xref: /openbmc/linux/net/xdp/xsk_buff_pool.c (revision a4767912) 
1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <net/xsk_buff_pool.h>
4 #include <net/xdp_sock.h>
5 #include <net/xdp_sock_drv.h>
6 
7 #include "xsk_queue.h"
8 #include "xdp_umem.h"
9 #include "xsk.h"
10 
11 void xp_add_xsk(struct xsk_buff_pool *pool, struct xdp_sock *xs)
12 {
13 	unsigned long flags;
14 
15 	if (!xs->tx)
16 		return;
17 
18 	spin_lock_irqsave(&pool->xsk_tx_list_lock, flags);
19 	list_add_rcu(&xs->tx_list, &pool->xsk_tx_list);
20 	spin_unlock_irqrestore(&pool->xsk_tx_list_lock, flags);
21 }
22 
23 void xp_del_xsk(struct xsk_buff_pool *pool, struct xdp_sock *xs)
24 {
25 	unsigned long flags;
26 
27 	if (!xs->tx)
28 		return;
29 
30 	spin_lock_irqsave(&pool->xsk_tx_list_lock, flags);
31 	list_del_rcu(&xs->tx_list);
32 	spin_unlock_irqrestore(&pool->xsk_tx_list_lock, flags);
33 }
34 
35 void xp_destroy(struct xsk_buff_pool *pool)
36 {
37 	if (!pool)
38 		return;
39 
40 	kvfree(pool->heads);
41 	kvfree(pool);
42 }
43 
44 struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
45 						struct xdp_umem *umem)
46 {
47 	struct xsk_buff_pool *pool;
48 	struct xdp_buff_xsk *xskb;
49 	u32 i;
50 
51 	pool = kvzalloc(struct_size(pool, free_heads, umem->chunks),
52 			GFP_KERNEL);
53 	if (!pool)
54 		goto out;
55 
56 	pool->heads = kvcalloc(umem->chunks, sizeof(*pool->heads), GFP_KERNEL);
57 	if (!pool->heads)
58 		goto out;
59 
60 	pool->chunk_mask = ~((u64)umem->chunk_size - 1);
61 	pool->addrs_cnt = umem->size;
62 	pool->heads_cnt = umem->chunks;
63 	pool->free_heads_cnt = umem->chunks;
64 	pool->headroom = umem->headroom;
65 	pool->chunk_size = umem->chunk_size;
66 	pool->unaligned = umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
67 	pool->frame_len = umem->chunk_size - umem->headroom -
68 		XDP_PACKET_HEADROOM;
69 	pool->umem = umem;
70 	pool->addrs = umem->addrs;
71 	INIT_LIST_HEAD(&pool->free_list);
72 	INIT_LIST_HEAD(&pool->xsk_tx_list);
73 	spin_lock_init(&pool->xsk_tx_list_lock);
74 	refcount_set(&pool->users, 1);
75 
76 	pool->fq = xs->fq_tmp;
77 	pool->cq = xs->cq_tmp;
78 	xs->fq_tmp = NULL;
79 	xs->cq_tmp = NULL;
80 
81 	for (i = 0; i < pool->free_heads_cnt; i++) {
82 		xskb = &pool->heads[i];
83 		xskb->pool = pool;
84 		xskb->xdp.frame_sz = umem->chunk_size - umem->headroom;
85 		pool->free_heads[i] = xskb;
86 	}
87 
88 	return pool;
89 
90 out:
91 	xp_destroy(pool);
92 	return NULL;
93 }
94 
95 void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq)
96 {
97 	u32 i;
98 
99 	for (i = 0; i < pool->heads_cnt; i++)
100 		pool->heads[i].xdp.rxq = rxq;
101 }
102 EXPORT_SYMBOL(xp_set_rxq_info);
103 
104 static void xp_disable_drv_zc(struct xsk_buff_pool *pool)
105 {
106 	struct netdev_bpf bpf;
107 	int err;
108 
109 	ASSERT_RTNL();
110 
111 	if (pool->umem->zc) {
112 		bpf.command = XDP_SETUP_XSK_POOL;
113 		bpf.xsk.pool = NULL;
114 		bpf.xsk.queue_id = pool->queue_id;
115 
116 		err = pool->netdev->netdev_ops->ndo_bpf(pool->netdev, &bpf);
117 
118 		if (err)
119 			WARN(1, "Failed to disable zero-copy!\n");
120 	}
121 }
122 
123 static int __xp_assign_dev(struct xsk_buff_pool *pool,
124 			   struct net_device *netdev, u16 queue_id, u16 flags)
125 {
126 	bool force_zc, force_copy;
127 	struct netdev_bpf bpf;
128 	int err = 0;
129 
130 	ASSERT_RTNL();
131 
132 	force_zc = flags & XDP_ZEROCOPY;
133 	force_copy = flags & XDP_COPY;
134 
135 	if (force_zc && force_copy)
136 		return -EINVAL;
137 
138 	if (xsk_get_pool_from_qid(netdev, queue_id))
139 		return -EBUSY;
140 
141 	pool->netdev = netdev;
142 	pool->queue_id = queue_id;
143 	err = xsk_reg_pool_at_qid(netdev, pool, queue_id);
144 	if (err)
145 		return err;
146 
147 	if (flags & XDP_USE_NEED_WAKEUP) {
148 		pool->uses_need_wakeup = true;
149 		/* Tx needs to be explicitly woken up the first time.
150 		 * Also for supporting drivers that do not implement this
151 		 * feature. They will always have to call sendto().
152 		 */
153 		pool->cached_need_wakeup = XDP_WAKEUP_TX;
154 	}
155 
156 	dev_hold(netdev);
157 
158 	if (force_copy)
159 		/* For copy-mode, we are done. */
160 		return 0;
161 
162 	if (!netdev->netdev_ops->ndo_bpf ||
163 	    !netdev->netdev_ops->ndo_xsk_wakeup) {
164 		err = -EOPNOTSUPP;
165 		goto err_unreg_pool;
166 	}
167 
168 	bpf.command = XDP_SETUP_XSK_POOL;
169 	bpf.xsk.pool = pool;
170 	bpf.xsk.queue_id = queue_id;
171 
172 	err = netdev->netdev_ops->ndo_bpf(netdev, &bpf);
173 	if (err)
174 		goto err_unreg_pool;
175 
176 	if (!pool->dma_pages) {
177 		WARN(1, "Driver did not DMA map zero-copy buffers");
178 		err = -EINVAL;
179 		goto err_unreg_xsk;
180 	}
181 	pool->umem->zc = true;
182 	return 0;
183 
184 err_unreg_xsk:
185 	xp_disable_drv_zc(pool);
186 err_unreg_pool:
187 	if (!force_zc)
188 		err = 0; /* fallback to copy mode */
189 	if (err) {
190 		xsk_clear_pool_at_qid(netdev, queue_id);
191 		dev_put(netdev);
192 	}
193 	return err;
194 }
195 
196 int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
197 		  u16 queue_id, u16 flags)
198 {
199 	return __xp_assign_dev(pool, dev, queue_id, flags);
200 }
201 
202 int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
203 			 struct net_device *dev, u16 queue_id)
204 {
205 	u16 flags;
206 
207 	/* One fill and completion ring required for each queue id. */
208 	if (!pool->fq || !pool->cq)
209 		return -EINVAL;
210 
211 	flags = umem->zc ? XDP_ZEROCOPY : XDP_COPY;
212 	if (pool->uses_need_wakeup)
213 		flags |= XDP_USE_NEED_WAKEUP;
214 
215 	return __xp_assign_dev(pool, dev, queue_id, flags);
216 }
217 
218 void xp_clear_dev(struct xsk_buff_pool *pool)
219 {
220 	if (!pool->netdev)
221 		return;
222 
223 	xp_disable_drv_zc(pool);
224 	xsk_clear_pool_at_qid(pool->netdev, pool->queue_id);
225 	dev_put(pool->netdev);
226 	pool->netdev = NULL;
227 }
228 
229 static void xp_release_deferred(struct work_struct *work)
230 {
231 	struct xsk_buff_pool *pool = container_of(work, struct xsk_buff_pool,
232 						  work);
233 
234 	rtnl_lock();
235 	xp_clear_dev(pool);
236 	rtnl_unlock();
237 
238 	if (pool->fq) {
239 		xskq_destroy(pool->fq);
240 		pool->fq = NULL;
241 	}
242 
243 	if (pool->cq) {
244 		xskq_destroy(pool->cq);
245 		pool->cq = NULL;
246 	}
247 
248 	xdp_put_umem(pool->umem, false);
249 	xp_destroy(pool);
250 }
251 
252 void xp_get_pool(struct xsk_buff_pool *pool)
253 {
254 	refcount_inc(&pool->users);
255 }
256 
257 bool xp_put_pool(struct xsk_buff_pool *pool)
258 {
259 	if (!pool)
260 		return false;
261 
262 	if (refcount_dec_and_test(&pool->users)) {
263 		INIT_WORK(&pool->work, xp_release_deferred);
264 		schedule_work(&pool->work);
265 		return true;
266 	}
267 
268 	return false;
269 }
270 
271 static struct xsk_dma_map *xp_find_dma_map(struct xsk_buff_pool *pool)
272 {
273 	struct xsk_dma_map *dma_map;
274 
275 	list_for_each_entry(dma_map, &pool->umem->xsk_dma_list, list) {
276 		if (dma_map->netdev == pool->netdev)
277 			return dma_map;
278 	}
279 
280 	return NULL;
281 }
282 
283 static struct xsk_dma_map *xp_create_dma_map(struct device *dev, struct net_device *netdev,
284 					     u32 nr_pages, struct xdp_umem *umem)
285 {
286 	struct xsk_dma_map *dma_map;
287 
288 	dma_map = kzalloc(sizeof(*dma_map), GFP_KERNEL);
289 	if (!dma_map)
290 		return NULL;
291 
292 	dma_map->dma_pages = kvcalloc(nr_pages, sizeof(*dma_map->dma_pages), GFP_KERNEL);
293 	if (!dma_map->dma_pages) {
294 		kfree(dma_map);
295 		return NULL;
296 	}
297 
298 	dma_map->netdev = netdev;
299 	dma_map->dev = dev;
300 	dma_map->dma_need_sync = false;
301 	dma_map->dma_pages_cnt = nr_pages;
302 	refcount_set(&dma_map->users, 1);
303 	list_add(&dma_map->list, &umem->xsk_dma_list);
304 	return dma_map;
305 }
306 
307 static void xp_destroy_dma_map(struct xsk_dma_map *dma_map)
308 {
309 	list_del(&dma_map->list);
310 	kvfree(dma_map->dma_pages);
311 	kfree(dma_map);
312 }
313 
314 static void __xp_dma_unmap(struct xsk_dma_map *dma_map, unsigned long attrs)
315 {
316 	dma_addr_t *dma;
317 	u32 i;
318 
319 	for (i = 0; i < dma_map->dma_pages_cnt; i++) {
320 		dma = &dma_map->dma_pages[i];
321 		if (*dma) {
322 			dma_unmap_page_attrs(dma_map->dev, *dma, PAGE_SIZE,
323 					     DMA_BIDIRECTIONAL, attrs);
324 			*dma = 0;
325 		}
326 	}
327 
328 	xp_destroy_dma_map(dma_map);
329 }
330 
331 void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs)
332 {
333 	struct xsk_dma_map *dma_map;
334 
335 	if (pool->dma_pages_cnt == 0)
336 		return;
337 
338 	dma_map = xp_find_dma_map(pool);
339 	if (!dma_map) {
340 		WARN(1, "Could not find dma_map for device");
341 		return;
342 	}
343 
344 	if (!refcount_dec_and_test(&dma_map->users))
345 		return;
346 
347 	__xp_dma_unmap(dma_map, attrs);
348 	kvfree(pool->dma_pages);
349 	pool->dma_pages_cnt = 0;
350 	pool->dev = NULL;
351 }
352 EXPORT_SYMBOL(xp_dma_unmap);
353 
354 static void xp_check_dma_contiguity(struct xsk_dma_map *dma_map)
355 {
356 	u32 i;
357 
358 	for (i = 0; i < dma_map->dma_pages_cnt - 1; i++) {
359 		if (dma_map->dma_pages[i] + PAGE_SIZE == dma_map->dma_pages[i + 1])
360 			dma_map->dma_pages[i] |= XSK_NEXT_PG_CONTIG_MASK;
361 		else
362 			dma_map->dma_pages[i] &= ~XSK_NEXT_PG_CONTIG_MASK;
363 	}
364 }
365 
366 static int xp_init_dma_info(struct xsk_buff_pool *pool, struct xsk_dma_map *dma_map)
367 {
368 	pool->dma_pages = kvcalloc(dma_map->dma_pages_cnt, sizeof(*pool->dma_pages), GFP_KERNEL);
369 	if (!pool->dma_pages)
370 		return -ENOMEM;
371 
372 	pool->dev = dma_map->dev;
373 	pool->dma_pages_cnt = dma_map->dma_pages_cnt;
374 	pool->dma_need_sync = dma_map->dma_need_sync;
375 	memcpy(pool->dma_pages, dma_map->dma_pages,
376 	       pool->dma_pages_cnt * sizeof(*pool->dma_pages));
377 
378 	return 0;
379 }
380 
381 int xp_dma_map(struct xsk_buff_pool *pool, struct device *dev,
382 	       unsigned long attrs, struct page **pages, u32 nr_pages)
383 {
384 	struct xsk_dma_map *dma_map;
385 	dma_addr_t dma;
386 	int err;
387 	u32 i;
388 
389 	dma_map = xp_find_dma_map(pool);
390 	if (dma_map) {
391 		err = xp_init_dma_info(pool, dma_map);
392 		if (err)
393 			return err;
394 
395 		refcount_inc(&dma_map->users);
396 		return 0;
397 	}
398 
399 	dma_map = xp_create_dma_map(dev, pool->netdev, nr_pages, pool->umem);
400 	if (!dma_map)
401 		return -ENOMEM;
402 
403 	for (i = 0; i < dma_map->dma_pages_cnt; i++) {
404 		dma = dma_map_page_attrs(dev, pages[i], 0, PAGE_SIZE,
405 					 DMA_BIDIRECTIONAL, attrs);
406 		if (dma_mapping_error(dev, dma)) {
407 			__xp_dma_unmap(dma_map, attrs);
408 			return -ENOMEM;
409 		}
410 		if (dma_need_sync(dev, dma))
411 			dma_map->dma_need_sync = true;
412 		dma_map->dma_pages[i] = dma;
413 	}
414 
415 	if (pool->unaligned)
416 		xp_check_dma_contiguity(dma_map);
417 
418 	err = xp_init_dma_info(pool, dma_map);
419 	if (err) {
420 		__xp_dma_unmap(dma_map, attrs);
421 		return err;
422 	}
423 
424 	return 0;
425 }
426 EXPORT_SYMBOL(xp_dma_map);
427 
428 static bool xp_addr_crosses_non_contig_pg(struct xsk_buff_pool *pool,
429 					  u64 addr)
430 {
431 	return xp_desc_crosses_non_contig_pg(pool, addr, pool->chunk_size);
432 }
433 
434 static bool xp_check_unaligned(struct xsk_buff_pool *pool, u64 *addr)
435 {
436 	*addr = xp_unaligned_extract_addr(*addr);
437 	if (*addr >= pool->addrs_cnt ||
438 	    *addr + pool->chunk_size > pool->addrs_cnt ||
439 	    xp_addr_crosses_non_contig_pg(pool, *addr))
440 		return false;
441 	return true;
442 }
443 
444 static bool xp_check_aligned(struct xsk_buff_pool *pool, u64 *addr)
445 {
446 	*addr = xp_aligned_extract_addr(pool, *addr);
447 	return *addr < pool->addrs_cnt;
448 }
449 
450 static struct xdp_buff_xsk *__xp_alloc(struct xsk_buff_pool *pool)
451 {
452 	struct xdp_buff_xsk *xskb;
453 	u64 addr;
454 	bool ok;
455 
456 	if (pool->free_heads_cnt == 0)
457 		return NULL;
458 
459 	xskb = pool->free_heads[--pool->free_heads_cnt];
460 
461 	for (;;) {
462 		if (!xskq_cons_peek_addr_unchecked(pool->fq, &addr)) {
463 			pool->fq->queue_empty_descs++;
464 			xp_release(xskb);
465 			return NULL;
466 		}
467 
468 		ok = pool->unaligned ? xp_check_unaligned(pool, &addr) :
469 		     xp_check_aligned(pool, &addr);
470 		if (!ok) {
471 			pool->fq->invalid_descs++;
472 			xskq_cons_release(pool->fq);
473 			continue;
474 		}
475 		break;
476 	}
477 	xskq_cons_release(pool->fq);
478 
479 	xskb->orig_addr = addr;
480 	xskb->xdp.data_hard_start = pool->addrs + addr + pool->headroom;
481 	if (pool->dma_pages_cnt) {
482 		xskb->frame_dma = (pool->dma_pages[addr >> PAGE_SHIFT] &
483 				   ~XSK_NEXT_PG_CONTIG_MASK) +
484 				  (addr & ~PAGE_MASK);
485 		xskb->dma = xskb->frame_dma + pool->headroom +
486 			    XDP_PACKET_HEADROOM;
487 	}
488 	return xskb;
489 }
490 
491 struct xdp_buff *xp_alloc(struct xsk_buff_pool *pool)
492 {
493 	struct xdp_buff_xsk *xskb;
494 
495 	if (!pool->free_list_cnt) {
496 		xskb = __xp_alloc(pool);
497 		if (!xskb)
498 			return NULL;
499 	} else {
500 		pool->free_list_cnt--;
501 		xskb = list_first_entry(&pool->free_list, struct xdp_buff_xsk,
502 					free_list_node);
503 		list_del(&xskb->free_list_node);
504 	}
505 
506 	xskb->xdp.data = xskb->xdp.data_hard_start + XDP_PACKET_HEADROOM;
507 	xskb->xdp.data_meta = xskb->xdp.data;
508 
509 	if (pool->dma_need_sync) {
510 		dma_sync_single_range_for_device(pool->dev, xskb->dma, 0,
511 						 pool->frame_len,
512 						 DMA_BIDIRECTIONAL);
513 	}
514 	return &xskb->xdp;
515 }
516 EXPORT_SYMBOL(xp_alloc);
517 
518 bool xp_can_alloc(struct xsk_buff_pool *pool, u32 count)
519 {
520 	if (pool->free_list_cnt >= count)
521 		return true;
522 	return xskq_cons_has_entries(pool->fq, count - pool->free_list_cnt);
523 }
524 EXPORT_SYMBOL(xp_can_alloc);
525 
526 void xp_free(struct xdp_buff_xsk *xskb)
527 {
528 	xskb->pool->free_list_cnt++;
529 	list_add(&xskb->free_list_node, &xskb->pool->free_list);
530 }
531 EXPORT_SYMBOL(xp_free);
532 
533 void *xp_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
534 {
535 	addr = pool->unaligned ? xp_unaligned_add_offset_to_addr(addr) : addr;
536 	return pool->addrs + addr;
537 }
538 EXPORT_SYMBOL(xp_raw_get_data);
539 
540 dma_addr_t xp_raw_get_dma(struct xsk_buff_pool *pool, u64 addr)
541 {
542 	addr = pool->unaligned ? xp_unaligned_add_offset_to_addr(addr) : addr;
543 	return (pool->dma_pages[addr >> PAGE_SHIFT] &
544 		~XSK_NEXT_PG_CONTIG_MASK) +
545 		(addr & ~PAGE_MASK);
546 }
547 EXPORT_SYMBOL(xp_raw_get_dma);
548 
549 void xp_dma_sync_for_cpu_slow(struct xdp_buff_xsk *xskb)
550 {
551 	dma_sync_single_range_for_cpu(xskb->pool->dev, xskb->dma, 0,
552 				      xskb->pool->frame_len, DMA_BIDIRECTIONAL);
553 }
554 EXPORT_SYMBOL(xp_dma_sync_for_cpu_slow);
555 
556 void xp_dma_sync_for_device_slow(struct xsk_buff_pool *pool, dma_addr_t dma,
557 				 size_t size)
558 {
559 	dma_sync_single_range_for_device(pool->dev, dma, 0,
560 					 size, DMA_BIDIRECTIONAL);
561 }
562 EXPORT_SYMBOL(xp_dma_sync_for_device_slow);
563