xref: /openbmc/linux/net/xdp/xdp_umem.c (revision f125e2d4) 
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 #include <linux/vmalloc.h>
18 
19 #include "xdp_umem.h"
20 #include "xsk_queue.h"
21 
22 #define XDP_UMEM_MIN_CHUNK_SIZE 2048
23 
24 static DEFINE_IDA(umem_ida);
25 
26 void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
27 {
28 	unsigned long flags;
29 
30 	if (!xs->tx)
31 		return;
32 
33 	spin_lock_irqsave(&umem->xsk_list_lock, flags);
34 	list_add_rcu(&xs->list, &umem->xsk_list);
35 	spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
36 }
37 
38 void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
39 {
40 	unsigned long flags;
41 
42 	if (!xs->tx)
43 		return;
44 
45 	spin_lock_irqsave(&umem->xsk_list_lock, flags);
46 	list_del_rcu(&xs->list);
47 	spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
48 }
49 
50 /* The umem is stored both in the _rx struct and the _tx struct as we do
51  * not know if the device has more tx queues than rx, or the opposite.
52  * This might also change during run time.
53  */
54 static int xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem,
55 			       u16 queue_id)
56 {
57 	if (queue_id >= max_t(unsigned int,
58 			      dev->real_num_rx_queues,
59 			      dev->real_num_tx_queues))
60 		return -EINVAL;
61 
62 	if (queue_id < dev->real_num_rx_queues)
63 		dev->_rx[queue_id].umem = umem;
64 	if (queue_id < dev->real_num_tx_queues)
65 		dev->_tx[queue_id].umem = umem;
66 
67 	return 0;
68 }
69 
70 struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
71 				       u16 queue_id)
72 {
73 	if (queue_id < dev->real_num_rx_queues)
74 		return dev->_rx[queue_id].umem;
75 	if (queue_id < dev->real_num_tx_queues)
76 		return dev->_tx[queue_id].umem;
77 
78 	return NULL;
79 }
80 EXPORT_SYMBOL(xdp_get_umem_from_qid);
81 
82 static void xdp_clear_umem_at_qid(struct net_device *dev, u16 queue_id)
83 {
84 	if (queue_id < dev->real_num_rx_queues)
85 		dev->_rx[queue_id].umem = NULL;
86 	if (queue_id < dev->real_num_tx_queues)
87 		dev->_tx[queue_id].umem = NULL;
88 }
89 
90 int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
91 			u16 queue_id, u16 flags)
92 {
93 	bool force_zc, force_copy;
94 	struct netdev_bpf bpf;
95 	int err = 0;
96 
97 	ASSERT_RTNL();
98 
99 	force_zc = flags & XDP_ZEROCOPY;
100 	force_copy = flags & XDP_COPY;
101 
102 	if (force_zc && force_copy)
103 		return -EINVAL;
104 
105 	if (xdp_get_umem_from_qid(dev, queue_id))
106 		return -EBUSY;
107 
108 	err = xdp_reg_umem_at_qid(dev, umem, queue_id);
109 	if (err)
110 		return err;
111 
112 	umem->dev = dev;
113 	umem->queue_id = queue_id;
114 
115 	if (flags & XDP_USE_NEED_WAKEUP) {
116 		umem->flags |= XDP_UMEM_USES_NEED_WAKEUP;
117 		/* Tx needs to be explicitly woken up the first time.
118 		 * Also for supporting drivers that do not implement this
119 		 * feature. They will always have to call sendto().
120 		 */
121 		xsk_set_tx_need_wakeup(umem);
122 	}
123 
124 	dev_hold(dev);
125 
126 	if (force_copy)
127 		/* For copy-mode, we are done. */
128 		return 0;
129 
130 	if (!dev->netdev_ops->ndo_bpf || !dev->netdev_ops->ndo_xsk_wakeup) {
131 		err = -EOPNOTSUPP;
132 		goto err_unreg_umem;
133 	}
134 
135 	bpf.command = XDP_SETUP_XSK_UMEM;
136 	bpf.xsk.umem = umem;
137 	bpf.xsk.queue_id = queue_id;
138 
139 	err = dev->netdev_ops->ndo_bpf(dev, &bpf);
140 	if (err)
141 		goto err_unreg_umem;
142 
143 	umem->zc = true;
144 	return 0;
145 
146 err_unreg_umem:
147 	if (!force_zc)
148 		err = 0; /* fallback to copy mode */
149 	if (err)
150 		xdp_clear_umem_at_qid(dev, queue_id);
151 	return err;
152 }
153 
154 void xdp_umem_clear_dev(struct xdp_umem *umem)
155 {
156 	struct netdev_bpf bpf;
157 	int err;
158 
159 	ASSERT_RTNL();
160 
161 	if (!umem->dev)
162 		return;
163 
164 	if (umem->zc) {
165 		bpf.command = XDP_SETUP_XSK_UMEM;
166 		bpf.xsk.umem = NULL;
167 		bpf.xsk.queue_id = umem->queue_id;
168 
169 		err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf);
170 
171 		if (err)
172 			WARN(1, "failed to disable umem!\n");
173 	}
174 
175 	xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
176 
177 	dev_put(umem->dev);
178 	umem->dev = NULL;
179 	umem->zc = false;
180 }
181 
182 static void xdp_umem_unmap_pages(struct xdp_umem *umem)
183 {
184 	unsigned int i;
185 
186 	for (i = 0; i < umem->npgs; i++)
187 		if (PageHighMem(umem->pgs[i]))
188 			vunmap(umem->pages[i].addr);
189 }
190 
191 static int xdp_umem_map_pages(struct xdp_umem *umem)
192 {
193 	unsigned int i;
194 	void *addr;
195 
196 	for (i = 0; i < umem->npgs; i++) {
197 		if (PageHighMem(umem->pgs[i]))
198 			addr = vmap(&umem->pgs[i], 1, VM_MAP, PAGE_KERNEL);
199 		else
200 			addr = page_address(umem->pgs[i]);
201 
202 		if (!addr) {
203 			xdp_umem_unmap_pages(umem);
204 			return -ENOMEM;
205 		}
206 
207 		umem->pages[i].addr = addr;
208 	}
209 
210 	return 0;
211 }
212 
213 static void xdp_umem_unpin_pages(struct xdp_umem *umem)
214 {
215 	unpin_user_pages_dirty_lock(umem->pgs, umem->npgs, true);
216 
217 	kfree(umem->pgs);
218 	umem->pgs = NULL;
219 }
220 
221 static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
222 {
223 	if (umem->user) {
224 		atomic_long_sub(umem->npgs, &umem->user->locked_vm);
225 		free_uid(umem->user);
226 	}
227 }
228 
229 static void xdp_umem_release(struct xdp_umem *umem)
230 {
231 	rtnl_lock();
232 	xdp_umem_clear_dev(umem);
233 	rtnl_unlock();
234 
235 	ida_simple_remove(&umem_ida, umem->id);
236 
237 	if (umem->fq) {
238 		xskq_destroy(umem->fq);
239 		umem->fq = NULL;
240 	}
241 
242 	if (umem->cq) {
243 		xskq_destroy(umem->cq);
244 		umem->cq = NULL;
245 	}
246 
247 	xsk_reuseq_destroy(umem);
248 
249 	xdp_umem_unmap_pages(umem);
250 	xdp_umem_unpin_pages(umem);
251 
252 	kvfree(umem->pages);
253 	umem->pages = NULL;
254 
255 	xdp_umem_unaccount_pages(umem);
256 	kfree(umem);
257 }
258 
259 static void xdp_umem_release_deferred(struct work_struct *work)
260 {
261 	struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
262 
263 	xdp_umem_release(umem);
264 }
265 
266 void xdp_get_umem(struct xdp_umem *umem)
267 {
268 	refcount_inc(&umem->users);
269 }
270 
271 void xdp_put_umem(struct xdp_umem *umem)
272 {
273 	if (!umem)
274 		return;
275 
276 	if (refcount_dec_and_test(&umem->users)) {
277 		INIT_WORK(&umem->work, xdp_umem_release_deferred);
278 		schedule_work(&umem->work);
279 	}
280 }
281 
282 static int xdp_umem_pin_pages(struct xdp_umem *umem)
283 {
284 	unsigned int gup_flags = FOLL_WRITE;
285 	long npgs;
286 	int err;
287 
288 	umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs),
289 			    GFP_KERNEL | __GFP_NOWARN);
290 	if (!umem->pgs)
291 		return -ENOMEM;
292 
293 	down_read(&current->mm->mmap_sem);
294 	npgs = pin_user_pages(umem->address, umem->npgs,
295 			      gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
296 	up_read(&current->mm->mmap_sem);
297 
298 	if (npgs != umem->npgs) {
299 		if (npgs >= 0) {
300 			umem->npgs = npgs;
301 			err = -ENOMEM;
302 			goto out_pin;
303 		}
304 		err = npgs;
305 		goto out_pgs;
306 	}
307 	return 0;
308 
309 out_pin:
310 	xdp_umem_unpin_pages(umem);
311 out_pgs:
312 	kfree(umem->pgs);
313 	umem->pgs = NULL;
314 	return err;
315 }
316 
317 static int xdp_umem_account_pages(struct xdp_umem *umem)
318 {
319 	unsigned long lock_limit, new_npgs, old_npgs;
320 
321 	if (capable(CAP_IPC_LOCK))
322 		return 0;
323 
324 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
325 	umem->user = get_uid(current_user());
326 
327 	do {
328 		old_npgs = atomic_long_read(&umem->user->locked_vm);
329 		new_npgs = old_npgs + umem->npgs;
330 		if (new_npgs > lock_limit) {
331 			free_uid(umem->user);
332 			umem->user = NULL;
333 			return -ENOBUFS;
334 		}
335 	} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
336 				     new_npgs) != old_npgs);
337 	return 0;
338 }
339 
340 static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
341 {
342 	bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
343 	u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
344 	unsigned int chunks, chunks_per_page;
345 	u64 addr = mr->addr, size = mr->len;
346 	int size_chk, err;
347 
348 	if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
349 		/* Strictly speaking we could support this, if:
350 		 * - huge pages, or*
351 		 * - using an IOMMU, or
352 		 * - making sure the memory area is consecutive
353 		 * but for now, we simply say "computer says no".
354 		 */
355 		return -EINVAL;
356 	}
357 
358 	if (mr->flags & ~(XDP_UMEM_UNALIGNED_CHUNK_FLAG |
359 			XDP_UMEM_USES_NEED_WAKEUP))
360 		return -EINVAL;
361 
362 	if (!unaligned_chunks && !is_power_of_2(chunk_size))
363 		return -EINVAL;
364 
365 	if (!PAGE_ALIGNED(addr)) {
366 		/* Memory area has to be page size aligned. For
367 		 * simplicity, this might change.
368 		 */
369 		return -EINVAL;
370 	}
371 
372 	if ((addr + size) < addr)
373 		return -EINVAL;
374 
375 	chunks = (unsigned int)div_u64(size, chunk_size);
376 	if (chunks == 0)
377 		return -EINVAL;
378 
379 	if (!unaligned_chunks) {
380 		chunks_per_page = PAGE_SIZE / chunk_size;
381 		if (chunks < chunks_per_page || chunks % chunks_per_page)
382 			return -EINVAL;
383 	}
384 
385 	size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM;
386 	if (size_chk < 0)
387 		return -EINVAL;
388 
389 	umem->address = (unsigned long)addr;
390 	umem->chunk_mask = unaligned_chunks ? XSK_UNALIGNED_BUF_ADDR_MASK
391 					    : ~((u64)chunk_size - 1);
392 	umem->size = size;
393 	umem->headroom = headroom;
394 	umem->chunk_size_nohr = chunk_size - headroom;
395 	umem->npgs = size / PAGE_SIZE;
396 	umem->pgs = NULL;
397 	umem->user = NULL;
398 	umem->flags = mr->flags;
399 	INIT_LIST_HEAD(&umem->xsk_list);
400 	spin_lock_init(&umem->xsk_list_lock);
401 
402 	refcount_set(&umem->users, 1);
403 
404 	err = xdp_umem_account_pages(umem);
405 	if (err)
406 		return err;
407 
408 	err = xdp_umem_pin_pages(umem);
409 	if (err)
410 		goto out_account;
411 
412 	umem->pages = kvcalloc(umem->npgs, sizeof(*umem->pages),
413 			       GFP_KERNEL_ACCOUNT);
414 	if (!umem->pages) {
415 		err = -ENOMEM;
416 		goto out_pin;
417 	}
418 
419 	err = xdp_umem_map_pages(umem);
420 	if (!err)
421 		return 0;
422 
423 	kvfree(umem->pages);
424 
425 out_pin:
426 	xdp_umem_unpin_pages(umem);
427 out_account:
428 	xdp_umem_unaccount_pages(umem);
429 	return err;
430 }
431 
432 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
433 {
434 	struct xdp_umem *umem;
435 	int err;
436 
437 	umem = kzalloc(sizeof(*umem), GFP_KERNEL);
438 	if (!umem)
439 		return ERR_PTR(-ENOMEM);
440 
441 	err = ida_simple_get(&umem_ida, 0, 0, GFP_KERNEL);
442 	if (err < 0) {
443 		kfree(umem);
444 		return ERR_PTR(err);
445 	}
446 	umem->id = err;
447 
448 	err = xdp_umem_reg(umem, mr);
449 	if (err) {
450 		ida_simple_remove(&umem_ida, umem->id);
451 		kfree(umem);
452 		return ERR_PTR(err);
453 	}
454 
455 	return umem;
456 }
457 
458 bool xdp_umem_validate_queues(struct xdp_umem *umem)
459 {
460 	return umem->fq && umem->cq;
461 }
462