xref: /dpdk/drivers/net/virtio/virtio_rxtx.c (revision 696573046e9e4e43a1c736c2dd86b04f75abc729)
1 /*-
2  *   BSD LICENSE
3  *
4  *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
5  *   All rights reserved.
6  *
7  *   Redistribution and use in source and binary forms, with or without
8  *   modification, are permitted provided that the following conditions
9  *   are met:
10  *
11  *     * Redistributions of source code must retain the above copyright
12  *       notice, this list of conditions and the following disclaimer.
13  *     * Redistributions in binary form must reproduce the above copyright
14  *       notice, this list of conditions and the following disclaimer in
15  *       the documentation and/or other materials provided with the
16  *       distribution.
17  *     * Neither the name of Intel Corporation nor the names of its
18  *       contributors may be used to endorse or promote products derived
19  *       from this software without specific prior written permission.
20  *
21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24  *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25  *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26  *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27  *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28  *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29  *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 
34 #include <stdint.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <errno.h>
39 
40 #include <rte_cycles.h>
41 #include <rte_memory.h>
42 #include <rte_memzone.h>
43 #include <rte_branch_prediction.h>
44 #include <rte_mempool.h>
45 #include <rte_malloc.h>
46 #include <rte_mbuf.h>
47 #include <rte_ether.h>
48 #include <rte_ethdev.h>
49 #include <rte_prefetch.h>
50 #include <rte_string_fns.h>
51 #include <rte_errno.h>
52 #include <rte_byteorder.h>
53 #include <rte_cpuflags.h>
54 #include <rte_net.h>
55 #include <rte_ip.h>
56 #include <rte_udp.h>
57 #include <rte_tcp.h>
58 
59 #include "virtio_logs.h"
60 #include "virtio_ethdev.h"
61 #include "virtio_pci.h"
62 #include "virtqueue.h"
63 #include "virtio_rxtx.h"
64 
65 #ifdef RTE_LIBRTE_VIRTIO_DEBUG_DUMP
66 #define VIRTIO_DUMP_PACKET(m, len) rte_pktmbuf_dump(stdout, m, len)
67 #else
68 #define  VIRTIO_DUMP_PACKET(m, len) do { } while (0)
69 #endif
70 
71 
72 #define VIRTIO_SIMPLE_FLAGS ((uint32_t)ETH_TXQ_FLAGS_NOMULTSEGS | \
73 	ETH_TXQ_FLAGS_NOOFFLOADS)
74 
75 static void
76 vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
77 {
78 	struct vring_desc *dp, *dp_tail;
79 	struct vq_desc_extra *dxp;
80 	uint16_t desc_idx_last = desc_idx;
81 
82 	dp  = &vq->vq_ring.desc[desc_idx];
83 	dxp = &vq->vq_descx[desc_idx];
84 	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt + dxp->ndescs);
85 	if ((dp->flags & VRING_DESC_F_INDIRECT) == 0) {
86 		while (dp->flags & VRING_DESC_F_NEXT) {
87 			desc_idx_last = dp->next;
88 			dp = &vq->vq_ring.desc[dp->next];
89 		}
90 	}
91 	dxp->ndescs = 0;
92 
93 	/*
94 	 * We must append the existing free chain, if any, to the end of
95 	 * newly freed chain. If the virtqueue was completely used, then
96 	 * head would be VQ_RING_DESC_CHAIN_END (ASSERTed above).
97 	 */
98 	if (vq->vq_desc_tail_idx == VQ_RING_DESC_CHAIN_END) {
99 		vq->vq_desc_head_idx = desc_idx;
100 	} else {
101 		dp_tail = &vq->vq_ring.desc[vq->vq_desc_tail_idx];
102 		dp_tail->next = desc_idx;
103 	}
104 
105 	vq->vq_desc_tail_idx = desc_idx_last;
106 	dp->next = VQ_RING_DESC_CHAIN_END;
107 }
108 
109 static uint16_t
110 virtqueue_dequeue_burst_rx(struct virtqueue *vq, struct rte_mbuf **rx_pkts,
111 			   uint32_t *len, uint16_t num)
112 {
113 	struct vring_used_elem *uep;
114 	struct rte_mbuf *cookie;
115 	uint16_t used_idx, desc_idx;
116 	uint16_t i;
117 
118 	/*  Caller does the check */
119 	for (i = 0; i < num ; i++) {
120 		used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 1));
121 		uep = &vq->vq_ring.used->ring[used_idx];
122 		desc_idx = (uint16_t) uep->id;
123 		len[i] = uep->len;
124 		cookie = (struct rte_mbuf *)vq->vq_descx[desc_idx].cookie;
125 
126 		if (unlikely(cookie == NULL)) {
127 			PMD_DRV_LOG(ERR, "vring descriptor with no mbuf cookie at %u\n",
128 				vq->vq_used_cons_idx);
129 			break;
130 		}
131 
132 		rte_prefetch0(cookie);
133 		rte_packet_prefetch(rte_pktmbuf_mtod(cookie, void *));
134 		rx_pkts[i]  = cookie;
135 		vq->vq_used_cons_idx++;
136 		vq_ring_free_chain(vq, desc_idx);
137 		vq->vq_descx[desc_idx].cookie = NULL;
138 	}
139 
140 	return i;
141 }
142 
143 #ifndef DEFAULT_TX_FREE_THRESH
144 #define DEFAULT_TX_FREE_THRESH 32
145 #endif
146 
147 /* Cleanup from completed transmits. */
148 static void
149 virtio_xmit_cleanup(struct virtqueue *vq, uint16_t num)
150 {
151 	uint16_t i, used_idx, desc_idx;
152 	for (i = 0; i < num; i++) {
153 		struct vring_used_elem *uep;
154 		struct vq_desc_extra *dxp;
155 
156 		used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 1));
157 		uep = &vq->vq_ring.used->ring[used_idx];
158 
159 		desc_idx = (uint16_t) uep->id;
160 		dxp = &vq->vq_descx[desc_idx];
161 		vq->vq_used_cons_idx++;
162 		vq_ring_free_chain(vq, desc_idx);
163 
164 		if (dxp->cookie != NULL) {
165 			rte_pktmbuf_free(dxp->cookie);
166 			dxp->cookie = NULL;
167 		}
168 	}
169 }
170 
171 
172 static inline int
173 virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf *cookie)
174 {
175 	struct vq_desc_extra *dxp;
176 	struct virtio_hw *hw = vq->hw;
177 	struct vring_desc *start_dp;
178 	uint16_t needed = 1;
179 	uint16_t head_idx, idx;
180 
181 	if (unlikely(vq->vq_free_cnt == 0))
182 		return -ENOSPC;
183 	if (unlikely(vq->vq_free_cnt < needed))
184 		return -EMSGSIZE;
185 
186 	head_idx = vq->vq_desc_head_idx;
187 	if (unlikely(head_idx >= vq->vq_nentries))
188 		return -EFAULT;
189 
190 	idx = head_idx;
191 	dxp = &vq->vq_descx[idx];
192 	dxp->cookie = (void *)cookie;
193 	dxp->ndescs = needed;
194 
195 	start_dp = vq->vq_ring.desc;
196 	start_dp[idx].addr =
197 		VIRTIO_MBUF_ADDR(cookie, vq) +
198 		RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
199 	start_dp[idx].len =
200 		cookie->buf_len - RTE_PKTMBUF_HEADROOM + hw->vtnet_hdr_size;
201 	start_dp[idx].flags =  VRING_DESC_F_WRITE;
202 	idx = start_dp[idx].next;
203 	vq->vq_desc_head_idx = idx;
204 	if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
205 		vq->vq_desc_tail_idx = idx;
206 	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
207 	vq_update_avail_ring(vq, head_idx);
208 
209 	return 0;
210 }
211 
212 /* When doing TSO, the IP length is not included in the pseudo header
213  * checksum of the packet given to the PMD, but for virtio it is
214  * expected.
215  */
216 static void
217 virtio_tso_fix_cksum(struct rte_mbuf *m)
218 {
219 	/* common case: header is not fragmented */
220 	if (likely(rte_pktmbuf_data_len(m) >= m->l2_len + m->l3_len +
221 			m->l4_len)) {
222 		struct ipv4_hdr *iph;
223 		struct ipv6_hdr *ip6h;
224 		struct tcp_hdr *th;
225 		uint16_t prev_cksum, new_cksum, ip_len, ip_paylen;
226 		uint32_t tmp;
227 
228 		iph = rte_pktmbuf_mtod_offset(m, struct ipv4_hdr *, m->l2_len);
229 		th = RTE_PTR_ADD(iph, m->l3_len);
230 		if ((iph->version_ihl >> 4) == 4) {
231 			iph->hdr_checksum = 0;
232 			iph->hdr_checksum = rte_ipv4_cksum(iph);
233 			ip_len = iph->total_length;
234 			ip_paylen = rte_cpu_to_be_16(rte_be_to_cpu_16(ip_len) -
235 				m->l3_len);
236 		} else {
237 			ip6h = (struct ipv6_hdr *)iph;
238 			ip_paylen = ip6h->payload_len;
239 		}
240 
241 		/* calculate the new phdr checksum not including ip_paylen */
242 		prev_cksum = th->cksum;
243 		tmp = prev_cksum;
244 		tmp += ip_paylen;
245 		tmp = (tmp & 0xffff) + (tmp >> 16);
246 		new_cksum = tmp;
247 
248 		/* replace it in the packet */
249 		th->cksum = new_cksum;
250 	}
251 }
252 
253 static inline int
254 tx_offload_enabled(struct virtio_hw *hw)
255 {
256 	return vtpci_with_feature(hw, VIRTIO_NET_F_CSUM) ||
257 		vtpci_with_feature(hw, VIRTIO_NET_F_HOST_TSO4) ||
258 		vtpci_with_feature(hw, VIRTIO_NET_F_HOST_TSO6);
259 }
260 
261 static inline void
262 virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
263 		       uint16_t needed, int use_indirect, int can_push)
264 {
265 	struct virtio_tx_region *txr = txvq->virtio_net_hdr_mz->addr;
266 	struct vq_desc_extra *dxp;
267 	struct virtqueue *vq = txvq->vq;
268 	struct vring_desc *start_dp;
269 	uint16_t seg_num = cookie->nb_segs;
270 	uint16_t head_idx, idx;
271 	uint16_t head_size = vq->hw->vtnet_hdr_size;
272 	struct virtio_net_hdr *hdr;
273 	int offload;
274 
275 	offload = tx_offload_enabled(vq->hw);
276 	head_idx = vq->vq_desc_head_idx;
277 	idx = head_idx;
278 	dxp = &vq->vq_descx[idx];
279 	dxp->cookie = (void *)cookie;
280 	dxp->ndescs = needed;
281 
282 	start_dp = vq->vq_ring.desc;
283 
284 	if (can_push) {
285 		/* prepend cannot fail, checked by caller */
286 		hdr = (struct virtio_net_hdr *)
287 			rte_pktmbuf_prepend(cookie, head_size);
288 		/* if offload disabled, it is not zeroed below, do it now */
289 		if (offload == 0)
290 			memset(hdr, 0, head_size);
291 	} else if (use_indirect) {
292 		/* setup tx ring slot to point to indirect
293 		 * descriptor list stored in reserved region.
294 		 *
295 		 * the first slot in indirect ring is already preset
296 		 * to point to the header in reserved region
297 		 */
298 		start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
299 			RTE_PTR_DIFF(&txr[idx].tx_indir, txr);
300 		start_dp[idx].len   = (seg_num + 1) * sizeof(struct vring_desc);
301 		start_dp[idx].flags = VRING_DESC_F_INDIRECT;
302 		hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;
303 
304 		/* loop below will fill in rest of the indirect elements */
305 		start_dp = txr[idx].tx_indir;
306 		idx = 1;
307 	} else {
308 		/* setup first tx ring slot to point to header
309 		 * stored in reserved region.
310 		 */
311 		start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
312 			RTE_PTR_DIFF(&txr[idx].tx_hdr, txr);
313 		start_dp[idx].len   = vq->hw->vtnet_hdr_size;
314 		start_dp[idx].flags = VRING_DESC_F_NEXT;
315 		hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;
316 
317 		idx = start_dp[idx].next;
318 	}
319 
320 	/* Checksum Offload / TSO */
321 	if (offload) {
322 		if (cookie->ol_flags & PKT_TX_TCP_SEG)
323 			cookie->ol_flags |= PKT_TX_TCP_CKSUM;
324 
325 		switch (cookie->ol_flags & PKT_TX_L4_MASK) {
326 		case PKT_TX_UDP_CKSUM:
327 			hdr->csum_start = cookie->l2_len + cookie->l3_len;
328 			hdr->csum_offset = offsetof(struct udp_hdr,
329 				dgram_cksum);
330 			hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
331 			break;
332 
333 		case PKT_TX_TCP_CKSUM:
334 			hdr->csum_start = cookie->l2_len + cookie->l3_len;
335 			hdr->csum_offset = offsetof(struct tcp_hdr, cksum);
336 			hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
337 			break;
338 
339 		default:
340 			hdr->csum_start = 0;
341 			hdr->csum_offset = 0;
342 			hdr->flags = 0;
343 			break;
344 		}
345 
346 		/* TCP Segmentation Offload */
347 		if (cookie->ol_flags & PKT_TX_TCP_SEG) {
348 			virtio_tso_fix_cksum(cookie);
349 			hdr->gso_type = (cookie->ol_flags & PKT_TX_IPV6) ?
350 				VIRTIO_NET_HDR_GSO_TCPV6 :
351 				VIRTIO_NET_HDR_GSO_TCPV4;
352 			hdr->gso_size = cookie->tso_segsz;
353 			hdr->hdr_len =
354 				cookie->l2_len +
355 				cookie->l3_len +
356 				cookie->l4_len;
357 		} else {
358 			hdr->gso_type = 0;
359 			hdr->gso_size = 0;
360 			hdr->hdr_len = 0;
361 		}
362 	}
363 
364 	do {
365 		start_dp[idx].addr  = VIRTIO_MBUF_DATA_DMA_ADDR(cookie, vq);
366 		start_dp[idx].len   = cookie->data_len;
367 		start_dp[idx].flags = cookie->next ? VRING_DESC_F_NEXT : 0;
368 		idx = start_dp[idx].next;
369 	} while ((cookie = cookie->next) != NULL);
370 
371 	if (use_indirect)
372 		idx = vq->vq_ring.desc[head_idx].next;
373 
374 	vq->vq_desc_head_idx = idx;
375 	if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
376 		vq->vq_desc_tail_idx = idx;
377 	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
378 	vq_update_avail_ring(vq, head_idx);
379 }
380 
381 static void
382 virtio_dev_vring_start(struct virtqueue *vq)
383 {
384 	int size = vq->vq_nentries;
385 	struct vring *vr = &vq->vq_ring;
386 	uint8_t *ring_mem = vq->vq_ring_virt_mem;
387 
388 	PMD_INIT_FUNC_TRACE();
389 
390 	/*
391 	 * Reinitialise since virtio port might have been stopped and restarted
392 	 */
393 	memset(vq->vq_ring_virt_mem, 0, vq->vq_ring_size);
394 	vring_init(vr, size, ring_mem, VIRTIO_PCI_VRING_ALIGN);
395 	vq->vq_used_cons_idx = 0;
396 	vq->vq_desc_head_idx = 0;
397 	vq->vq_avail_idx = 0;
398 	vq->vq_desc_tail_idx = (uint16_t)(vq->vq_nentries - 1);
399 	vq->vq_free_cnt = vq->vq_nentries;
400 	memset(vq->vq_descx, 0, sizeof(struct vq_desc_extra) * vq->vq_nentries);
401 
402 	vring_desc_init(vr->desc, size);
403 
404 	/*
405 	 * Disable device(host) interrupting guest
406 	 */
407 	virtqueue_disable_intr(vq);
408 }
409 
410 void
411 virtio_dev_cq_start(struct rte_eth_dev *dev)
412 {
413 	struct virtio_hw *hw = dev->data->dev_private;
414 
415 	if (hw->cvq && hw->cvq->vq) {
416 		virtio_dev_vring_start(hw->cvq->vq);
417 		VIRTQUEUE_DUMP((struct virtqueue *)hw->cvq->vq);
418 	}
419 }
420 
421 void
422 virtio_dev_rxtx_start(struct rte_eth_dev *dev)
423 {
424 	/*
425 	 * Start receive and transmit vrings
426 	 * -	Setup vring structure for all queues
427 	 * -	Initialize descriptor for the rx vring
428 	 * -	Allocate blank mbufs for the each rx descriptor
429 	 *
430 	 */
431 	uint16_t i;
432 	uint16_t desc_idx;
433 	struct virtio_hw *hw = dev->data->dev_private;
434 
435 	PMD_INIT_FUNC_TRACE();
436 
437 	/* Start rx vring. */
438 	for (i = 0; i < dev->data->nb_rx_queues; i++) {
439 		struct virtnet_rx *rxvq = dev->data->rx_queues[i];
440 		struct virtqueue *vq = rxvq->vq;
441 		int error, nbufs;
442 		struct rte_mbuf *m;
443 
444 		virtio_dev_vring_start(vq);
445 		if (rxvq->mpool == NULL) {
446 			rte_exit(EXIT_FAILURE,
447 				"Cannot allocate mbufs for rx virtqueue");
448 		}
449 
450 		/* Allocate blank mbufs for the each rx descriptor */
451 		nbufs = 0;
452 		error = ENOSPC;
453 
454 		if (hw->use_simple_rxtx) {
455 			for (desc_idx = 0; desc_idx < vq->vq_nentries;
456 			     desc_idx++) {
457 				vq->vq_ring.avail->ring[desc_idx] = desc_idx;
458 				vq->vq_ring.desc[desc_idx].flags =
459 					VRING_DESC_F_WRITE;
460 			}
461 		}
462 
463 		memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
464 		for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST;
465 		     desc_idx++) {
466 			vq->sw_ring[vq->vq_nentries + desc_idx] =
467 				&rxvq->fake_mbuf;
468 		}
469 
470 		while (!virtqueue_full(vq)) {
471 			m = rte_mbuf_raw_alloc(rxvq->mpool);
472 			if (m == NULL)
473 				break;
474 
475 			/******************************************
476 			*         Enqueue allocated buffers        *
477 			*******************************************/
478 			if (hw->use_simple_rxtx)
479 				error = virtqueue_enqueue_recv_refill_simple(vq, m);
480 			else
481 				error = virtqueue_enqueue_recv_refill(vq, m);
482 
483 			if (error) {
484 				rte_pktmbuf_free(m);
485 				break;
486 			}
487 			nbufs++;
488 		}
489 
490 		vq_update_avail_idx(vq);
491 
492 		PMD_INIT_LOG(DEBUG, "Allocated %d bufs", nbufs);
493 
494 		VIRTQUEUE_DUMP(vq);
495 	}
496 
497 	/* Start tx vring. */
498 	for (i = 0; i < dev->data->nb_tx_queues; i++) {
499 		struct virtnet_tx *txvq = dev->data->tx_queues[i];
500 		struct virtqueue *vq = txvq->vq;
501 
502 		virtio_dev_vring_start(vq);
503 		if (hw->use_simple_rxtx) {
504 			uint16_t mid_idx  = vq->vq_nentries >> 1;
505 
506 			for (desc_idx = 0; desc_idx < mid_idx; desc_idx++) {
507 				vq->vq_ring.avail->ring[desc_idx] =
508 					desc_idx + mid_idx;
509 				vq->vq_ring.desc[desc_idx + mid_idx].next =
510 					desc_idx;
511 				vq->vq_ring.desc[desc_idx + mid_idx].addr =
512 					txvq->virtio_net_hdr_mem +
513 					offsetof(struct virtio_tx_region, tx_hdr);
514 				vq->vq_ring.desc[desc_idx + mid_idx].len =
515 					vq->hw->vtnet_hdr_size;
516 				vq->vq_ring.desc[desc_idx + mid_idx].flags =
517 					VRING_DESC_F_NEXT;
518 				vq->vq_ring.desc[desc_idx].flags = 0;
519 			}
520 			for (desc_idx = mid_idx; desc_idx < vq->vq_nentries;
521 			     desc_idx++)
522 				vq->vq_ring.avail->ring[desc_idx] = desc_idx;
523 		}
524 
525 		VIRTQUEUE_DUMP(vq);
526 	}
527 }
528 
529 int
530 virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
531 			uint16_t queue_idx,
532 			uint16_t nb_desc,
533 			unsigned int socket_id,
534 			__rte_unused const struct rte_eth_rxconf *rx_conf,
535 			struct rte_mempool *mp)
536 {
537 	uint16_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_RQ_QUEUE_IDX;
538 	struct virtnet_rx *rxvq;
539 	int ret;
540 
541 	PMD_INIT_FUNC_TRACE();
542 	ret = virtio_dev_queue_setup(dev, VTNET_RQ, queue_idx, vtpci_queue_idx,
543 			nb_desc, socket_id, (void **)&rxvq);
544 	if (ret < 0) {
545 		PMD_INIT_LOG(ERR, "rvq initialization failed");
546 		return ret;
547 	}
548 
549 	/* Create mempool for rx mbuf allocation */
550 	rxvq->mpool = mp;
551 
552 	dev->data->rx_queues[queue_idx] = rxvq;
553 
554 	virtio_rxq_vec_setup(rxvq);
555 
556 	return 0;
557 }
558 
559 void
560 virtio_dev_rx_queue_release(void *rxq)
561 {
562 	struct virtnet_rx *rxvq = rxq;
563 	struct virtqueue *vq;
564 	const struct rte_memzone *mz;
565 
566 	if (rxvq == NULL)
567 		return;
568 
569 	/*
570 	 * rxvq is freed when vq is freed, and as mz should be freed after the
571 	 * del_queue, so we reserve the mz pointer first.
572 	 */
573 	vq = rxvq->vq;
574 	mz = rxvq->mz;
575 
576 	virtio_dev_queue_release(vq);
577 	rte_memzone_free(mz);
578 }
579 
580 static void
581 virtio_update_rxtx_handler(struct rte_eth_dev *dev,
582 			   const struct rte_eth_txconf *tx_conf)
583 {
584 	uint8_t use_simple_rxtx = 0;
585 	struct virtio_hw *hw = dev->data->dev_private;
586 
587 #if defined RTE_ARCH_X86
588 	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE3))
589 		use_simple_rxtx = 1;
590 #elif defined RTE_ARCH_ARM64 || defined CONFIG_RTE_ARCH_ARM
591 	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_NEON))
592 		use_simple_rxtx = 1;
593 #endif
594 	/* Use simple rx/tx func if single segment and no offloads */
595 	if (use_simple_rxtx &&
596 	    (tx_conf->txq_flags & VIRTIO_SIMPLE_FLAGS) == VIRTIO_SIMPLE_FLAGS &&
597 	    !vtpci_with_feature(hw, VIRTIO_NET_F_MRG_RXBUF)) {
598 		PMD_INIT_LOG(INFO, "Using simple rx/tx path");
599 		dev->tx_pkt_burst = virtio_xmit_pkts_simple;
600 		dev->rx_pkt_burst = virtio_recv_pkts_vec;
601 		hw->use_simple_rxtx = use_simple_rxtx;
602 	}
603 }
604 
605 /*
606  * struct rte_eth_dev *dev: Used to update dev
607  * uint16_t nb_desc: Defaults to values read from config space
608  * unsigned int socket_id: Used to allocate memzone
609  * const struct rte_eth_txconf *tx_conf: Used to setup tx engine
610  * uint16_t queue_idx: Just used as an index in dev txq list
611  */
612 int
613 virtio_dev_tx_queue_setup(struct rte_eth_dev *dev,
614 			uint16_t queue_idx,
615 			uint16_t nb_desc,
616 			unsigned int socket_id,
617 			const struct rte_eth_txconf *tx_conf)
618 {
619 	uint8_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_TQ_QUEUE_IDX;
620 	struct virtnet_tx *txvq;
621 	struct virtqueue *vq;
622 	uint16_t tx_free_thresh;
623 	int ret;
624 
625 	PMD_INIT_FUNC_TRACE();
626 
627 
628 	virtio_update_rxtx_handler(dev, tx_conf);
629 
630 	ret = virtio_dev_queue_setup(dev, VTNET_TQ, queue_idx, vtpci_queue_idx,
631 			nb_desc, socket_id, (void **)&txvq);
632 	if (ret < 0) {
633 		PMD_INIT_LOG(ERR, "tvq initialization failed");
634 		return ret;
635 	}
636 	vq = txvq->vq;
637 
638 	tx_free_thresh = tx_conf->tx_free_thresh;
639 	if (tx_free_thresh == 0)
640 		tx_free_thresh =
641 			RTE_MIN(vq->vq_nentries / 4, DEFAULT_TX_FREE_THRESH);
642 
643 	if (tx_free_thresh >= (vq->vq_nentries - 3)) {
644 		RTE_LOG(ERR, PMD, "tx_free_thresh must be less than the "
645 			"number of TX entries minus 3 (%u)."
646 			" (tx_free_thresh=%u port=%u queue=%u)\n",
647 			vq->vq_nentries - 3,
648 			tx_free_thresh, dev->data->port_id, queue_idx);
649 		return -EINVAL;
650 	}
651 
652 	vq->vq_free_thresh = tx_free_thresh;
653 
654 	dev->data->tx_queues[queue_idx] = txvq;
655 	return 0;
656 }
657 
658 void
659 virtio_dev_tx_queue_release(void *txq)
660 {
661 	struct virtnet_tx *txvq = txq;
662 	struct virtqueue *vq;
663 	const struct rte_memzone *mz;
664 	const struct rte_memzone *hdr_mz;
665 
666 	if (txvq == NULL)
667 		return;
668 
669 	/*
670 	 * txvq is freed when vq is freed, and as mz should be freed after the
671 	 * del_queue, so we reserve the mz pointer first.
672 	 */
673 	vq = txvq->vq;
674 	mz = txvq->mz;
675 	hdr_mz = txvq->virtio_net_hdr_mz;
676 
677 	virtio_dev_queue_release(vq);
678 	rte_memzone_free(mz);
679 	rte_memzone_free(hdr_mz);
680 }
681 
682 static void
683 virtio_discard_rxbuf(struct virtqueue *vq, struct rte_mbuf *m)
684 {
685 	int error;
686 	/*
687 	 * Requeue the discarded mbuf. This should always be
688 	 * successful since it was just dequeued.
689 	 */
690 	error = virtqueue_enqueue_recv_refill(vq, m);
691 	if (unlikely(error)) {
692 		RTE_LOG(ERR, PMD, "cannot requeue discarded mbuf");
693 		rte_pktmbuf_free(m);
694 	}
695 }
696 
697 static void
698 virtio_update_packet_stats(struct virtnet_stats *stats, struct rte_mbuf *mbuf)
699 {
700 	uint32_t s = mbuf->pkt_len;
701 	struct ether_addr *ea;
702 
703 	if (s == 64) {
704 		stats->size_bins[1]++;
705 	} else if (s > 64 && s < 1024) {
706 		uint32_t bin;
707 
708 		/* count zeros, and offset into correct bin */
709 		bin = (sizeof(s) * 8) - __builtin_clz(s) - 5;
710 		stats->size_bins[bin]++;
711 	} else {
712 		if (s < 64)
713 			stats->size_bins[0]++;
714 		else if (s < 1519)
715 			stats->size_bins[6]++;
716 		else if (s >= 1519)
717 			stats->size_bins[7]++;
718 	}
719 
720 	ea = rte_pktmbuf_mtod(mbuf, struct ether_addr *);
721 	if (is_multicast_ether_addr(ea)) {
722 		if (is_broadcast_ether_addr(ea))
723 			stats->broadcast++;
724 		else
725 			stats->multicast++;
726 	}
727 }
728 
729 /* Optionally fill offload information in structure */
730 static int
731 virtio_rx_offload(struct rte_mbuf *m, struct virtio_net_hdr *hdr)
732 {
733 	struct rte_net_hdr_lens hdr_lens;
734 	uint32_t hdrlen, ptype;
735 	int l4_supported = 0;
736 
737 	/* nothing to do */
738 	if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
739 		return 0;
740 
741 	m->ol_flags |= PKT_RX_IP_CKSUM_UNKNOWN;
742 
743 	ptype = rte_net_get_ptype(m, &hdr_lens, RTE_PTYPE_ALL_MASK);
744 	m->packet_type = ptype;
745 	if ((ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_TCP ||
746 	    (ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_UDP ||
747 	    (ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_SCTP)
748 		l4_supported = 1;
749 
750 	if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
751 		hdrlen = hdr_lens.l2_len + hdr_lens.l3_len + hdr_lens.l4_len;
752 		if (hdr->csum_start <= hdrlen && l4_supported) {
753 			m->ol_flags |= PKT_RX_L4_CKSUM_NONE;
754 		} else {
755 			/* Unknown proto or tunnel, do sw cksum. We can assume
756 			 * the cksum field is in the first segment since the
757 			 * buffers we provided to the host are large enough.
758 			 * In case of SCTP, this will be wrong since it's a CRC
759 			 * but there's nothing we can do.
760 			 */
761 			uint16_t csum, off;
762 
763 			rte_raw_cksum_mbuf(m, hdr->csum_start,
764 				rte_pktmbuf_pkt_len(m) - hdr->csum_start,
765 				&csum);
766 			if (likely(csum != 0xffff))
767 				csum = ~csum;
768 			off = hdr->csum_offset + hdr->csum_start;
769 			if (rte_pktmbuf_data_len(m) >= off + 1)
770 				*rte_pktmbuf_mtod_offset(m, uint16_t *,
771 					off) = csum;
772 		}
773 	} else if (hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID && l4_supported) {
774 		m->ol_flags |= PKT_RX_L4_CKSUM_GOOD;
775 	}
776 
777 	/* GSO request, save required information in mbuf */
778 	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
779 		/* Check unsupported modes */
780 		if ((hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN) ||
781 		    (hdr->gso_size == 0)) {
782 			return -EINVAL;
783 		}
784 
785 		/* Update mss lengthes in mbuf */
786 		m->tso_segsz = hdr->gso_size;
787 		switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
788 			case VIRTIO_NET_HDR_GSO_TCPV4:
789 			case VIRTIO_NET_HDR_GSO_TCPV6:
790 				m->ol_flags |= PKT_RX_LRO | \
791 					PKT_RX_L4_CKSUM_NONE;
792 				break;
793 			default:
794 				return -EINVAL;
795 		}
796 	}
797 
798 	return 0;
799 }
800 
801 static inline int
802 rx_offload_enabled(struct virtio_hw *hw)
803 {
804 	return vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_CSUM) ||
805 		vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO4) ||
806 		vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO6);
807 }
808 
809 #define VIRTIO_MBUF_BURST_SZ 64
810 #define DESC_PER_CACHELINE (RTE_CACHE_LINE_SIZE / sizeof(struct vring_desc))
811 uint16_t
812 virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
813 {
814 	struct virtnet_rx *rxvq = rx_queue;
815 	struct virtqueue *vq = rxvq->vq;
816 	struct virtio_hw *hw;
817 	struct rte_mbuf *rxm, *new_mbuf;
818 	uint16_t nb_used, num, nb_rx;
819 	uint32_t len[VIRTIO_MBUF_BURST_SZ];
820 	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
821 	int error;
822 	uint32_t i, nb_enqueued;
823 	uint32_t hdr_size;
824 	int offload;
825 	struct virtio_net_hdr *hdr;
826 
827 	nb_used = VIRTQUEUE_NUSED(vq);
828 
829 	virtio_rmb();
830 
831 	num = (uint16_t)(likely(nb_used <= nb_pkts) ? nb_used : nb_pkts);
832 	num = (uint16_t)(likely(num <= VIRTIO_MBUF_BURST_SZ) ? num : VIRTIO_MBUF_BURST_SZ);
833 	if (likely(num > DESC_PER_CACHELINE))
834 		num = num - ((vq->vq_used_cons_idx + num) % DESC_PER_CACHELINE);
835 
836 	num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, num);
837 	PMD_RX_LOG(DEBUG, "used:%d dequeue:%d", nb_used, num);
838 
839 	hw = vq->hw;
840 	nb_rx = 0;
841 	nb_enqueued = 0;
842 	hdr_size = hw->vtnet_hdr_size;
843 	offload = rx_offload_enabled(hw);
844 
845 	for (i = 0; i < num ; i++) {
846 		rxm = rcv_pkts[i];
847 
848 		PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);
849 
850 		if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
851 			PMD_RX_LOG(ERR, "Packet drop");
852 			nb_enqueued++;
853 			virtio_discard_rxbuf(vq, rxm);
854 			rxvq->stats.errors++;
855 			continue;
856 		}
857 
858 		rxm->port = rxvq->port_id;
859 		rxm->data_off = RTE_PKTMBUF_HEADROOM;
860 		rxm->ol_flags = 0;
861 		rxm->vlan_tci = 0;
862 
863 		rxm->nb_segs = 1;
864 		rxm->next = NULL;
865 		rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
866 		rxm->data_len = (uint16_t)(len[i] - hdr_size);
867 
868 		hdr = (struct virtio_net_hdr *)((char *)rxm->buf_addr +
869 			RTE_PKTMBUF_HEADROOM - hdr_size);
870 
871 		if (hw->vlan_strip)
872 			rte_vlan_strip(rxm);
873 
874 		if (offload && virtio_rx_offload(rxm, hdr) < 0) {
875 			virtio_discard_rxbuf(vq, rxm);
876 			rxvq->stats.errors++;
877 			continue;
878 		}
879 
880 		VIRTIO_DUMP_PACKET(rxm, rxm->data_len);
881 
882 		rx_pkts[nb_rx++] = rxm;
883 
884 		rxvq->stats.bytes += rx_pkts[nb_rx - 1]->pkt_len;
885 		virtio_update_packet_stats(&rxvq->stats, rxm);
886 	}
887 
888 	rxvq->stats.packets += nb_rx;
889 
890 	/* Allocate new mbuf for the used descriptor */
891 	error = ENOSPC;
892 	while (likely(!virtqueue_full(vq))) {
893 		new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
894 		if (unlikely(new_mbuf == NULL)) {
895 			struct rte_eth_dev *dev
896 				= &rte_eth_devices[rxvq->port_id];
897 			dev->data->rx_mbuf_alloc_failed++;
898 			break;
899 		}
900 		error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
901 		if (unlikely(error)) {
902 			rte_pktmbuf_free(new_mbuf);
903 			break;
904 		}
905 		nb_enqueued++;
906 	}
907 
908 	if (likely(nb_enqueued)) {
909 		vq_update_avail_idx(vq);
910 
911 		if (unlikely(virtqueue_kick_prepare(vq))) {
912 			virtqueue_notify(vq);
913 			PMD_RX_LOG(DEBUG, "Notified");
914 		}
915 	}
916 
917 	return nb_rx;
918 }
919 
920 uint16_t
921 virtio_recv_mergeable_pkts(void *rx_queue,
922 			struct rte_mbuf **rx_pkts,
923 			uint16_t nb_pkts)
924 {
925 	struct virtnet_rx *rxvq = rx_queue;
926 	struct virtqueue *vq = rxvq->vq;
927 	struct virtio_hw *hw;
928 	struct rte_mbuf *rxm, *new_mbuf;
929 	uint16_t nb_used, num, nb_rx;
930 	uint32_t len[VIRTIO_MBUF_BURST_SZ];
931 	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
932 	struct rte_mbuf *prev;
933 	int error;
934 	uint32_t i, nb_enqueued;
935 	uint32_t seg_num;
936 	uint16_t extra_idx;
937 	uint32_t seg_res;
938 	uint32_t hdr_size;
939 	int offload;
940 
941 	nb_used = VIRTQUEUE_NUSED(vq);
942 
943 	virtio_rmb();
944 
945 	PMD_RX_LOG(DEBUG, "used:%d", nb_used);
946 
947 	hw = vq->hw;
948 	nb_rx = 0;
949 	i = 0;
950 	nb_enqueued = 0;
951 	seg_num = 0;
952 	extra_idx = 0;
953 	seg_res = 0;
954 	hdr_size = hw->vtnet_hdr_size;
955 	offload = rx_offload_enabled(hw);
956 
957 	while (i < nb_used) {
958 		struct virtio_net_hdr_mrg_rxbuf *header;
959 
960 		if (nb_rx == nb_pkts)
961 			break;
962 
963 		num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, 1);
964 		if (num != 1)
965 			continue;
966 
967 		i++;
968 
969 		PMD_RX_LOG(DEBUG, "dequeue:%d", num);
970 		PMD_RX_LOG(DEBUG, "packet len:%d", len[0]);
971 
972 		rxm = rcv_pkts[0];
973 
974 		if (unlikely(len[0] < hdr_size + ETHER_HDR_LEN)) {
975 			PMD_RX_LOG(ERR, "Packet drop");
976 			nb_enqueued++;
977 			virtio_discard_rxbuf(vq, rxm);
978 			rxvq->stats.errors++;
979 			continue;
980 		}
981 
982 		header = (struct virtio_net_hdr_mrg_rxbuf *)((char *)rxm->buf_addr +
983 			RTE_PKTMBUF_HEADROOM - hdr_size);
984 		seg_num = header->num_buffers;
985 
986 		if (seg_num == 0)
987 			seg_num = 1;
988 
989 		rxm->data_off = RTE_PKTMBUF_HEADROOM;
990 		rxm->nb_segs = seg_num;
991 		rxm->next = NULL;
992 		rxm->ol_flags = 0;
993 		rxm->vlan_tci = 0;
994 		rxm->pkt_len = (uint32_t)(len[0] - hdr_size);
995 		rxm->data_len = (uint16_t)(len[0] - hdr_size);
996 
997 		rxm->port = rxvq->port_id;
998 		rx_pkts[nb_rx] = rxm;
999 		prev = rxm;
1000 
1001 		if (offload && virtio_rx_offload(rxm, &header->hdr) < 0) {
1002 			virtio_discard_rxbuf(vq, rxm);
1003 			rxvq->stats.errors++;
1004 			continue;
1005 		}
1006 
1007 		seg_res = seg_num - 1;
1008 
1009 		while (seg_res != 0) {
1010 			/*
1011 			 * Get extra segments for current uncompleted packet.
1012 			 */
1013 			uint16_t  rcv_cnt =
1014 				RTE_MIN(seg_res, RTE_DIM(rcv_pkts));
1015 			if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
1016 				uint32_t rx_num =
1017 					virtqueue_dequeue_burst_rx(vq,
1018 					rcv_pkts, len, rcv_cnt);
1019 				i += rx_num;
1020 				rcv_cnt = rx_num;
1021 			} else {
1022 				PMD_RX_LOG(ERR,
1023 					   "No enough segments for packet.");
1024 				nb_enqueued++;
1025 				virtio_discard_rxbuf(vq, rxm);
1026 				rxvq->stats.errors++;
1027 				break;
1028 			}
1029 
1030 			extra_idx = 0;
1031 
1032 			while (extra_idx < rcv_cnt) {
1033 				rxm = rcv_pkts[extra_idx];
1034 
1035 				rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
1036 				rxm->next = NULL;
1037 				rxm->pkt_len = (uint32_t)(len[extra_idx]);
1038 				rxm->data_len = (uint16_t)(len[extra_idx]);
1039 
1040 				if (prev)
1041 					prev->next = rxm;
1042 
1043 				prev = rxm;
1044 				rx_pkts[nb_rx]->pkt_len += rxm->pkt_len;
1045 				extra_idx++;
1046 			};
1047 			seg_res -= rcv_cnt;
1048 		}
1049 
1050 		if (hw->vlan_strip)
1051 			rte_vlan_strip(rx_pkts[nb_rx]);
1052 
1053 		VIRTIO_DUMP_PACKET(rx_pkts[nb_rx],
1054 			rx_pkts[nb_rx]->data_len);
1055 
1056 		rxvq->stats.bytes += rx_pkts[nb_rx]->pkt_len;
1057 		virtio_update_packet_stats(&rxvq->stats, rx_pkts[nb_rx]);
1058 		nb_rx++;
1059 	}
1060 
1061 	rxvq->stats.packets += nb_rx;
1062 
1063 	/* Allocate new mbuf for the used descriptor */
1064 	error = ENOSPC;
1065 	while (likely(!virtqueue_full(vq))) {
1066 		new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
1067 		if (unlikely(new_mbuf == NULL)) {
1068 			struct rte_eth_dev *dev
1069 				= &rte_eth_devices[rxvq->port_id];
1070 			dev->data->rx_mbuf_alloc_failed++;
1071 			break;
1072 		}
1073 		error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
1074 		if (unlikely(error)) {
1075 			rte_pktmbuf_free(new_mbuf);
1076 			break;
1077 		}
1078 		nb_enqueued++;
1079 	}
1080 
1081 	if (likely(nb_enqueued)) {
1082 		vq_update_avail_idx(vq);
1083 
1084 		if (unlikely(virtqueue_kick_prepare(vq))) {
1085 			virtqueue_notify(vq);
1086 			PMD_RX_LOG(DEBUG, "Notified");
1087 		}
1088 	}
1089 
1090 	return nb_rx;
1091 }
1092 
1093 uint16_t
1094 virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
1095 {
1096 	struct virtnet_tx *txvq = tx_queue;
1097 	struct virtqueue *vq = txvq->vq;
1098 	struct virtio_hw *hw = vq->hw;
1099 	uint16_t hdr_size = hw->vtnet_hdr_size;
1100 	uint16_t nb_used, nb_tx;
1101 	int error;
1102 
1103 	if (unlikely(nb_pkts < 1))
1104 		return nb_pkts;
1105 
1106 	PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
1107 	nb_used = VIRTQUEUE_NUSED(vq);
1108 
1109 	virtio_rmb();
1110 	if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))
1111 		virtio_xmit_cleanup(vq, nb_used);
1112 
1113 	for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
1114 		struct rte_mbuf *txm = tx_pkts[nb_tx];
1115 		int can_push = 0, use_indirect = 0, slots, need;
1116 
1117 		/* Do VLAN tag insertion */
1118 		if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
1119 			error = rte_vlan_insert(&txm);
1120 			if (unlikely(error)) {
1121 				rte_pktmbuf_free(txm);
1122 				continue;
1123 			}
1124 		}
1125 
1126 		/* optimize ring usage */
1127 		if (vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) &&
1128 		    rte_mbuf_refcnt_read(txm) == 1 &&
1129 		    RTE_MBUF_DIRECT(txm) &&
1130 		    txm->nb_segs == 1 &&
1131 		    rte_pktmbuf_headroom(txm) >= hdr_size &&
1132 		    rte_is_aligned(rte_pktmbuf_mtod(txm, char *),
1133 				   __alignof__(struct virtio_net_hdr_mrg_rxbuf)))
1134 			can_push = 1;
1135 		else if (vtpci_with_feature(hw, VIRTIO_RING_F_INDIRECT_DESC) &&
1136 			 txm->nb_segs < VIRTIO_MAX_TX_INDIRECT)
1137 			use_indirect = 1;
1138 
1139 		/* How many main ring entries are needed to this Tx?
1140 		 * any_layout => number of segments
1141 		 * indirect   => 1
1142 		 * default    => number of segments + 1
1143 		 */
1144 		slots = use_indirect ? 1 : (txm->nb_segs + !can_push);
1145 		need = slots - vq->vq_free_cnt;
1146 
1147 		/* Positive value indicates it need free vring descriptors */
1148 		if (unlikely(need > 0)) {
1149 			nb_used = VIRTQUEUE_NUSED(vq);
1150 			virtio_rmb();
1151 			need = RTE_MIN(need, (int)nb_used);
1152 
1153 			virtio_xmit_cleanup(vq, need);
1154 			need = slots - vq->vq_free_cnt;
1155 			if (unlikely(need > 0)) {
1156 				PMD_TX_LOG(ERR,
1157 					   "No free tx descriptors to transmit");
1158 				break;
1159 			}
1160 		}
1161 
1162 		/* Enqueue Packet buffers */
1163 		virtqueue_enqueue_xmit(txvq, txm, slots, use_indirect, can_push);
1164 
1165 		txvq->stats.bytes += txm->pkt_len;
1166 		virtio_update_packet_stats(&txvq->stats, txm);
1167 	}
1168 
1169 	txvq->stats.packets += nb_tx;
1170 
1171 	if (likely(nb_tx)) {
1172 		vq_update_avail_idx(vq);
1173 
1174 		if (unlikely(virtqueue_kick_prepare(vq))) {
1175 			virtqueue_notify(vq);
1176 			PMD_TX_LOG(DEBUG, "Notified backend after xmit");
1177 		}
1178 	}
1179 
1180 	return nb_tx;
1181 }
1182