Merge tag 'mips_6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux
[linux-2.6-microblaze.git] / drivers / net / xen-netback / xenbus.c
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
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
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
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
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
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
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  */
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
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
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
280 static void backend_connect(struct backend_info *be)
281 {
282         if (be->vif)
283                 connect(be);
284 }
285
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  */
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
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  */
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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  */
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
1171 int xenvif_xenbus_init(void)
1172 {
1173         return xenbus_register_backend(&netback_driver);
1174 }
1175
1176 void xenvif_xenbus_fini(void)
1177 {
1178         return xenbus_unregister_driver(&netback_driver);
1179 }