GNU Linux-libre 5.10.219-gnu1
[releases.git] / drivers / hv / channel_mgmt.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2009, Microsoft Corporation.
4  *
5  * Authors:
6  *   Haiyang Zhang <haiyangz@microsoft.com>
7  *   Hank Janssen  <hjanssen@microsoft.com>
8  */
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11 #include <linux/kernel.h>
12 #include <linux/interrupt.h>
13 #include <linux/sched.h>
14 #include <linux/wait.h>
15 #include <linux/mm.h>
16 #include <linux/slab.h>
17 #include <linux/list.h>
18 #include <linux/module.h>
19 #include <linux/completion.h>
20 #include <linux/delay.h>
21 #include <linux/cpu.h>
22 #include <linux/hyperv.h>
23 #include <asm/mshyperv.h>
24
25 #include "hyperv_vmbus.h"
26
27 static void init_vp_index(struct vmbus_channel *channel);
28
29 const struct vmbus_device vmbus_devs[] = {
30         /* IDE */
31         { .dev_type = HV_IDE,
32           HV_IDE_GUID,
33           .perf_device = true,
34         },
35
36         /* SCSI */
37         { .dev_type = HV_SCSI,
38           HV_SCSI_GUID,
39           .perf_device = true,
40         },
41
42         /* Fibre Channel */
43         { .dev_type = HV_FC,
44           HV_SYNTHFC_GUID,
45           .perf_device = true,
46         },
47
48         /* Synthetic NIC */
49         { .dev_type = HV_NIC,
50           HV_NIC_GUID,
51           .perf_device = true,
52         },
53
54         /* Network Direct */
55         { .dev_type = HV_ND,
56           HV_ND_GUID,
57           .perf_device = true,
58         },
59
60         /* PCIE */
61         { .dev_type = HV_PCIE,
62           HV_PCIE_GUID,
63           .perf_device = false,
64         },
65
66         /* Synthetic Frame Buffer */
67         { .dev_type = HV_FB,
68           HV_SYNTHVID_GUID,
69           .perf_device = false,
70         },
71
72         /* Synthetic Keyboard */
73         { .dev_type = HV_KBD,
74           HV_KBD_GUID,
75           .perf_device = false,
76         },
77
78         /* Synthetic MOUSE */
79         { .dev_type = HV_MOUSE,
80           HV_MOUSE_GUID,
81           .perf_device = false,
82         },
83
84         /* KVP */
85         { .dev_type = HV_KVP,
86           HV_KVP_GUID,
87           .perf_device = false,
88         },
89
90         /* Time Synch */
91         { .dev_type = HV_TS,
92           HV_TS_GUID,
93           .perf_device = false,
94         },
95
96         /* Heartbeat */
97         { .dev_type = HV_HB,
98           HV_HEART_BEAT_GUID,
99           .perf_device = false,
100         },
101
102         /* Shutdown */
103         { .dev_type = HV_SHUTDOWN,
104           HV_SHUTDOWN_GUID,
105           .perf_device = false,
106         },
107
108         /* File copy */
109         { .dev_type = HV_FCOPY,
110           HV_FCOPY_GUID,
111           .perf_device = false,
112         },
113
114         /* Backup */
115         { .dev_type = HV_BACKUP,
116           HV_VSS_GUID,
117           .perf_device = false,
118         },
119
120         /* Dynamic Memory */
121         { .dev_type = HV_DM,
122           HV_DM_GUID,
123           .perf_device = false,
124         },
125
126         /* Unknown GUID */
127         { .dev_type = HV_UNKNOWN,
128           .perf_device = false,
129         },
130 };
131
132 static const struct {
133         guid_t guid;
134 } vmbus_unsupported_devs[] = {
135         { HV_AVMA1_GUID },
136         { HV_AVMA2_GUID },
137         { HV_RDV_GUID   },
138 };
139
140 /*
141  * The rescinded channel may be blocked waiting for a response from the host;
142  * take care of that.
143  */
144 static void vmbus_rescind_cleanup(struct vmbus_channel *channel)
145 {
146         struct vmbus_channel_msginfo *msginfo;
147         unsigned long flags;
148
149
150         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
151         channel->rescind = true;
152         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
153                                 msglistentry) {
154
155                 if (msginfo->waiting_channel == channel) {
156                         complete(&msginfo->waitevent);
157                         break;
158                 }
159         }
160         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
161 }
162
163 static bool is_unsupported_vmbus_devs(const guid_t *guid)
164 {
165         int i;
166
167         for (i = 0; i < ARRAY_SIZE(vmbus_unsupported_devs); i++)
168                 if (guid_equal(guid, &vmbus_unsupported_devs[i].guid))
169                         return true;
170         return false;
171 }
172
173 static u16 hv_get_dev_type(const struct vmbus_channel *channel)
174 {
175         const guid_t *guid = &channel->offermsg.offer.if_type;
176         u16 i;
177
178         if (is_hvsock_channel(channel) || is_unsupported_vmbus_devs(guid))
179                 return HV_UNKNOWN;
180
181         for (i = HV_IDE; i < HV_UNKNOWN; i++) {
182                 if (guid_equal(guid, &vmbus_devs[i].guid))
183                         return i;
184         }
185         pr_info("Unknown GUID: %pUl\n", guid);
186         return i;
187 }
188
189 /**
190  * vmbus_prep_negotiate_resp() - Create default response for Negotiate message
191  * @icmsghdrp: Pointer to msg header structure
192  * @buf: Raw buffer channel data
193  * @fw_version: The framework versions we can support.
194  * @fw_vercnt: The size of @fw_version.
195  * @srv_version: The service versions we can support.
196  * @srv_vercnt: The size of @srv_version.
197  * @nego_fw_version: The selected framework version.
198  * @nego_srv_version: The selected service version.
199  *
200  * Note: Versions are given in decreasing order.
201  *
202  * Set up and fill in default negotiate response message.
203  * Mainly used by Hyper-V drivers.
204  */
205 bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
206                                 u8 *buf, const int *fw_version, int fw_vercnt,
207                                 const int *srv_version, int srv_vercnt,
208                                 int *nego_fw_version, int *nego_srv_version)
209 {
210         int icframe_major, icframe_minor;
211         int icmsg_major, icmsg_minor;
212         int fw_major, fw_minor;
213         int srv_major, srv_minor;
214         int i, j;
215         bool found_match = false;
216         struct icmsg_negotiate *negop;
217
218         icmsghdrp->icmsgsize = 0x10;
219         negop = (struct icmsg_negotiate *)&buf[
220                 sizeof(struct vmbuspipe_hdr) +
221                 sizeof(struct icmsg_hdr)];
222
223         icframe_major = negop->icframe_vercnt;
224         icframe_minor = 0;
225
226         icmsg_major = negop->icmsg_vercnt;
227         icmsg_minor = 0;
228
229         /*
230          * Select the framework version number we will
231          * support.
232          */
233
234         for (i = 0; i < fw_vercnt; i++) {
235                 fw_major = (fw_version[i] >> 16);
236                 fw_minor = (fw_version[i] & 0xFFFF);
237
238                 for (j = 0; j < negop->icframe_vercnt; j++) {
239                         if ((negop->icversion_data[j].major == fw_major) &&
240                             (negop->icversion_data[j].minor == fw_minor)) {
241                                 icframe_major = negop->icversion_data[j].major;
242                                 icframe_minor = negop->icversion_data[j].minor;
243                                 found_match = true;
244                                 break;
245                         }
246                 }
247
248                 if (found_match)
249                         break;
250         }
251
252         if (!found_match)
253                 goto fw_error;
254
255         found_match = false;
256
257         for (i = 0; i < srv_vercnt; i++) {
258                 srv_major = (srv_version[i] >> 16);
259                 srv_minor = (srv_version[i] & 0xFFFF);
260
261                 for (j = negop->icframe_vercnt;
262                         (j < negop->icframe_vercnt + negop->icmsg_vercnt);
263                         j++) {
264
265                         if ((negop->icversion_data[j].major == srv_major) &&
266                                 (negop->icversion_data[j].minor == srv_minor)) {
267
268                                 icmsg_major = negop->icversion_data[j].major;
269                                 icmsg_minor = negop->icversion_data[j].minor;
270                                 found_match = true;
271                                 break;
272                         }
273                 }
274
275                 if (found_match)
276                         break;
277         }
278
279         /*
280          * Respond with the framework and service
281          * version numbers we can support.
282          */
283
284 fw_error:
285         if (!found_match) {
286                 negop->icframe_vercnt = 0;
287                 negop->icmsg_vercnt = 0;
288         } else {
289                 negop->icframe_vercnt = 1;
290                 negop->icmsg_vercnt = 1;
291         }
292
293         if (nego_fw_version)
294                 *nego_fw_version = (icframe_major << 16) | icframe_minor;
295
296         if (nego_srv_version)
297                 *nego_srv_version = (icmsg_major << 16) | icmsg_minor;
298
299         negop->icversion_data[0].major = icframe_major;
300         negop->icversion_data[0].minor = icframe_minor;
301         negop->icversion_data[1].major = icmsg_major;
302         negop->icversion_data[1].minor = icmsg_minor;
303         return found_match;
304 }
305
306 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
307
308 /*
309  * alloc_channel - Allocate and initialize a vmbus channel object
310  */
311 static struct vmbus_channel *alloc_channel(void)
312 {
313         struct vmbus_channel *channel;
314
315         channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
316         if (!channel)
317                 return NULL;
318
319         spin_lock_init(&channel->sched_lock);
320         init_completion(&channel->rescind_event);
321
322         INIT_LIST_HEAD(&channel->sc_list);
323
324         tasklet_init(&channel->callback_event,
325                      vmbus_on_event, (unsigned long)channel);
326
327         hv_ringbuffer_pre_init(channel);
328
329         return channel;
330 }
331
332 /*
333  * free_channel - Release the resources used by the vmbus channel object
334  */
335 static void free_channel(struct vmbus_channel *channel)
336 {
337         tasklet_kill(&channel->callback_event);
338         vmbus_remove_channel_attr_group(channel);
339
340         kobject_put(&channel->kobj);
341 }
342
343 void vmbus_channel_map_relid(struct vmbus_channel *channel)
344 {
345         if (WARN_ON(channel->offermsg.child_relid >= MAX_CHANNEL_RELIDS))
346                 return;
347         /*
348          * The mapping of the channel's relid is visible from the CPUs that
349          * execute vmbus_chan_sched() by the time that vmbus_chan_sched() will
350          * execute:
351          *
352          *  (a) In the "normal (i.e., not resuming from hibernation)" path,
353          *      the full barrier in virt_store_mb() guarantees that the store
354          *      is propagated to all CPUs before the add_channel_work work
355          *      is queued.  In turn, add_channel_work is queued before the
356          *      channel's ring buffer is allocated/initialized and the
357          *      OPENCHANNEL message for the channel is sent in vmbus_open().
358          *      Hyper-V won't start sending the interrupts for the channel
359          *      before the OPENCHANNEL message is acked.  The memory barrier
360          *      in vmbus_chan_sched() -> sync_test_and_clear_bit() ensures
361          *      that vmbus_chan_sched() must find the channel's relid in
362          *      recv_int_page before retrieving the channel pointer from the
363          *      array of channels.
364          *
365          *  (b) In the "resuming from hibernation" path, the virt_store_mb()
366          *      guarantees that the store is propagated to all CPUs before
367          *      the VMBus connection is marked as ready for the resume event
368          *      (cf. check_ready_for_resume_event()).  The interrupt handler
369          *      of the VMBus driver and vmbus_chan_sched() can not run before
370          *      vmbus_bus_resume() has completed execution (cf. resume_noirq).
371          */
372         virt_store_mb(
373                 vmbus_connection.channels[channel->offermsg.child_relid],
374                 channel);
375 }
376
377 void vmbus_channel_unmap_relid(struct vmbus_channel *channel)
378 {
379         if (WARN_ON(channel->offermsg.child_relid >= MAX_CHANNEL_RELIDS))
380                 return;
381         WRITE_ONCE(
382                 vmbus_connection.channels[channel->offermsg.child_relid],
383                 NULL);
384 }
385
386 static void vmbus_release_relid(u32 relid)
387 {
388         struct vmbus_channel_relid_released msg;
389         int ret;
390
391         memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
392         msg.child_relid = relid;
393         msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
394         ret = vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released),
395                              true);
396
397         trace_vmbus_release_relid(&msg, ret);
398 }
399
400 void hv_process_channel_removal(struct vmbus_channel *channel)
401 {
402         lockdep_assert_held(&vmbus_connection.channel_mutex);
403         BUG_ON(!channel->rescind);
404
405         /*
406          * hv_process_channel_removal() could find INVALID_RELID only for
407          * hv_sock channels.  See the inline comments in vmbus_onoffer().
408          */
409         WARN_ON(channel->offermsg.child_relid == INVALID_RELID &&
410                 !is_hvsock_channel(channel));
411
412         /*
413          * Upon suspend, an in-use hv_sock channel is removed from the array of
414          * channels and the relid is invalidated.  After hibernation, when the
415          * user-space appplication destroys the channel, it's unnecessary and
416          * unsafe to remove the channel from the array of channels.  See also
417          * the inline comments before the call of vmbus_release_relid() below.
418          */
419         if (channel->offermsg.child_relid != INVALID_RELID)
420                 vmbus_channel_unmap_relid(channel);
421
422         if (channel->primary_channel == NULL)
423                 list_del(&channel->listentry);
424         else
425                 list_del(&channel->sc_list);
426
427         /*
428          * If this is a "perf" channel, updates the hv_numa_map[] masks so that
429          * init_vp_index() can (re-)use the CPU.
430          */
431         if (hv_is_perf_channel(channel))
432                 hv_clear_alloced_cpu(channel->target_cpu);
433
434         /*
435          * Upon suspend, an in-use hv_sock channel is marked as "rescinded" and
436          * the relid is invalidated; after hibernation, when the user-space app
437          * destroys the channel, the relid is INVALID_RELID, and in this case
438          * it's unnecessary and unsafe to release the old relid, since the same
439          * relid can refer to a completely different channel now.
440          */
441         if (channel->offermsg.child_relid != INVALID_RELID)
442                 vmbus_release_relid(channel->offermsg.child_relid);
443
444         free_channel(channel);
445 }
446
447 void vmbus_free_channels(void)
448 {
449         struct vmbus_channel *channel, *tmp;
450
451         list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,
452                 listentry) {
453                 /* hv_process_channel_removal() needs this */
454                 channel->rescind = true;
455
456                 vmbus_device_unregister(channel->device_obj);
457         }
458 }
459
460 /* Note: the function can run concurrently for primary/sub channels. */
461 static void vmbus_add_channel_work(struct work_struct *work)
462 {
463         struct vmbus_channel *newchannel =
464                 container_of(work, struct vmbus_channel, add_channel_work);
465         struct vmbus_channel *primary_channel = newchannel->primary_channel;
466         int ret;
467
468         /*
469          * This state is used to indicate a successful open
470          * so that when we do close the channel normally, we
471          * can cleanup properly.
472          */
473         newchannel->state = CHANNEL_OPEN_STATE;
474
475         if (primary_channel != NULL) {
476                 /* newchannel is a sub-channel. */
477                 struct hv_device *dev = primary_channel->device_obj;
478
479                 if (vmbus_add_channel_kobj(dev, newchannel))
480                         goto err_deq_chan;
481
482                 if (primary_channel->sc_creation_callback != NULL)
483                         primary_channel->sc_creation_callback(newchannel);
484
485                 newchannel->probe_done = true;
486                 return;
487         }
488
489         /*
490          * Start the process of binding the primary channel to the driver
491          */
492         newchannel->device_obj = vmbus_device_create(
493                 &newchannel->offermsg.offer.if_type,
494                 &newchannel->offermsg.offer.if_instance,
495                 newchannel);
496         if (!newchannel->device_obj)
497                 goto err_deq_chan;
498
499         newchannel->device_obj->device_id = newchannel->device_id;
500         /*
501          * Add the new device to the bus. This will kick off device-driver
502          * binding which eventually invokes the device driver's AddDevice()
503          * method.
504          *
505          * If vmbus_device_register() fails, the 'device_obj' is freed in
506          * vmbus_device_release() as called by device_unregister() in the
507          * error path of vmbus_device_register(). In the outside error
508          * path, there's no need to free it.
509          */
510         ret = vmbus_device_register(newchannel->device_obj);
511
512         if (ret != 0) {
513                 pr_err("unable to add child device object (relid %d)\n",
514                         newchannel->offermsg.child_relid);
515                 goto err_deq_chan;
516         }
517
518         newchannel->probe_done = true;
519         return;
520
521 err_deq_chan:
522         mutex_lock(&vmbus_connection.channel_mutex);
523
524         /*
525          * We need to set the flag, otherwise
526          * vmbus_onoffer_rescind() can be blocked.
527          */
528         newchannel->probe_done = true;
529
530         if (primary_channel == NULL)
531                 list_del(&newchannel->listentry);
532         else
533                 list_del(&newchannel->sc_list);
534
535         /* vmbus_process_offer() has mapped the channel. */
536         vmbus_channel_unmap_relid(newchannel);
537
538         mutex_unlock(&vmbus_connection.channel_mutex);
539
540         vmbus_release_relid(newchannel->offermsg.child_relid);
541
542         free_channel(newchannel);
543 }
544
545 /*
546  * vmbus_process_offer - Process the offer by creating a channel/device
547  * associated with this offer
548  */
549 static void vmbus_process_offer(struct vmbus_channel *newchannel)
550 {
551         struct vmbus_channel *channel;
552         struct workqueue_struct *wq;
553         bool fnew = true;
554
555         /*
556          * Synchronize vmbus_process_offer() and CPU hotplugging:
557          *
558          * CPU1                         CPU2
559          *
560          * [vmbus_process_offer()]      [Hot removal of the CPU]
561          *
562          * CPU_READ_LOCK                CPUS_WRITE_LOCK
563          * LOAD cpu_online_mask         SEARCH chn_list
564          * STORE target_cpu             LOAD target_cpu
565          * INSERT chn_list              STORE cpu_online_mask
566          * CPUS_READ_UNLOCK             CPUS_WRITE_UNLOCK
567          *
568          * Forbids: CPU1's LOAD from *not* seing CPU2's STORE &&
569          *              CPU2's SEARCH from *not* seeing CPU1's INSERT
570          *
571          * Forbids: CPU2's SEARCH from seeing CPU1's INSERT &&
572          *              CPU2's LOAD from *not* seing CPU1's STORE
573          */
574         cpus_read_lock();
575
576         /*
577          * Serializes the modifications of the chn_list list as well as
578          * the accesses to next_numa_node_id in init_vp_index().
579          */
580         mutex_lock(&vmbus_connection.channel_mutex);
581
582         init_vp_index(newchannel);
583
584         /* Remember the channels that should be cleaned up upon suspend. */
585         if (is_hvsock_channel(newchannel) || is_sub_channel(newchannel))
586                 atomic_inc(&vmbus_connection.nr_chan_close_on_suspend);
587
588         /*
589          * Now that we have acquired the channel_mutex,
590          * we can release the potentially racing rescind thread.
591          */
592         atomic_dec(&vmbus_connection.offer_in_progress);
593
594         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
595                 if (guid_equal(&channel->offermsg.offer.if_type,
596                                &newchannel->offermsg.offer.if_type) &&
597                     guid_equal(&channel->offermsg.offer.if_instance,
598                                &newchannel->offermsg.offer.if_instance)) {
599                         fnew = false;
600                         break;
601                 }
602         }
603
604         if (fnew) {
605                 list_add_tail(&newchannel->listentry,
606                               &vmbus_connection.chn_list);
607         } else {
608                 /*
609                  * Check to see if this is a valid sub-channel.
610                  */
611                 if (newchannel->offermsg.offer.sub_channel_index == 0) {
612                         mutex_unlock(&vmbus_connection.channel_mutex);
613                         cpus_read_unlock();
614                         /*
615                          * Don't call free_channel(), because newchannel->kobj
616                          * is not initialized yet.
617                          */
618                         kfree(newchannel);
619                         WARN_ON_ONCE(1);
620                         return;
621                 }
622                 /*
623                  * Process the sub-channel.
624                  */
625                 newchannel->primary_channel = channel;
626                 list_add_tail(&newchannel->sc_list, &channel->sc_list);
627         }
628
629         vmbus_channel_map_relid(newchannel);
630
631         mutex_unlock(&vmbus_connection.channel_mutex);
632         cpus_read_unlock();
633
634         /*
635          * vmbus_process_offer() mustn't call channel->sc_creation_callback()
636          * directly for sub-channels, because sc_creation_callback() ->
637          * vmbus_open() may never get the host's response to the
638          * OPEN_CHANNEL message (the host may rescind a channel at any time,
639          * e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind()
640          * may not wake up the vmbus_open() as it's blocked due to a non-zero
641          * vmbus_connection.offer_in_progress, and finally we have a deadlock.
642          *
643          * The above is also true for primary channels, if the related device
644          * drivers use sync probing mode by default.
645          *
646          * And, usually the handling of primary channels and sub-channels can
647          * depend on each other, so we should offload them to different
648          * workqueues to avoid possible deadlock, e.g. in sync-probing mode,
649          * NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() ->
650          * rtnl_lock(), and causes deadlock: the former gets the rtnl_lock
651          * and waits for all the sub-channels to appear, but the latter
652          * can't get the rtnl_lock and this blocks the handling of
653          * sub-channels.
654          */
655         INIT_WORK(&newchannel->add_channel_work, vmbus_add_channel_work);
656         wq = fnew ? vmbus_connection.handle_primary_chan_wq :
657                     vmbus_connection.handle_sub_chan_wq;
658         queue_work(wq, &newchannel->add_channel_work);
659 }
660
661 /*
662  * We use this state to statically distribute the channel interrupt load.
663  */
664 static int next_numa_node_id;
665
666 /*
667  * Starting with Win8, we can statically distribute the incoming
668  * channel interrupt load by binding a channel to VCPU.
669  *
670  * For pre-win8 hosts or non-performance critical channels we assign the
671  * VMBUS_CONNECT_CPU.
672  *
673  * Starting with win8, performance critical channels will be distributed
674  * evenly among all the available NUMA nodes.  Once the node is assigned,
675  * we will assign the CPU based on a simple round robin scheme.
676  */
677 static void init_vp_index(struct vmbus_channel *channel)
678 {
679         bool perf_chn = hv_is_perf_channel(channel);
680         cpumask_var_t available_mask;
681         struct cpumask *alloced_mask;
682         u32 target_cpu;
683         int numa_node;
684
685         if ((vmbus_proto_version == VERSION_WS2008) ||
686             (vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
687             !alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
688                 /*
689                  * Prior to win8, all channel interrupts are
690                  * delivered on VMBUS_CONNECT_CPU.
691                  * Also if the channel is not a performance critical
692                  * channel, bind it to VMBUS_CONNECT_CPU.
693                  * In case alloc_cpumask_var() fails, bind it to
694                  * VMBUS_CONNECT_CPU.
695                  */
696                 channel->target_cpu = VMBUS_CONNECT_CPU;
697                 if (perf_chn)
698                         hv_set_alloced_cpu(VMBUS_CONNECT_CPU);
699                 return;
700         }
701
702         while (true) {
703                 numa_node = next_numa_node_id++;
704                 if (numa_node == nr_node_ids) {
705                         next_numa_node_id = 0;
706                         continue;
707                 }
708                 if (cpumask_empty(cpumask_of_node(numa_node)))
709                         continue;
710                 break;
711         }
712         alloced_mask = &hv_context.hv_numa_map[numa_node];
713
714         if (cpumask_weight(alloced_mask) ==
715             cpumask_weight(cpumask_of_node(numa_node))) {
716                 /*
717                  * We have cycled through all the CPUs in the node;
718                  * reset the alloced map.
719                  */
720                 cpumask_clear(alloced_mask);
721         }
722
723         cpumask_xor(available_mask, alloced_mask, cpumask_of_node(numa_node));
724
725         target_cpu = cpumask_first(available_mask);
726         cpumask_set_cpu(target_cpu, alloced_mask);
727
728         channel->target_cpu = target_cpu;
729
730         free_cpumask_var(available_mask);
731 }
732
733 #define UNLOAD_DELAY_UNIT_MS    10              /* 10 milliseconds */
734 #define UNLOAD_WAIT_MS          (100*1000)      /* 100 seconds */
735 #define UNLOAD_WAIT_LOOPS       (UNLOAD_WAIT_MS/UNLOAD_DELAY_UNIT_MS)
736 #define UNLOAD_MSG_MS           (5*1000)        /* Every 5 seconds */
737 #define UNLOAD_MSG_LOOPS        (UNLOAD_MSG_MS/UNLOAD_DELAY_UNIT_MS)
738
739 static void vmbus_wait_for_unload(void)
740 {
741         int cpu;
742         void *page_addr;
743         struct hv_message *msg;
744         struct vmbus_channel_message_header *hdr;
745         u32 message_type, i;
746
747         /*
748          * CHANNELMSG_UNLOAD_RESPONSE is always delivered to the CPU which was
749          * used for initial contact or to CPU0 depending on host version. When
750          * we're crashing on a different CPU let's hope that IRQ handler on
751          * the cpu which receives CHANNELMSG_UNLOAD_RESPONSE is still
752          * functional and vmbus_unload_response() will complete
753          * vmbus_connection.unload_event. If not, the last thing we can do is
754          * read message pages for all CPUs directly.
755          *
756          * Wait up to 100 seconds since an Azure host must writeback any dirty
757          * data in its disk cache before the VMbus UNLOAD request will
758          * complete. This flushing has been empirically observed to take up
759          * to 50 seconds in cases with a lot of dirty data, so allow additional
760          * leeway and for inaccuracies in mdelay(). But eventually time out so
761          * that the panic path can't get hung forever in case the response
762          * message isn't seen.
763          */
764         for (i = 1; i <= UNLOAD_WAIT_LOOPS; i++) {
765                 if (completion_done(&vmbus_connection.unload_event))
766                         goto completed;
767
768                 for_each_present_cpu(cpu) {
769                         struct hv_per_cpu_context *hv_cpu
770                                 = per_cpu_ptr(hv_context.cpu_context, cpu);
771
772                         /*
773                          * In a CoCo VM the synic_message_page is not allocated
774                          * in hv_synic_alloc(). Instead it is set/cleared in
775                          * hv_synic_enable_regs() and hv_synic_disable_regs()
776                          * such that it is set only when the CPU is online. If
777                          * not all present CPUs are online, the message page
778                          * might be NULL, so skip such CPUs.
779                          */
780                         page_addr = hv_cpu->synic_message_page;
781                         if (!page_addr)
782                                 continue;
783
784                         msg = (struct hv_message *)page_addr
785                                 + VMBUS_MESSAGE_SINT;
786
787                         message_type = READ_ONCE(msg->header.message_type);
788                         if (message_type == HVMSG_NONE)
789                                 continue;
790
791                         hdr = (struct vmbus_channel_message_header *)
792                                 msg->u.payload;
793
794                         if (hdr->msgtype == CHANNELMSG_UNLOAD_RESPONSE)
795                                 complete(&vmbus_connection.unload_event);
796
797                         vmbus_signal_eom(msg, message_type);
798                 }
799
800                 /*
801                  * Give a notice periodically so someone watching the
802                  * serial output won't think it is completely hung.
803                  */
804                 if (!(i % UNLOAD_MSG_LOOPS))
805                         pr_notice("Waiting for VMBus UNLOAD to complete\n");
806
807                 mdelay(UNLOAD_DELAY_UNIT_MS);
808         }
809         pr_err("Continuing even though VMBus UNLOAD did not complete\n");
810
811 completed:
812         /*
813          * We're crashing and already got the UNLOAD_RESPONSE, cleanup all
814          * maybe-pending messages on all CPUs to be able to receive new
815          * messages after we reconnect.
816          */
817         for_each_present_cpu(cpu) {
818                 struct hv_per_cpu_context *hv_cpu
819                         = per_cpu_ptr(hv_context.cpu_context, cpu);
820
821                 page_addr = hv_cpu->synic_message_page;
822                 if (!page_addr)
823                         continue;
824
825                 msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
826                 msg->header.message_type = HVMSG_NONE;
827         }
828 }
829
830 /*
831  * vmbus_unload_response - Handler for the unload response.
832  */
833 static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
834 {
835         /*
836          * This is a global event; just wakeup the waiting thread.
837          * Once we successfully unload, we can cleanup the monitor state.
838          */
839         complete(&vmbus_connection.unload_event);
840 }
841
842 void vmbus_initiate_unload(bool crash)
843 {
844         struct vmbus_channel_message_header hdr;
845
846         if (xchg(&vmbus_connection.conn_state, DISCONNECTED) == DISCONNECTED)
847                 return;
848
849         /* Pre-Win2012R2 hosts don't support reconnect */
850         if (vmbus_proto_version < VERSION_WIN8_1)
851                 return;
852
853         init_completion(&vmbus_connection.unload_event);
854         memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
855         hdr.msgtype = CHANNELMSG_UNLOAD;
856         vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header),
857                        !crash);
858
859         /*
860          * vmbus_initiate_unload() is also called on crash and the crash can be
861          * happening in an interrupt context, where scheduling is impossible.
862          */
863         if (!crash)
864                 wait_for_completion(&vmbus_connection.unload_event);
865         else
866                 vmbus_wait_for_unload();
867 }
868
869 static void check_ready_for_resume_event(void)
870 {
871         /*
872          * If all the old primary channels have been fixed up, then it's safe
873          * to resume.
874          */
875         if (atomic_dec_and_test(&vmbus_connection.nr_chan_fixup_on_resume))
876                 complete(&vmbus_connection.ready_for_resume_event);
877 }
878
879 static void vmbus_setup_channel_state(struct vmbus_channel *channel,
880                                       struct vmbus_channel_offer_channel *offer)
881 {
882         /*
883          * Setup state for signalling the host.
884          */
885         channel->sig_event = VMBUS_EVENT_CONNECTION_ID;
886
887         if (vmbus_proto_version != VERSION_WS2008) {
888                 channel->is_dedicated_interrupt =
889                                 (offer->is_dedicated_interrupt != 0);
890                 channel->sig_event = offer->connection_id;
891         }
892
893         memcpy(&channel->offermsg, offer,
894                sizeof(struct vmbus_channel_offer_channel));
895         channel->monitor_grp = (u8)offer->monitorid / 32;
896         channel->monitor_bit = (u8)offer->monitorid % 32;
897         channel->device_id = hv_get_dev_type(channel);
898 }
899
900 /*
901  * find_primary_channel_by_offer - Get the channel object given the new offer.
902  * This is only used in the resume path of hibernation.
903  */
904 static struct vmbus_channel *
905 find_primary_channel_by_offer(const struct vmbus_channel_offer_channel *offer)
906 {
907         struct vmbus_channel *channel = NULL, *iter;
908         const guid_t *inst1, *inst2;
909
910         /* Ignore sub-channel offers. */
911         if (offer->offer.sub_channel_index != 0)
912                 return NULL;
913
914         mutex_lock(&vmbus_connection.channel_mutex);
915
916         list_for_each_entry(iter, &vmbus_connection.chn_list, listentry) {
917                 inst1 = &iter->offermsg.offer.if_instance;
918                 inst2 = &offer->offer.if_instance;
919
920                 if (guid_equal(inst1, inst2)) {
921                         channel = iter;
922                         break;
923                 }
924         }
925
926         mutex_unlock(&vmbus_connection.channel_mutex);
927
928         return channel;
929 }
930
931 /*
932  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
933  *
934  */
935 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
936 {
937         struct vmbus_channel_offer_channel *offer;
938         struct vmbus_channel *oldchannel, *newchannel;
939         size_t offer_sz;
940
941         offer = (struct vmbus_channel_offer_channel *)hdr;
942
943         trace_vmbus_onoffer(offer);
944
945         oldchannel = find_primary_channel_by_offer(offer);
946
947         if (oldchannel != NULL) {
948                 /*
949                  * We're resuming from hibernation: all the sub-channel and
950                  * hv_sock channels we had before the hibernation should have
951                  * been cleaned up, and now we must be seeing a re-offered
952                  * primary channel that we had before the hibernation.
953                  */
954
955                 /*
956                  * { Initially: channel relid = INVALID_RELID,
957                  *              channels[valid_relid] = NULL }
958                  *
959                  * CPU1                                 CPU2
960                  *
961                  * [vmbus_onoffer()]                    [vmbus_device_release()]
962                  *
963                  * LOCK channel_mutex                   LOCK channel_mutex
964                  * STORE channel relid = valid_relid    LOAD r1 = channel relid
965                  * MAP_RELID channel                    if (r1 != INVALID_RELID)
966                  * UNLOCK channel_mutex                   UNMAP_RELID channel
967                  *                                      UNLOCK channel_mutex
968                  *
969                  * Forbids: r1 == valid_relid &&
970                  *              channels[valid_relid] == channel
971                  *
972                  * Note.  r1 can be INVALID_RELID only for an hv_sock channel.
973                  * None of the hv_sock channels which were present before the
974                  * suspend are re-offered upon the resume.  See the WARN_ON()
975                  * in hv_process_channel_removal().
976                  */
977                 mutex_lock(&vmbus_connection.channel_mutex);
978
979                 atomic_dec(&vmbus_connection.offer_in_progress);
980
981                 WARN_ON(oldchannel->offermsg.child_relid != INVALID_RELID);
982                 /* Fix up the relid. */
983                 oldchannel->offermsg.child_relid = offer->child_relid;
984
985                 offer_sz = sizeof(*offer);
986                 if (memcmp(offer, &oldchannel->offermsg, offer_sz) != 0) {
987                         /*
988                          * This is not an error, since the host can also change
989                          * the other field(s) of the offer, e.g. on WS RS5
990                          * (Build 17763), the offer->connection_id of the
991                          * Mellanox VF vmbus device can change when the host
992                          * reoffers the device upon resume.
993                          */
994                         pr_debug("vmbus offer changed: relid=%d\n",
995                                  offer->child_relid);
996
997                         print_hex_dump_debug("Old vmbus offer: ",
998                                              DUMP_PREFIX_OFFSET, 16, 4,
999                                              &oldchannel->offermsg, offer_sz,
1000                                              false);
1001                         print_hex_dump_debug("New vmbus offer: ",
1002                                              DUMP_PREFIX_OFFSET, 16, 4,
1003                                              offer, offer_sz, false);
1004
1005                         /* Fix up the old channel. */
1006                         vmbus_setup_channel_state(oldchannel, offer);
1007                 }
1008
1009                 /* Add the channel back to the array of channels. */
1010                 vmbus_channel_map_relid(oldchannel);
1011                 check_ready_for_resume_event();
1012
1013                 mutex_unlock(&vmbus_connection.channel_mutex);
1014                 return;
1015         }
1016
1017         /* Allocate the channel object and save this offer. */
1018         newchannel = alloc_channel();
1019         if (!newchannel) {
1020                 vmbus_release_relid(offer->child_relid);
1021                 atomic_dec(&vmbus_connection.offer_in_progress);
1022                 pr_err("Unable to allocate channel object\n");
1023                 return;
1024         }
1025
1026         vmbus_setup_channel_state(newchannel, offer);
1027
1028         vmbus_process_offer(newchannel);
1029 }
1030
1031 static void check_ready_for_suspend_event(void)
1032 {
1033         /*
1034          * If all the sub-channels or hv_sock channels have been cleaned up,
1035          * then it's safe to suspend.
1036          */
1037         if (atomic_dec_and_test(&vmbus_connection.nr_chan_close_on_suspend))
1038                 complete(&vmbus_connection.ready_for_suspend_event);
1039 }
1040
1041 /*
1042  * vmbus_onoffer_rescind - Rescind offer handler.
1043  *
1044  * We queue a work item to process this offer synchronously
1045  */
1046 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
1047 {
1048         struct vmbus_channel_rescind_offer *rescind;
1049         struct vmbus_channel *channel;
1050         struct device *dev;
1051         bool clean_up_chan_for_suspend;
1052
1053         rescind = (struct vmbus_channel_rescind_offer *)hdr;
1054
1055         trace_vmbus_onoffer_rescind(rescind);
1056
1057         /*
1058          * The offer msg and the corresponding rescind msg
1059          * from the host are guranteed to be ordered -
1060          * offer comes in first and then the rescind.
1061          * Since we process these events in work elements,
1062          * and with preemption, we may end up processing
1063          * the events out of order.  We rely on the synchronization
1064          * provided by offer_in_progress and by channel_mutex for
1065          * ordering these events:
1066          *
1067          * { Initially: offer_in_progress = 1 }
1068          *
1069          * CPU1                         CPU2
1070          *
1071          * [vmbus_onoffer()]            [vmbus_onoffer_rescind()]
1072          *
1073          * LOCK channel_mutex           WAIT_ON offer_in_progress == 0
1074          * DECREMENT offer_in_progress  LOCK channel_mutex
1075          * STORE channels[]             LOAD channels[]
1076          * UNLOCK channel_mutex         UNLOCK channel_mutex
1077          *
1078          * Forbids: CPU2's LOAD from *not* seeing CPU1's STORE
1079          */
1080
1081         while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
1082                 /*
1083                  * We wait here until any channel offer is currently
1084                  * being processed.
1085                  */
1086                 msleep(1);
1087         }
1088
1089         mutex_lock(&vmbus_connection.channel_mutex);
1090         channel = relid2channel(rescind->child_relid);
1091         mutex_unlock(&vmbus_connection.channel_mutex);
1092
1093         if (channel == NULL) {
1094                 /*
1095                  * We failed in processing the offer message;
1096                  * we would have cleaned up the relid in that
1097                  * failure path.
1098                  */
1099                 return;
1100         }
1101
1102         clean_up_chan_for_suspend = is_hvsock_channel(channel) ||
1103                                     is_sub_channel(channel);
1104         /*
1105          * Before setting channel->rescind in vmbus_rescind_cleanup(), we
1106          * should make sure the channel callback is not running any more.
1107          */
1108         vmbus_reset_channel_cb(channel);
1109
1110         /*
1111          * Now wait for offer handling to complete.
1112          */
1113         vmbus_rescind_cleanup(channel);
1114         while (READ_ONCE(channel->probe_done) == false) {
1115                 /*
1116                  * We wait here until any channel offer is currently
1117                  * being processed.
1118                  */
1119                 msleep(1);
1120         }
1121
1122         /*
1123          * At this point, the rescind handling can proceed safely.
1124          */
1125
1126         if (channel->device_obj) {
1127                 if (channel->chn_rescind_callback) {
1128                         channel->chn_rescind_callback(channel);
1129
1130                         if (clean_up_chan_for_suspend)
1131                                 check_ready_for_suspend_event();
1132
1133                         return;
1134                 }
1135                 /*
1136                  * We will have to unregister this device from the
1137                  * driver core.
1138                  */
1139                 dev = get_device(&channel->device_obj->device);
1140                 if (dev) {
1141                         vmbus_device_unregister(channel->device_obj);
1142                         put_device(dev);
1143                 }
1144         } else if (channel->primary_channel != NULL) {
1145                 /*
1146                  * Sub-channel is being rescinded. Following is the channel
1147                  * close sequence when initiated from the driveri (refer to
1148                  * vmbus_close() for details):
1149                  * 1. Close all sub-channels first
1150                  * 2. Then close the primary channel.
1151                  */
1152                 mutex_lock(&vmbus_connection.channel_mutex);
1153                 if (channel->state == CHANNEL_OPEN_STATE) {
1154                         /*
1155                          * The channel is currently not open;
1156                          * it is safe for us to cleanup the channel.
1157                          */
1158                         hv_process_channel_removal(channel);
1159                 } else {
1160                         complete(&channel->rescind_event);
1161                 }
1162                 mutex_unlock(&vmbus_connection.channel_mutex);
1163         }
1164
1165         /* The "channel" may have been freed. Do not access it any longer. */
1166
1167         if (clean_up_chan_for_suspend)
1168                 check_ready_for_suspend_event();
1169 }
1170
1171 void vmbus_hvsock_device_unregister(struct vmbus_channel *channel)
1172 {
1173         BUG_ON(!is_hvsock_channel(channel));
1174
1175         /* We always get a rescind msg when a connection is closed. */
1176         while (!READ_ONCE(channel->probe_done) || !READ_ONCE(channel->rescind))
1177                 msleep(1);
1178
1179         vmbus_device_unregister(channel->device_obj);
1180 }
1181 EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister);
1182
1183
1184 /*
1185  * vmbus_onoffers_delivered -
1186  * This is invoked when all offers have been delivered.
1187  *
1188  * Nothing to do here.
1189  */
1190 static void vmbus_onoffers_delivered(
1191                         struct vmbus_channel_message_header *hdr)
1192 {
1193 }
1194
1195 /*
1196  * vmbus_onopen_result - Open result handler.
1197  *
1198  * This is invoked when we received a response to our channel open request.
1199  * Find the matching request, copy the response and signal the requesting
1200  * thread.
1201  */
1202 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
1203 {
1204         struct vmbus_channel_open_result *result;
1205         struct vmbus_channel_msginfo *msginfo;
1206         struct vmbus_channel_message_header *requestheader;
1207         struct vmbus_channel_open_channel *openmsg;
1208         unsigned long flags;
1209
1210         result = (struct vmbus_channel_open_result *)hdr;
1211
1212         trace_vmbus_onopen_result(result);
1213
1214         /*
1215          * Find the open msg, copy the result and signal/unblock the wait event
1216          */
1217         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1218
1219         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1220                                 msglistentry) {
1221                 requestheader =
1222                         (struct vmbus_channel_message_header *)msginfo->msg;
1223
1224                 if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
1225                         openmsg =
1226                         (struct vmbus_channel_open_channel *)msginfo->msg;
1227                         if (openmsg->child_relid == result->child_relid &&
1228                             openmsg->openid == result->openid) {
1229                                 memcpy(&msginfo->response.open_result,
1230                                        result,
1231                                        sizeof(
1232                                         struct vmbus_channel_open_result));
1233                                 complete(&msginfo->waitevent);
1234                                 break;
1235                         }
1236                 }
1237         }
1238         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1239 }
1240
1241 /*
1242  * vmbus_ongpadl_created - GPADL created handler.
1243  *
1244  * This is invoked when we received a response to our gpadl create request.
1245  * Find the matching request, copy the response and signal the requesting
1246  * thread.
1247  */
1248 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
1249 {
1250         struct vmbus_channel_gpadl_created *gpadlcreated;
1251         struct vmbus_channel_msginfo *msginfo;
1252         struct vmbus_channel_message_header *requestheader;
1253         struct vmbus_channel_gpadl_header *gpadlheader;
1254         unsigned long flags;
1255
1256         gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
1257
1258         trace_vmbus_ongpadl_created(gpadlcreated);
1259
1260         /*
1261          * Find the establish msg, copy the result and signal/unblock the wait
1262          * event
1263          */
1264         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1265
1266         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1267                                 msglistentry) {
1268                 requestheader =
1269                         (struct vmbus_channel_message_header *)msginfo->msg;
1270
1271                 if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
1272                         gpadlheader =
1273                         (struct vmbus_channel_gpadl_header *)requestheader;
1274
1275                         if ((gpadlcreated->child_relid ==
1276                              gpadlheader->child_relid) &&
1277                             (gpadlcreated->gpadl == gpadlheader->gpadl)) {
1278                                 memcpy(&msginfo->response.gpadl_created,
1279                                        gpadlcreated,
1280                                        sizeof(
1281                                         struct vmbus_channel_gpadl_created));
1282                                 complete(&msginfo->waitevent);
1283                                 break;
1284                         }
1285                 }
1286         }
1287         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1288 }
1289
1290 /*
1291  * vmbus_ongpadl_torndown - GPADL torndown handler.
1292  *
1293  * This is invoked when we received a response to our gpadl teardown request.
1294  * Find the matching request, copy the response and signal the requesting
1295  * thread.
1296  */
1297 static void vmbus_ongpadl_torndown(
1298                         struct vmbus_channel_message_header *hdr)
1299 {
1300         struct vmbus_channel_gpadl_torndown *gpadl_torndown;
1301         struct vmbus_channel_msginfo *msginfo;
1302         struct vmbus_channel_message_header *requestheader;
1303         struct vmbus_channel_gpadl_teardown *gpadl_teardown;
1304         unsigned long flags;
1305
1306         gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
1307
1308         trace_vmbus_ongpadl_torndown(gpadl_torndown);
1309
1310         /*
1311          * Find the open msg, copy the result and signal/unblock the wait event
1312          */
1313         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1314
1315         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1316                                 msglistentry) {
1317                 requestheader =
1318                         (struct vmbus_channel_message_header *)msginfo->msg;
1319
1320                 if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
1321                         gpadl_teardown =
1322                         (struct vmbus_channel_gpadl_teardown *)requestheader;
1323
1324                         if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
1325                                 memcpy(&msginfo->response.gpadl_torndown,
1326                                        gpadl_torndown,
1327                                        sizeof(
1328                                         struct vmbus_channel_gpadl_torndown));
1329                                 complete(&msginfo->waitevent);
1330                                 break;
1331                         }
1332                 }
1333         }
1334         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1335 }
1336
1337 /*
1338  * vmbus_onversion_response - Version response handler
1339  *
1340  * This is invoked when we received a response to our initiate contact request.
1341  * Find the matching request, copy the response and signal the requesting
1342  * thread.
1343  */
1344 static void vmbus_onversion_response(
1345                 struct vmbus_channel_message_header *hdr)
1346 {
1347         struct vmbus_channel_msginfo *msginfo;
1348         struct vmbus_channel_message_header *requestheader;
1349         struct vmbus_channel_version_response *version_response;
1350         unsigned long flags;
1351
1352         version_response = (struct vmbus_channel_version_response *)hdr;
1353
1354         trace_vmbus_onversion_response(version_response);
1355
1356         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1357
1358         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1359                                 msglistentry) {
1360                 requestheader =
1361                         (struct vmbus_channel_message_header *)msginfo->msg;
1362
1363                 if (requestheader->msgtype ==
1364                     CHANNELMSG_INITIATE_CONTACT) {
1365                         memcpy(&msginfo->response.version_response,
1366                               version_response,
1367                               sizeof(struct vmbus_channel_version_response));
1368                         complete(&msginfo->waitevent);
1369                 }
1370         }
1371         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1372 }
1373
1374 /* Channel message dispatch table */
1375 const struct vmbus_channel_message_table_entry
1376 channel_message_table[CHANNELMSG_COUNT] = {
1377         { CHANNELMSG_INVALID,                   0, NULL, 0},
1378         { CHANNELMSG_OFFERCHANNEL,              0, vmbus_onoffer,
1379                 sizeof(struct vmbus_channel_offer_channel)},
1380         { CHANNELMSG_RESCIND_CHANNELOFFER,      0, vmbus_onoffer_rescind,
1381                 sizeof(struct vmbus_channel_rescind_offer) },
1382         { CHANNELMSG_REQUESTOFFERS,             0, NULL, 0},
1383         { CHANNELMSG_ALLOFFERS_DELIVERED,       1, vmbus_onoffers_delivered, 0},
1384         { CHANNELMSG_OPENCHANNEL,               0, NULL, 0},
1385         { CHANNELMSG_OPENCHANNEL_RESULT,        1, vmbus_onopen_result,
1386                 sizeof(struct vmbus_channel_open_result)},
1387         { CHANNELMSG_CLOSECHANNEL,              0, NULL, 0},
1388         { CHANNELMSG_GPADL_HEADER,              0, NULL, 0},
1389         { CHANNELMSG_GPADL_BODY,                0, NULL, 0},
1390         { CHANNELMSG_GPADL_CREATED,             1, vmbus_ongpadl_created,
1391                 sizeof(struct vmbus_channel_gpadl_created)},
1392         { CHANNELMSG_GPADL_TEARDOWN,            0, NULL, 0},
1393         { CHANNELMSG_GPADL_TORNDOWN,            1, vmbus_ongpadl_torndown,
1394                 sizeof(struct vmbus_channel_gpadl_torndown) },
1395         { CHANNELMSG_RELID_RELEASED,            0, NULL, 0},
1396         { CHANNELMSG_INITIATE_CONTACT,          0, NULL, 0},
1397         { CHANNELMSG_VERSION_RESPONSE,          1, vmbus_onversion_response,
1398                 sizeof(struct vmbus_channel_version_response)},
1399         { CHANNELMSG_UNLOAD,                    0, NULL, 0},
1400         { CHANNELMSG_UNLOAD_RESPONSE,           1, vmbus_unload_response, 0},
1401         { CHANNELMSG_18,                        0, NULL, 0},
1402         { CHANNELMSG_19,                        0, NULL, 0},
1403         { CHANNELMSG_20,                        0, NULL, 0},
1404         { CHANNELMSG_TL_CONNECT_REQUEST,        0, NULL, 0},
1405         { CHANNELMSG_MODIFYCHANNEL,             0, NULL, 0},
1406         { CHANNELMSG_TL_CONNECT_RESULT,         0, NULL, 0},
1407 };
1408
1409 /*
1410  * vmbus_onmessage - Handler for channel protocol messages.
1411  *
1412  * This is invoked in the vmbus worker thread context.
1413  */
1414 void vmbus_onmessage(struct vmbus_channel_message_header *hdr)
1415 {
1416         trace_vmbus_on_message(hdr);
1417
1418         /*
1419          * vmbus_on_msg_dpc() makes sure the hdr->msgtype here can not go
1420          * out of bound and the message_handler pointer can not be NULL.
1421          */
1422         channel_message_table[hdr->msgtype].message_handler(hdr);
1423 }
1424
1425 /*
1426  * vmbus_request_offers - Send a request to get all our pending offers.
1427  */
1428 int vmbus_request_offers(void)
1429 {
1430         struct vmbus_channel_message_header *msg;
1431         struct vmbus_channel_msginfo *msginfo;
1432         int ret;
1433
1434         msginfo = kmalloc(sizeof(*msginfo) +
1435                           sizeof(struct vmbus_channel_message_header),
1436                           GFP_KERNEL);
1437         if (!msginfo)
1438                 return -ENOMEM;
1439
1440         msg = (struct vmbus_channel_message_header *)msginfo->msg;
1441
1442         msg->msgtype = CHANNELMSG_REQUESTOFFERS;
1443
1444         ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_message_header),
1445                              true);
1446
1447         trace_vmbus_request_offers(ret);
1448
1449         if (ret != 0) {
1450                 pr_err("Unable to request offers - %d\n", ret);
1451
1452                 goto cleanup;
1453         }
1454
1455 cleanup:
1456         kfree(msginfo);
1457
1458         return ret;
1459 }
1460
1461 static void invoke_sc_cb(struct vmbus_channel *primary_channel)
1462 {
1463         struct list_head *cur, *tmp;
1464         struct vmbus_channel *cur_channel;
1465
1466         if (primary_channel->sc_creation_callback == NULL)
1467                 return;
1468
1469         list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
1470                 cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
1471
1472                 primary_channel->sc_creation_callback(cur_channel);
1473         }
1474 }
1475
1476 void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
1477                                 void (*sc_cr_cb)(struct vmbus_channel *new_sc))
1478 {
1479         primary_channel->sc_creation_callback = sc_cr_cb;
1480 }
1481 EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
1482
1483 bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
1484 {
1485         bool ret;
1486
1487         ret = !list_empty(&primary->sc_list);
1488
1489         if (ret) {
1490                 /*
1491                  * Invoke the callback on sub-channel creation.
1492                  * This will present a uniform interface to the
1493                  * clients.
1494                  */
1495                 invoke_sc_cb(primary);
1496         }
1497
1498         return ret;
1499 }
1500 EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);
1501
1502 void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel,
1503                 void (*chn_rescind_cb)(struct vmbus_channel *))
1504 {
1505         channel->chn_rescind_callback = chn_rescind_cb;
1506 }
1507 EXPORT_SYMBOL_GPL(vmbus_set_chn_rescind_callback);