Root/drivers/iommu/iova.c

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
22void
23init_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
31static 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
46static 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
55static 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 */
81static int
82iova_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
93static 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        }
120adjust_limit_pfn:
121        limit_pfn = curr_iova->pfn_lo - 1;
122move_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
178static void
179iova_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 */
210struct iova *
211alloc_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 */
246struct 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 */
285void
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 */
304void
305free_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 */
318void 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
334static 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
345static 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
361static 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 */
379struct iova *
380reserve_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);
406finish:
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 */
419void
420copy_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

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