1 // SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
2 /*
3 * Copyright(c) 2020 Cornelis Networks, Inc.
4 * Copyright(c) 2016 - 2017 Intel Corporation.
5 */
6
7 #include <linux/list.h>
8 #include <linux/rculist.h>
9 #include <linux/mmu_notifier.h>
10 #include <linux/interval_tree_generic.h>
11 #include <linux/sched/mm.h>
12
13 #include "mmu_rb.h"
14 #include "trace.h"
15
16 static unsigned long mmu_node_start(struct mmu_rb_node *);
17 static unsigned long mmu_node_last(struct mmu_rb_node *);
18 static int mmu_notifier_range_start(struct mmu_notifier *,
19 const struct mmu_notifier_range *);
20 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *,
21 unsigned long, unsigned long);
22 static void do_remove(struct mmu_rb_handler *handler,
23 struct list_head *del_list);
24 static void handle_remove(struct work_struct *work);
25
26 static const struct mmu_notifier_ops mn_opts = {
27 .invalidate_range_start = mmu_notifier_range_start,
28 };
29
30 INTERVAL_TREE_DEFINE(struct mmu_rb_node, node, unsigned long, __last,
31 mmu_node_start, mmu_node_last, static, __mmu_int_rb);
32
mmu_node_start(struct mmu_rb_node * node)33 static unsigned long mmu_node_start(struct mmu_rb_node *node)
34 {
35 return node->addr & PAGE_MASK;
36 }
37
mmu_node_last(struct mmu_rb_node * node)38 static unsigned long mmu_node_last(struct mmu_rb_node *node)
39 {
40 return PAGE_ALIGN(node->addr + node->len) - 1;
41 }
42
hfi1_mmu_rb_register(void * ops_arg,struct mmu_rb_ops * ops,struct workqueue_struct * wq,struct mmu_rb_handler ** handler)43 int hfi1_mmu_rb_register(void *ops_arg,
44 struct mmu_rb_ops *ops,
45 struct workqueue_struct *wq,
46 struct mmu_rb_handler **handler)
47 {
48 struct mmu_rb_handler *h;
49 int ret;
50
51 h = kzalloc(sizeof(*h), GFP_KERNEL);
52 if (!h)
53 return -ENOMEM;
54
55 h->root = RB_ROOT_CACHED;
56 h->ops = ops;
57 h->ops_arg = ops_arg;
58 INIT_HLIST_NODE(&h->mn.hlist);
59 spin_lock_init(&h->lock);
60 h->mn.ops = &mn_opts;
61 INIT_WORK(&h->del_work, handle_remove);
62 INIT_LIST_HEAD(&h->del_list);
63 INIT_LIST_HEAD(&h->lru_list);
64 h->wq = wq;
65
66 ret = mmu_notifier_register(&h->mn, current->mm);
67 if (ret) {
68 kfree(h);
69 return ret;
70 }
71
72 *handler = h;
73 return 0;
74 }
75
hfi1_mmu_rb_unregister(struct mmu_rb_handler * handler)76 void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler)
77 {
78 struct mmu_rb_node *rbnode;
79 struct rb_node *node;
80 unsigned long flags;
81 struct list_head del_list;
82
83 /* Unregister first so we don't get any more notifications. */
84 mmu_notifier_unregister(&handler->mn, handler->mn.mm);
85
86 /*
87 * Make sure the wq delete handler is finished running. It will not
88 * be triggered once the mmu notifiers are unregistered above.
89 */
90 flush_work(&handler->del_work);
91
92 INIT_LIST_HEAD(&del_list);
93
94 spin_lock_irqsave(&handler->lock, flags);
95 while ((node = rb_first_cached(&handler->root))) {
96 rbnode = rb_entry(node, struct mmu_rb_node, node);
97 rb_erase_cached(node, &handler->root);
98 /* move from LRU list to delete list */
99 list_move(&rbnode->list, &del_list);
100 }
101 spin_unlock_irqrestore(&handler->lock, flags);
102
103 do_remove(handler, &del_list);
104
105 kfree(handler);
106 }
107
hfi1_mmu_rb_insert(struct mmu_rb_handler * handler,struct mmu_rb_node * mnode)108 int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
109 struct mmu_rb_node *mnode)
110 {
111 struct mmu_rb_node *node;
112 unsigned long flags;
113 int ret = 0;
114
115 trace_hfi1_mmu_rb_insert(mnode->addr, mnode->len);
116
117 if (current->mm != handler->mn.mm)
118 return -EPERM;
119
120 spin_lock_irqsave(&handler->lock, flags);
121 node = __mmu_rb_search(handler, mnode->addr, mnode->len);
122 if (node) {
123 ret = -EINVAL;
124 goto unlock;
125 }
126 __mmu_int_rb_insert(mnode, &handler->root);
127 list_add(&mnode->list, &handler->lru_list);
128
129 ret = handler->ops->insert(handler->ops_arg, mnode);
130 if (ret) {
131 __mmu_int_rb_remove(mnode, &handler->root);
132 list_del(&mnode->list); /* remove from LRU list */
133 }
134 mnode->handler = handler;
135 unlock:
136 spin_unlock_irqrestore(&handler->lock, flags);
137 return ret;
138 }
139
140 /* Caller must hold handler lock */
__mmu_rb_search(struct mmu_rb_handler * handler,unsigned long addr,unsigned long len)141 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *handler,
142 unsigned long addr,
143 unsigned long len)
144 {
145 struct mmu_rb_node *node = NULL;
146
147 trace_hfi1_mmu_rb_search(addr, len);
148 if (!handler->ops->filter) {
149 node = __mmu_int_rb_iter_first(&handler->root, addr,
150 (addr + len) - 1);
151 } else {
152 for (node = __mmu_int_rb_iter_first(&handler->root, addr,
153 (addr + len) - 1);
154 node;
155 node = __mmu_int_rb_iter_next(node, addr,
156 (addr + len) - 1)) {
157 if (handler->ops->filter(node, addr, len))
158 return node;
159 }
160 }
161 return node;
162 }
163
hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler * handler,unsigned long addr,unsigned long len,struct mmu_rb_node ** rb_node)164 bool hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler *handler,
165 unsigned long addr, unsigned long len,
166 struct mmu_rb_node **rb_node)
167 {
168 struct mmu_rb_node *node;
169 unsigned long flags;
170 bool ret = false;
171
172 if (current->mm != handler->mn.mm)
173 return ret;
174
175 spin_lock_irqsave(&handler->lock, flags);
176 node = __mmu_rb_search(handler, addr, len);
177 if (node) {
178 if (node->addr == addr && node->len == len)
179 goto unlock;
180 __mmu_int_rb_remove(node, &handler->root);
181 list_del(&node->list); /* remove from LRU list */
182 ret = true;
183 }
184 unlock:
185 spin_unlock_irqrestore(&handler->lock, flags);
186 *rb_node = node;
187 return ret;
188 }
189
hfi1_mmu_rb_evict(struct mmu_rb_handler * handler,void * evict_arg)190 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
191 {
192 struct mmu_rb_node *rbnode, *ptr;
193 struct list_head del_list;
194 unsigned long flags;
195 bool stop = false;
196
197 if (current->mm != handler->mn.mm)
198 return;
199
200 INIT_LIST_HEAD(&del_list);
201
202 spin_lock_irqsave(&handler->lock, flags);
203 list_for_each_entry_safe_reverse(rbnode, ptr, &handler->lru_list,
204 list) {
205 if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg,
206 &stop)) {
207 __mmu_int_rb_remove(rbnode, &handler->root);
208 /* move from LRU list to delete list */
209 list_move(&rbnode->list, &del_list);
210 }
211 if (stop)
212 break;
213 }
214 spin_unlock_irqrestore(&handler->lock, flags);
215
216 while (!list_empty(&del_list)) {
217 rbnode = list_first_entry(&del_list, struct mmu_rb_node, list);
218 list_del(&rbnode->list);
219 handler->ops->remove(handler->ops_arg, rbnode);
220 }
221 }
222
223 /*
224 * It is up to the caller to ensure that this function does not race with the
225 * mmu invalidate notifier which may be calling the users remove callback on
226 * 'node'.
227 */
hfi1_mmu_rb_remove(struct mmu_rb_handler * handler,struct mmu_rb_node * node)228 void hfi1_mmu_rb_remove(struct mmu_rb_handler *handler,
229 struct mmu_rb_node *node)
230 {
231 unsigned long flags;
232
233 if (current->mm != handler->mn.mm)
234 return;
235
236 /* Validity of handler and node pointers has been checked by caller. */
237 trace_hfi1_mmu_rb_remove(node->addr, node->len);
238 spin_lock_irqsave(&handler->lock, flags);
239 __mmu_int_rb_remove(node, &handler->root);
240 list_del(&node->list); /* remove from LRU list */
241 spin_unlock_irqrestore(&handler->lock, flags);
242
243 handler->ops->remove(handler->ops_arg, node);
244 }
245
mmu_notifier_range_start(struct mmu_notifier * mn,const struct mmu_notifier_range * range)246 static int mmu_notifier_range_start(struct mmu_notifier *mn,
247 const struct mmu_notifier_range *range)
248 {
249 struct mmu_rb_handler *handler =
250 container_of(mn, struct mmu_rb_handler, mn);
251 struct rb_root_cached *root = &handler->root;
252 struct mmu_rb_node *node, *ptr = NULL;
253 unsigned long flags;
254 bool added = false;
255
256 spin_lock_irqsave(&handler->lock, flags);
257 for (node = __mmu_int_rb_iter_first(root, range->start, range->end-1);
258 node; node = ptr) {
259 /* Guard against node removal. */
260 ptr = __mmu_int_rb_iter_next(node, range->start,
261 range->end - 1);
262 trace_hfi1_mmu_mem_invalidate(node->addr, node->len);
263 if (handler->ops->invalidate(handler->ops_arg, node)) {
264 __mmu_int_rb_remove(node, root);
265 /* move from LRU list to delete list */
266 list_move(&node->list, &handler->del_list);
267 added = true;
268 }
269 }
270 spin_unlock_irqrestore(&handler->lock, flags);
271
272 if (added)
273 queue_work(handler->wq, &handler->del_work);
274
275 return 0;
276 }
277
278 /*
279 * Call the remove function for the given handler and the list. This
280 * is expected to be called with a delete list extracted from handler.
281 * The caller should not be holding the handler lock.
282 */
do_remove(struct mmu_rb_handler * handler,struct list_head * del_list)283 static void do_remove(struct mmu_rb_handler *handler,
284 struct list_head *del_list)
285 {
286 struct mmu_rb_node *node;
287
288 while (!list_empty(del_list)) {
289 node = list_first_entry(del_list, struct mmu_rb_node, list);
290 list_del(&node->list);
291 handler->ops->remove(handler->ops_arg, node);
292 }
293 }
294
295 /*
296 * Work queue function to remove all nodes that have been queued up to
297 * be removed. The key feature is that mm->mmap_lock is not being held
298 * and the remove callback can sleep while taking it, if needed.
299 */
handle_remove(struct work_struct * work)300 static void handle_remove(struct work_struct *work)
301 {
302 struct mmu_rb_handler *handler = container_of(work,
303 struct mmu_rb_handler,
304 del_work);
305 struct list_head del_list;
306 unsigned long flags;
307
308 /* remove anything that is queued to get removed */
309 spin_lock_irqsave(&handler->lock, flags);
310 list_replace_init(&handler->del_list, &del_list);
311 spin_unlock_irqrestore(&handler->lock, flags);
312
313 do_remove(handler, &del_list);
314 }
315