1 /*
2 * Copyright(c) 2020 Cornelis Networks, Inc.
3 * Copyright(c) 2016 - 2017 Intel Corporation.
4 *
5 * This file is provided under a dual BSD/GPLv2 license. When using or
6 * redistributing this file, you may do so under either license.
7 *
8 * GPL LICENSE SUMMARY
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of version 2 of the GNU General Public License as
12 * published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * BSD LICENSE
20 *
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
23 * are met:
24 *
25 * - Redistributions of source code must retain the above copyright
26 * notice, this list of conditions and the following disclaimer.
27 * - Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in
29 * the documentation and/or other materials provided with the
30 * distribution.
31 * - Neither the name of Intel Corporation nor the names of its
32 * contributors may be used to endorse or promote products derived
33 * from this software without specific prior written permission.
34 *
35 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
38 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
39 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
42 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
43 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
44 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
45 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
46 *
47 */
48 #include <linux/list.h>
49 #include <linux/rculist.h>
50 #include <linux/mmu_notifier.h>
51 #include <linux/interval_tree_generic.h>
52 #include <linux/sched/mm.h>
53
54 #include "mmu_rb.h"
55 #include "trace.h"
56
57 static unsigned long mmu_node_start(struct mmu_rb_node *);
58 static unsigned long mmu_node_last(struct mmu_rb_node *);
59 static int mmu_notifier_range_start(struct mmu_notifier *,
60 const struct mmu_notifier_range *);
61 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *,
62 unsigned long, unsigned long);
63 static void release_immediate(struct kref *refcount);
64 static void handle_remove(struct work_struct *work);
65
66 static const struct mmu_notifier_ops mn_opts = {
67 .invalidate_range_start = mmu_notifier_range_start,
68 };
69
70 INTERVAL_TREE_DEFINE(struct mmu_rb_node, node, unsigned long, __last,
71 mmu_node_start, mmu_node_last, static, __mmu_int_rb);
72
mmu_node_start(struct mmu_rb_node * node)73 static unsigned long mmu_node_start(struct mmu_rb_node *node)
74 {
75 return node->addr & PAGE_MASK;
76 }
77
mmu_node_last(struct mmu_rb_node * node)78 static unsigned long mmu_node_last(struct mmu_rb_node *node)
79 {
80 return PAGE_ALIGN(node->addr + node->len) - 1;
81 }
82
hfi1_mmu_rb_register(void * ops_arg,struct mmu_rb_ops * ops,struct workqueue_struct * wq,struct mmu_rb_handler ** handler)83 int hfi1_mmu_rb_register(void *ops_arg,
84 struct mmu_rb_ops *ops,
85 struct workqueue_struct *wq,
86 struct mmu_rb_handler **handler)
87 {
88 struct mmu_rb_handler *h;
89 int ret;
90
91 h = kzalloc(sizeof(*h), GFP_KERNEL);
92 if (!h)
93 return -ENOMEM;
94
95 h->root = RB_ROOT_CACHED;
96 h->ops = ops;
97 h->ops_arg = ops_arg;
98 INIT_HLIST_NODE(&h->mn.hlist);
99 spin_lock_init(&h->lock);
100 h->mn.ops = &mn_opts;
101 INIT_WORK(&h->del_work, handle_remove);
102 INIT_LIST_HEAD(&h->del_list);
103 INIT_LIST_HEAD(&h->lru_list);
104 h->wq = wq;
105
106 ret = mmu_notifier_register(&h->mn, current->mm);
107 if (ret) {
108 kfree(h);
109 return ret;
110 }
111
112 *handler = h;
113 return 0;
114 }
115
hfi1_mmu_rb_unregister(struct mmu_rb_handler * handler)116 void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler)
117 {
118 struct mmu_rb_node *rbnode;
119 struct rb_node *node;
120 unsigned long flags;
121 struct list_head del_list;
122
123 /* Prevent freeing of mm until we are completely finished. */
124 mmgrab(handler->mn.mm);
125
126 /* Unregister first so we don't get any more notifications. */
127 mmu_notifier_unregister(&handler->mn, handler->mn.mm);
128
129 /*
130 * Make sure the wq delete handler is finished running. It will not
131 * be triggered once the mmu notifiers are unregistered above.
132 */
133 flush_work(&handler->del_work);
134
135 INIT_LIST_HEAD(&del_list);
136
137 spin_lock_irqsave(&handler->lock, flags);
138 while ((node = rb_first_cached(&handler->root))) {
139 rbnode = rb_entry(node, struct mmu_rb_node, node);
140 rb_erase_cached(node, &handler->root);
141 /* move from LRU list to delete list */
142 list_move(&rbnode->list, &del_list);
143 }
144 spin_unlock_irqrestore(&handler->lock, flags);
145
146 while (!list_empty(&del_list)) {
147 rbnode = list_first_entry(&del_list, struct mmu_rb_node, list);
148 list_del(&rbnode->list);
149 kref_put(&rbnode->refcount, release_immediate);
150 }
151
152 /* Now the mm may be freed. */
153 mmdrop(handler->mn.mm);
154
155 kfree(handler);
156 }
157
hfi1_mmu_rb_insert(struct mmu_rb_handler * handler,struct mmu_rb_node * mnode)158 int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
159 struct mmu_rb_node *mnode)
160 {
161 struct mmu_rb_node *node;
162 unsigned long flags;
163 int ret = 0;
164
165 trace_hfi1_mmu_rb_insert(mnode->addr, mnode->len);
166
167 if (current->mm != handler->mn.mm)
168 return -EPERM;
169
170 spin_lock_irqsave(&handler->lock, flags);
171 node = __mmu_rb_search(handler, mnode->addr, mnode->len);
172 if (node) {
173 ret = -EEXIST;
174 goto unlock;
175 }
176 __mmu_int_rb_insert(mnode, &handler->root);
177 list_add_tail(&mnode->list, &handler->lru_list);
178 mnode->handler = handler;
179 unlock:
180 spin_unlock_irqrestore(&handler->lock, flags);
181 return ret;
182 }
183
184 /* Caller must hold handler lock */
hfi1_mmu_rb_get_first(struct mmu_rb_handler * handler,unsigned long addr,unsigned long len)185 struct mmu_rb_node *hfi1_mmu_rb_get_first(struct mmu_rb_handler *handler,
186 unsigned long addr, unsigned long len)
187 {
188 struct mmu_rb_node *node;
189
190 trace_hfi1_mmu_rb_search(addr, len);
191 node = __mmu_int_rb_iter_first(&handler->root, addr, (addr + len) - 1);
192 if (node)
193 list_move_tail(&node->list, &handler->lru_list);
194 return node;
195 }
196
197 /* Caller must hold handler lock */
__mmu_rb_search(struct mmu_rb_handler * handler,unsigned long addr,unsigned long len)198 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *handler,
199 unsigned long addr,
200 unsigned long len)
201 {
202 struct mmu_rb_node *node = NULL;
203
204 trace_hfi1_mmu_rb_search(addr, len);
205 if (!handler->ops->filter) {
206 node = __mmu_int_rb_iter_first(&handler->root, addr,
207 (addr + len) - 1);
208 } else {
209 for (node = __mmu_int_rb_iter_first(&handler->root, addr,
210 (addr + len) - 1);
211 node;
212 node = __mmu_int_rb_iter_next(node, addr,
213 (addr + len) - 1)) {
214 if (handler->ops->filter(node, addr, len))
215 return node;
216 }
217 }
218 return node;
219 }
220
221 /*
222 * Must NOT call while holding mnode->handler->lock.
223 * mnode->handler->ops->remove() may sleep and mnode->handler->lock is a
224 * spinlock.
225 */
release_immediate(struct kref * refcount)226 static void release_immediate(struct kref *refcount)
227 {
228 struct mmu_rb_node *mnode =
229 container_of(refcount, struct mmu_rb_node, refcount);
230 mnode->handler->ops->remove(mnode->handler->ops_arg, mnode);
231 }
232
233 /* Caller must hold mnode->handler->lock */
release_nolock(struct kref * refcount)234 static void release_nolock(struct kref *refcount)
235 {
236 struct mmu_rb_node *mnode =
237 container_of(refcount, struct mmu_rb_node, refcount);
238 list_move(&mnode->list, &mnode->handler->del_list);
239 queue_work(mnode->handler->wq, &mnode->handler->del_work);
240 }
241
242 /*
243 * struct mmu_rb_node->refcount kref_put() callback.
244 * Adds mmu_rb_node to mmu_rb_node->handler->del_list and queues
245 * handler->del_work on handler->wq.
246 * Does not remove mmu_rb_node from handler->lru_list or handler->rb_root.
247 * Acquires mmu_rb_node->handler->lock; do not call while already holding
248 * handler->lock.
249 */
hfi1_mmu_rb_release(struct kref * refcount)250 void hfi1_mmu_rb_release(struct kref *refcount)
251 {
252 struct mmu_rb_node *mnode =
253 container_of(refcount, struct mmu_rb_node, refcount);
254 struct mmu_rb_handler *handler = mnode->handler;
255 unsigned long flags;
256
257 spin_lock_irqsave(&handler->lock, flags);
258 list_move(&mnode->list, &mnode->handler->del_list);
259 spin_unlock_irqrestore(&handler->lock, flags);
260 queue_work(handler->wq, &handler->del_work);
261 }
262
hfi1_mmu_rb_evict(struct mmu_rb_handler * handler,void * evict_arg)263 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
264 {
265 struct mmu_rb_node *rbnode, *ptr;
266 struct list_head del_list;
267 unsigned long flags;
268 bool stop = false;
269
270 if (current->mm != handler->mn.mm)
271 return;
272
273 INIT_LIST_HEAD(&del_list);
274
275 spin_lock_irqsave(&handler->lock, flags);
276 list_for_each_entry_safe(rbnode, ptr, &handler->lru_list, list) {
277 /* refcount == 1 implies mmu_rb_handler has only rbnode ref */
278 if (kref_read(&rbnode->refcount) > 1)
279 continue;
280
281 if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg,
282 &stop)) {
283 __mmu_int_rb_remove(rbnode, &handler->root);
284 /* move from LRU list to delete list */
285 list_move(&rbnode->list, &del_list);
286 }
287 if (stop)
288 break;
289 }
290 spin_unlock_irqrestore(&handler->lock, flags);
291
292 list_for_each_entry_safe(rbnode, ptr, &del_list, list) {
293 kref_put(&rbnode->refcount, release_immediate);
294 }
295 }
296
mmu_notifier_range_start(struct mmu_notifier * mn,const struct mmu_notifier_range * range)297 static int mmu_notifier_range_start(struct mmu_notifier *mn,
298 const struct mmu_notifier_range *range)
299 {
300 struct mmu_rb_handler *handler =
301 container_of(mn, struct mmu_rb_handler, mn);
302 struct rb_root_cached *root = &handler->root;
303 struct mmu_rb_node *node, *ptr = NULL;
304 unsigned long flags;
305
306 spin_lock_irqsave(&handler->lock, flags);
307 for (node = __mmu_int_rb_iter_first(root, range->start, range->end-1);
308 node; node = ptr) {
309 /* Guard against node removal. */
310 ptr = __mmu_int_rb_iter_next(node, range->start,
311 range->end - 1);
312 trace_hfi1_mmu_mem_invalidate(node->addr, node->len);
313 /* Remove from rb tree and lru_list. */
314 __mmu_int_rb_remove(node, root);
315 list_del_init(&node->list);
316 kref_put(&node->refcount, release_nolock);
317 }
318 spin_unlock_irqrestore(&handler->lock, flags);
319
320 return 0;
321 }
322
323 /*
324 * Work queue function to remove all nodes that have been queued up to
325 * be removed. The key feature is that mm->mmap_lock is not being held
326 * and the remove callback can sleep while taking it, if needed.
327 */
handle_remove(struct work_struct * work)328 static void handle_remove(struct work_struct *work)
329 {
330 struct mmu_rb_handler *handler = container_of(work,
331 struct mmu_rb_handler,
332 del_work);
333 struct list_head del_list;
334 unsigned long flags;
335 struct mmu_rb_node *node;
336
337 /* remove anything that is queued to get removed */
338 spin_lock_irqsave(&handler->lock, flags);
339 list_replace_init(&handler->del_list, &del_list);
340 spin_unlock_irqrestore(&handler->lock, flags);
341
342 while (!list_empty(&del_list)) {
343 node = list_first_entry(&del_list, struct mmu_rb_node, list);
344 list_del(&node->list);
345 handler->ops->remove(handler->ops_arg, node);
346 }
347 }
348