Add new node and rebalance tree. */
159 	rb_link_node(&iova->node, parent, new);
160 	rb_insert_color(&iova->node, root);
161 }
162 
__alloc_and_insert_iova_range(struct iova_domain * iovad,unsigned long size,unsigned long limit_pfn,struct iova * new,bool size_aligned)163 static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
164 		unsigned long size, unsigned long limit_pfn,
165 			struct iova *new, bool size_aligned)
166 {
167 	struct rb_node *curr, *prev;
168 	struct iova *curr_iova;
169 	unsigned long flags;
170 	unsigned long new_pfn, retry_pfn;
171 	unsigned long align_mask = ~0UL;
172 	unsigned long high_pfn = limit_pfn, low_pfn = iovad->start_pfn;
173 
174 	if (size_aligned)
175 		align_mask <<= fls_long(size - 1);
176 
177 	/* Walk the tree backwards */
178 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
179 	if (limit_pfn <= iovad->dma_32bit_pfn &&
180 			size >= iovad->max32_alloc_size)
181 		goto iova32_full;
182 
183 	curr = __get_cached_rbnode(iovad, limit_pfn);
184 	curr_iova = to_iova(curr);
185 	retry_pfn = curr_iova->pfn_hi;
186 
187 retry:
188 	do {
189 		high_pfn = min(high_pfn, curr_iova->pfn_lo);
190 		new_pfn = (high_pfn - size) & align_mask;
191 		prev = curr;
192 		curr = rb_prev(curr);
193 		curr_iova = to_iova(curr);
194 	} while (curr && new_pfn <= curr_iova->pfn_hi && new_pfn >= low_pfn);
195 
196 	if (high_pfn < size || new_pfn < low_pfn) {
197 		if (low_pfn == iovad->start_pfn && retry_pfn < limit_pfn) {
198 			high_pfn = limit_pfn;
199 			low_pfn = retry_pfn + 1;
200 			curr = iova_find_limit(iovad, limit_pfn);
201 			curr_iova = to_iova(curr);
202 			goto retry;
203 		}
204 		iovad->max32_alloc_size = size;
205 		goto iova32_full;
206 	}
207 
208 	/* pfn_lo will point to size aligned address if size_aligned is set */
209 	new->pfn_lo = new_pfn;
210 	new->pfn_hi = new->pfn_lo + size - 1;
211 
212 	/* If we have 'prev', it's a valid place to start the insertion. */
213 	iova_insert_rbtree(&iovad->rbroot, new, prev);
214 	__cached_rbnode_insert_update(iovad, new);
215 
216 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
217 	return 0;
218 
219 iova32_full:
220 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
221 	return -ENOMEM;
222 }
223 
224 static struct kmem_cache *iova_cache;
225 static unsigned int iova_cache_users;
226 static DEFINE_MUTEX(iova_cache_mutex);
227 
alloc_iova_mem(void)228 static struct iova *alloc_iova_mem(void)
229 {
230 	return kmem_cache_zalloc(iova_cache, GFP_ATOMIC | __GFP_NOWARN);
231 }
232 
free_iova_mem(struct iova * iova)233 static void free_iova_mem(struct iova *iova)
234 {
235 	if (iova->pfn_lo != IOVA_ANCHOR)
236 		kmem_cache_free(iova_cache, iova);
237 }
238 
239 /**
240  * alloc_iova - allocates an iova
241  * @iovad: - iova domain in question
242  * @size: - size of page frames to allocate
243  * @limit_pfn: - max limit address
244  * @size_aligned: - set if size_aligned address range is required
245  * This function allocates an iova in the range iovad->start_pfn to limit_pfn,
246  * searching top-down from limit_pfn to iovad->start_pfn. If the size_aligned
247  * flag is set then the allocated address iova->pfn_lo will be naturally
248  * aligned on roundup_power_of_two(size).
249  */
250 struct iova *
alloc_iova(struct iova_domain * iovad,unsigned long size,unsigned long limit_pfn,bool size_aligned)251 alloc_iova(struct iova_domain *iovad, unsigned long size,
252 	unsigned long limit_pfn,
253 	bool size_aligned)
254 {
255 	struct iova *new_iova;
256 	int ret;
257 
258 	new_iova = alloc_iova_mem();
259 	if (!new_iova)
260 		return NULL;
261 
262 	ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn + 1,
263 			new_iova, size_aligned);
264 
265 	if (ret) {
266 		free_iova_mem(new_iova);
267 		return NULL;
268 	}
269 
270 	return new_iova;
271 }
272 EXPORT_SYMBOL_GPL(alloc_iova);
273 
274 static struct iova *
private_find_iova(struct iova_domain * iovad,unsigned long pfn)275 private_find_iova(struct iova_domain *iovad, unsigned long pfn)
276 {
277 	struct rb_node *node = iovad->rbroot.rb_node;
278 
279 	assert_spin_locked(&iovad->iova_rbtree_lock);
280 
281 	while (node) {
282 		struct iova *iova = to_iova(node);
283 
284 		if (pfn < iova->pfn_lo)
285 			node = node->rb_left;
286 		else if (pfn > iova->pfn_hi)
287 			node = node->rb_right;
288 		else
289 			return iova;	/* pfn falls within iova's range */
290 	}
291 
292 	return NULL;
293 }
294 
remove_iova(struct iova_domain * iovad,struct iova * iova)295 static void remove_iova(struct iova_domain *iovad, struct iova *iova)
296 {
297 	assert_spin_locked(&iovad->iova_rbtree_lock);
298 	__cached_rbnode_delete_update(iovad, iova);
299 	rb_erase(&iova->node, &iovad->rbroot);
300 }
301 
302 /**
303  * find_iova - finds an iova for a given pfn
304  * @iovad: - iova domain in question.
305  * @pfn: - page frame number
306  * This function finds and returns an iova belonging to the
307  * given domain which matches the given pfn.
308  */
find_iova(struct iova_domain * iovad,unsigned long pfn)309 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
310 {
311 	unsigned long flags;
312 	struct iova *iova;
313 
314 	/* Take the lock so that no other thread is manipulating the rbtree */
315 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
316 	iova = private_find_iova(iovad, pfn);
317 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
318 	return iova;
319 }
320 EXPORT_SYMBOL_GPL(find_iova);
321 
322 /**
323  * __free_iova - frees the given iova
324  * @iovad: iova domain in question.
325  * @iova: iova in question.
326  * Frees the given iova belonging to the giving domain
327  */
328 void
__free_iova(struct iova_domain * iovad,struct iova * iova)329 __free_iova(struct iova_domain *iovad, struct iova *iova)
330 {
331 	unsigned long flags;
332 
333 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
334 	remove_iova(iovad, iova);
335 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
336 	free_iova_mem(iova);
337 }
338 EXPORT_SYMBOL_GPL(__free_iova);
339 
340 /**
341  * free_iova - finds and frees the iova for a given pfn
342  * @iovad: - iova domain in question.
343  * @pfn: - pfn that is allocated previously
344  * This functions finds an iova for a given pfn and then
345  * frees the iova from that domain.
346  */
347 void
free_iova(struct iova_domain * iovad,unsigned long pfn)348 free_iova(struct iova_domain *iovad, unsigned long pfn)
349 {
350 	unsigned long flags;
351 	struct iova *iova;
352 
353 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
354 	iova = private_find_iova(iovad, pfn);
355 	if (!iova) {
356 		spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
357 		return;
358 	}
359 	remove_iova(iovad, iova);
360 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
361 	free_iova_mem(iova);
362 }
363 EXPORT_SYMBOL_GPL(free_iova);
364 
365 /**
366  * alloc_iova_fast - allocates an iova from rcache
367  * @iovad: - iova domain in question
368  * @size: - size of page frames to allocate
369  * @limit_pfn: - max limit address
370  * @flush_rcache: - set to flush rcache on regular allocation failure
371  * This function tries to satisfy an iova allocation from the rcache,
372  * and falls back to regular allocation on failure. If regular allocation
373  * fails too and the flush_rcache flag is set then the rcache will be flushed.
374 */
375 unsigned long
alloc_iova_fast(struct iova_domain * iovad,unsigned long size,unsigned long limit_pfn,bool flush_rcache)376 alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
377 		unsigned long limit_pfn, bool flush_rcache)
378 {
379 	unsigned long iova_pfn;
380 	struct iova *new_iova;
381 
382 	/*
383 	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
384 	 * will come back to bite us badly, so we have to waste a bit of space
385 	 * rounding up anything cacheable to make sure that can't happen. The
386 	 * order of the unadjusted size will still match upon freeing.
387 	 */
388 	if (size < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
389 		size = roundup_pow_of_two(size);
390 
391 	iova_pfn = iova_rcache_get(iovad, size, limit_pfn + 1);
392 	if (iova_pfn)
393 		return iova_pfn;
394 
395 retry:
396 	new_iova = alloc_iova(iovad, size, limit_pfn, true);
397 	if (!new_iova) {
398 		unsigned int cpu;
399 
400 		if (!flush_rcache)
401 			return 0;
402 
403 		/* Try replenishing IOVAs by flushing rcache. */
404 		flush_rcache = false;
405 		for_each_online_cpu(cpu)
406 			free_cpu_cached_iovas(cpu, iovad);
407 		free_global_cached_iovas(iovad);
408 		goto retry;
409 	}
410 
411 	return new_iova->pfn_lo;
412 }
413 EXPORT_SYMBOL_GPL(alloc_iova_fast);
414 
415 /**
416  * free_iova_fast - free iova pfn range into rcache
417  * @iovad: - iova domain in question.
418  * @pfn: - pfn that is allocated previously
419  * @size: - # of pages in range
420  * This functions frees an iova range by trying to put it into the rcache,
421  * falling back to regular iova deallocation via free_iova() if this fails.
422  */
423 void
free_iova_fast(struct iova_domain * iovad,unsigned long pfn,unsigned long size)424 free_iova_fast(struct iova_domain *iovad, unsigned long pfn, unsigned long size)
425 {
426 	if (iova_rcache_insert(iovad, pfn, size))
427 		return;
428 
429 	free_iova(iovad, pfn);
430 }
431 EXPORT_SYMBOL_GPL(free_iova_fast);
432 
iova_domain_free_rcaches(struct iova_domain * iovad)433 static void iova_domain_free_rcaches(struct iova_domain *iovad)
434 {
435 	cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
436 					    &iovad->cpuhp_dead);
437 	free_iova_rcaches(iovad);
438 }
439 
440 /**
441  * put_iova_domain - destroys the iova domain
442  * @iovad: - iova domain in question.
443  * All the iova's in that domain are destroyed.
444  */
put_iova_domain(struct iova_domain * iovad)445 void put_iova_domain(struct iova_domain *iovad)
446 {
447 	struct iova *iova, *tmp;
448 
449 	if (iovad->rcaches)
450 		iova_domain_free_rcaches(iovad);
451 
452 	rbtree_postorder_for_each_entry_safe(iova, tmp, &iovad->rbroot, node)
453 		free_iova_mem(iova);
454 }
455 EXPORT_SYMBOL_GPL(put_iova_domain);
456 
457 static int
__is_range_overlap(struct rb_node * node,unsigned long pfn_lo,unsigned long pfn_hi)458 __is_range_overlap(struct rb_node *node,
459 	unsigned long pfn_lo, unsigned long pfn_hi)
460 {
461 	struct iova *iova = to_iova(node);
462 
463 	if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
464 		return 1;
465 	return 0;
466 }
467 
468 static inline struct iova *
alloc_and_init_iova(unsigned long pfn_lo,unsigned long pfn_hi)469 alloc_and_init_iova(unsigned long pfn_lo, unsigned long pfn_hi)
470 {
471 	struct iova *iova;
472 
473 	iova = alloc_iova_mem();
474 	if (iova) {
475 		iova->pfn_lo = pfn_lo;
476 		iova->pfn_hi = pfn_hi;
477 	}
478 
479 	return iova;
480 }
481 
482 static struct iova *
__insert_new_range(struct iova_domain * iovad,unsigned long pfn_lo,unsigned long pfn_hi)483 __insert_new_range(struct iova_domain *iovad,
484 	unsigned long pfn_lo, unsigned long pfn_hi)
485 {
486 	struct iova *iova;
487 
488 	iova = alloc_and_init_iova(pfn_lo, pfn_hi);
489 	if (iova)
490 		iova_insert_rbtree(&iovad->rbroot, iova, NULL);
491 
492 	return iova;
493 }
494 
495 static void
__adjust_overlap_range(struct iova * iova,unsigned long * pfn_lo,unsigned long * pfn_hi)496 __adjust_overlap_range(struct iova *iova,
497 	unsigned long *pfn_lo, unsigned long *pfn_hi)
498 {
499 	if (*pfn_lo < iova->pfn_lo)
500 		iova->pfn_lo = *pfn_lo;
501 	if (*pfn_hi > iova->pfn_hi)
502 		*pfn_lo = iova->pfn_hi + 1;
503 }
504 
505 /**
506  * reserve_iova - reserves an iova in the given range
507  * @iovad: - iova domain pointer
508  * @pfn_lo: - lower page frame address
509  * @pfn_hi:- higher pfn adderss
510  * This function allocates reserves the address range from pfn_lo to pfn_hi so
511  * that this address is not dished out as part of alloc_iova.
512  */
513 struct iova *
reserve_iova(struct iova_domain * iovad,unsigned long pfn_lo,unsigned long pfn_hi)514 reserve_iova(struct iova_domain *iovad,
515 	unsigned long pfn_lo, unsigned long pfn_hi)
516 {
517 	struct rb_node *node;
518 	unsigned long flags;
519 	struct iova *iova;
520 	unsigned int overlap = 0;
521 
522 	/* Don't allow nonsensical pfns */
523 	if (WARN_ON((pfn_hi | pfn_lo) > (ULLONG_MAX >> iova_shift(iovad))))
524 		return NULL;
525 
526 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
527 	for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
528 		if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
529 			iova = to_iova(node);
530 			__adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
531 			if ((pfn_lo >= iova->pfn_lo) &&
532 				(pfn_hi <= iova->pfn_hi))
533 				goto finish;
534 			overlap = 1;
535 
536 		} else if (overlap)
537 				break;
538 	}
539 
540 	/* We are here either because this is the first reserver node
541 	 * or need to insert remaining non overlap addr range
542 	 */
543 	iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
544 finish:
545 
546 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
547 	return iova;
548 }
549 EXPORT_SYMBOL_GPL(reserve_iova);
550 
551 /*
552  * Magazine caches for IOVA ranges.  For an introduction to magazines,
553  * see the USENIX 2001 paper "Magazines and Vmem: Extending the Slab
554  * Allocator to Many CPUs and Arbitrary Resources" by Bonwick and Adams.
555  * For simplicity, we use a static magazine size and don't implement the
556  * dynamic size tuning described in the paper.
557  */
558 
559 /*
560  * As kmalloc's buffer size is fixed to power of 2, 127 is chosen to
561  * assure size of 'iova_magazine' to be 1024 bytes, so that no memory
562  * will be wasted. Since only full magazines are inserted into the depot,
563  * we don't need to waste PFN capacity on a separate list head either.
564  */
565 #define IOVA_MAG_SIZE 127
566 
567 #define IOVA_DEPOT_DELAY msecs_to_jiffies(100)
568 
569 struct iova_magazine {
570 	union {
571 		unsigned long size;
572 		struct iova_magazine *next;
573 	};
574 	unsigned long pfns[IOVA_MAG_SIZE];
575 };
576 static_assert(!(sizeof(struct iova_magazine) & (sizeof(struct iova_magazine) - 1)));
577 
578 struct iova_cpu_rcache {
579 	spinlock_t lock;
580 	struct iova_magazine *loaded;
581 	struct iova_magazine *prev;
582 };
583 
584 struct iova_rcache {
585 	spinlock_t lock;
586 	unsigned int depot_size;
587 	struct iova_magazine *depot;
588 	struct iova_cpu_rcache __percpu *cpu_rcaches;
589 	struct iova_domain *iovad;
590 	struct delayed_work work;
591 };
592 
593 static struct kmem_cache *iova_magazine_cache;
594 
iova_rcache_range(void)595 unsigned long iova_rcache_range(void)
596 {
597 	return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
598 }
599 
iova_magazine_alloc(gfp_t flags)600 static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
601 {
602 	struct iova_magazine *mag;
603 
604 	mag = kmem_cache_alloc(iova_magazine_cache, flags);
605 	if (mag)
606 		mag->size = 0;
607 
608 	return mag;
609 }
610 
iova_magazine_free(struct iova_magazine * mag)611 static void iova_magazine_free(struct iova_magazine *mag)
612 {
613 	kmem_cache_free(iova_magazine_cache, mag);
614 }
615 
616 static void
iova_magazine_free_pfns(struct iova_magazine * mag,struct iova_domain * iovad)617 iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
618 {
619 	unsigned long flags;
620 	int i;
621 
622 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
623 
624 	for (i = 0 ; i < mag->size; ++i) {
625 		struct iova *iova = private_find_iova(iovad, mag->pfns[i]);
626 
627 		if (WARN_ON(!iova))
628 			continue;
629 
630 		remove_iova(iovad, iova);
631 		free_iova_mem(iova);
632 	}
633 
634 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
635 
636 	mag->size = 0;
637 }
638 
iova_magazine_full(struct iova_magazine * mag)639 static bool iova_magazine_full(struct iova_magazine *mag)
640 {
641 	return mag->size == IOVA_MAG_SIZE;
642 }
643 
iova_magazine_empty(struct iova_magazine * mag)644 static bool iova_magazine_empty(struct iova_magazine *mag)
645 {
646 	return mag->size == 0;
647 }
648 
iova_magazine_pop(struct iova_magazine * mag,unsigned long limit_pfn)649 static unsigned long iova_magazine_pop(struct iova_magazine *mag,
650 				       unsigned long limit_pfn)
651 {
652 	int i;
653 	unsigned long pfn;
654 
655 	/* Only fall back to the rbtree if we have no suitable pfns at all */
656 	for (i = mag->size - 1; mag->pfns[i] > limit_pfn; i--)
657 		if (i == 0)
658 			return 0;
659 
660 	/* Swap it to pop it */
661 	pfn = mag->pfns[i];
662 	mag->pfns[i] = mag->pfns[--mag->size];
663 
664 	return pfn;
665 }
666 
iova_magazine_push(struct iova_magazine * mag,unsigned long pfn)667 static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn)
668 {
669 	mag->pfns[mag->size++] = pfn;
670 }
671 
iova_depot_pop(struct iova_rcache * rcache)672 static struct iova_magazine *iova_depot_pop(struct iova_rcache *rcache)
673 {
674 	struct iova_magazine *mag = rcache->depot;
675 
676 	rcache->depot = mag->next;
677 	mag->size = IOVA_MAG_SIZE;
678 	rcache->depot_size--;
679 	return mag;
680 }
681 
iova_depot_push(struct iova_rcache * rcache,struct iova_magazine * mag)682 static void iova_depot_push(struct iova_rcache *rcache, struct iova_magazine *mag)
683 {
684 	mag->next = rcache->depot;
685 	rcache->depot = mag;
686 	rcache->depot_size++;
687 }
688 
iova_depot_work_func(struct work_struct * work)689 static void iova_depot_work_func(struct work_struct *work)
690 {
691 	struct iova_rcache *rcache = container_of(work, typeof(*rcache), work.work);
692 	struct iova_magazine *mag = NULL;
693 	unsigned long flags;
694 
695 	spin_lock_irqsave(&rcache->lock, flags);
696 	if (rcache->depot_size > num_online_cpus())
697 		mag = iova_depot_pop(rcache);
698 	spin_unlock_irqrestore(&rcache->lock, flags);
699 
700 	if (mag) {
701 		iova_magazine_free_pfns(mag, rcache->iovad);
702 		iova_magazine_free(mag);
703 		schedule_delayed_work(&rcache->work, IOVA_DEPOT_DELAY);
704 	}
705 }
706 
iova_domain_init_rcaches(struct iova_domain * iovad)707 int iova_domain_init_rcaches(struct iova_domain *iovad)
708 {
709 	unsigned int cpu;
710 	int i, ret;
711 
712 	iovad->rcaches = kcalloc(IOVA_RANGE_CACHE_MAX_SIZE,
713 				 sizeof(struct iova_rcache),
714 				 GFP_KERNEL);
715 	if (!iovad->rcaches)
716 		return -ENOMEM;
717 
718 	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
719 		struct iova_cpu_rcache *cpu_rcache;
720 		struct iova_rcache *rcache;
721 
722 		rcache = &iovad->rcaches[i];
723 		spin_lock_init(&rcache->lock);
724 		rcache->iovad = iovad;
725 		INIT_DELAYED_WORK(&rcache->work, iova_depot_work_func);
726 		rcache->cpu_rcaches = __alloc_percpu(sizeof(*cpu_rcache),
727 						     cache_line_size());
728 		if (!rcache->cpu_rcaches) {
729 			ret = -ENOMEM;
730 			goto out_err;
731 		}
732 		for_each_possible_cpu(cpu) {
733 			cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
734 
735 			spin_lock_init(&cpu_rcache->lock);
736 			cpu_rcache->loaded = iova_magazine_alloc(GFP_KERNEL);
737 			cpu_rcache->prev = iova_magazine_alloc(GFP_KERNEL);
738 			if (!cpu_rcache->loaded || !cpu_rcache->prev) {
739 				ret = -ENOMEM;
740 				goto out_err;
741 			}
742 		}
743 	}
744 
745 	ret = cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
746 					       &iovad->cpuhp_dead);
747 	if (ret)
748 		goto out_err;
749 	return 0;
750 
751 out_err:
752 	free_iova_rcaches(iovad);
753 	return ret;
754 }
755 EXPORT_SYMBOL_GPL(iova_domain_init_rcaches);
756 
757 /*
758  * Try inserting IOVA range starting with 'iova_pfn' into 'rcache', and
759  * return true on success.  Can fail if rcache is full and we can't free
760  * space, and free_iova() (our only caller) will then return the IOVA
761  * range to the rbtree instead.
762  */
__iova_rcache_insert(struct iova_domain * iovad,struct iova_rcache * rcache,unsigned long iova_pfn)763 static bool __iova_rcache_insert(struct iova_domain *iovad,
764 				 struct iova_rcache *rcache,
765 				 unsigned long iova_pfn)
766 {
767 	struct iova_cpu_rcache *cpu_rcache;
768 	bool can_insert = false;
769 	unsigned long flags;
770 
771 	cpu_rcache = raw_cpu_ptr(rcache->cpu_rcaches);
772 	spin_lock_irqsave(&cpu_rcache->lock, flags);
773 
774 	if (!iova_magazine_full(cpu_rcache->loaded)) {
775 		can_insert = true;
776 	} else if (!iova_magazine_full(cpu_rcache->prev)) {
777 		swap(cpu_rcache->prev, cpu_rcache->loaded);
778 		can_insert = true;
779 	} else {
780 		struct iova_magazine *new_mag = iova_magazine_alloc(GFP_ATOMIC);
781 
782 		if (new_mag) {
783 			spin_lock(&rcache->lock);
784 			iova_depot_push(rcache, cpu_rcache->loaded);
785 			spin_unlock(&rcache->lock);
786 			schedule_delayed_work(&rcache->work, IOVA_DEPOT_DELAY);
787 
788 			cpu_rcache->loaded = new_mag;
789 			can_insert = true;
790 		}
791 	}
792 
793 	if (can_insert)
794 		iova_magazine_push(cpu_rcache->loaded, iova_pfn);
795 
796 	spin_unlock_irqrestore(&cpu_rcache->lock, flags);
797 
798 	return can_insert;
799 }
800 
iova_rcache_insert(struct iova_domain * iovad,unsigned long pfn,unsigned long size)801 static bool iova_rcache_insert(struct iova_domain *iovad, unsigned long pfn,
802 			       unsigned long size)
803 {
804 	unsigned int log_size = order_base_2(size);
805 
806 	if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
807 		return false;
808 
809 	return __iova_rcache_insert(iovad, &iovad->rcaches[log_size], pfn);
810 }
811 
812 /*
813  * Caller wants to allocate a new IOVA range from 'rcache'.  If we can
814  * satisfy the request, return a matching non-NULL range and remove
815  * it from the 'rcache'.
816  */
__iova_rcache_get(struct iova_rcache * rcache,unsigned long limit_pfn)817 static unsigned long __iova_rcache_get(struct iova_rcache *rcache,
818 				       unsigned long limit_pfn)
819 {
820 	struct iova_cpu_rcache *cpu_rcache;
821 	unsigned long iova_pfn = 0;
822 	bool has_pfn = false;
823 	unsigned long flags;
824 
825 	cpu_rcache = raw_cpu_ptr(rcache->cpu_rcaches);
826 	spin_lock_irqsave(&cpu_rcache->lock, flags);
827 
828 	if (!iova_magazine_empty(cpu_rcache->loaded)) {
829 		has_pfn = true;
830 	} else if (!iova_magazine_empty(cpu_rcache->prev)) {
831 		swap(cpu_rcache->prev, cpu_rcache->loaded);
832 		has_pfn = true;
833 	} else {
834 		spin_lock(&rcache->lock);
835 		if (rcache->depot) {
836 			iova_magazine_free(cpu_rcache->loaded);
837 			cpu_rcache->loaded = iova_depot_pop(rcache);
838 			has_pfn = true;
839 		}
840 		spin_unlock(&rcache->lock);
841 	}
842 
843 	if (has_pfn)
844 		iova_pfn = iova_magazine_pop(cpu_rcache->loaded, limit_pfn);
845 
846 	spin_unlock_irqrestore(&cpu_rcache->lock, flags);
847 
848 	return iova_pfn;
849 }
850 
851 /*
852  * Try to satisfy IOVA allocation range from rcache.  Fail if requested
853  * size is too big or the DMA limit we are given isn't satisfied by the
854  * top element in the magazine.
855  */
iova_rcache_get(struct iova_domain * iovad,unsigned long size,unsigned long limit_pfn)856 static unsigned long iova_rcache_get(struct iova_domain *iovad,
857 				     unsigned long size,
858 				     unsigned long limit_pfn)
859 {
860 	unsigned int log_size = order_base_2(size);
861 
862 	if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
863 		return 0;
864 
865 	return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn - size);
866 }
867 
868 /*
869  * free rcache data structures.
870  */
free_iova_rcaches(struct iova_domain * iovad)871 static void free_iova_rcaches(struct iova_domain *iovad)
872 {
873 	struct iova_rcache *rcache;
874 	struct iova_cpu_rcache *cpu_rcache;
875 	unsigned int cpu;
876 
877 	for (int i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
878 		rcache = &iovad->rcaches[i];
879 		if (!rcache->cpu_rcaches)
880 			break;
881 		for_each_possible_cpu(cpu) {
882 			cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
883 			iova_magazine_free(cpu_rcache->loaded);
884 			iova_magazine_free(cpu_rcache->prev);
885 		}
886 		free_percpu(rcache->cpu_rcaches);
887 		cancel_delayed_work_sync(&rcache->work);
888 		while (rcache->depot)
889 			iova_magazine_free(iova_depot_pop(rcache));
890 	}
891 
892 	kfree(iovad->rcaches);
893 	iovad->rcaches = NULL;
894 }
895 
896 /*
897  * free all the IOVA ranges cached by a cpu (used when cpu is unplugged)
898  */
free_cpu_cached_iovas(unsigned int cpu,struct iova_domain * iovad)899 static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad)
900 {
901 	struct iova_cpu_rcache *cpu_rcache;
902 	struct iova_rcache *rcache;
903 	unsigned long flags;
904 	int i;
905 
906 	for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
907 		rcache = &iovad->rcaches[i];
908 		cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
909 		spin_lock_irqsave(&cpu_rcache->lock, flags);
910 		iova_magazine_free_pfns(cpu_rcache->loaded, iovad);
911 		iova_magazine_free_pfns(cpu_rcache->prev, iovad);
912 		spin_unlock_irqrestore(&cpu_rcache->lock, flags);
913 	}
914 }
915 
916 /*
917  * free all the IOVA ranges of global cache
918  */
free_global_cached_iovas(struct iova_domain * iovad)919 static void free_global_cached_iovas(struct iova_domain *iovad)
920 {
921 	struct iova_rcache *rcache;
922 	unsigned long flags;
923 
924 	for (int i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
925 		rcache = &iovad->rcaches[i];
926 		spin_lock_irqsave(&rcache->lock, flags);
927 		while (rcache->depot) {
928 			struct iova_magazine *mag = iova_depot_pop(rcache);
929 
930 			iova_magazine_free_pfns(mag, iovad);
931 			iova_magazine_free(mag);
932 		}
933 		spin_unlock_irqrestore(&rcache->lock, flags);
934 	}
935 }
936 
iova_cpuhp_dead(unsigned int cpu,struct hlist_node * node)937 static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
938 {
939 	struct iova_domain *iovad;
940 
941 	iovad = hlist_entry_safe(node, struct iova_domain, cpuhp_dead);
942 
943 	free_cpu_cached_iovas(cpu, iovad);
944 	return 0;
945 }
946 
iova_cache_get(void)947 int iova_cache_get(void)
948 {
949 	int err = -ENOMEM;
950 
951 	mutex_lock(&iova_cache_mutex);
952 	if (!iova_cache_users) {
953 		iova_cache = kmem_cache_create("iommu_iova", sizeof(struct iova), 0,
954 					       SLAB_HWCACHE_ALIGN, NULL);
955 		if (!iova_cache)
956 			goto out_err;
957 
958 		iova_magazine_cache = kmem_cache_create("iommu_iova_magazine",
959 							sizeof(struct iova_magazine),
960 							0, SLAB_HWCACHE_ALIGN, NULL);
961 		if (!iova_magazine_cache)
962 			goto out_err;
963 
964 		err = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead",
965 					      NULL, iova_cpuhp_dead);
966 		if (err) {
967 			pr_err("IOVA: Couldn't register cpuhp handler: %pe\n", ERR_PTR(err));
968 			goto out_err;
969 		}
970 	}
971 
972 	iova_cache_users++;
973 	mutex_unlock(&iova_cache_mutex);
974 
975 	return 0;
976 
977 out_err:
978 	kmem_cache_destroy(iova_cache);
979 	kmem_cache_destroy(iova_magazine_cache);
980 	mutex_unlock(&iova_cache_mutex);
981 	return err;
982 }
983 EXPORT_SYMBOL_GPL(iova_cache_get);
984 
iova_cache_put(void)985 void iova_cache_put(void)
986 {
987 	mutex_lock(&iova_cache_mutex);
988 	if (WARN_ON(!iova_cache_users)) {
989 		mutex_unlock(&iova_cache_mutex);
990 		return;
991 	}
992 	iova_cache_users--;
993 	if (!iova_cache_users) {
994 		cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
995 		kmem_cache_destroy(iova_cache);
996 		kmem_cache_destroy(iova_magazine_cache);
997 	}
998 	mutex_unlock(&iova_cache_mutex);
999 }
1000 EXPORT_SYMBOL_GPL(iova_cache_put);
1001 
1002 MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>");
1003 MODULE_DESCRIPTION("IOMMU I/O Virtual Address management");
1004 MODULE_LICENSE("GPL");
1005