xref: /dpdk/drivers/net/virtio/virtio_user/virtio_user_dev.c (revision 3caef7e1625f9ef1cf6785522917cb844eab5168)
1 /* SPDX-License-Identifier: BSD-3-Clause
2  * Copyright(c) 2010-2016 Intel Corporation
3  */
4 
5 #include <stdint.h>
6 #include <stdio.h>
7 #include <fcntl.h>
8 #include <string.h>
9 #include <errno.h>
10 #include <sys/mman.h>
11 #include <unistd.h>
12 #include <sys/eventfd.h>
13 #include <sys/types.h>
14 #include <sys/stat.h>
15 
16 #include <rte_eal_memconfig.h>
17 
18 #include "vhost.h"
19 #include "virtio_user_dev.h"
20 #include "../virtio_ethdev.h"
21 
22 #define VIRTIO_USER_MEM_EVENT_CLB_NAME "virtio_user_mem_event_clb"
23 
24 static int
25 virtio_user_create_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
26 {
27 	/* Of all per virtqueue MSGs, make sure VHOST_SET_VRING_CALL come
28 	 * firstly because vhost depends on this msg to allocate virtqueue
29 	 * pair.
30 	 */
31 	struct vhost_vring_file file;
32 
33 	file.index = queue_sel;
34 	file.fd = dev->callfds[queue_sel];
35 	dev->ops->send_request(dev, VHOST_USER_SET_VRING_CALL, &file);
36 
37 	return 0;
38 }
39 
40 static int
41 virtio_user_kick_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
42 {
43 	struct vhost_vring_file file;
44 	struct vhost_vring_state state;
45 	struct vring *vring = &dev->vrings[queue_sel];
46 	struct vhost_vring_addr addr = {
47 		.index = queue_sel,
48 		.desc_user_addr = (uint64_t)(uintptr_t)vring->desc,
49 		.avail_user_addr = (uint64_t)(uintptr_t)vring->avail,
50 		.used_user_addr = (uint64_t)(uintptr_t)vring->used,
51 		.log_guest_addr = 0,
52 		.flags = 0, /* disable log */
53 	};
54 
55 	state.index = queue_sel;
56 	state.num = vring->num;
57 	dev->ops->send_request(dev, VHOST_USER_SET_VRING_NUM, &state);
58 
59 	state.index = queue_sel;
60 	state.num = 0; /* no reservation */
61 	if (dev->features & (1ULL << VIRTIO_F_RING_PACKED))
62 		state.num |= (1 << 15);
63 	dev->ops->send_request(dev, VHOST_USER_SET_VRING_BASE, &state);
64 
65 	dev->ops->send_request(dev, VHOST_USER_SET_VRING_ADDR, &addr);
66 
67 	/* Of all per virtqueue MSGs, make sure VHOST_USER_SET_VRING_KICK comes
68 	 * lastly because vhost depends on this msg to judge if
69 	 * virtio is ready.
70 	 */
71 	file.index = queue_sel;
72 	file.fd = dev->kickfds[queue_sel];
73 	dev->ops->send_request(dev, VHOST_USER_SET_VRING_KICK, &file);
74 
75 	return 0;
76 }
77 
78 static int
79 virtio_user_queue_setup(struct virtio_user_dev *dev,
80 			int (*fn)(struct virtio_user_dev *, uint32_t))
81 {
82 	uint32_t i, queue_sel;
83 
84 	for (i = 0; i < dev->max_queue_pairs; ++i) {
85 		queue_sel = 2 * i + VTNET_SQ_RQ_QUEUE_IDX;
86 		if (fn(dev, queue_sel) < 0) {
87 			PMD_DRV_LOG(INFO, "setup rx vq fails: %u", i);
88 			return -1;
89 		}
90 	}
91 	for (i = 0; i < dev->max_queue_pairs; ++i) {
92 		queue_sel = 2 * i + VTNET_SQ_TQ_QUEUE_IDX;
93 		if (fn(dev, queue_sel) < 0) {
94 			PMD_DRV_LOG(INFO, "setup tx vq fails: %u", i);
95 			return -1;
96 		}
97 	}
98 
99 	return 0;
100 }
101 
102 int
103 is_vhost_user_by_type(const char *path)
104 {
105 	struct stat sb;
106 
107 	if (stat(path, &sb) == -1)
108 		return 0;
109 
110 	return S_ISSOCK(sb.st_mode);
111 }
112 
113 int
114 virtio_user_start_device(struct virtio_user_dev *dev)
115 {
116 	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
117 	uint64_t features;
118 	int ret;
119 
120 	/*
121 	 * XXX workaround!
122 	 *
123 	 * We need to make sure that the locks will be
124 	 * taken in the correct order to avoid deadlocks.
125 	 *
126 	 * Before releasing this lock, this thread should
127 	 * not trigger any memory hotplug events.
128 	 *
129 	 * This is a temporary workaround, and should be
130 	 * replaced when we get proper supports from the
131 	 * memory subsystem in the future.
132 	 */
133 	rte_rwlock_read_lock(&mcfg->memory_hotplug_lock);
134 	pthread_mutex_lock(&dev->mutex);
135 
136 	if (is_vhost_user_by_type(dev->path) && dev->vhostfd < 0)
137 		goto error;
138 
139 	/* Step 0: tell vhost to create queues */
140 	if (virtio_user_queue_setup(dev, virtio_user_create_queue) < 0)
141 		goto error;
142 
143 	/* Step 1: set features */
144 	features = dev->features;
145 	/* Strip VIRTIO_NET_F_MAC, as MAC address is handled in vdev init */
146 	features &= ~(1ull << VIRTIO_NET_F_MAC);
147 	/* Strip VIRTIO_NET_F_CTRL_VQ, as devices do not really need to know */
148 	features &= ~(1ull << VIRTIO_NET_F_CTRL_VQ);
149 	features &= ~(1ull << VIRTIO_NET_F_STATUS);
150 	ret = dev->ops->send_request(dev, VHOST_USER_SET_FEATURES, &features);
151 	if (ret < 0)
152 		goto error;
153 	PMD_DRV_LOG(INFO, "set features: %" PRIx64, features);
154 
155 	/* Step 2: share memory regions */
156 	ret = dev->ops->send_request(dev, VHOST_USER_SET_MEM_TABLE, NULL);
157 	if (ret < 0)
158 		goto error;
159 
160 	/* Step 3: kick queues */
161 	if (virtio_user_queue_setup(dev, virtio_user_kick_queue) < 0)
162 		goto error;
163 
164 	/* Step 4: enable queues
165 	 * we enable the 1st queue pair by default.
166 	 */
167 	dev->ops->enable_qp(dev, 0, 1);
168 
169 	dev->started = true;
170 	pthread_mutex_unlock(&dev->mutex);
171 	rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
172 
173 	return 0;
174 error:
175 	pthread_mutex_unlock(&dev->mutex);
176 	rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
177 	/* TODO: free resource here or caller to check */
178 	return -1;
179 }
180 
181 int virtio_user_stop_device(struct virtio_user_dev *dev)
182 {
183 	struct vhost_vring_state state;
184 	uint32_t i;
185 	int error = 0;
186 
187 	pthread_mutex_lock(&dev->mutex);
188 	if (!dev->started)
189 		goto out;
190 
191 	for (i = 0; i < dev->max_queue_pairs; ++i)
192 		dev->ops->enable_qp(dev, i, 0);
193 
194 	/* Stop the backend. */
195 	for (i = 0; i < dev->max_queue_pairs * 2; ++i) {
196 		state.index = i;
197 		if (dev->ops->send_request(dev, VHOST_USER_GET_VRING_BASE,
198 					   &state) < 0) {
199 			PMD_DRV_LOG(ERR, "get_vring_base failed, index=%u\n",
200 				    i);
201 			error = -1;
202 			goto out;
203 		}
204 	}
205 
206 	dev->started = false;
207 out:
208 	pthread_mutex_unlock(&dev->mutex);
209 
210 	return error;
211 }
212 
213 static inline void
214 parse_mac(struct virtio_user_dev *dev, const char *mac)
215 {
216 	int i, r;
217 	uint32_t tmp[ETHER_ADDR_LEN];
218 
219 	if (!mac)
220 		return;
221 
222 	r = sscanf(mac, "%x:%x:%x:%x:%x:%x", &tmp[0],
223 			&tmp[1], &tmp[2], &tmp[3], &tmp[4], &tmp[5]);
224 	if (r == ETHER_ADDR_LEN) {
225 		for (i = 0; i < ETHER_ADDR_LEN; ++i)
226 			dev->mac_addr[i] = (uint8_t)tmp[i];
227 		dev->mac_specified = 1;
228 	} else {
229 		/* ignore the wrong mac, use random mac */
230 		PMD_DRV_LOG(ERR, "wrong format of mac: %s", mac);
231 	}
232 }
233 
234 static int
235 virtio_user_dev_init_notify(struct virtio_user_dev *dev)
236 {
237 	uint32_t i, j;
238 	int callfd;
239 	int kickfd;
240 
241 	for (i = 0; i < VIRTIO_MAX_VIRTQUEUES; ++i) {
242 		if (i >= dev->max_queue_pairs * 2) {
243 			dev->kickfds[i] = -1;
244 			dev->callfds[i] = -1;
245 			continue;
246 		}
247 
248 		/* May use invalid flag, but some backend uses kickfd and
249 		 * callfd as criteria to judge if dev is alive. so finally we
250 		 * use real event_fd.
251 		 */
252 		callfd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
253 		if (callfd < 0) {
254 			PMD_DRV_LOG(ERR, "callfd error, %s", strerror(errno));
255 			break;
256 		}
257 		kickfd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
258 		if (kickfd < 0) {
259 			PMD_DRV_LOG(ERR, "kickfd error, %s", strerror(errno));
260 			break;
261 		}
262 		dev->callfds[i] = callfd;
263 		dev->kickfds[i] = kickfd;
264 	}
265 
266 	if (i < VIRTIO_MAX_VIRTQUEUES) {
267 		for (j = 0; j <= i; ++j) {
268 			close(dev->callfds[j]);
269 			close(dev->kickfds[j]);
270 		}
271 
272 		return -1;
273 	}
274 
275 	return 0;
276 }
277 
278 static int
279 virtio_user_fill_intr_handle(struct virtio_user_dev *dev)
280 {
281 	uint32_t i;
282 	struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
283 
284 	if (!eth_dev->intr_handle) {
285 		eth_dev->intr_handle = malloc(sizeof(*eth_dev->intr_handle));
286 		if (!eth_dev->intr_handle) {
287 			PMD_DRV_LOG(ERR, "fail to allocate intr_handle");
288 			return -1;
289 		}
290 		memset(eth_dev->intr_handle, 0, sizeof(*eth_dev->intr_handle));
291 	}
292 
293 	for (i = 0; i < dev->max_queue_pairs; ++i)
294 		eth_dev->intr_handle->efds[i] = dev->callfds[i];
295 	eth_dev->intr_handle->nb_efd = dev->max_queue_pairs;
296 	eth_dev->intr_handle->max_intr = dev->max_queue_pairs + 1;
297 	eth_dev->intr_handle->type = RTE_INTR_HANDLE_VDEV;
298 	/* For virtio vdev, no need to read counter for clean */
299 	eth_dev->intr_handle->efd_counter_size = 0;
300 	eth_dev->intr_handle->fd = -1;
301 	if (dev->vhostfd >= 0)
302 		eth_dev->intr_handle->fd = dev->vhostfd;
303 	else if (dev->is_server)
304 		eth_dev->intr_handle->fd = dev->listenfd;
305 
306 	return 0;
307 }
308 
309 static void
310 virtio_user_mem_event_cb(enum rte_mem_event type __rte_unused,
311 						 const void *addr __rte_unused,
312 						 size_t len __rte_unused,
313 						 void *arg)
314 {
315 	struct virtio_user_dev *dev = arg;
316 	struct rte_memseg_list *msl;
317 	uint16_t i;
318 
319 	/* ignore externally allocated memory */
320 	msl = rte_mem_virt2memseg_list(addr);
321 	if (msl->external)
322 		return;
323 
324 	pthread_mutex_lock(&dev->mutex);
325 
326 	if (dev->started == false)
327 		goto exit;
328 
329 	/* Step 1: pause the active queues */
330 	for (i = 0; i < dev->queue_pairs; i++)
331 		dev->ops->enable_qp(dev, i, 0);
332 
333 	/* Step 2: update memory regions */
334 	dev->ops->send_request(dev, VHOST_USER_SET_MEM_TABLE, NULL);
335 
336 	/* Step 3: resume the active queues */
337 	for (i = 0; i < dev->queue_pairs; i++)
338 		dev->ops->enable_qp(dev, i, 1);
339 
340 exit:
341 	pthread_mutex_unlock(&dev->mutex);
342 }
343 
344 static int
345 virtio_user_dev_setup(struct virtio_user_dev *dev)
346 {
347 	uint32_t q;
348 
349 	dev->vhostfd = -1;
350 	dev->vhostfds = NULL;
351 	dev->tapfds = NULL;
352 
353 	if (dev->is_server) {
354 		if (access(dev->path, F_OK) == 0 &&
355 		    !is_vhost_user_by_type(dev->path)) {
356 			PMD_DRV_LOG(ERR, "Server mode doesn't support vhost-kernel!");
357 			return -1;
358 		}
359 		dev->ops = &virtio_ops_user;
360 	} else {
361 		if (is_vhost_user_by_type(dev->path)) {
362 			dev->ops = &virtio_ops_user;
363 		} else {
364 			dev->ops = &virtio_ops_kernel;
365 
366 			dev->vhostfds = malloc(dev->max_queue_pairs *
367 					       sizeof(int));
368 			dev->tapfds = malloc(dev->max_queue_pairs *
369 					     sizeof(int));
370 			if (!dev->vhostfds || !dev->tapfds) {
371 				PMD_INIT_LOG(ERR, "Failed to malloc");
372 				return -1;
373 			}
374 
375 			for (q = 0; q < dev->max_queue_pairs; ++q) {
376 				dev->vhostfds[q] = -1;
377 				dev->tapfds[q] = -1;
378 			}
379 		}
380 	}
381 
382 	if (dev->ops->setup(dev) < 0)
383 		return -1;
384 
385 	if (virtio_user_dev_init_notify(dev) < 0)
386 		return -1;
387 
388 	if (virtio_user_fill_intr_handle(dev) < 0)
389 		return -1;
390 
391 	return 0;
392 }
393 
394 /* Use below macro to filter features from vhost backend */
395 #define VIRTIO_USER_SUPPORTED_FEATURES			\
396 	(1ULL << VIRTIO_NET_F_MAC		|	\
397 	 1ULL << VIRTIO_NET_F_STATUS		|	\
398 	 1ULL << VIRTIO_NET_F_MQ		|	\
399 	 1ULL << VIRTIO_NET_F_CTRL_MAC_ADDR	|	\
400 	 1ULL << VIRTIO_NET_F_CTRL_VQ		|	\
401 	 1ULL << VIRTIO_NET_F_CTRL_RX		|	\
402 	 1ULL << VIRTIO_NET_F_CTRL_VLAN		|	\
403 	 1ULL << VIRTIO_NET_F_CSUM		|	\
404 	 1ULL << VIRTIO_NET_F_HOST_TSO4		|	\
405 	 1ULL << VIRTIO_NET_F_HOST_TSO6		|	\
406 	 1ULL << VIRTIO_NET_F_MRG_RXBUF		|	\
407 	 1ULL << VIRTIO_RING_F_INDIRECT_DESC	|	\
408 	 1ULL << VIRTIO_NET_F_GUEST_CSUM	|	\
409 	 1ULL << VIRTIO_NET_F_GUEST_TSO4	|	\
410 	 1ULL << VIRTIO_NET_F_GUEST_TSO6	|	\
411 	 1ULL << VIRTIO_F_IN_ORDER		|	\
412 	 1ULL << VIRTIO_F_VERSION_1		|	\
413 	 1ULL << VIRTIO_F_RING_PACKED)
414 
415 int
416 virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
417 		     int cq, int queue_size, const char *mac, char **ifname,
418 		     int mrg_rxbuf, int in_order, int packed_vq)
419 {
420 	pthread_mutex_init(&dev->mutex, NULL);
421 	snprintf(dev->path, PATH_MAX, "%s", path);
422 	dev->started = 0;
423 	dev->max_queue_pairs = queues;
424 	dev->queue_pairs = 1; /* mq disabled by default */
425 	dev->queue_size = queue_size;
426 	dev->mac_specified = 0;
427 	dev->frontend_features = 0;
428 	dev->unsupported_features = ~VIRTIO_USER_SUPPORTED_FEATURES;
429 	parse_mac(dev, mac);
430 
431 	if (*ifname) {
432 		dev->ifname = *ifname;
433 		*ifname = NULL;
434 	}
435 
436 	if (virtio_user_dev_setup(dev) < 0) {
437 		PMD_INIT_LOG(ERR, "backend set up fails");
438 		return -1;
439 	}
440 
441 	if (!dev->is_server) {
442 		if (dev->ops->send_request(dev, VHOST_USER_SET_OWNER,
443 					   NULL) < 0) {
444 			PMD_INIT_LOG(ERR, "set_owner fails: %s",
445 				     strerror(errno));
446 			return -1;
447 		}
448 
449 		if (dev->ops->send_request(dev, VHOST_USER_GET_FEATURES,
450 					   &dev->device_features) < 0) {
451 			PMD_INIT_LOG(ERR, "get_features failed: %s",
452 				     strerror(errno));
453 			return -1;
454 		}
455 	} else {
456 		/* We just pretend vhost-user can support all these features.
457 		 * Note that this could be problematic that if some feature is
458 		 * negotiated but not supported by the vhost-user which comes
459 		 * later.
460 		 */
461 		dev->device_features = VIRTIO_USER_SUPPORTED_FEATURES;
462 	}
463 
464 	if (!mrg_rxbuf)
465 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_MRG_RXBUF);
466 
467 	if (!in_order)
468 		dev->unsupported_features |= (1ull << VIRTIO_F_IN_ORDER);
469 
470 	if (packed_vq) {
471 		if (cq) {
472 			PMD_INIT_LOG(ERR, "control vq not supported yet with "
473 					  "packed virtqueues\n");
474 			return -1;
475 		}
476 	} else {
477 		dev->unsupported_features |= (1ull << VIRTIO_F_RING_PACKED);
478 	}
479 
480 	if (dev->mac_specified)
481 		dev->frontend_features |= (1ull << VIRTIO_NET_F_MAC);
482 	else
483 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_MAC);
484 
485 	if (cq) {
486 		/* device does not really need to know anything about CQ,
487 		 * so if necessary, we just claim to support CQ
488 		 */
489 		dev->frontend_features |= (1ull << VIRTIO_NET_F_CTRL_VQ);
490 	} else {
491 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_CTRL_VQ);
492 		/* Also disable features that depend on VIRTIO_NET_F_CTRL_VQ */
493 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_CTRL_RX);
494 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_CTRL_VLAN);
495 		dev->unsupported_features |=
496 			(1ull << VIRTIO_NET_F_GUEST_ANNOUNCE);
497 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
498 		dev->unsupported_features |=
499 			(1ull << VIRTIO_NET_F_CTRL_MAC_ADDR);
500 	}
501 
502 	/* The backend will not report this feature, we add it explicitly */
503 	if (is_vhost_user_by_type(dev->path))
504 		dev->frontend_features |= (1ull << VIRTIO_NET_F_STATUS);
505 
506 	/*
507 	 * Device features =
508 	 *     (frontend_features | backend_features) & ~unsupported_features;
509 	 */
510 	dev->device_features |= dev->frontend_features;
511 	dev->device_features &= ~dev->unsupported_features;
512 
513 	if (rte_mem_event_callback_register(VIRTIO_USER_MEM_EVENT_CLB_NAME,
514 				virtio_user_mem_event_cb, dev)) {
515 		if (rte_errno != ENOTSUP) {
516 			PMD_INIT_LOG(ERR, "Failed to register mem event"
517 					" callback\n");
518 			return -1;
519 		}
520 	}
521 
522 	return 0;
523 }
524 
525 void
526 virtio_user_dev_uninit(struct virtio_user_dev *dev)
527 {
528 	uint32_t i;
529 
530 	virtio_user_stop_device(dev);
531 
532 	rte_mem_event_callback_unregister(VIRTIO_USER_MEM_EVENT_CLB_NAME, dev);
533 
534 	for (i = 0; i < dev->max_queue_pairs * 2; ++i) {
535 		close(dev->callfds[i]);
536 		close(dev->kickfds[i]);
537 	}
538 
539 	close(dev->vhostfd);
540 
541 	if (dev->is_server && dev->listenfd >= 0) {
542 		close(dev->listenfd);
543 		dev->listenfd = -1;
544 	}
545 
546 	if (dev->vhostfds) {
547 		for (i = 0; i < dev->max_queue_pairs; ++i)
548 			close(dev->vhostfds[i]);
549 		free(dev->vhostfds);
550 		free(dev->tapfds);
551 	}
552 
553 	free(dev->ifname);
554 
555 	if (dev->is_server)
556 		unlink(dev->path);
557 }
558 
559 uint8_t
560 virtio_user_handle_mq(struct virtio_user_dev *dev, uint16_t q_pairs)
561 {
562 	uint16_t i;
563 	uint8_t ret = 0;
564 
565 	if (q_pairs > dev->max_queue_pairs) {
566 		PMD_INIT_LOG(ERR, "multi-q config %u, but only %u supported",
567 			     q_pairs, dev->max_queue_pairs);
568 		return -1;
569 	}
570 
571 	/* Server mode can't enable queue pairs if vhostfd is invalid,
572 	 * always return 0 in this case.
573 	 */
574 	if (!dev->is_server || dev->vhostfd >= 0) {
575 		for (i = 0; i < q_pairs; ++i)
576 			ret |= dev->ops->enable_qp(dev, i, 1);
577 		for (i = q_pairs; i < dev->max_queue_pairs; ++i)
578 			ret |= dev->ops->enable_qp(dev, i, 0);
579 	}
580 	dev->queue_pairs = q_pairs;
581 
582 	return ret;
583 }
584 
585 static uint32_t
586 virtio_user_handle_ctrl_msg(struct virtio_user_dev *dev, struct vring *vring,
587 			    uint16_t idx_hdr)
588 {
589 	struct virtio_net_ctrl_hdr *hdr;
590 	virtio_net_ctrl_ack status = ~0;
591 	uint16_t i, idx_data, idx_status;
592 	uint32_t n_descs = 0;
593 
594 	/* locate desc for header, data, and status */
595 	idx_data = vring->desc[idx_hdr].next;
596 	n_descs++;
597 
598 	i = idx_data;
599 	while (vring->desc[i].flags == VRING_DESC_F_NEXT) {
600 		i = vring->desc[i].next;
601 		n_descs++;
602 	}
603 
604 	/* locate desc for status */
605 	idx_status = i;
606 	n_descs++;
607 
608 	hdr = (void *)(uintptr_t)vring->desc[idx_hdr].addr;
609 	if (hdr->class == VIRTIO_NET_CTRL_MQ &&
610 	    hdr->cmd == VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET) {
611 		uint16_t queues;
612 
613 		queues = *(uint16_t *)(uintptr_t)vring->desc[idx_data].addr;
614 		status = virtio_user_handle_mq(dev, queues);
615 	}
616 
617 	/* Update status */
618 	*(virtio_net_ctrl_ack *)(uintptr_t)vring->desc[idx_status].addr = status;
619 
620 	return n_descs;
621 }
622 
623 void
624 virtio_user_handle_cq(struct virtio_user_dev *dev, uint16_t queue_idx)
625 {
626 	uint16_t avail_idx, desc_idx;
627 	struct vring_used_elem *uep;
628 	uint32_t n_descs;
629 	struct vring *vring = &dev->vrings[queue_idx];
630 
631 	/* Consume avail ring, using used ring idx as first one */
632 	while (vring->used->idx != vring->avail->idx) {
633 		avail_idx = (vring->used->idx) & (vring->num - 1);
634 		desc_idx = vring->avail->ring[avail_idx];
635 
636 		n_descs = virtio_user_handle_ctrl_msg(dev, vring, desc_idx);
637 
638 		/* Update used ring */
639 		uep = &vring->used->ring[avail_idx];
640 		uep->id = avail_idx;
641 		uep->len = n_descs;
642 
643 		vring->used->idx++;
644 	}
645 }
646