xref: /openbmc/linux/drivers/net/ethernet/sfc/falcon/rx.c (revision 55fd7e02)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /****************************************************************************
3  * Driver for Solarflare network controllers and boards
4  * Copyright 2005-2006 Fen Systems Ltd.
5  * Copyright 2005-2013 Solarflare Communications Inc.
6  */
7 
8 #include <linux/socket.h>
9 #include <linux/in.h>
10 #include <linux/slab.h>
11 #include <linux/ip.h>
12 #include <linux/ipv6.h>
13 #include <linux/tcp.h>
14 #include <linux/udp.h>
15 #include <linux/prefetch.h>
16 #include <linux/moduleparam.h>
17 #include <linux/iommu.h>
18 #include <net/ip.h>
19 #include <net/checksum.h>
20 #include "net_driver.h"
21 #include "efx.h"
22 #include "filter.h"
23 #include "nic.h"
24 #include "selftest.h"
25 #include "workarounds.h"
26 
27 /* Preferred number of descriptors to fill at once */
28 #define EF4_RX_PREFERRED_BATCH 8U
29 
30 /* Number of RX buffers to recycle pages for.  When creating the RX page recycle
31  * ring, this number is divided by the number of buffers per page to calculate
32  * the number of pages to store in the RX page recycle ring.
33  */
34 #define EF4_RECYCLE_RING_SIZE_IOMMU 4096
35 #define EF4_RECYCLE_RING_SIZE_NOIOMMU (2 * EF4_RX_PREFERRED_BATCH)
36 
37 /* Size of buffer allocated for skb header area. */
38 #define EF4_SKB_HEADERS  128u
39 
40 /* This is the percentage fill level below which new RX descriptors
41  * will be added to the RX descriptor ring.
42  */
43 static unsigned int rx_refill_threshold;
44 
45 /* Each packet can consume up to ceil(max_frame_len / buffer_size) buffers */
46 #define EF4_RX_MAX_FRAGS DIV_ROUND_UP(EF4_MAX_FRAME_LEN(EF4_MAX_MTU), \
47 				      EF4_RX_USR_BUF_SIZE)
48 
49 /*
50  * RX maximum head room required.
51  *
52  * This must be at least 1 to prevent overflow, plus one packet-worth
53  * to allow pipelined receives.
54  */
55 #define EF4_RXD_HEAD_ROOM (1 + EF4_RX_MAX_FRAGS)
56 
57 static inline u8 *ef4_rx_buf_va(struct ef4_rx_buffer *buf)
58 {
59 	return page_address(buf->page) + buf->page_offset;
60 }
61 
62 static inline u32 ef4_rx_buf_hash(struct ef4_nic *efx, const u8 *eh)
63 {
64 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
65 	return __le32_to_cpup((const __le32 *)(eh + efx->rx_packet_hash_offset));
66 #else
67 	const u8 *data = eh + efx->rx_packet_hash_offset;
68 	return (u32)data[0]	  |
69 	       (u32)data[1] << 8  |
70 	       (u32)data[2] << 16 |
71 	       (u32)data[3] << 24;
72 #endif
73 }
74 
75 static inline struct ef4_rx_buffer *
76 ef4_rx_buf_next(struct ef4_rx_queue *rx_queue, struct ef4_rx_buffer *rx_buf)
77 {
78 	if (unlikely(rx_buf == ef4_rx_buffer(rx_queue, rx_queue->ptr_mask)))
79 		return ef4_rx_buffer(rx_queue, 0);
80 	else
81 		return rx_buf + 1;
82 }
83 
84 static inline void ef4_sync_rx_buffer(struct ef4_nic *efx,
85 				      struct ef4_rx_buffer *rx_buf,
86 				      unsigned int len)
87 {
88 	dma_sync_single_for_cpu(&efx->pci_dev->dev, rx_buf->dma_addr, len,
89 				DMA_FROM_DEVICE);
90 }
91 
92 void ef4_rx_config_page_split(struct ef4_nic *efx)
93 {
94 	efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align,
95 				      EF4_RX_BUF_ALIGNMENT);
96 	efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
97 		((PAGE_SIZE - sizeof(struct ef4_rx_page_state)) /
98 		 efx->rx_page_buf_step);
99 	efx->rx_buffer_truesize = (PAGE_SIZE << efx->rx_buffer_order) /
100 		efx->rx_bufs_per_page;
101 	efx->rx_pages_per_batch = DIV_ROUND_UP(EF4_RX_PREFERRED_BATCH,
102 					       efx->rx_bufs_per_page);
103 }
104 
105 /* Check the RX page recycle ring for a page that can be reused. */
106 static struct page *ef4_reuse_page(struct ef4_rx_queue *rx_queue)
107 {
108 	struct ef4_nic *efx = rx_queue->efx;
109 	struct page *page;
110 	struct ef4_rx_page_state *state;
111 	unsigned index;
112 
113 	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
114 	page = rx_queue->page_ring[index];
115 	if (page == NULL)
116 		return NULL;
117 
118 	rx_queue->page_ring[index] = NULL;
119 	/* page_remove cannot exceed page_add. */
120 	if (rx_queue->page_remove != rx_queue->page_add)
121 		++rx_queue->page_remove;
122 
123 	/* If page_count is 1 then we hold the only reference to this page. */
124 	if (page_count(page) == 1) {
125 		++rx_queue->page_recycle_count;
126 		return page;
127 	} else {
128 		state = page_address(page);
129 		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
130 			       PAGE_SIZE << efx->rx_buffer_order,
131 			       DMA_FROM_DEVICE);
132 		put_page(page);
133 		++rx_queue->page_recycle_failed;
134 	}
135 
136 	return NULL;
137 }
138 
139 /**
140  * ef4_init_rx_buffers - create EF4_RX_BATCH page-based RX buffers
141  *
142  * @rx_queue:		Efx RX queue
143  *
144  * This allocates a batch of pages, maps them for DMA, and populates
145  * struct ef4_rx_buffers for each one. Return a negative error code or
146  * 0 on success. If a single page can be used for multiple buffers,
147  * then the page will either be inserted fully, or not at all.
148  */
149 static int ef4_init_rx_buffers(struct ef4_rx_queue *rx_queue, bool atomic)
150 {
151 	struct ef4_nic *efx = rx_queue->efx;
152 	struct ef4_rx_buffer *rx_buf;
153 	struct page *page;
154 	unsigned int page_offset;
155 	struct ef4_rx_page_state *state;
156 	dma_addr_t dma_addr;
157 	unsigned index, count;
158 
159 	count = 0;
160 	do {
161 		page = ef4_reuse_page(rx_queue);
162 		if (page == NULL) {
163 			page = alloc_pages(__GFP_COMP |
164 					   (atomic ? GFP_ATOMIC : GFP_KERNEL),
165 					   efx->rx_buffer_order);
166 			if (unlikely(page == NULL))
167 				return -ENOMEM;
168 			dma_addr =
169 				dma_map_page(&efx->pci_dev->dev, page, 0,
170 					     PAGE_SIZE << efx->rx_buffer_order,
171 					     DMA_FROM_DEVICE);
172 			if (unlikely(dma_mapping_error(&efx->pci_dev->dev,
173 						       dma_addr))) {
174 				__free_pages(page, efx->rx_buffer_order);
175 				return -EIO;
176 			}
177 			state = page_address(page);
178 			state->dma_addr = dma_addr;
179 		} else {
180 			state = page_address(page);
181 			dma_addr = state->dma_addr;
182 		}
183 
184 		dma_addr += sizeof(struct ef4_rx_page_state);
185 		page_offset = sizeof(struct ef4_rx_page_state);
186 
187 		do {
188 			index = rx_queue->added_count & rx_queue->ptr_mask;
189 			rx_buf = ef4_rx_buffer(rx_queue, index);
190 			rx_buf->dma_addr = dma_addr + efx->rx_ip_align;
191 			rx_buf->page = page;
192 			rx_buf->page_offset = page_offset + efx->rx_ip_align;
193 			rx_buf->len = efx->rx_dma_len;
194 			rx_buf->flags = 0;
195 			++rx_queue->added_count;
196 			get_page(page);
197 			dma_addr += efx->rx_page_buf_step;
198 			page_offset += efx->rx_page_buf_step;
199 		} while (page_offset + efx->rx_page_buf_step <= PAGE_SIZE);
200 
201 		rx_buf->flags = EF4_RX_BUF_LAST_IN_PAGE;
202 	} while (++count < efx->rx_pages_per_batch);
203 
204 	return 0;
205 }
206 
207 /* Unmap a DMA-mapped page.  This function is only called for the final RX
208  * buffer in a page.
209  */
210 static void ef4_unmap_rx_buffer(struct ef4_nic *efx,
211 				struct ef4_rx_buffer *rx_buf)
212 {
213 	struct page *page = rx_buf->page;
214 
215 	if (page) {
216 		struct ef4_rx_page_state *state = page_address(page);
217 		dma_unmap_page(&efx->pci_dev->dev,
218 			       state->dma_addr,
219 			       PAGE_SIZE << efx->rx_buffer_order,
220 			       DMA_FROM_DEVICE);
221 	}
222 }
223 
224 static void ef4_free_rx_buffers(struct ef4_rx_queue *rx_queue,
225 				struct ef4_rx_buffer *rx_buf,
226 				unsigned int num_bufs)
227 {
228 	do {
229 		if (rx_buf->page) {
230 			put_page(rx_buf->page);
231 			rx_buf->page = NULL;
232 		}
233 		rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
234 	} while (--num_bufs);
235 }
236 
237 /* Attempt to recycle the page if there is an RX recycle ring; the page can
238  * only be added if this is the final RX buffer, to prevent pages being used in
239  * the descriptor ring and appearing in the recycle ring simultaneously.
240  */
241 static void ef4_recycle_rx_page(struct ef4_channel *channel,
242 				struct ef4_rx_buffer *rx_buf)
243 {
244 	struct page *page = rx_buf->page;
245 	struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);
246 	struct ef4_nic *efx = rx_queue->efx;
247 	unsigned index;
248 
249 	/* Only recycle the page after processing the final buffer. */
250 	if (!(rx_buf->flags & EF4_RX_BUF_LAST_IN_PAGE))
251 		return;
252 
253 	index = rx_queue->page_add & rx_queue->page_ptr_mask;
254 	if (rx_queue->page_ring[index] == NULL) {
255 		unsigned read_index = rx_queue->page_remove &
256 			rx_queue->page_ptr_mask;
257 
258 		/* The next slot in the recycle ring is available, but
259 		 * increment page_remove if the read pointer currently
260 		 * points here.
261 		 */
262 		if (read_index == index)
263 			++rx_queue->page_remove;
264 		rx_queue->page_ring[index] = page;
265 		++rx_queue->page_add;
266 		return;
267 	}
268 	++rx_queue->page_recycle_full;
269 	ef4_unmap_rx_buffer(efx, rx_buf);
270 	put_page(rx_buf->page);
271 }
272 
273 static void ef4_fini_rx_buffer(struct ef4_rx_queue *rx_queue,
274 			       struct ef4_rx_buffer *rx_buf)
275 {
276 	/* Release the page reference we hold for the buffer. */
277 	if (rx_buf->page)
278 		put_page(rx_buf->page);
279 
280 	/* If this is the last buffer in a page, unmap and free it. */
281 	if (rx_buf->flags & EF4_RX_BUF_LAST_IN_PAGE) {
282 		ef4_unmap_rx_buffer(rx_queue->efx, rx_buf);
283 		ef4_free_rx_buffers(rx_queue, rx_buf, 1);
284 	}
285 	rx_buf->page = NULL;
286 }
287 
288 /* Recycle the pages that are used by buffers that have just been received. */
289 static void ef4_recycle_rx_pages(struct ef4_channel *channel,
290 				 struct ef4_rx_buffer *rx_buf,
291 				 unsigned int n_frags)
292 {
293 	struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);
294 
295 	do {
296 		ef4_recycle_rx_page(channel, rx_buf);
297 		rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
298 	} while (--n_frags);
299 }
300 
301 static void ef4_discard_rx_packet(struct ef4_channel *channel,
302 				  struct ef4_rx_buffer *rx_buf,
303 				  unsigned int n_frags)
304 {
305 	struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);
306 
307 	ef4_recycle_rx_pages(channel, rx_buf, n_frags);
308 
309 	ef4_free_rx_buffers(rx_queue, rx_buf, n_frags);
310 }
311 
312 /**
313  * ef4_fast_push_rx_descriptors - push new RX descriptors quickly
314  * @rx_queue:		RX descriptor queue
315  *
316  * This will aim to fill the RX descriptor queue up to
317  * @rx_queue->@max_fill. If there is insufficient atomic
318  * memory to do so, a slow fill will be scheduled.
319  *
320  * The caller must provide serialisation (none is used here). In practise,
321  * this means this function must run from the NAPI handler, or be called
322  * when NAPI is disabled.
323  */
324 void ef4_fast_push_rx_descriptors(struct ef4_rx_queue *rx_queue, bool atomic)
325 {
326 	struct ef4_nic *efx = rx_queue->efx;
327 	unsigned int fill_level, batch_size;
328 	int space, rc = 0;
329 
330 	if (!rx_queue->refill_enabled)
331 		return;
332 
333 	/* Calculate current fill level, and exit if we don't need to fill */
334 	fill_level = (rx_queue->added_count - rx_queue->removed_count);
335 	EF4_BUG_ON_PARANOID(fill_level > rx_queue->efx->rxq_entries);
336 	if (fill_level >= rx_queue->fast_fill_trigger)
337 		goto out;
338 
339 	/* Record minimum fill level */
340 	if (unlikely(fill_level < rx_queue->min_fill)) {
341 		if (fill_level)
342 			rx_queue->min_fill = fill_level;
343 	}
344 
345 	batch_size = efx->rx_pages_per_batch * efx->rx_bufs_per_page;
346 	space = rx_queue->max_fill - fill_level;
347 	EF4_BUG_ON_PARANOID(space < batch_size);
348 
349 	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
350 		   "RX queue %d fast-filling descriptor ring from"
351 		   " level %d to level %d\n",
352 		   ef4_rx_queue_index(rx_queue), fill_level,
353 		   rx_queue->max_fill);
354 
355 
356 	do {
357 		rc = ef4_init_rx_buffers(rx_queue, atomic);
358 		if (unlikely(rc)) {
359 			/* Ensure that we don't leave the rx queue empty */
360 			if (rx_queue->added_count == rx_queue->removed_count)
361 				ef4_schedule_slow_fill(rx_queue);
362 			goto out;
363 		}
364 	} while ((space -= batch_size) >= batch_size);
365 
366 	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
367 		   "RX queue %d fast-filled descriptor ring "
368 		   "to level %d\n", ef4_rx_queue_index(rx_queue),
369 		   rx_queue->added_count - rx_queue->removed_count);
370 
371  out:
372 	if (rx_queue->notified_count != rx_queue->added_count)
373 		ef4_nic_notify_rx_desc(rx_queue);
374 }
375 
376 void ef4_rx_slow_fill(struct timer_list *t)
377 {
378 	struct ef4_rx_queue *rx_queue = from_timer(rx_queue, t, slow_fill);
379 
380 	/* Post an event to cause NAPI to run and refill the queue */
381 	ef4_nic_generate_fill_event(rx_queue);
382 	++rx_queue->slow_fill_count;
383 }
384 
385 static void ef4_rx_packet__check_len(struct ef4_rx_queue *rx_queue,
386 				     struct ef4_rx_buffer *rx_buf,
387 				     int len)
388 {
389 	struct ef4_nic *efx = rx_queue->efx;
390 	unsigned max_len = rx_buf->len - efx->type->rx_buffer_padding;
391 
392 	if (likely(len <= max_len))
393 		return;
394 
395 	/* The packet must be discarded, but this is only a fatal error
396 	 * if the caller indicated it was
397 	 */
398 	rx_buf->flags |= EF4_RX_PKT_DISCARD;
399 
400 	if ((len > rx_buf->len) && EF4_WORKAROUND_8071(efx)) {
401 		if (net_ratelimit())
402 			netif_err(efx, rx_err, efx->net_dev,
403 				  " RX queue %d seriously overlength "
404 				  "RX event (0x%x > 0x%x+0x%x). Leaking\n",
405 				  ef4_rx_queue_index(rx_queue), len, max_len,
406 				  efx->type->rx_buffer_padding);
407 		ef4_schedule_reset(efx, RESET_TYPE_RX_RECOVERY);
408 	} else {
409 		if (net_ratelimit())
410 			netif_err(efx, rx_err, efx->net_dev,
411 				  " RX queue %d overlength RX event "
412 				  "(0x%x > 0x%x)\n",
413 				  ef4_rx_queue_index(rx_queue), len, max_len);
414 	}
415 
416 	ef4_rx_queue_channel(rx_queue)->n_rx_overlength++;
417 }
418 
419 /* Pass a received packet up through GRO.  GRO can handle pages
420  * regardless of checksum state and skbs with a good checksum.
421  */
422 static void
423 ef4_rx_packet_gro(struct ef4_channel *channel, struct ef4_rx_buffer *rx_buf,
424 		  unsigned int n_frags, u8 *eh)
425 {
426 	struct napi_struct *napi = &channel->napi_str;
427 	struct ef4_nic *efx = channel->efx;
428 	struct sk_buff *skb;
429 
430 	skb = napi_get_frags(napi);
431 	if (unlikely(!skb)) {
432 		struct ef4_rx_queue *rx_queue;
433 
434 		rx_queue = ef4_channel_get_rx_queue(channel);
435 		ef4_free_rx_buffers(rx_queue, rx_buf, n_frags);
436 		return;
437 	}
438 
439 	if (efx->net_dev->features & NETIF_F_RXHASH)
440 		skb_set_hash(skb, ef4_rx_buf_hash(efx, eh),
441 			     PKT_HASH_TYPE_L3);
442 	skb->ip_summed = ((rx_buf->flags & EF4_RX_PKT_CSUMMED) ?
443 			  CHECKSUM_UNNECESSARY : CHECKSUM_NONE);
444 
445 	for (;;) {
446 		skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags,
447 				   rx_buf->page, rx_buf->page_offset,
448 				   rx_buf->len);
449 		rx_buf->page = NULL;
450 		skb->len += rx_buf->len;
451 		if (skb_shinfo(skb)->nr_frags == n_frags)
452 			break;
453 
454 		rx_buf = ef4_rx_buf_next(&channel->rx_queue, rx_buf);
455 	}
456 
457 	skb->data_len = skb->len;
458 	skb->truesize += n_frags * efx->rx_buffer_truesize;
459 
460 	skb_record_rx_queue(skb, channel->rx_queue.core_index);
461 
462 	napi_gro_frags(napi);
463 }
464 
465 /* Allocate and construct an SKB around page fragments */
466 static struct sk_buff *ef4_rx_mk_skb(struct ef4_channel *channel,
467 				     struct ef4_rx_buffer *rx_buf,
468 				     unsigned int n_frags,
469 				     u8 *eh, int hdr_len)
470 {
471 	struct ef4_nic *efx = channel->efx;
472 	struct sk_buff *skb;
473 
474 	/* Allocate an SKB to store the headers */
475 	skb = netdev_alloc_skb(efx->net_dev,
476 			       efx->rx_ip_align + efx->rx_prefix_size +
477 			       hdr_len);
478 	if (unlikely(skb == NULL)) {
479 		atomic_inc(&efx->n_rx_noskb_drops);
480 		return NULL;
481 	}
482 
483 	EF4_BUG_ON_PARANOID(rx_buf->len < hdr_len);
484 
485 	memcpy(skb->data + efx->rx_ip_align, eh - efx->rx_prefix_size,
486 	       efx->rx_prefix_size + hdr_len);
487 	skb_reserve(skb, efx->rx_ip_align + efx->rx_prefix_size);
488 	__skb_put(skb, hdr_len);
489 
490 	/* Append the remaining page(s) onto the frag list */
491 	if (rx_buf->len > hdr_len) {
492 		rx_buf->page_offset += hdr_len;
493 		rx_buf->len -= hdr_len;
494 
495 		for (;;) {
496 			skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags,
497 					   rx_buf->page, rx_buf->page_offset,
498 					   rx_buf->len);
499 			rx_buf->page = NULL;
500 			skb->len += rx_buf->len;
501 			skb->data_len += rx_buf->len;
502 			if (skb_shinfo(skb)->nr_frags == n_frags)
503 				break;
504 
505 			rx_buf = ef4_rx_buf_next(&channel->rx_queue, rx_buf);
506 		}
507 	} else {
508 		__free_pages(rx_buf->page, efx->rx_buffer_order);
509 		rx_buf->page = NULL;
510 		n_frags = 0;
511 	}
512 
513 	skb->truesize += n_frags * efx->rx_buffer_truesize;
514 
515 	/* Move past the ethernet header */
516 	skb->protocol = eth_type_trans(skb, efx->net_dev);
517 
518 	skb_mark_napi_id(skb, &channel->napi_str);
519 
520 	return skb;
521 }
522 
523 void ef4_rx_packet(struct ef4_rx_queue *rx_queue, unsigned int index,
524 		   unsigned int n_frags, unsigned int len, u16 flags)
525 {
526 	struct ef4_nic *efx = rx_queue->efx;
527 	struct ef4_channel *channel = ef4_rx_queue_channel(rx_queue);
528 	struct ef4_rx_buffer *rx_buf;
529 
530 	rx_queue->rx_packets++;
531 
532 	rx_buf = ef4_rx_buffer(rx_queue, index);
533 	rx_buf->flags |= flags;
534 
535 	/* Validate the number of fragments and completed length */
536 	if (n_frags == 1) {
537 		if (!(flags & EF4_RX_PKT_PREFIX_LEN))
538 			ef4_rx_packet__check_len(rx_queue, rx_buf, len);
539 	} else if (unlikely(n_frags > EF4_RX_MAX_FRAGS) ||
540 		   unlikely(len <= (n_frags - 1) * efx->rx_dma_len) ||
541 		   unlikely(len > n_frags * efx->rx_dma_len) ||
542 		   unlikely(!efx->rx_scatter)) {
543 		/* If this isn't an explicit discard request, either
544 		 * the hardware or the driver is broken.
545 		 */
546 		WARN_ON(!(len == 0 && rx_buf->flags & EF4_RX_PKT_DISCARD));
547 		rx_buf->flags |= EF4_RX_PKT_DISCARD;
548 	}
549 
550 	netif_vdbg(efx, rx_status, efx->net_dev,
551 		   "RX queue %d received ids %x-%x len %d %s%s\n",
552 		   ef4_rx_queue_index(rx_queue), index,
553 		   (index + n_frags - 1) & rx_queue->ptr_mask, len,
554 		   (rx_buf->flags & EF4_RX_PKT_CSUMMED) ? " [SUMMED]" : "",
555 		   (rx_buf->flags & EF4_RX_PKT_DISCARD) ? " [DISCARD]" : "");
556 
557 	/* Discard packet, if instructed to do so.  Process the
558 	 * previous receive first.
559 	 */
560 	if (unlikely(rx_buf->flags & EF4_RX_PKT_DISCARD)) {
561 		ef4_rx_flush_packet(channel);
562 		ef4_discard_rx_packet(channel, rx_buf, n_frags);
563 		return;
564 	}
565 
566 	if (n_frags == 1 && !(flags & EF4_RX_PKT_PREFIX_LEN))
567 		rx_buf->len = len;
568 
569 	/* Release and/or sync the DMA mapping - assumes all RX buffers
570 	 * consumed in-order per RX queue.
571 	 */
572 	ef4_sync_rx_buffer(efx, rx_buf, rx_buf->len);
573 
574 	/* Prefetch nice and early so data will (hopefully) be in cache by
575 	 * the time we look at it.
576 	 */
577 	prefetch(ef4_rx_buf_va(rx_buf));
578 
579 	rx_buf->page_offset += efx->rx_prefix_size;
580 	rx_buf->len -= efx->rx_prefix_size;
581 
582 	if (n_frags > 1) {
583 		/* Release/sync DMA mapping for additional fragments.
584 		 * Fix length for last fragment.
585 		 */
586 		unsigned int tail_frags = n_frags - 1;
587 
588 		for (;;) {
589 			rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
590 			if (--tail_frags == 0)
591 				break;
592 			ef4_sync_rx_buffer(efx, rx_buf, efx->rx_dma_len);
593 		}
594 		rx_buf->len = len - (n_frags - 1) * efx->rx_dma_len;
595 		ef4_sync_rx_buffer(efx, rx_buf, rx_buf->len);
596 	}
597 
598 	/* All fragments have been DMA-synced, so recycle pages. */
599 	rx_buf = ef4_rx_buffer(rx_queue, index);
600 	ef4_recycle_rx_pages(channel, rx_buf, n_frags);
601 
602 	/* Pipeline receives so that we give time for packet headers to be
603 	 * prefetched into cache.
604 	 */
605 	ef4_rx_flush_packet(channel);
606 	channel->rx_pkt_n_frags = n_frags;
607 	channel->rx_pkt_index = index;
608 }
609 
610 static void ef4_rx_deliver(struct ef4_channel *channel, u8 *eh,
611 			   struct ef4_rx_buffer *rx_buf,
612 			   unsigned int n_frags)
613 {
614 	struct sk_buff *skb;
615 	u16 hdr_len = min_t(u16, rx_buf->len, EF4_SKB_HEADERS);
616 
617 	skb = ef4_rx_mk_skb(channel, rx_buf, n_frags, eh, hdr_len);
618 	if (unlikely(skb == NULL)) {
619 		struct ef4_rx_queue *rx_queue;
620 
621 		rx_queue = ef4_channel_get_rx_queue(channel);
622 		ef4_free_rx_buffers(rx_queue, rx_buf, n_frags);
623 		return;
624 	}
625 	skb_record_rx_queue(skb, channel->rx_queue.core_index);
626 
627 	/* Set the SKB flags */
628 	skb_checksum_none_assert(skb);
629 	if (likely(rx_buf->flags & EF4_RX_PKT_CSUMMED))
630 		skb->ip_summed = CHECKSUM_UNNECESSARY;
631 
632 	if (channel->type->receive_skb)
633 		if (channel->type->receive_skb(channel, skb))
634 			return;
635 
636 	/* Pass the packet up */
637 	netif_receive_skb(skb);
638 }
639 
640 /* Handle a received packet.  Second half: Touches packet payload. */
641 void __ef4_rx_packet(struct ef4_channel *channel)
642 {
643 	struct ef4_nic *efx = channel->efx;
644 	struct ef4_rx_buffer *rx_buf =
645 		ef4_rx_buffer(&channel->rx_queue, channel->rx_pkt_index);
646 	u8 *eh = ef4_rx_buf_va(rx_buf);
647 
648 	/* Read length from the prefix if necessary.  This already
649 	 * excludes the length of the prefix itself.
650 	 */
651 	if (rx_buf->flags & EF4_RX_PKT_PREFIX_LEN)
652 		rx_buf->len = le16_to_cpup((__le16 *)
653 					   (eh + efx->rx_packet_len_offset));
654 
655 	/* If we're in loopback test, then pass the packet directly to the
656 	 * loopback layer, and free the rx_buf here
657 	 */
658 	if (unlikely(efx->loopback_selftest)) {
659 		struct ef4_rx_queue *rx_queue;
660 
661 		ef4_loopback_rx_packet(efx, eh, rx_buf->len);
662 		rx_queue = ef4_channel_get_rx_queue(channel);
663 		ef4_free_rx_buffers(rx_queue, rx_buf,
664 				    channel->rx_pkt_n_frags);
665 		goto out;
666 	}
667 
668 	if (unlikely(!(efx->net_dev->features & NETIF_F_RXCSUM)))
669 		rx_buf->flags &= ~EF4_RX_PKT_CSUMMED;
670 
671 	if ((rx_buf->flags & EF4_RX_PKT_TCP) && !channel->type->receive_skb)
672 		ef4_rx_packet_gro(channel, rx_buf, channel->rx_pkt_n_frags, eh);
673 	else
674 		ef4_rx_deliver(channel, eh, rx_buf, channel->rx_pkt_n_frags);
675 out:
676 	channel->rx_pkt_n_frags = 0;
677 }
678 
679 int ef4_probe_rx_queue(struct ef4_rx_queue *rx_queue)
680 {
681 	struct ef4_nic *efx = rx_queue->efx;
682 	unsigned int entries;
683 	int rc;
684 
685 	/* Create the smallest power-of-two aligned ring */
686 	entries = max(roundup_pow_of_two(efx->rxq_entries), EF4_MIN_DMAQ_SIZE);
687 	EF4_BUG_ON_PARANOID(entries > EF4_MAX_DMAQ_SIZE);
688 	rx_queue->ptr_mask = entries - 1;
689 
690 	netif_dbg(efx, probe, efx->net_dev,
691 		  "creating RX queue %d size %#x mask %#x\n",
692 		  ef4_rx_queue_index(rx_queue), efx->rxq_entries,
693 		  rx_queue->ptr_mask);
694 
695 	/* Allocate RX buffers */
696 	rx_queue->buffer = kcalloc(entries, sizeof(*rx_queue->buffer),
697 				   GFP_KERNEL);
698 	if (!rx_queue->buffer)
699 		return -ENOMEM;
700 
701 	rc = ef4_nic_probe_rx(rx_queue);
702 	if (rc) {
703 		kfree(rx_queue->buffer);
704 		rx_queue->buffer = NULL;
705 	}
706 
707 	return rc;
708 }
709 
710 static void ef4_init_rx_recycle_ring(struct ef4_nic *efx,
711 				     struct ef4_rx_queue *rx_queue)
712 {
713 	unsigned int bufs_in_recycle_ring, page_ring_size;
714 
715 	/* Set the RX recycle ring size */
716 #ifdef CONFIG_PPC64
717 	bufs_in_recycle_ring = EF4_RECYCLE_RING_SIZE_IOMMU;
718 #else
719 	if (iommu_present(&pci_bus_type))
720 		bufs_in_recycle_ring = EF4_RECYCLE_RING_SIZE_IOMMU;
721 	else
722 		bufs_in_recycle_ring = EF4_RECYCLE_RING_SIZE_NOIOMMU;
723 #endif /* CONFIG_PPC64 */
724 
725 	page_ring_size = roundup_pow_of_two(bufs_in_recycle_ring /
726 					    efx->rx_bufs_per_page);
727 	rx_queue->page_ring = kcalloc(page_ring_size,
728 				      sizeof(*rx_queue->page_ring), GFP_KERNEL);
729 	rx_queue->page_ptr_mask = page_ring_size - 1;
730 }
731 
732 void ef4_init_rx_queue(struct ef4_rx_queue *rx_queue)
733 {
734 	struct ef4_nic *efx = rx_queue->efx;
735 	unsigned int max_fill, trigger, max_trigger;
736 
737 	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
738 		  "initialising RX queue %d\n", ef4_rx_queue_index(rx_queue));
739 
740 	/* Initialise ptr fields */
741 	rx_queue->added_count = 0;
742 	rx_queue->notified_count = 0;
743 	rx_queue->removed_count = 0;
744 	rx_queue->min_fill = -1U;
745 	ef4_init_rx_recycle_ring(efx, rx_queue);
746 
747 	rx_queue->page_remove = 0;
748 	rx_queue->page_add = rx_queue->page_ptr_mask + 1;
749 	rx_queue->page_recycle_count = 0;
750 	rx_queue->page_recycle_failed = 0;
751 	rx_queue->page_recycle_full = 0;
752 
753 	/* Initialise limit fields */
754 	max_fill = efx->rxq_entries - EF4_RXD_HEAD_ROOM;
755 	max_trigger =
756 		max_fill - efx->rx_pages_per_batch * efx->rx_bufs_per_page;
757 	if (rx_refill_threshold != 0) {
758 		trigger = max_fill * min(rx_refill_threshold, 100U) / 100U;
759 		if (trigger > max_trigger)
760 			trigger = max_trigger;
761 	} else {
762 		trigger = max_trigger;
763 	}
764 
765 	rx_queue->max_fill = max_fill;
766 	rx_queue->fast_fill_trigger = trigger;
767 	rx_queue->refill_enabled = true;
768 
769 	/* Set up RX descriptor ring */
770 	ef4_nic_init_rx(rx_queue);
771 }
772 
773 void ef4_fini_rx_queue(struct ef4_rx_queue *rx_queue)
774 {
775 	int i;
776 	struct ef4_nic *efx = rx_queue->efx;
777 	struct ef4_rx_buffer *rx_buf;
778 
779 	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
780 		  "shutting down RX queue %d\n", ef4_rx_queue_index(rx_queue));
781 
782 	del_timer_sync(&rx_queue->slow_fill);
783 
784 	/* Release RX buffers from the current read ptr to the write ptr */
785 	if (rx_queue->buffer) {
786 		for (i = rx_queue->removed_count; i < rx_queue->added_count;
787 		     i++) {
788 			unsigned index = i & rx_queue->ptr_mask;
789 			rx_buf = ef4_rx_buffer(rx_queue, index);
790 			ef4_fini_rx_buffer(rx_queue, rx_buf);
791 		}
792 	}
793 
794 	/* Unmap and release the pages in the recycle ring. Remove the ring. */
795 	for (i = 0; i <= rx_queue->page_ptr_mask; i++) {
796 		struct page *page = rx_queue->page_ring[i];
797 		struct ef4_rx_page_state *state;
798 
799 		if (page == NULL)
800 			continue;
801 
802 		state = page_address(page);
803 		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
804 			       PAGE_SIZE << efx->rx_buffer_order,
805 			       DMA_FROM_DEVICE);
806 		put_page(page);
807 	}
808 	kfree(rx_queue->page_ring);
809 	rx_queue->page_ring = NULL;
810 }
811 
812 void ef4_remove_rx_queue(struct ef4_rx_queue *rx_queue)
813 {
814 	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
815 		  "destroying RX queue %d\n", ef4_rx_queue_index(rx_queue));
816 
817 	ef4_nic_remove_rx(rx_queue);
818 
819 	kfree(rx_queue->buffer);
820 	rx_queue->buffer = NULL;
821 }
822 
823 
824 module_param(rx_refill_threshold, uint, 0444);
825 MODULE_PARM_DESC(rx_refill_threshold,
826 		 "RX descriptor ring refill threshold (%)");
827 
828 #ifdef CONFIG_RFS_ACCEL
829 
830 int ef4_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb,
831 		   u16 rxq_index, u32 flow_id)
832 {
833 	struct ef4_nic *efx = netdev_priv(net_dev);
834 	struct ef4_channel *channel;
835 	struct ef4_filter_spec spec;
836 	struct flow_keys fk;
837 	int rc;
838 
839 	if (flow_id == RPS_FLOW_ID_INVALID)
840 		return -EINVAL;
841 
842 	if (!skb_flow_dissect_flow_keys(skb, &fk, 0))
843 		return -EPROTONOSUPPORT;
844 
845 	if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6))
846 		return -EPROTONOSUPPORT;
847 	if (fk.control.flags & FLOW_DIS_IS_FRAGMENT)
848 		return -EPROTONOSUPPORT;
849 
850 	ef4_filter_init_rx(&spec, EF4_FILTER_PRI_HINT,
851 			   efx->rx_scatter ? EF4_FILTER_FLAG_RX_SCATTER : 0,
852 			   rxq_index);
853 	spec.match_flags =
854 		EF4_FILTER_MATCH_ETHER_TYPE | EF4_FILTER_MATCH_IP_PROTO |
855 		EF4_FILTER_MATCH_LOC_HOST | EF4_FILTER_MATCH_LOC_PORT |
856 		EF4_FILTER_MATCH_REM_HOST | EF4_FILTER_MATCH_REM_PORT;
857 	spec.ether_type = fk.basic.n_proto;
858 	spec.ip_proto = fk.basic.ip_proto;
859 
860 	if (fk.basic.n_proto == htons(ETH_P_IP)) {
861 		spec.rem_host[0] = fk.addrs.v4addrs.src;
862 		spec.loc_host[0] = fk.addrs.v4addrs.dst;
863 	} else {
864 		memcpy(spec.rem_host, &fk.addrs.v6addrs.src, sizeof(struct in6_addr));
865 		memcpy(spec.loc_host, &fk.addrs.v6addrs.dst, sizeof(struct in6_addr));
866 	}
867 
868 	spec.rem_port = fk.ports.src;
869 	spec.loc_port = fk.ports.dst;
870 
871 	rc = efx->type->filter_rfs_insert(efx, &spec);
872 	if (rc < 0)
873 		return rc;
874 
875 	/* Remember this so we can check whether to expire the filter later */
876 	channel = ef4_get_channel(efx, rxq_index);
877 	channel->rps_flow_id[rc] = flow_id;
878 	++channel->rfs_filters_added;
879 
880 	if (spec.ether_type == htons(ETH_P_IP))
881 		netif_info(efx, rx_status, efx->net_dev,
882 			   "steering %s %pI4:%u:%pI4:%u to queue %u [flow %u filter %d]\n",
883 			   (spec.ip_proto == IPPROTO_TCP) ? "TCP" : "UDP",
884 			   spec.rem_host, ntohs(spec.rem_port), spec.loc_host,
885 			   ntohs(spec.loc_port), rxq_index, flow_id, rc);
886 	else
887 		netif_info(efx, rx_status, efx->net_dev,
888 			   "steering %s [%pI6]:%u:[%pI6]:%u to queue %u [flow %u filter %d]\n",
889 			   (spec.ip_proto == IPPROTO_TCP) ? "TCP" : "UDP",
890 			   spec.rem_host, ntohs(spec.rem_port), spec.loc_host,
891 			   ntohs(spec.loc_port), rxq_index, flow_id, rc);
892 
893 	return rc;
894 }
895 
896 bool __ef4_filter_rfs_expire(struct ef4_nic *efx, unsigned int quota)
897 {
898 	bool (*expire_one)(struct ef4_nic *efx, u32 flow_id, unsigned int index);
899 	unsigned int channel_idx, index, size;
900 	u32 flow_id;
901 
902 	if (!spin_trylock_bh(&efx->filter_lock))
903 		return false;
904 
905 	expire_one = efx->type->filter_rfs_expire_one;
906 	channel_idx = efx->rps_expire_channel;
907 	index = efx->rps_expire_index;
908 	size = efx->type->max_rx_ip_filters;
909 	while (quota--) {
910 		struct ef4_channel *channel = ef4_get_channel(efx, channel_idx);
911 		flow_id = channel->rps_flow_id[index];
912 
913 		if (flow_id != RPS_FLOW_ID_INVALID &&
914 		    expire_one(efx, flow_id, index)) {
915 			netif_info(efx, rx_status, efx->net_dev,
916 				   "expired filter %d [queue %u flow %u]\n",
917 				   index, channel_idx, flow_id);
918 			channel->rps_flow_id[index] = RPS_FLOW_ID_INVALID;
919 		}
920 		if (++index == size) {
921 			if (++channel_idx == efx->n_channels)
922 				channel_idx = 0;
923 			index = 0;
924 		}
925 	}
926 	efx->rps_expire_channel = channel_idx;
927 	efx->rps_expire_index = index;
928 
929 	spin_unlock_bh(&efx->filter_lock);
930 	return true;
931 }
932 
933 #endif /* CONFIG_RFS_ACCEL */
934 
935 /**
936  * ef4_filter_is_mc_recipient - test whether spec is a multicast recipient
937  * @spec: Specification to test
938  *
939  * Return: %true if the specification is a non-drop RX filter that
940  * matches a local MAC address I/G bit value of 1 or matches a local
941  * IPv4 or IPv6 address value in the respective multicast address
942  * range.  Otherwise %false.
943  */
944 bool ef4_filter_is_mc_recipient(const struct ef4_filter_spec *spec)
945 {
946 	if (!(spec->flags & EF4_FILTER_FLAG_RX) ||
947 	    spec->dmaq_id == EF4_FILTER_RX_DMAQ_ID_DROP)
948 		return false;
949 
950 	if (spec->match_flags &
951 	    (EF4_FILTER_MATCH_LOC_MAC | EF4_FILTER_MATCH_LOC_MAC_IG) &&
952 	    is_multicast_ether_addr(spec->loc_mac))
953 		return true;
954 
955 	if ((spec->match_flags &
956 	     (EF4_FILTER_MATCH_ETHER_TYPE | EF4_FILTER_MATCH_LOC_HOST)) ==
957 	    (EF4_FILTER_MATCH_ETHER_TYPE | EF4_FILTER_MATCH_LOC_HOST)) {
958 		if (spec->ether_type == htons(ETH_P_IP) &&
959 		    ipv4_is_multicast(spec->loc_host[0]))
960 			return true;
961 		if (spec->ether_type == htons(ETH_P_IPV6) &&
962 		    ((const u8 *)spec->loc_host)[0] == 0xff)
963 			return true;
964 	}
965 
966 	return false;
967 }
968