xref: /linux/net/xdp/xdp_umem.c (revision 44f57d78) 
1 // SPDX-License-Identifier: GPL-2.0
2 /* XDP user-space packet buffer
3  * Copyright(c) 2018 Intel Corporation.
4  */
5 
6 #include <linux/init.h>
7 #include <linux/sched/mm.h>
8 #include <linux/sched/signal.h>
9 #include <linux/sched/task.h>
10 #include <linux/uaccess.h>
11 #include <linux/slab.h>
12 #include <linux/bpf.h>
13 #include <linux/mm.h>
14 #include <linux/netdevice.h>
15 #include <linux/rtnetlink.h>
16 #include <linux/idr.h>
17 
18 #include "xdp_umem.h"
19 #include "xsk_queue.h"
20 
21 #define XDP_UMEM_MIN_CHUNK_SIZE 2048
22 
23 static DEFINE_IDA(umem_ida);
24 
25 void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
26 {
27 	unsigned long flags;
28 
29 	spin_lock_irqsave(&umem->xsk_list_lock, flags);
30 	list_add_rcu(&xs->list, &umem->xsk_list);
31 	spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
32 }
33 
34 void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
35 {
36 	unsigned long flags;
37 
38 	spin_lock_irqsave(&umem->xsk_list_lock, flags);
39 	list_del_rcu(&xs->list);
40 	spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
41 }
42 
43 /* The umem is stored both in the _rx struct and the _tx struct as we do
44  * not know if the device has more tx queues than rx, or the opposite.
45  * This might also change during run time.
46  */
47 static int xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem,
48 			       u16 queue_id)
49 {
50 	if (queue_id >= max_t(unsigned int,
51 			      dev->real_num_rx_queues,
52 			      dev->real_num_tx_queues))
53 		return -EINVAL;
54 
55 	if (queue_id < dev->real_num_rx_queues)
56 		dev->_rx[queue_id].umem = umem;
57 	if (queue_id < dev->real_num_tx_queues)
58 		dev->_tx[queue_id].umem = umem;
59 
60 	return 0;
61 }
62 
63 struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
64 				       u16 queue_id)
65 {
66 	if (queue_id < dev->real_num_rx_queues)
67 		return dev->_rx[queue_id].umem;
68 	if (queue_id < dev->real_num_tx_queues)
69 		return dev->_tx[queue_id].umem;
70 
71 	return NULL;
72 }
73 EXPORT_SYMBOL(xdp_get_umem_from_qid);
74 
75 static void xdp_clear_umem_at_qid(struct net_device *dev, u16 queue_id)
76 {
77 	if (queue_id < dev->real_num_rx_queues)
78 		dev->_rx[queue_id].umem = NULL;
79 	if (queue_id < dev->real_num_tx_queues)
80 		dev->_tx[queue_id].umem = NULL;
81 }
82 
83 int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
84 			u16 queue_id, u16 flags)
85 {
86 	bool force_zc, force_copy;
87 	struct netdev_bpf bpf;
88 	int err = 0;
89 
90 	force_zc = flags & XDP_ZEROCOPY;
91 	force_copy = flags & XDP_COPY;
92 
93 	if (force_zc && force_copy)
94 		return -EINVAL;
95 
96 	rtnl_lock();
97 	if (xdp_get_umem_from_qid(dev, queue_id)) {
98 		err = -EBUSY;
99 		goto out_rtnl_unlock;
100 	}
101 
102 	err = xdp_reg_umem_at_qid(dev, umem, queue_id);
103 	if (err)
104 		goto out_rtnl_unlock;
105 
106 	umem->dev = dev;
107 	umem->queue_id = queue_id;
108 	if (force_copy)
109 		/* For copy-mode, we are done. */
110 		goto out_rtnl_unlock;
111 
112 	if (!dev->netdev_ops->ndo_bpf ||
113 	    !dev->netdev_ops->ndo_xsk_async_xmit) {
114 		err = -EOPNOTSUPP;
115 		goto err_unreg_umem;
116 	}
117 
118 	bpf.command = XDP_SETUP_XSK_UMEM;
119 	bpf.xsk.umem = umem;
120 	bpf.xsk.queue_id = queue_id;
121 
122 	err = dev->netdev_ops->ndo_bpf(dev, &bpf);
123 	if (err)
124 		goto err_unreg_umem;
125 	rtnl_unlock();
126 
127 	dev_hold(dev);
128 	umem->zc = true;
129 	return 0;
130 
131 err_unreg_umem:
132 	if (!force_zc)
133 		err = 0; /* fallback to copy mode */
134 	if (err)
135 		xdp_clear_umem_at_qid(dev, queue_id);
136 out_rtnl_unlock:
137 	rtnl_unlock();
138 	return err;
139 }
140 
141 static void xdp_umem_clear_dev(struct xdp_umem *umem)
142 {
143 	struct netdev_bpf bpf;
144 	int err;
145 
146 	if (!umem->dev)
147 		return;
148 
149 	if (umem->zc) {
150 		bpf.command = XDP_SETUP_XSK_UMEM;
151 		bpf.xsk.umem = NULL;
152 		bpf.xsk.queue_id = umem->queue_id;
153 
154 		rtnl_lock();
155 		err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf);
156 		rtnl_unlock();
157 
158 		if (err)
159 			WARN(1, "failed to disable umem!\n");
160 	}
161 
162 	rtnl_lock();
163 	xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
164 	rtnl_unlock();
165 
166 	if (umem->zc) {
167 		dev_put(umem->dev);
168 		umem->zc = false;
169 	}
170 }
171 
172 static void xdp_umem_unpin_pages(struct xdp_umem *umem)
173 {
174 	unsigned int i;
175 
176 	for (i = 0; i < umem->npgs; i++) {
177 		struct page *page = umem->pgs[i];
178 
179 		set_page_dirty_lock(page);
180 		put_page(page);
181 	}
182 
183 	kfree(umem->pgs);
184 	umem->pgs = NULL;
185 }
186 
187 static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
188 {
189 	if (umem->user) {
190 		atomic_long_sub(umem->npgs, &umem->user->locked_vm);
191 		free_uid(umem->user);
192 	}
193 }
194 
195 static void xdp_umem_release(struct xdp_umem *umem)
196 {
197 	xdp_umem_clear_dev(umem);
198 
199 	ida_simple_remove(&umem_ida, umem->id);
200 
201 	if (umem->fq) {
202 		xskq_destroy(umem->fq);
203 		umem->fq = NULL;
204 	}
205 
206 	if (umem->cq) {
207 		xskq_destroy(umem->cq);
208 		umem->cq = NULL;
209 	}
210 
211 	xsk_reuseq_destroy(umem);
212 
213 	xdp_umem_unpin_pages(umem);
214 
215 	kfree(umem->pages);
216 	umem->pages = NULL;
217 
218 	xdp_umem_unaccount_pages(umem);
219 	kfree(umem);
220 }
221 
222 static void xdp_umem_release_deferred(struct work_struct *work)
223 {
224 	struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
225 
226 	xdp_umem_release(umem);
227 }
228 
229 void xdp_get_umem(struct xdp_umem *umem)
230 {
231 	refcount_inc(&umem->users);
232 }
233 
234 void xdp_put_umem(struct xdp_umem *umem)
235 {
236 	if (!umem)
237 		return;
238 
239 	if (refcount_dec_and_test(&umem->users)) {
240 		INIT_WORK(&umem->work, xdp_umem_release_deferred);
241 		schedule_work(&umem->work);
242 	}
243 }
244 
245 static int xdp_umem_pin_pages(struct xdp_umem *umem)
246 {
247 	unsigned int gup_flags = FOLL_WRITE;
248 	long npgs;
249 	int err;
250 
251 	umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs),
252 			    GFP_KERNEL | __GFP_NOWARN);
253 	if (!umem->pgs)
254 		return -ENOMEM;
255 
256 	down_read(&current->mm->mmap_sem);
257 	npgs = get_user_pages(umem->address, umem->npgs,
258 			      gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
259 	up_read(&current->mm->mmap_sem);
260 
261 	if (npgs != umem->npgs) {
262 		if (npgs >= 0) {
263 			umem->npgs = npgs;
264 			err = -ENOMEM;
265 			goto out_pin;
266 		}
267 		err = npgs;
268 		goto out_pgs;
269 	}
270 	return 0;
271 
272 out_pin:
273 	xdp_umem_unpin_pages(umem);
274 out_pgs:
275 	kfree(umem->pgs);
276 	umem->pgs = NULL;
277 	return err;
278 }
279 
280 static int xdp_umem_account_pages(struct xdp_umem *umem)
281 {
282 	unsigned long lock_limit, new_npgs, old_npgs;
283 
284 	if (capable(CAP_IPC_LOCK))
285 		return 0;
286 
287 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
288 	umem->user = get_uid(current_user());
289 
290 	do {
291 		old_npgs = atomic_long_read(&umem->user->locked_vm);
292 		new_npgs = old_npgs + umem->npgs;
293 		if (new_npgs > lock_limit) {
294 			free_uid(umem->user);
295 			umem->user = NULL;
296 			return -ENOBUFS;
297 		}
298 	} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
299 				     new_npgs) != old_npgs);
300 	return 0;
301 }
302 
303 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
304 {
305 	u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
306 	unsigned int chunks, chunks_per_page;
307 	u64 addr = mr->addr, size = mr->len;
308 	int size_chk, err, i;
309 
310 	if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
311 		/* Strictly speaking we could support this, if:
312 		 * - huge pages, or*
313 		 * - using an IOMMU, or
314 		 * - making sure the memory area is consecutive
315 		 * but for now, we simply say "computer says no".
316 		 */
317 		return -EINVAL;
318 	}
319 
320 	if (!is_power_of_2(chunk_size))
321 		return -EINVAL;
322 
323 	if (!PAGE_ALIGNED(addr)) {
324 		/* Memory area has to be page size aligned. For
325 		 * simplicity, this might change.
326 		 */
327 		return -EINVAL;
328 	}
329 
330 	if ((addr + size) < addr)
331 		return -EINVAL;
332 
333 	chunks = (unsigned int)div_u64(size, chunk_size);
334 	if (chunks == 0)
335 		return -EINVAL;
336 
337 	chunks_per_page = PAGE_SIZE / chunk_size;
338 	if (chunks < chunks_per_page || chunks % chunks_per_page)
339 		return -EINVAL;
340 
341 	headroom = ALIGN(headroom, 64);
342 
343 	size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM;
344 	if (size_chk < 0)
345 		return -EINVAL;
346 
347 	umem->address = (unsigned long)addr;
348 	umem->chunk_mask = ~((u64)chunk_size - 1);
349 	umem->size = size;
350 	umem->headroom = headroom;
351 	umem->chunk_size_nohr = chunk_size - headroom;
352 	umem->npgs = size / PAGE_SIZE;
353 	umem->pgs = NULL;
354 	umem->user = NULL;
355 	INIT_LIST_HEAD(&umem->xsk_list);
356 	spin_lock_init(&umem->xsk_list_lock);
357 
358 	refcount_set(&umem->users, 1);
359 
360 	err = xdp_umem_account_pages(umem);
361 	if (err)
362 		return err;
363 
364 	err = xdp_umem_pin_pages(umem);
365 	if (err)
366 		goto out_account;
367 
368 	umem->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL);
369 	if (!umem->pages) {
370 		err = -ENOMEM;
371 		goto out_account;
372 	}
373 
374 	for (i = 0; i < umem->npgs; i++)
375 		umem->pages[i].addr = page_address(umem->pgs[i]);
376 
377 	return 0;
378 
379 out_account:
380 	xdp_umem_unaccount_pages(umem);
381 	return err;
382 }
383 
384 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
385 {
386 	struct xdp_umem *umem;
387 	int err;
388 
389 	umem = kzalloc(sizeof(*umem), GFP_KERNEL);
390 	if (!umem)
391 		return ERR_PTR(-ENOMEM);
392 
393 	err = ida_simple_get(&umem_ida, 0, 0, GFP_KERNEL);
394 	if (err < 0) {
395 		kfree(umem);
396 		return ERR_PTR(err);
397 	}
398 	umem->id = err;
399 
400 	err = xdp_umem_reg(umem, mr);
401 	if (err) {
402 		ida_simple_remove(&umem_ida, umem->id);
403 		kfree(umem);
404 		return ERR_PTR(err);
405 	}
406 
407 	return umem;
408 }
409 
410 bool xdp_umem_validate_queues(struct xdp_umem *umem)
411 {
412 	return umem->fq && umem->cq;
413 }
414