xref: /openbmc/linux/drivers/net/xen-netback/xenbus.c (revision 2a81ada3)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Xenbus code for netif backend
4  *
5  * Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
6  * Copyright (C) 2005 XenSource Ltd
7 */
8 
9 #include "common.h"
10 #include <linux/vmalloc.h>
11 #include <linux/rtnetlink.h>
12 
13 static int connect_data_rings(struct backend_info *be,
14 			      struct xenvif_queue *queue);
15 static void connect(struct backend_info *be);
16 static int read_xenbus_vif_flags(struct backend_info *be);
17 static int backend_create_xenvif(struct backend_info *be);
18 static void unregister_hotplug_status_watch(struct backend_info *be);
19 static void xen_unregister_watchers(struct xenvif *vif);
20 static void set_backend_state(struct backend_info *be,
21 			      enum xenbus_state state);
22 
23 #ifdef CONFIG_DEBUG_FS
24 struct dentry *xen_netback_dbg_root = NULL;
25 
xenvif_read_io_ring(struct seq_file * m,void * v)26 static int xenvif_read_io_ring(struct seq_file *m, void *v)
27 {
28 	struct xenvif_queue *queue = m->private;
29 	struct xen_netif_tx_back_ring *tx_ring = &queue->tx;
30 	struct xen_netif_rx_back_ring *rx_ring = &queue->rx;
31 	struct netdev_queue *dev_queue;
32 
33 	if (tx_ring->sring) {
34 		struct xen_netif_tx_sring *sring = tx_ring->sring;
35 
36 		seq_printf(m, "Queue %d\nTX: nr_ents %u\n", queue->id,
37 			   tx_ring->nr_ents);
38 		seq_printf(m, "req prod %u (%d) cons %u (%d) event %u (%d)\n",
39 			   sring->req_prod,
40 			   sring->req_prod - sring->rsp_prod,
41 			   tx_ring->req_cons,
42 			   tx_ring->req_cons - sring->rsp_prod,
43 			   sring->req_event,
44 			   sring->req_event - sring->rsp_prod);
45 		seq_printf(m, "rsp prod %u (base) pvt %u (%d) event %u (%d)\n",
46 			   sring->rsp_prod,
47 			   tx_ring->rsp_prod_pvt,
48 			   tx_ring->rsp_prod_pvt - sring->rsp_prod,
49 			   sring->rsp_event,
50 			   sring->rsp_event - sring->rsp_prod);
51 		seq_printf(m, "pending prod %u pending cons %u nr_pending_reqs %u\n",
52 			   queue->pending_prod,
53 			   queue->pending_cons,
54 			   nr_pending_reqs(queue));
55 		seq_printf(m, "dealloc prod %u dealloc cons %u dealloc_queue %u\n\n",
56 			   queue->dealloc_prod,
57 			   queue->dealloc_cons,
58 			   queue->dealloc_prod - queue->dealloc_cons);
59 	}
60 
61 	if (rx_ring->sring) {
62 		struct xen_netif_rx_sring *sring = rx_ring->sring;
63 
64 		seq_printf(m, "RX: nr_ents %u\n", rx_ring->nr_ents);
65 		seq_printf(m, "req prod %u (%d) cons %u (%d) event %u (%d)\n",
66 			   sring->req_prod,
67 			   sring->req_prod - sring->rsp_prod,
68 			   rx_ring->req_cons,
69 			   rx_ring->req_cons - sring->rsp_prod,
70 			   sring->req_event,
71 			   sring->req_event - sring->rsp_prod);
72 		seq_printf(m, "rsp prod %u (base) pvt %u (%d) event %u (%d)\n\n",
73 			   sring->rsp_prod,
74 			   rx_ring->rsp_prod_pvt,
75 			   rx_ring->rsp_prod_pvt - sring->rsp_prod,
76 			   sring->rsp_event,
77 			   sring->rsp_event - sring->rsp_prod);
78 	}
79 
80 	seq_printf(m, "NAPI state: %lx NAPI weight: %d TX queue len %u\n"
81 		   "Credit timer_pending: %d, credit: %lu, usec: %lu\n"
82 		   "remaining: %lu, expires: %lu, now: %lu\n",
83 		   queue->napi.state, queue->napi.weight,
84 		   skb_queue_len(&queue->tx_queue),
85 		   timer_pending(&queue->credit_timeout),
86 		   queue->credit_bytes,
87 		   queue->credit_usec,
88 		   queue->remaining_credit,
89 		   queue->credit_timeout.expires,
90 		   jiffies);
91 
92 	dev_queue = netdev_get_tx_queue(queue->vif->dev, queue->id);
93 
94 	seq_printf(m, "\nRx internal queue: len %u max %u pkts %u %s\n",
95 		   queue->rx_queue_len, queue->rx_queue_max,
96 		   skb_queue_len(&queue->rx_queue),
97 		   netif_tx_queue_stopped(dev_queue) ? "stopped" : "running");
98 
99 	return 0;
100 }
101 
102 #define XENVIF_KICK_STR "kick"
103 #define BUFFER_SIZE     32
104 
105 static ssize_t
xenvif_write_io_ring(struct file * filp,const char __user * buf,size_t count,loff_t * ppos)106 xenvif_write_io_ring(struct file *filp, const char __user *buf, size_t count,
107 		     loff_t *ppos)
108 {
109 	struct xenvif_queue *queue =
110 		((struct seq_file *)filp->private_data)->private;
111 	int len;
112 	char write[BUFFER_SIZE];
113 
114 	/* don't allow partial writes and check the length */
115 	if (*ppos != 0)
116 		return 0;
117 	if (count >= sizeof(write))
118 		return -ENOSPC;
119 
120 	len = simple_write_to_buffer(write,
121 				     sizeof(write) - 1,
122 				     ppos,
123 				     buf,
124 				     count);
125 	if (len < 0)
126 		return len;
127 
128 	write[len] = '\0';
129 
130 	if (!strncmp(write, XENVIF_KICK_STR, sizeof(XENVIF_KICK_STR) - 1))
131 		xenvif_interrupt(0, (void *)queue);
132 	else {
133 		pr_warn("Unknown command to io_ring_q%d. Available: kick\n",
134 			queue->id);
135 		count = -EINVAL;
136 	}
137 	return count;
138 }
139 
xenvif_io_ring_open(struct inode * inode,struct file * filp)140 static int xenvif_io_ring_open(struct inode *inode, struct file *filp)
141 {
142 	int ret;
143 	void *queue = NULL;
144 
145 	if (inode->i_private)
146 		queue = inode->i_private;
147 	ret = single_open(filp, xenvif_read_io_ring, queue);
148 	filp->f_mode |= FMODE_PWRITE;
149 	return ret;
150 }
151 
152 static const struct file_operations xenvif_dbg_io_ring_ops_fops = {
153 	.owner = THIS_MODULE,
154 	.open = xenvif_io_ring_open,
155 	.read = seq_read,
156 	.llseek = seq_lseek,
157 	.release = single_release,
158 	.write = xenvif_write_io_ring,
159 };
160 
xenvif_ctrl_show(struct seq_file * m,void * v)161 static int xenvif_ctrl_show(struct seq_file *m, void *v)
162 {
163 	struct xenvif *vif = m->private;
164 
165 	xenvif_dump_hash_info(vif, m);
166 
167 	return 0;
168 }
169 DEFINE_SHOW_ATTRIBUTE(xenvif_ctrl);
170 
xenvif_debugfs_addif(struct xenvif * vif)171 static void xenvif_debugfs_addif(struct xenvif *vif)
172 {
173 	int i;
174 
175 	vif->xenvif_dbg_root = debugfs_create_dir(vif->dev->name,
176 						  xen_netback_dbg_root);
177 	for (i = 0; i < vif->num_queues; ++i) {
178 		char filename[sizeof("io_ring_q") + 4];
179 
180 		snprintf(filename, sizeof(filename), "io_ring_q%d", i);
181 		debugfs_create_file(filename, 0600, vif->xenvif_dbg_root,
182 				    &vif->queues[i],
183 				    &xenvif_dbg_io_ring_ops_fops);
184 	}
185 
186 	if (vif->ctrl_irq)
187 		debugfs_create_file("ctrl", 0400, vif->xenvif_dbg_root, vif,
188 				    &xenvif_ctrl_fops);
189 }
190 
xenvif_debugfs_delif(struct xenvif * vif)191 static void xenvif_debugfs_delif(struct xenvif *vif)
192 {
193 	debugfs_remove_recursive(vif->xenvif_dbg_root);
194 	vif->xenvif_dbg_root = NULL;
195 }
196 #endif /* CONFIG_DEBUG_FS */
197 
198 /*
199  * Handle the creation of the hotplug script environment.  We add the script
200  * and vif variables to the environment, for the benefit of the vif-* hotplug
201  * scripts.
202  */
netback_uevent(const struct xenbus_device * xdev,struct kobj_uevent_env * env)203 static int netback_uevent(const struct xenbus_device *xdev,
204 			  struct kobj_uevent_env *env)
205 {
206 	struct backend_info *be = dev_get_drvdata(&xdev->dev);
207 
208 	if (!be)
209 		return 0;
210 
211 	if (add_uevent_var(env, "script=%s", be->hotplug_script))
212 		return -ENOMEM;
213 
214 	if (!be->vif)
215 		return 0;
216 
217 	return add_uevent_var(env, "vif=%s", be->vif->dev->name);
218 }
219 
220 
backend_create_xenvif(struct backend_info * be)221 static int backend_create_xenvif(struct backend_info *be)
222 {
223 	int err;
224 	long handle;
225 	struct xenbus_device *dev = be->dev;
226 	struct xenvif *vif;
227 
228 	if (be->vif != NULL)
229 		return 0;
230 
231 	err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
232 	if (err != 1) {
233 		xenbus_dev_fatal(dev, err, "reading handle");
234 		return (err < 0) ? err : -EINVAL;
235 	}
236 
237 	vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
238 	if (IS_ERR(vif)) {
239 		err = PTR_ERR(vif);
240 		xenbus_dev_fatal(dev, err, "creating interface");
241 		return err;
242 	}
243 	be->vif = vif;
244 	vif->be = be;
245 
246 	kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
247 	return 0;
248 }
249 
backend_disconnect(struct backend_info * be)250 static void backend_disconnect(struct backend_info *be)
251 {
252 	struct xenvif *vif = be->vif;
253 
254 	if (vif) {
255 		unsigned int num_queues = vif->num_queues;
256 		unsigned int queue_index;
257 
258 		xen_unregister_watchers(vif);
259 #ifdef CONFIG_DEBUG_FS
260 		xenvif_debugfs_delif(vif);
261 #endif /* CONFIG_DEBUG_FS */
262 		xenvif_disconnect_data(vif);
263 
264 		/* At this point some of the handlers may still be active
265 		 * so we need to have additional synchronization here.
266 		 */
267 		vif->num_queues = 0;
268 		synchronize_net();
269 
270 		for (queue_index = 0; queue_index < num_queues; ++queue_index)
271 			xenvif_deinit_queue(&vif->queues[queue_index]);
272 
273 		vfree(vif->queues);
274 		vif->queues = NULL;
275 
276 		xenvif_disconnect_ctrl(vif);
277 	}
278 }
279 
backend_connect(struct backend_info * be)280 static void backend_connect(struct backend_info *be)
281 {
282 	if (be->vif)
283 		connect(be);
284 }
285 
backend_switch_state(struct backend_info * be,enum xenbus_state state)286 static inline void backend_switch_state(struct backend_info *be,
287 					enum xenbus_state state)
288 {
289 	struct xenbus_device *dev = be->dev;
290 
291 	pr_debug("%s -> %s\n", dev->nodename, xenbus_strstate(state));
292 	be->state = state;
293 
294 	/* If we are waiting for a hotplug script then defer the
295 	 * actual xenbus state change.
296 	 */
297 	if (!be->have_hotplug_status_watch)
298 		xenbus_switch_state(dev, state);
299 }
300 
301 /* Handle backend state transitions:
302  *
303  * The backend state starts in Initialising and the following transitions are
304  * allowed.
305  *
306  * Initialising -> InitWait -> Connected
307  *          \
308  *           \        ^    \         |
309  *            \       |     \        |
310  *             \      |      \       |
311  *              \     |       \      |
312  *               \    |        \     |
313  *                \   |         \    |
314  *                 V  |          V   V
315  *
316  *                  Closed  <-> Closing
317  *
318  * The state argument specifies the eventual state of the backend and the
319  * function transitions to that state via the shortest path.
320  */
set_backend_state(struct backend_info * be,enum xenbus_state state)321 static void set_backend_state(struct backend_info *be,
322 			      enum xenbus_state state)
323 {
324 	while (be->state != state) {
325 		switch (be->state) {
326 		case XenbusStateInitialising:
327 			switch (state) {
328 			case XenbusStateInitWait:
329 			case XenbusStateConnected:
330 			case XenbusStateClosing:
331 				backend_switch_state(be, XenbusStateInitWait);
332 				break;
333 			case XenbusStateClosed:
334 				backend_switch_state(be, XenbusStateClosed);
335 				break;
336 			default:
337 				BUG();
338 			}
339 			break;
340 		case XenbusStateClosed:
341 			switch (state) {
342 			case XenbusStateInitWait:
343 			case XenbusStateConnected:
344 				backend_switch_state(be, XenbusStateInitWait);
345 				break;
346 			case XenbusStateClosing:
347 				backend_switch_state(be, XenbusStateClosing);
348 				break;
349 			default:
350 				BUG();
351 			}
352 			break;
353 		case XenbusStateInitWait:
354 			switch (state) {
355 			case XenbusStateConnected:
356 				backend_connect(be);
357 				backend_switch_state(be, XenbusStateConnected);
358 				break;
359 			case XenbusStateClosing:
360 			case XenbusStateClosed:
361 				backend_switch_state(be, XenbusStateClosing);
362 				break;
363 			default:
364 				BUG();
365 			}
366 			break;
367 		case XenbusStateConnected:
368 			switch (state) {
369 			case XenbusStateInitWait:
370 			case XenbusStateClosing:
371 			case XenbusStateClosed:
372 				backend_disconnect(be);
373 				backend_switch_state(be, XenbusStateClosing);
374 				break;
375 			default:
376 				BUG();
377 			}
378 			break;
379 		case XenbusStateClosing:
380 			switch (state) {
381 			case XenbusStateInitWait:
382 			case XenbusStateConnected:
383 			case XenbusStateClosed:
384 				backend_switch_state(be, XenbusStateClosed);
385 				break;
386 			default:
387 				BUG();
388 			}
389 			break;
390 		default:
391 			BUG();
392 		}
393 	}
394 }
395 
read_xenbus_frontend_xdp(struct backend_info * be,struct xenbus_device * dev)396 static void read_xenbus_frontend_xdp(struct backend_info *be,
397 				      struct xenbus_device *dev)
398 {
399 	struct xenvif *vif = be->vif;
400 	u16 headroom;
401 	int err;
402 
403 	err = xenbus_scanf(XBT_NIL, dev->otherend,
404 			   "xdp-headroom", "%hu", &headroom);
405 	if (err != 1) {
406 		vif->xdp_headroom = 0;
407 		return;
408 	}
409 	if (headroom > XEN_NETIF_MAX_XDP_HEADROOM)
410 		headroom = XEN_NETIF_MAX_XDP_HEADROOM;
411 	vif->xdp_headroom = headroom;
412 }
413 
414 /*
415  * Callback received when the frontend's state changes.
416  */
frontend_changed(struct xenbus_device * dev,enum xenbus_state frontend_state)417 static void frontend_changed(struct xenbus_device *dev,
418 			     enum xenbus_state frontend_state)
419 {
420 	struct backend_info *be = dev_get_drvdata(&dev->dev);
421 
422 	pr_debug("%s -> %s\n", dev->otherend, xenbus_strstate(frontend_state));
423 
424 	be->frontend_state = frontend_state;
425 
426 	switch (frontend_state) {
427 	case XenbusStateInitialising:
428 		set_backend_state(be, XenbusStateInitWait);
429 		break;
430 
431 	case XenbusStateInitialised:
432 		break;
433 
434 	case XenbusStateConnected:
435 		set_backend_state(be, XenbusStateConnected);
436 		break;
437 
438 	case XenbusStateReconfiguring:
439 		read_xenbus_frontend_xdp(be, dev);
440 		xenbus_switch_state(dev, XenbusStateReconfigured);
441 		break;
442 
443 	case XenbusStateClosing:
444 		set_backend_state(be, XenbusStateClosing);
445 		break;
446 
447 	case XenbusStateClosed:
448 		set_backend_state(be, XenbusStateClosed);
449 		if (xenbus_dev_is_online(dev))
450 			break;
451 		fallthrough;	/* if not online */
452 	case XenbusStateUnknown:
453 		set_backend_state(be, XenbusStateClosed);
454 		device_unregister(&dev->dev);
455 		break;
456 
457 	default:
458 		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
459 				 frontend_state);
460 		break;
461 	}
462 }
463 
464 
xen_net_read_rate(struct xenbus_device * dev,unsigned long * bytes,unsigned long * usec)465 static void xen_net_read_rate(struct xenbus_device *dev,
466 			      unsigned long *bytes, unsigned long *usec)
467 {
468 	char *s, *e;
469 	unsigned long b, u;
470 	char *ratestr;
471 
472 	/* Default to unlimited bandwidth. */
473 	*bytes = ~0UL;
474 	*usec = 0;
475 
476 	ratestr = xenbus_read(XBT_NIL, dev->nodename, "rate", NULL);
477 	if (IS_ERR(ratestr))
478 		return;
479 
480 	s = ratestr;
481 	b = simple_strtoul(s, &e, 10);
482 	if ((s == e) || (*e != ','))
483 		goto fail;
484 
485 	s = e + 1;
486 	u = simple_strtoul(s, &e, 10);
487 	if ((s == e) || (*e != '\0'))
488 		goto fail;
489 
490 	*bytes = b;
491 	*usec = u;
492 
493 	kfree(ratestr);
494 	return;
495 
496  fail:
497 	pr_warn("Failed to parse network rate limit. Traffic unlimited.\n");
498 	kfree(ratestr);
499 }
500 
xen_net_read_mac(struct xenbus_device * dev,u8 mac[])501 static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
502 {
503 	char *s, *e, *macstr;
504 	int i;
505 
506 	macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
507 	if (IS_ERR(macstr))
508 		return PTR_ERR(macstr);
509 
510 	for (i = 0; i < ETH_ALEN; i++) {
511 		mac[i] = simple_strtoul(s, &e, 16);
512 		if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
513 			kfree(macstr);
514 			return -ENOENT;
515 		}
516 		s = e+1;
517 	}
518 
519 	kfree(macstr);
520 	return 0;
521 }
522 
xen_net_rate_changed(struct xenbus_watch * watch,const char * path,const char * token)523 static void xen_net_rate_changed(struct xenbus_watch *watch,
524 				 const char *path, const char *token)
525 {
526 	struct xenvif *vif = container_of(watch, struct xenvif, credit_watch);
527 	struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
528 	unsigned long   credit_bytes;
529 	unsigned long   credit_usec;
530 	unsigned int queue_index;
531 
532 	xen_net_read_rate(dev, &credit_bytes, &credit_usec);
533 	for (queue_index = 0; queue_index < vif->num_queues; queue_index++) {
534 		struct xenvif_queue *queue = &vif->queues[queue_index];
535 
536 		queue->credit_bytes = credit_bytes;
537 		queue->credit_usec = credit_usec;
538 		if (!mod_timer_pending(&queue->credit_timeout, jiffies) &&
539 			queue->remaining_credit > queue->credit_bytes) {
540 			queue->remaining_credit = queue->credit_bytes;
541 		}
542 	}
543 }
544 
xen_register_credit_watch(struct xenbus_device * dev,struct xenvif * vif)545 static int xen_register_credit_watch(struct xenbus_device *dev,
546 				     struct xenvif *vif)
547 {
548 	int err = 0;
549 	char *node;
550 	unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
551 
552 	if (vif->credit_watch.node)
553 		return -EADDRINUSE;
554 
555 	node = kmalloc(maxlen, GFP_KERNEL);
556 	if (!node)
557 		return -ENOMEM;
558 	snprintf(node, maxlen, "%s/rate", dev->nodename);
559 	vif->credit_watch.node = node;
560 	vif->credit_watch.will_handle = NULL;
561 	vif->credit_watch.callback = xen_net_rate_changed;
562 	err = register_xenbus_watch(&vif->credit_watch);
563 	if (err) {
564 		pr_err("Failed to set watcher %s\n", vif->credit_watch.node);
565 		kfree(node);
566 		vif->credit_watch.node = NULL;
567 		vif->credit_watch.will_handle = NULL;
568 		vif->credit_watch.callback = NULL;
569 	}
570 	return err;
571 }
572 
xen_unregister_credit_watch(struct xenvif * vif)573 static void xen_unregister_credit_watch(struct xenvif *vif)
574 {
575 	if (vif->credit_watch.node) {
576 		unregister_xenbus_watch(&vif->credit_watch);
577 		kfree(vif->credit_watch.node);
578 		vif->credit_watch.node = NULL;
579 	}
580 }
581 
xen_mcast_ctrl_changed(struct xenbus_watch * watch,const char * path,const char * token)582 static void xen_mcast_ctrl_changed(struct xenbus_watch *watch,
583 				   const char *path, const char *token)
584 {
585 	struct xenvif *vif = container_of(watch, struct xenvif,
586 					  mcast_ctrl_watch);
587 	struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
588 
589 	vif->multicast_control = !!xenbus_read_unsigned(dev->otherend,
590 					"request-multicast-control", 0);
591 }
592 
xen_register_mcast_ctrl_watch(struct xenbus_device * dev,struct xenvif * vif)593 static int xen_register_mcast_ctrl_watch(struct xenbus_device *dev,
594 					 struct xenvif *vif)
595 {
596 	int err = 0;
597 	char *node;
598 	unsigned maxlen = strlen(dev->otherend) +
599 		sizeof("/request-multicast-control");
600 
601 	if (vif->mcast_ctrl_watch.node) {
602 		pr_err_ratelimited("Watch is already registered\n");
603 		return -EADDRINUSE;
604 	}
605 
606 	node = kmalloc(maxlen, GFP_KERNEL);
607 	if (!node) {
608 		pr_err("Failed to allocate memory for watch\n");
609 		return -ENOMEM;
610 	}
611 	snprintf(node, maxlen, "%s/request-multicast-control",
612 		 dev->otherend);
613 	vif->mcast_ctrl_watch.node = node;
614 	vif->mcast_ctrl_watch.will_handle = NULL;
615 	vif->mcast_ctrl_watch.callback = xen_mcast_ctrl_changed;
616 	err = register_xenbus_watch(&vif->mcast_ctrl_watch);
617 	if (err) {
618 		pr_err("Failed to set watcher %s\n",
619 		       vif->mcast_ctrl_watch.node);
620 		kfree(node);
621 		vif->mcast_ctrl_watch.node = NULL;
622 		vif->mcast_ctrl_watch.will_handle = NULL;
623 		vif->mcast_ctrl_watch.callback = NULL;
624 	}
625 	return err;
626 }
627 
xen_unregister_mcast_ctrl_watch(struct xenvif * vif)628 static void xen_unregister_mcast_ctrl_watch(struct xenvif *vif)
629 {
630 	if (vif->mcast_ctrl_watch.node) {
631 		unregister_xenbus_watch(&vif->mcast_ctrl_watch);
632 		kfree(vif->mcast_ctrl_watch.node);
633 		vif->mcast_ctrl_watch.node = NULL;
634 	}
635 }
636 
xen_register_watchers(struct xenbus_device * dev,struct xenvif * vif)637 static void xen_register_watchers(struct xenbus_device *dev,
638 				  struct xenvif *vif)
639 {
640 	xen_register_credit_watch(dev, vif);
641 	xen_register_mcast_ctrl_watch(dev, vif);
642 }
643 
xen_unregister_watchers(struct xenvif * vif)644 static void xen_unregister_watchers(struct xenvif *vif)
645 {
646 	xen_unregister_mcast_ctrl_watch(vif);
647 	xen_unregister_credit_watch(vif);
648 }
649 
unregister_hotplug_status_watch(struct backend_info * be)650 static void unregister_hotplug_status_watch(struct backend_info *be)
651 {
652 	if (be->have_hotplug_status_watch) {
653 		unregister_xenbus_watch(&be->hotplug_status_watch);
654 		kfree(be->hotplug_status_watch.node);
655 	}
656 	be->have_hotplug_status_watch = 0;
657 }
658 
hotplug_status_changed(struct xenbus_watch * watch,const char * path,const char * token)659 static void hotplug_status_changed(struct xenbus_watch *watch,
660 				   const char *path,
661 				   const char *token)
662 {
663 	struct backend_info *be = container_of(watch,
664 					       struct backend_info,
665 					       hotplug_status_watch);
666 	char *str;
667 	unsigned int len;
668 
669 	str = xenbus_read(XBT_NIL, be->dev->nodename, "hotplug-status", &len);
670 	if (IS_ERR(str))
671 		return;
672 	if (len == sizeof("connected")-1 && !memcmp(str, "connected", len)) {
673 		/* Complete any pending state change */
674 		xenbus_switch_state(be->dev, be->state);
675 
676 		/* Not interested in this watch anymore. */
677 		unregister_hotplug_status_watch(be);
678 	}
679 	kfree(str);
680 }
681 
connect_ctrl_ring(struct backend_info * be)682 static int connect_ctrl_ring(struct backend_info *be)
683 {
684 	struct xenbus_device *dev = be->dev;
685 	struct xenvif *vif = be->vif;
686 	unsigned int val;
687 	grant_ref_t ring_ref;
688 	unsigned int evtchn;
689 	int err;
690 
691 	err = xenbus_scanf(XBT_NIL, dev->otherend,
692 			   "ctrl-ring-ref", "%u", &val);
693 	if (err < 0)
694 		goto done; /* The frontend does not have a control ring */
695 
696 	ring_ref = val;
697 
698 	err = xenbus_scanf(XBT_NIL, dev->otherend,
699 			   "event-channel-ctrl", "%u", &val);
700 	if (err < 0) {
701 		xenbus_dev_fatal(dev, err,
702 				 "reading %s/event-channel-ctrl",
703 				 dev->otherend);
704 		goto fail;
705 	}
706 
707 	evtchn = val;
708 
709 	err = xenvif_connect_ctrl(vif, ring_ref, evtchn);
710 	if (err) {
711 		xenbus_dev_fatal(dev, err,
712 				 "mapping shared-frame %u port %u",
713 				 ring_ref, evtchn);
714 		goto fail;
715 	}
716 
717 done:
718 	return 0;
719 
720 fail:
721 	return err;
722 }
723 
connect(struct backend_info * be)724 static void connect(struct backend_info *be)
725 {
726 	int err;
727 	struct xenbus_device *dev = be->dev;
728 	unsigned long credit_bytes, credit_usec;
729 	unsigned int queue_index;
730 	unsigned int requested_num_queues;
731 	struct xenvif_queue *queue;
732 
733 	/* Check whether the frontend requested multiple queues
734 	 * and read the number requested.
735 	 */
736 	requested_num_queues = xenbus_read_unsigned(dev->otherend,
737 					"multi-queue-num-queues", 1);
738 	if (requested_num_queues > xenvif_max_queues) {
739 		/* buggy or malicious guest */
740 		xenbus_dev_fatal(dev, -EINVAL,
741 				 "guest requested %u queues, exceeding the maximum of %u.",
742 				 requested_num_queues, xenvif_max_queues);
743 		return;
744 	}
745 
746 	err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
747 	if (err) {
748 		xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
749 		return;
750 	}
751 
752 	xen_net_read_rate(dev, &credit_bytes, &credit_usec);
753 	xen_unregister_watchers(be->vif);
754 	xen_register_watchers(dev, be->vif);
755 	read_xenbus_vif_flags(be);
756 
757 	err = connect_ctrl_ring(be);
758 	if (err) {
759 		xenbus_dev_fatal(dev, err, "connecting control ring");
760 		return;
761 	}
762 
763 	/* Use the number of queues requested by the frontend */
764 	be->vif->queues = vzalloc(array_size(requested_num_queues,
765 					     sizeof(struct xenvif_queue)));
766 	if (!be->vif->queues) {
767 		xenbus_dev_fatal(dev, -ENOMEM,
768 				 "allocating queues");
769 		return;
770 	}
771 
772 	be->vif->num_queues = requested_num_queues;
773 	be->vif->stalled_queues = requested_num_queues;
774 
775 	for (queue_index = 0; queue_index < requested_num_queues; ++queue_index) {
776 		queue = &be->vif->queues[queue_index];
777 		queue->vif = be->vif;
778 		queue->id = queue_index;
779 		snprintf(queue->name, sizeof(queue->name), "%s-q%u",
780 				be->vif->dev->name, queue->id);
781 
782 		err = xenvif_init_queue(queue);
783 		if (err) {
784 			/* xenvif_init_queue() cleans up after itself on
785 			 * failure, but we need to clean up any previously
786 			 * initialised queues. Set num_queues to i so that
787 			 * earlier queues can be destroyed using the regular
788 			 * disconnect logic.
789 			 */
790 			be->vif->num_queues = queue_index;
791 			goto err;
792 		}
793 
794 		queue->credit_bytes = credit_bytes;
795 		queue->remaining_credit = credit_bytes;
796 		queue->credit_usec = credit_usec;
797 
798 		err = connect_data_rings(be, queue);
799 		if (err) {
800 			/* connect_data_rings() cleans up after itself on
801 			 * failure, but we need to clean up after
802 			 * xenvif_init_queue() here, and also clean up any
803 			 * previously initialised queues.
804 			 */
805 			xenvif_deinit_queue(queue);
806 			be->vif->num_queues = queue_index;
807 			goto err;
808 		}
809 	}
810 
811 #ifdef CONFIG_DEBUG_FS
812 	xenvif_debugfs_addif(be->vif);
813 #endif /* CONFIG_DEBUG_FS */
814 
815 	/* Initialisation completed, tell core driver the number of
816 	 * active queues.
817 	 */
818 	rtnl_lock();
819 	netif_set_real_num_tx_queues(be->vif->dev, requested_num_queues);
820 	netif_set_real_num_rx_queues(be->vif->dev, requested_num_queues);
821 	rtnl_unlock();
822 
823 	xenvif_carrier_on(be->vif);
824 
825 	unregister_hotplug_status_watch(be);
826 	err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch, NULL,
827 				   hotplug_status_changed,
828 				   "%s/%s", dev->nodename, "hotplug-status");
829 	if (!err)
830 		be->have_hotplug_status_watch = 1;
831 
832 	netif_tx_wake_all_queues(be->vif->dev);
833 
834 	return;
835 
836 err:
837 	if (be->vif->num_queues > 0)
838 		xenvif_disconnect_data(be->vif); /* Clean up existing queues */
839 	for (queue_index = 0; queue_index < be->vif->num_queues; ++queue_index)
840 		xenvif_deinit_queue(&be->vif->queues[queue_index]);
841 	vfree(be->vif->queues);
842 	be->vif->queues = NULL;
843 	be->vif->num_queues = 0;
844 	xenvif_disconnect_ctrl(be->vif);
845 	return;
846 }
847 
848 
connect_data_rings(struct backend_info * be,struct xenvif_queue * queue)849 static int connect_data_rings(struct backend_info *be,
850 			      struct xenvif_queue *queue)
851 {
852 	struct xenbus_device *dev = be->dev;
853 	unsigned int num_queues = queue->vif->num_queues;
854 	unsigned long tx_ring_ref, rx_ring_ref;
855 	unsigned int tx_evtchn, rx_evtchn;
856 	int err;
857 	char *xspath;
858 	size_t xspathsize;
859 	const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
860 
861 	/* If the frontend requested 1 queue, or we have fallen back
862 	 * to single queue due to lack of frontend support for multi-
863 	 * queue, expect the remaining XenStore keys in the toplevel
864 	 * directory. Otherwise, expect them in a subdirectory called
865 	 * queue-N.
866 	 */
867 	if (num_queues == 1) {
868 		xspath = kstrdup(dev->otherend, GFP_KERNEL);
869 		if (!xspath) {
870 			xenbus_dev_fatal(dev, -ENOMEM,
871 					 "reading ring references");
872 			return -ENOMEM;
873 		}
874 	} else {
875 		xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
876 		xspath = kzalloc(xspathsize, GFP_KERNEL);
877 		if (!xspath) {
878 			xenbus_dev_fatal(dev, -ENOMEM,
879 					 "reading ring references");
880 			return -ENOMEM;
881 		}
882 		snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend,
883 			 queue->id);
884 	}
885 
886 	err = xenbus_gather(XBT_NIL, xspath,
887 			    "tx-ring-ref", "%lu", &tx_ring_ref,
888 			    "rx-ring-ref", "%lu", &rx_ring_ref, NULL);
889 	if (err) {
890 		xenbus_dev_fatal(dev, err,
891 				 "reading %s/ring-ref",
892 				 xspath);
893 		goto err;
894 	}
895 
896 	/* Try split event channels first, then single event channel. */
897 	err = xenbus_gather(XBT_NIL, xspath,
898 			    "event-channel-tx", "%u", &tx_evtchn,
899 			    "event-channel-rx", "%u", &rx_evtchn, NULL);
900 	if (err < 0) {
901 		err = xenbus_scanf(XBT_NIL, xspath,
902 				   "event-channel", "%u", &tx_evtchn);
903 		if (err < 0) {
904 			xenbus_dev_fatal(dev, err,
905 					 "reading %s/event-channel(-tx/rx)",
906 					 xspath);
907 			goto err;
908 		}
909 		rx_evtchn = tx_evtchn;
910 	}
911 
912 	/* Map the shared frame, irq etc. */
913 	err = xenvif_connect_data(queue, tx_ring_ref, rx_ring_ref,
914 				  tx_evtchn, rx_evtchn);
915 	if (err) {
916 		xenbus_dev_fatal(dev, err,
917 				 "mapping shared-frames %lu/%lu port tx %u rx %u",
918 				 tx_ring_ref, rx_ring_ref,
919 				 tx_evtchn, rx_evtchn);
920 		goto err;
921 	}
922 
923 	err = 0;
924 err: /* Regular return falls through with err == 0 */
925 	kfree(xspath);
926 	return err;
927 }
928 
read_xenbus_vif_flags(struct backend_info * be)929 static int read_xenbus_vif_flags(struct backend_info *be)
930 {
931 	struct xenvif *vif = be->vif;
932 	struct xenbus_device *dev = be->dev;
933 	unsigned int rx_copy;
934 	int err;
935 
936 	err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
937 			   &rx_copy);
938 	if (err == -ENOENT) {
939 		err = 0;
940 		rx_copy = 0;
941 	}
942 	if (err < 0) {
943 		xenbus_dev_fatal(dev, err, "reading %s/request-rx-copy",
944 				 dev->otherend);
945 		return err;
946 	}
947 	if (!rx_copy)
948 		return -EOPNOTSUPP;
949 
950 	if (!xenbus_read_unsigned(dev->otherend, "feature-rx-notify", 0)) {
951 		/* - Reduce drain timeout to poll more frequently for
952 		 *   Rx requests.
953 		 * - Disable Rx stall detection.
954 		 */
955 		be->vif->drain_timeout = msecs_to_jiffies(30);
956 		be->vif->stall_timeout = 0;
957 	}
958 
959 	vif->can_sg = !!xenbus_read_unsigned(dev->otherend, "feature-sg", 0);
960 
961 	vif->gso_mask = 0;
962 
963 	if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv4", 0))
964 		vif->gso_mask |= GSO_BIT(TCPV4);
965 
966 	if (xenbus_read_unsigned(dev->otherend, "feature-gso-tcpv6", 0))
967 		vif->gso_mask |= GSO_BIT(TCPV6);
968 
969 	vif->ip_csum = !xenbus_read_unsigned(dev->otherend,
970 					     "feature-no-csum-offload", 0);
971 
972 	vif->ipv6_csum = !!xenbus_read_unsigned(dev->otherend,
973 						"feature-ipv6-csum-offload", 0);
974 
975 	read_xenbus_frontend_xdp(be, dev);
976 
977 	return 0;
978 }
979 
netback_remove(struct xenbus_device * dev)980 static void netback_remove(struct xenbus_device *dev)
981 {
982 	struct backend_info *be = dev_get_drvdata(&dev->dev);
983 
984 	unregister_hotplug_status_watch(be);
985 	xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
986 	if (be->vif) {
987 		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
988 		backend_disconnect(be);
989 		xenvif_free(be->vif);
990 		be->vif = NULL;
991 	}
992 	kfree(be->hotplug_script);
993 	kfree(be);
994 	dev_set_drvdata(&dev->dev, NULL);
995 }
996 
997 /*
998  * Entry point to this code when a new device is created.  Allocate the basic
999  * structures and switch to InitWait.
1000  */
netback_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)1001 static int netback_probe(struct xenbus_device *dev,
1002 			 const struct xenbus_device_id *id)
1003 {
1004 	const char *message;
1005 	struct xenbus_transaction xbt;
1006 	int err;
1007 	int sg;
1008 	const char *script;
1009 	struct backend_info *be = kzalloc(sizeof(*be), GFP_KERNEL);
1010 
1011 	if (!be) {
1012 		xenbus_dev_fatal(dev, -ENOMEM,
1013 				 "allocating backend structure");
1014 		return -ENOMEM;
1015 	}
1016 
1017 	be->dev = dev;
1018 	dev_set_drvdata(&dev->dev, be);
1019 
1020 	sg = 1;
1021 
1022 	do {
1023 		err = xenbus_transaction_start(&xbt);
1024 		if (err) {
1025 			xenbus_dev_fatal(dev, err, "starting transaction");
1026 			goto fail;
1027 		}
1028 
1029 		err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", sg);
1030 		if (err) {
1031 			message = "writing feature-sg";
1032 			goto abort_transaction;
1033 		}
1034 
1035 		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4",
1036 				    "%d", sg);
1037 		if (err) {
1038 			message = "writing feature-gso-tcpv4";
1039 			goto abort_transaction;
1040 		}
1041 
1042 		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
1043 				    "%d", sg);
1044 		if (err) {
1045 			message = "writing feature-gso-tcpv6";
1046 			goto abort_transaction;
1047 		}
1048 
1049 		/* We support partial checksum setup for IPv6 packets */
1050 		err = xenbus_printf(xbt, dev->nodename,
1051 				    "feature-ipv6-csum-offload",
1052 				    "%d", 1);
1053 		if (err) {
1054 			message = "writing feature-ipv6-csum-offload";
1055 			goto abort_transaction;
1056 		}
1057 
1058 		/* We support rx-copy path. */
1059 		err = xenbus_printf(xbt, dev->nodename,
1060 				    "feature-rx-copy", "%d", 1);
1061 		if (err) {
1062 			message = "writing feature-rx-copy";
1063 			goto abort_transaction;
1064 		}
1065 
1066 		/* we can adjust a headroom for netfront XDP processing */
1067 		err = xenbus_printf(xbt, dev->nodename,
1068 				    "feature-xdp-headroom", "%d",
1069 				    provides_xdp_headroom);
1070 		if (err) {
1071 			message = "writing feature-xdp-headroom";
1072 			goto abort_transaction;
1073 		}
1074 
1075 		/* We don't support rx-flip path (except old guests who
1076 		 * don't grok this feature flag).
1077 		 */
1078 		err = xenbus_printf(xbt, dev->nodename,
1079 				    "feature-rx-flip", "%d", 0);
1080 		if (err) {
1081 			message = "writing feature-rx-flip";
1082 			goto abort_transaction;
1083 		}
1084 
1085 		/* We support dynamic multicast-control. */
1086 		err = xenbus_printf(xbt, dev->nodename,
1087 				    "feature-multicast-control", "%d", 1);
1088 		if (err) {
1089 			message = "writing feature-multicast-control";
1090 			goto abort_transaction;
1091 		}
1092 
1093 		err = xenbus_printf(xbt, dev->nodename,
1094 				    "feature-dynamic-multicast-control",
1095 				    "%d", 1);
1096 		if (err) {
1097 			message = "writing feature-dynamic-multicast-control";
1098 			goto abort_transaction;
1099 		}
1100 
1101 		err = xenbus_transaction_end(xbt, 0);
1102 	} while (err == -EAGAIN);
1103 
1104 	if (err) {
1105 		xenbus_dev_fatal(dev, err, "completing transaction");
1106 		goto fail;
1107 	}
1108 
1109 	/* Split event channels support, this is optional so it is not
1110 	 * put inside the above loop.
1111 	 */
1112 	err = xenbus_printf(XBT_NIL, dev->nodename,
1113 			    "feature-split-event-channels",
1114 			    "%u", separate_tx_rx_irq);
1115 	if (err)
1116 		pr_debug("Error writing feature-split-event-channels\n");
1117 
1118 	/* Multi-queue support: This is an optional feature. */
1119 	err = xenbus_printf(XBT_NIL, dev->nodename,
1120 			    "multi-queue-max-queues", "%u", xenvif_max_queues);
1121 	if (err)
1122 		pr_debug("Error writing multi-queue-max-queues\n");
1123 
1124 	err = xenbus_printf(XBT_NIL, dev->nodename,
1125 			    "feature-ctrl-ring",
1126 			    "%u", true);
1127 	if (err)
1128 		pr_debug("Error writing feature-ctrl-ring\n");
1129 
1130 	backend_switch_state(be, XenbusStateInitWait);
1131 
1132 	script = xenbus_read(XBT_NIL, dev->nodename, "script", NULL);
1133 	if (IS_ERR(script)) {
1134 		err = PTR_ERR(script);
1135 		xenbus_dev_fatal(dev, err, "reading script");
1136 		goto fail;
1137 	}
1138 
1139 	be->hotplug_script = script;
1140 
1141 	/* This kicks hotplug scripts, so do it immediately. */
1142 	err = backend_create_xenvif(be);
1143 	if (err)
1144 		goto fail;
1145 
1146 	return 0;
1147 
1148 abort_transaction:
1149 	xenbus_transaction_end(xbt, 1);
1150 	xenbus_dev_fatal(dev, err, "%s", message);
1151 fail:
1152 	pr_debug("failed\n");
1153 	netback_remove(dev);
1154 	return err;
1155 }
1156 
1157 static const struct xenbus_device_id netback_ids[] = {
1158 	{ "vif" },
1159 	{ "" }
1160 };
1161 
1162 static struct xenbus_driver netback_driver = {
1163 	.ids = netback_ids,
1164 	.probe = netback_probe,
1165 	.remove = netback_remove,
1166 	.uevent = netback_uevent,
1167 	.otherend_changed = frontend_changed,
1168 	.allow_rebind = true,
1169 };
1170 
xenvif_xenbus_init(void)1171 int xenvif_xenbus_init(void)
1172 {
1173 	return xenbus_register_backend(&netback_driver);
1174 }
1175 
xenvif_xenbus_fini(void)1176 void xenvif_xenbus_fini(void)
1177 {
1178 	return xenbus_unregister_driver(&netback_driver);
1179 }
1180