drivers/hv/channel_mgmt.c

   1 /*
   2  * Copyright (c) 2009, Microsoft Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  15  * Place - Suite 330, Boston, MA 02111-1307 USA.
  16  *
  17  * Authors:
  18  *   Haiyang Zhang <haiyangz@microsoft.com>
  19  *   Hank Janssen  <hjanssen@microsoft.com>
  20  */
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/kernel.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/sched.h>
  26 #include <linux/wait.h>
  27 #include <linux/mm.h>
  28 #include <linux/slab.h>
  29 #include <linux/list.h>
  30 #include <linux/module.h>
  31 #include <linux/completion.h>
  32 #include <linux/delay.h>
  33 #include <linux/hyperv.h>
  34 #include <asm/mshyperv.h>
  35
  36 #include "hyperv_vmbus.h"
  37
  38 static void init_vp_index(struct vmbus_channel *channel, u16 dev_type);
  39
  40 static const struct vmbus_device vmbus_devs[] = {
  41         /* IDE */
  42         { .dev_type = HV_IDE,
  43           HV_IDE_GUID,
  44           .perf_device = true,
  45         },
  46
  47         /* SCSI */
  48         { .dev_type = HV_SCSI,
  49           HV_SCSI_GUID,
  50           .perf_device = true,
  51         },
  52
  53         /* Fibre Channel */
  54         { .dev_type = HV_FC,
  55           HV_SYNTHFC_GUID,
  56           .perf_device = true,
  57         },
  58
  59         /* Synthetic NIC */
  60         { .dev_type = HV_NIC,
  61           HV_NIC_GUID,
  62           .perf_device = true,
  63         },
  64
  65         /* Network Direct */
  66         { .dev_type = HV_ND,
  67           HV_ND_GUID,
  68           .perf_device = true,
  69         },
  70
  71         /* PCIE */
  72         { .dev_type = HV_PCIE,
  73           HV_PCIE_GUID,
  74           .perf_device = false,
  75         },
  76
  77         /* Synthetic Frame Buffer */
  78         { .dev_type = HV_FB,
  79           HV_SYNTHVID_GUID,
  80           .perf_device = false,
  81         },
  82
  83         /* Synthetic Keyboard */
  84         { .dev_type = HV_KBD,
  85           HV_KBD_GUID,
  86           .perf_device = false,
  87         },
  88
  89         /* Synthetic MOUSE */
  90         { .dev_type = HV_MOUSE,
  91           HV_MOUSE_GUID,
  92           .perf_device = false,
  93         },
  94
  95         /* KVP */
  96         { .dev_type = HV_KVP,
  97           HV_KVP_GUID,
  98           .perf_device = false,
  99         },
 100
 101         /* Time Synch */
 102         { .dev_type = HV_TS,
 103           HV_TS_GUID,
 104           .perf_device = false,
 105         },
 106
 107         /* Heartbeat */
 108         { .dev_type = HV_HB,
 109           HV_HEART_BEAT_GUID,
 110           .perf_device = false,
 111         },
 112
 113         /* Shutdown */
 114         { .dev_type = HV_SHUTDOWN,
 115           HV_SHUTDOWN_GUID,
 116           .perf_device = false,
 117         },
 118
 119         /* File copy */
 120         { .dev_type = HV_FCOPY,
 121           HV_FCOPY_GUID,
 122           .perf_device = false,
 123         },
 124
 125         /* Backup */
 126         { .dev_type = HV_BACKUP,
 127           HV_VSS_GUID,
 128           .perf_device = false,
 129         },
 130
 131         /* Dynamic Memory */
 132         { .dev_type = HV_DM,
 133           HV_DM_GUID,
 134           .perf_device = false,
 135         },
 136
 137         /* Unknown GUID */
 138         { .dev_type = HV_UNKNOWN,
 139           .perf_device = false,
 140         },
 141 };
 142
 143 static const struct {
 144         guid_t guid;
 145 } vmbus_unsupported_devs[] = {
 146         { HV_AVMA1_GUID },
 147         { HV_AVMA2_GUID },
 148         { HV_RDV_GUID   },
 149 };
 150
 151 /*
 152  * The rescinded channel may be blocked waiting for a response from the host;
 153  * take care of that.
 154  */
 155 static void vmbus_rescind_cleanup(struct vmbus_channel *channel)
 156 {
 157         struct vmbus_channel_msginfo *msginfo;
 158         unsigned long flags;
 159
 160
 161         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 162         channel->rescind = true;
 163         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 164                                 msglistentry) {
 165
 166                 if (msginfo->waiting_channel == channel) {
 167                         complete(&msginfo->waitevent);
 168                         break;
 169                 }
 170         }
 171         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 172 }
 173
 174 static bool is_unsupported_vmbus_devs(const guid_t *guid)
 175 {
 176         int i;
 177
 178         for (i = 0; i < ARRAY_SIZE(vmbus_unsupported_devs); i++)
 179                 if (guid_equal(guid, &vmbus_unsupported_devs[i].guid))
 180                         return true;
 181         return false;
 182 }
 183
 184 static u16 hv_get_dev_type(const struct vmbus_channel *channel)
 185 {
 186         const guid_t *guid = &channel->offermsg.offer.if_type;
 187         u16 i;
 188
 189         if (is_hvsock_channel(channel) || is_unsupported_vmbus_devs(guid))
 190                 return HV_UNKNOWN;
 191
 192         for (i = HV_IDE; i < HV_UNKNOWN; i++) {
 193                 if (guid_equal(guid, &vmbus_devs[i].guid))
 194                         return i;
 195         }
 196         pr_info("Unknown GUID: %pUl\n", guid);
 197         return i;
 198 }
 199
 200 /**
 201  * vmbus_prep_negotiate_resp() - Create default response for Negotiate message
 202  * @icmsghdrp: Pointer to msg header structure
 203  * @buf: Raw buffer channel data
 204  * @fw_version: The framework versions we can support.
 205  * @fw_vercnt: The size of @fw_version.
 206  * @srv_version: The service versions we can support.
 207  * @srv_vercnt: The size of @srv_version.
 208  * @nego_fw_version: The selected framework version.
 209  * @nego_srv_version: The selected service version.
 210  *
 211  * Note: Versions are given in decreasing order.
 212  *
 213  * Set up and fill in default negotiate response message.
 214  * Mainly used by Hyper-V drivers.
 215  */
 216 bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
 217                                 u8 *buf, const int *fw_version, int fw_vercnt,
 218                                 const int *srv_version, int srv_vercnt,
 219                                 int *nego_fw_version, int *nego_srv_version)
 220 {
 221         int icframe_major, icframe_minor;
 222         int icmsg_major, icmsg_minor;
 223         int fw_major, fw_minor;
 224         int srv_major, srv_minor;
 225         int i, j;
 226         bool found_match = false;
 227         struct icmsg_negotiate *negop;
 228
 229         icmsghdrp->icmsgsize = 0x10;
 230         negop = (struct icmsg_negotiate *)&buf[
 231                 sizeof(struct vmbuspipe_hdr) +
 232                 sizeof(struct icmsg_hdr)];
 233
 234         icframe_major = negop->icframe_vercnt;
 235         icframe_minor = 0;
 236
 237         icmsg_major = negop->icmsg_vercnt;
 238         icmsg_minor = 0;
 239
 240         /*
 241          * Select the framework version number we will
 242          * support.
 243          */
 244
 245         for (i = 0; i < fw_vercnt; i++) {
 246                 fw_major = (fw_version[i] >> 16);
 247                 fw_minor = (fw_version[i] & 0xFFFF);
 248
 249                 for (j = 0; j < negop->icframe_vercnt; j++) {
 250                         if ((negop->icversion_data[j].major == fw_major) &&
 251                             (negop->icversion_data[j].minor == fw_minor)) {
 252                                 icframe_major = negop->icversion_data[j].major;
 253                                 icframe_minor = negop->icversion_data[j].minor;
 254                                 found_match = true;
 255                                 break;
 256                         }
 257                 }
 258
 259                 if (found_match)
 260                         break;
 261         }
 262
 263         if (!found_match)
 264                 goto fw_error;
 265
 266         found_match = false;
 267
 268         for (i = 0; i < srv_vercnt; i++) {
 269                 srv_major = (srv_version[i] >> 16);
 270                 srv_minor = (srv_version[i] & 0xFFFF);
 271
 272                 for (j = negop->icframe_vercnt;
 273                         (j < negop->icframe_vercnt + negop->icmsg_vercnt);
 274                         j++) {
 275
 276                         if ((negop->icversion_data[j].major == srv_major) &&
 277                                 (negop->icversion_data[j].minor == srv_minor)) {
 278
 279                                 icmsg_major = negop->icversion_data[j].major;
 280                                 icmsg_minor = negop->icversion_data[j].minor;
 281                                 found_match = true;
 282                                 break;
 283                         }
 284                 }
 285
 286                 if (found_match)
 287                         break;
 288         }
 289
 290         /*
 291          * Respond with the framework and service
 292          * version numbers we can support.
 293          */
 294
 295 fw_error:
 296         if (!found_match) {
 297                 negop->icframe_vercnt = 0;
 298                 negop->icmsg_vercnt = 0;
 299         } else {
 300                 negop->icframe_vercnt = 1;
 301                 negop->icmsg_vercnt = 1;
 302         }
 303
 304         if (nego_fw_version)
 305                 *nego_fw_version = (icframe_major << 16) | icframe_minor;
 306
 307         if (nego_srv_version)
 308                 *nego_srv_version = (icmsg_major << 16) | icmsg_minor;
 309
 310         negop->icversion_data[0].major = icframe_major;
 311         negop->icversion_data[0].minor = icframe_minor;
 312         negop->icversion_data[1].major = icmsg_major;
 313         negop->icversion_data[1].minor = icmsg_minor;
 314         return found_match;
 315 }
 316
 317 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
 318
 319 /*
 320  * alloc_channel - Allocate and initialize a vmbus channel object
 321  */
 322 static struct vmbus_channel *alloc_channel(void)
 323 {
 324         struct vmbus_channel *channel;
 325
 326         channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
 327         if (!channel)
 328                 return NULL;
 329
 330         spin_lock_init(&channel->lock);
 331         init_completion(&channel->rescind_event);
 332
 333         INIT_LIST_HEAD(&channel->sc_list);
 334         INIT_LIST_HEAD(&channel->percpu_list);
 335
 336         tasklet_init(&channel->callback_event,
 337                      vmbus_on_event, (unsigned long)channel);
 338
 339         hv_ringbuffer_pre_init(channel);
 340
 341         return channel;
 342 }
 343
 344 /*
 345  * free_channel - Release the resources used by the vmbus channel object
 346  */
 347 static void free_channel(struct vmbus_channel *channel)
 348 {
 349         tasklet_kill(&channel->callback_event);
 350         vmbus_remove_channel_attr_group(channel);
 351
 352         kobject_put(&channel->kobj);
 353 }
 354
 355 static void percpu_channel_enq(void *arg)
 356 {
 357         struct vmbus_channel *channel = arg;
 358         struct hv_per_cpu_context *hv_cpu
 359                 = this_cpu_ptr(hv_context.cpu_context);
 360
 361         list_add_tail_rcu(&channel->percpu_list, &hv_cpu->chan_list);
 362 }
 363
 364 static void percpu_channel_deq(void *arg)
 365 {
 366         struct vmbus_channel *channel = arg;
 367
 368         list_del_rcu(&channel->percpu_list);
 369 }
 370
 371
 372 static void vmbus_release_relid(u32 relid)
 373 {
 374         struct vmbus_channel_relid_released msg;
 375         int ret;
 376
 377         memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
 378         msg.child_relid = relid;
 379         msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
 380         ret = vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released),
 381                              true);
 382
 383         trace_vmbus_release_relid(&msg, ret);
 384 }
 385
 386 void hv_process_channel_removal(struct vmbus_channel *channel)
 387 {
 388         struct vmbus_channel *primary_channel;
 389         unsigned long flags;
 390
 391         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 392         BUG_ON(!channel->rescind);
 393
 394         if (channel->target_cpu != get_cpu()) {
 395                 put_cpu();
 396                 smp_call_function_single(channel->target_cpu,
 397                                          percpu_channel_deq, channel, true);
 398         } else {
 399                 percpu_channel_deq(channel);
 400                 put_cpu();
 401         }
 402
 403         if (channel->primary_channel == NULL) {
 404                 list_del(&channel->listentry);
 405
 406                 primary_channel = channel;
 407         } else {
 408                 primary_channel = channel->primary_channel;
 409                 spin_lock_irqsave(&primary_channel->lock, flags);
 410                 list_del(&channel->sc_list);
 411                 spin_unlock_irqrestore(&primary_channel->lock, flags);
 412         }
 413
 414         /*
 415          * We need to free the bit for init_vp_index() to work in the case
 416          * of sub-channel, when we reload drivers like hv_netvsc.
 417          */
 418         if (channel->affinity_policy == HV_LOCALIZED)
 419                 cpumask_clear_cpu(channel->target_cpu,
 420                                   &primary_channel->alloced_cpus_in_node);
 421
 422         vmbus_release_relid(channel->offermsg.child_relid);
 423
 424         free_channel(channel);
 425 }
 426
 427 void vmbus_free_channels(void)
 428 {
 429         struct vmbus_channel *channel, *tmp;
 430
 431         list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,
 432                 listentry) {
 433                 /* hv_process_channel_removal() needs this */
 434                 channel->rescind = true;
 435
 436                 vmbus_device_unregister(channel->device_obj);
 437         }
 438 }
 439
 440 /* Note: the function can run concurrently for primary/sub channels. */
 441 static void vmbus_add_channel_work(struct work_struct *work)
 442 {
 443         struct vmbus_channel *newchannel =
 444                 container_of(work, struct vmbus_channel, add_channel_work);
 445         struct vmbus_channel *primary_channel = newchannel->primary_channel;
 446         unsigned long flags;
 447         u16 dev_type;
 448         int ret;
 449
 450         dev_type = hv_get_dev_type(newchannel);
 451
 452         init_vp_index(newchannel, dev_type);
 453
 454         if (newchannel->target_cpu != get_cpu()) {
 455                 put_cpu();
 456                 smp_call_function_single(newchannel->target_cpu,
 457                                          percpu_channel_enq,
 458                                          newchannel, true);
 459         } else {
 460                 percpu_channel_enq(newchannel);
 461                 put_cpu();
 462         }
 463
 464         /*
 465          * This state is used to indicate a successful open
 466          * so that when we do close the channel normally, we
 467          * can cleanup properly.
 468          */
 469         newchannel->state = CHANNEL_OPEN_STATE;
 470
 471         if (primary_channel != NULL) {
 472                 /* newchannel is a sub-channel. */
 473                 struct hv_device *dev = primary_channel->device_obj;
 474
 475                 if (vmbus_add_channel_kobj(dev, newchannel))
 476                         goto err_deq_chan;
 477
 478                 if (primary_channel->sc_creation_callback != NULL)
 479                         primary_channel->sc_creation_callback(newchannel);
 480
 481                 newchannel->probe_done = true;
 482                 return;
 483         }
 484
 485         /*
 486          * Start the process of binding the primary channel to the driver
 487          */
 488         newchannel->device_obj = vmbus_device_create(
 489                 &newchannel->offermsg.offer.if_type,
 490                 &newchannel->offermsg.offer.if_instance,
 491                 newchannel);
 492         if (!newchannel->device_obj)
 493                 goto err_deq_chan;
 494
 495         newchannel->device_obj->device_id = dev_type;
 496         /*
 497          * Add the new device to the bus. This will kick off device-driver
 498          * binding which eventually invokes the device driver's AddDevice()
 499          * method.
 500          */
 501         ret = vmbus_device_register(newchannel->device_obj);
 502
 503         if (ret != 0) {
 504                 pr_err("unable to add child device object (relid %d)\n",
 505                         newchannel->offermsg.child_relid);
 506                 kfree(newchannel->device_obj);
 507                 goto err_deq_chan;
 508         }
 509
 510         newchannel->probe_done = true;
 511         return;
 512
 513 err_deq_chan:
 514         mutex_lock(&vmbus_connection.channel_mutex);
 515
 516         /*
 517          * We need to set the flag, otherwise
 518          * vmbus_onoffer_rescind() can be blocked.
 519          */
 520         newchannel->probe_done = true;
 521
 522         if (primary_channel == NULL) {
 523                 list_del(&newchannel->listentry);
 524         } else {
 525                 spin_lock_irqsave(&primary_channel->lock, flags);
 526                 list_del(&newchannel->sc_list);
 527                 spin_unlock_irqrestore(&primary_channel->lock, flags);
 528         }
 529
 530         mutex_unlock(&vmbus_connection.channel_mutex);
 531
 532         if (newchannel->target_cpu != get_cpu()) {
 533                 put_cpu();
 534                 smp_call_function_single(newchannel->target_cpu,
 535                                          percpu_channel_deq,
 536                                          newchannel, true);
 537         } else {
 538                 percpu_channel_deq(newchannel);
 539                 put_cpu();
 540         }
 541
 542         vmbus_release_relid(newchannel->offermsg.child_relid);
 543
 544         free_channel(newchannel);
 545 }
 546
 547 /*
 548  * vmbus_process_offer - Process the offer by creating a channel/device
 549  * associated with this offer
 550  */
 551 static void vmbus_process_offer(struct vmbus_channel *newchannel)
 552 {
 553         struct vmbus_channel *channel;
 554         struct workqueue_struct *wq;
 555         unsigned long flags;
 556         bool fnew = true;
 557
 558         mutex_lock(&vmbus_connection.channel_mutex);
 559
 560         /*
 561          * Now that we have acquired the channel_mutex,
 562          * we can release the potentially racing rescind thread.
 563          */
 564         atomic_dec(&vmbus_connection.offer_in_progress);
 565
 566         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 567                 if (guid_equal(&channel->offermsg.offer.if_type,
 568                                &newchannel->offermsg.offer.if_type) &&
 569                     guid_equal(&channel->offermsg.offer.if_instance,
 570                                &newchannel->offermsg.offer.if_instance)) {
 571                         fnew = false;
 572                         break;
 573                 }
 574         }
 575
 576         if (fnew)
 577                 list_add_tail(&newchannel->listentry,
 578                               &vmbus_connection.chn_list);
 579         else {
 580                 /*
 581                  * Check to see if this is a valid sub-channel.
 582                  */
 583                 if (newchannel->offermsg.offer.sub_channel_index == 0) {
 584                         mutex_unlock(&vmbus_connection.channel_mutex);
 585                         /*
 586                          * Don't call free_channel(), because newchannel->kobj
 587                          * is not initialized yet.
 588                          */
 589                         kfree(newchannel);
 590                         WARN_ON_ONCE(1);
 591                         return;
 592                 }
 593                 /*
 594                  * Process the sub-channel.
 595                  */
 596                 newchannel->primary_channel = channel;
 597                 spin_lock_irqsave(&channel->lock, flags);
 598                 list_add_tail(&newchannel->sc_list, &channel->sc_list);
 599                 spin_unlock_irqrestore(&channel->lock, flags);
 600         }
 601
 602         mutex_unlock(&vmbus_connection.channel_mutex);
 603
 604         /*
 605          * vmbus_process_offer() mustn't call channel->sc_creation_callback()
 606          * directly for sub-channels, because sc_creation_callback() ->
 607          * vmbus_open() may never get the host's response to the
 608          * OPEN_CHANNEL message (the host may rescind a channel at any time,
 609          * e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind()
 610          * may not wake up the vmbus_open() as it's blocked due to a non-zero
 611          * vmbus_connection.offer_in_progress, and finally we have a deadlock.
 612          *
 613          * The above is also true for primary channels, if the related device
 614          * drivers use sync probing mode by default.
 615          *
 616          * And, usually the handling of primary channels and sub-channels can
 617          * depend on each other, so we should offload them to different
 618          * workqueues to avoid possible deadlock, e.g. in sync-probing mode,
 619          * NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() ->
 620          * rtnl_lock(), and causes deadlock: the former gets the rtnl_lock
 621          * and waits for all the sub-channels to appear, but the latter
 622          * can't get the rtnl_lock and this blocks the handling of
 623          * sub-channels.
 624          */
 625         INIT_WORK(&newchannel->add_channel_work, vmbus_add_channel_work);
 626         wq = fnew ? vmbus_connection.handle_primary_chan_wq :
 627                     vmbus_connection.handle_sub_chan_wq;
 628         queue_work(wq, &newchannel->add_channel_work);
 629 }
 630
 631 /*
 632  * We use this state to statically distribute the channel interrupt load.
 633  */
 634 static int next_numa_node_id;
 635 /*
 636  * init_vp_index() accesses global variables like next_numa_node_id, and
 637  * it can run concurrently for primary channels and sub-channels: see
 638  * vmbus_process_offer(), so we need the lock to protect the global
 639  * variables.
 640  */
 641 static DEFINE_SPINLOCK(bind_channel_to_cpu_lock);
 642
 643 /*
 644  * Starting with Win8, we can statically distribute the incoming
 645  * channel interrupt load by binding a channel to VCPU.
 646  * We distribute the interrupt loads to one or more NUMA nodes based on
 647  * the channel's affinity_policy.
 648  *
 649  * For pre-win8 hosts or non-performance critical channels we assign the
 650  * first CPU in the first NUMA node.
 651  */
 652 static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
 653 {
 654         u32 cur_cpu;
 655         bool perf_chn = vmbus_devs[dev_type].perf_device;
 656         struct vmbus_channel *primary = channel->primary_channel;
 657         int next_node;
 658         cpumask_var_t available_mask;
 659         struct cpumask *alloced_mask;
 660
 661         if ((vmbus_proto_version == VERSION_WS2008) ||
 662             (vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
 663             !alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
 664                 /*
 665                  * Prior to win8, all channel interrupts are
 666                  * delivered on cpu 0.
 667                  * Also if the channel is not a performance critical
 668                  * channel, bind it to cpu 0.
 669                  * In case alloc_cpumask_var() fails, bind it to cpu 0.
 670                  */
 671                 channel->numa_node = 0;
 672                 channel->target_cpu = 0;
 673                 channel->target_vp = hv_cpu_number_to_vp_number(0);
 674                 return;
 675         }
 676
 677         spin_lock(&bind_channel_to_cpu_lock);
 678
 679         /*
 680          * Based on the channel affinity policy, we will assign the NUMA
 681          * nodes.
 682          */
 683
 684         if ((channel->affinity_policy == HV_BALANCED) || (!primary)) {
 685                 while (true) {
 686                         next_node = next_numa_node_id++;
 687                         if (next_node == nr_node_ids) {
 688                                 next_node = next_numa_node_id = 0;
 689                                 continue;
 690                         }
 691                         if (cpumask_empty(cpumask_of_node(next_node)))
 692                                 continue;
 693                         break;
 694                 }
 695                 channel->numa_node = next_node;
 696                 primary = channel;
 697         }
 698         alloced_mask = &hv_context.hv_numa_map[primary->numa_node];
 699
 700         if (cpumask_weight(alloced_mask) ==
 701             cpumask_weight(cpumask_of_node(primary->numa_node))) {
 702                 /*
 703                  * We have cycled through all the CPUs in the node;
 704                  * reset the alloced map.
 705                  */
 706                 cpumask_clear(alloced_mask);
 707         }
 708
 709         cpumask_xor(available_mask, alloced_mask,
 710                     cpumask_of_node(primary->numa_node));
 711
 712         cur_cpu = -1;
 713
 714         if (primary->affinity_policy == HV_LOCALIZED) {
 715                 /*
 716                  * Normally Hyper-V host doesn't create more subchannels
 717                  * than there are VCPUs on the node but it is possible when not
 718                  * all present VCPUs on the node are initialized by guest.
 719                  * Clear the alloced_cpus_in_node to start over.
 720                  */
 721                 if (cpumask_equal(&primary->alloced_cpus_in_node,
 722                                   cpumask_of_node(primary->numa_node)))
 723                         cpumask_clear(&primary->alloced_cpus_in_node);
 724         }
 725
 726         while (true) {
 727                 cur_cpu = cpumask_next(cur_cpu, available_mask);
 728                 if (cur_cpu >= nr_cpu_ids) {
 729                         cur_cpu = -1;
 730                         cpumask_copy(available_mask,
 731                                      cpumask_of_node(primary->numa_node));
 732                         continue;
 733                 }
 734
 735                 if (primary->affinity_policy == HV_LOCALIZED) {
 736                         /*
 737                          * NOTE: in the case of sub-channel, we clear the
 738                          * sub-channel related bit(s) in
 739                          * primary->alloced_cpus_in_node in
 740                          * hv_process_channel_removal(), so when we
 741                          * reload drivers like hv_netvsc in SMP guest, here
 742                          * we're able to re-allocate
 743                          * bit from primary->alloced_cpus_in_node.
 744                          */
 745                         if (!cpumask_test_cpu(cur_cpu,
 746                                               &primary->alloced_cpus_in_node)) {
 747                                 cpumask_set_cpu(cur_cpu,
 748                                                 &primary->alloced_cpus_in_node);
 749                                 cpumask_set_cpu(cur_cpu, alloced_mask);
 750                                 break;
 751                         }
 752                 } else {
 753                         cpumask_set_cpu(cur_cpu, alloced_mask);
 754                         break;
 755                 }
 756         }
 757
 758         channel->target_cpu = cur_cpu;
 759         channel->target_vp = hv_cpu_number_to_vp_number(cur_cpu);
 760
 761         spin_unlock(&bind_channel_to_cpu_lock);
 762
 763         free_cpumask_var(available_mask);
 764 }
 765
 766 static void vmbus_wait_for_unload(void)
 767 {
 768         int cpu;
 769         void *page_addr;
 770         struct hv_message *msg;
 771         struct vmbus_channel_message_header *hdr;
 772         u32 message_type;
 773
 774         /*
 775          * CHANNELMSG_UNLOAD_RESPONSE is always delivered to the CPU which was
 776          * used for initial contact or to CPU0 depending on host version. When
 777          * we're crashing on a different CPU let's hope that IRQ handler on
 778          * the cpu which receives CHANNELMSG_UNLOAD_RESPONSE is still
 779          * functional and vmbus_unload_response() will complete
 780          * vmbus_connection.unload_event. If not, the last thing we can do is
 781          * read message pages for all CPUs directly.
 782          */
 783         while (1) {
 784                 if (completion_done(&vmbus_connection.unload_event))
 785                         break;
 786
 787                 for_each_online_cpu(cpu) {
 788                         struct hv_per_cpu_context *hv_cpu
 789                                 = per_cpu_ptr(hv_context.cpu_context, cpu);
 790
 791                         page_addr = hv_cpu->synic_message_page;
 792                         msg = (struct hv_message *)page_addr
 793                                 + VMBUS_MESSAGE_SINT;
 794
 795                         message_type = READ_ONCE(msg->header.message_type);
 796                         if (message_type == HVMSG_NONE)
 797                                 continue;
 798
 799                         hdr = (struct vmbus_channel_message_header *)
 800                                 msg->u.payload;
 801
 802                         if (hdr->msgtype == CHANNELMSG_UNLOAD_RESPONSE)
 803                                 complete(&vmbus_connection.unload_event);
 804
 805                         vmbus_signal_eom(msg, message_type);
 806                 }
 807
 808                 mdelay(10);
 809         }
 810
 811         /*
 812          * We're crashing and already got the UNLOAD_RESPONSE, cleanup all
 813          * maybe-pending messages on all CPUs to be able to receive new
 814          * messages after we reconnect.
 815          */
 816         for_each_online_cpu(cpu) {
 817                 struct hv_per_cpu_context *hv_cpu
 818                         = per_cpu_ptr(hv_context.cpu_context, cpu);
 819
 820                 page_addr = hv_cpu->synic_message_page;
 821                 msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
 822                 msg->header.message_type = HVMSG_NONE;
 823         }
 824 }
 825
 826 /*
 827  * vmbus_unload_response - Handler for the unload response.
 828  */
 829 static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
 830 {
 831         /*
 832          * This is a global event; just wakeup the waiting thread.
 833          * Once we successfully unload, we can cleanup the monitor state.
 834          */
 835         complete(&vmbus_connection.unload_event);
 836 }
 837
 838 void vmbus_initiate_unload(bool crash)
 839 {
 840         struct vmbus_channel_message_header hdr;
 841
 842         /* Pre-Win2012R2 hosts don't support reconnect */
 843         if (vmbus_proto_version < VERSION_WIN8_1)
 844                 return;
 845
 846         init_completion(&vmbus_connection.unload_event);
 847         memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
 848         hdr.msgtype = CHANNELMSG_UNLOAD;
 849         vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header),
 850                        !crash);
 851
 852         /*
 853          * vmbus_initiate_unload() is also called on crash and the crash can be
 854          * happening in an interrupt context, where scheduling is impossible.
 855          */
 856         if (!crash)
 857                 wait_for_completion(&vmbus_connection.unload_event);
 858         else
 859                 vmbus_wait_for_unload();
 860 }
 861
 862 /*
 863  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
 864  *
 865  */
 866 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 867 {
 868         struct vmbus_channel_offer_channel *offer;
 869         struct vmbus_channel *newchannel;
 870
 871         offer = (struct vmbus_channel_offer_channel *)hdr;
 872
 873         trace_vmbus_onoffer(offer);
 874
 875         /* Allocate the channel object and save this offer. */
 876         newchannel = alloc_channel();
 877         if (!newchannel) {
 878                 vmbus_release_relid(offer->child_relid);
 879                 atomic_dec(&vmbus_connection.offer_in_progress);
 880                 pr_err("Unable to allocate channel object\n");
 881                 return;
 882         }
 883
 884         /*
 885          * Setup state for signalling the host.
 886          */
 887         newchannel->sig_event = VMBUS_EVENT_CONNECTION_ID;
 888
 889         if (vmbus_proto_version != VERSION_WS2008) {
 890                 newchannel->is_dedicated_interrupt =
 891                                 (offer->is_dedicated_interrupt != 0);
 892                 newchannel->sig_event = offer->connection_id;
 893         }
 894
 895         memcpy(&newchannel->offermsg, offer,
 896                sizeof(struct vmbus_channel_offer_channel));
 897         newchannel->monitor_grp = (u8)offer->monitorid / 32;
 898         newchannel->monitor_bit = (u8)offer->monitorid % 32;
 899
 900         vmbus_process_offer(newchannel);
 901 }
 902
 903 /*
 904  * vmbus_onoffer_rescind - Rescind offer handler.
 905  *
 906  * We queue a work item to process this offer synchronously
 907  */
 908 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 909 {
 910         struct vmbus_channel_rescind_offer *rescind;
 911         struct vmbus_channel *channel;
 912         struct device *dev;
 913
 914         rescind = (struct vmbus_channel_rescind_offer *)hdr;
 915
 916         trace_vmbus_onoffer_rescind(rescind);
 917
 918         /*
 919          * The offer msg and the corresponding rescind msg
 920          * from the host are guranteed to be ordered -
 921          * offer comes in first and then the rescind.
 922          * Since we process these events in work elements,
 923          * and with preemption, we may end up processing
 924          * the events out of order. Given that we handle these
 925          * work elements on the same CPU, this is possible only
 926          * in the case of preemption. In any case wait here
 927          * until the offer processing has moved beyond the
 928          * point where the channel is discoverable.
 929          */
 930
 931         while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
 932                 /*
 933                  * We wait here until any channel offer is currently
 934                  * being processed.
 935                  */
 936                 msleep(1);
 937         }
 938
 939         mutex_lock(&vmbus_connection.channel_mutex);
 940         channel = relid2channel(rescind->child_relid);
 941         mutex_unlock(&vmbus_connection.channel_mutex);
 942
 943         if (channel == NULL) {
 944                 /*
 945                  * We failed in processing the offer message;
 946                  * we would have cleaned up the relid in that
 947                  * failure path.
 948                  */
 949                 return;
 950         }
 951
 952         /*
 953          * Before setting channel->rescind in vmbus_rescind_cleanup(), we
 954          * should make sure the channel callback is not running any more.
 955          */
 956         vmbus_reset_channel_cb(channel);
 957
 958         /*
 959          * Now wait for offer handling to complete.
 960          */
 961         vmbus_rescind_cleanup(channel);
 962         while (READ_ONCE(channel->probe_done) == false) {
 963                 /*
 964                  * We wait here until any channel offer is currently
 965                  * being processed.
 966                  */
 967                 msleep(1);
 968         }
 969
 970         /*
 971          * At this point, the rescind handling can proceed safely.
 972          */
 973
 974         if (channel->device_obj) {
 975                 if (channel->chn_rescind_callback) {
 976                         channel->chn_rescind_callback(channel);
 977                         return;
 978                 }
 979                 /*
 980                  * We will have to unregister this device from the
 981                  * driver core.
 982                  */
 983                 dev = get_device(&channel->device_obj->device);
 984                 if (dev) {
 985                         vmbus_device_unregister(channel->device_obj);
 986                         put_device(dev);
 987                 }
 988         }
 989         if (channel->primary_channel != NULL) {
 990                 /*
 991                  * Sub-channel is being rescinded. Following is the channel
 992                  * close sequence when initiated from the driveri (refer to
 993                  * vmbus_close() for details):
 994                  * 1. Close all sub-channels first
 995                  * 2. Then close the primary channel.
 996                  */
 997                 mutex_lock(&vmbus_connection.channel_mutex);
 998                 if (channel->state == CHANNEL_OPEN_STATE) {
 999                         /*
1000                          * The channel is currently not open;
1001                          * it is safe for us to cleanup the channel.
1002                          */
1003                         hv_process_channel_removal(channel);
1004                 } else {
1005                         complete(&channel->rescind_event);
1006                 }
1007                 mutex_unlock(&vmbus_connection.channel_mutex);
1008         }
1009 }
1010
1011 void vmbus_hvsock_device_unregister(struct vmbus_channel *channel)
1012 {
1013         BUG_ON(!is_hvsock_channel(channel));
1014
1015         /* We always get a rescind msg when a connection is closed. */
1016         while (!READ_ONCE(channel->probe_done) || !READ_ONCE(channel->rescind))
1017                 msleep(1);
1018
1019         vmbus_device_unregister(channel->device_obj);
1020 }
1021 EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister);
1022
1023
1024 /*
1025  * vmbus_onoffers_delivered -
1026  * This is invoked when all offers have been delivered.
1027  *
1028  * Nothing to do here.
1029  */
1030 static void vmbus_onoffers_delivered(
1031                         struct vmbus_channel_message_header *hdr)
1032 {
1033 }
1034
1035 /*
1036  * vmbus_onopen_result - Open result handler.
1037  *
1038  * This is invoked when we received a response to our channel open request.
1039  * Find the matching request, copy the response and signal the requesting
1040  * thread.
1041  */
1042 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
1043 {
1044         struct vmbus_channel_open_result *result;
1045         struct vmbus_channel_msginfo *msginfo;
1046         struct vmbus_channel_message_header *requestheader;
1047         struct vmbus_channel_open_channel *openmsg;
1048         unsigned long flags;
1049
1050         result = (struct vmbus_channel_open_result *)hdr;
1051
1052         trace_vmbus_onopen_result(result);
1053
1054         /*
1055          * Find the open msg, copy the result and signal/unblock the wait event
1056          */
1057         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1058
1059         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1060                                 msglistentry) {
1061                 requestheader =
1062                         (struct vmbus_channel_message_header *)msginfo->msg;
1063
1064                 if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
1065                         openmsg =
1066                         (struct vmbus_channel_open_channel *)msginfo->msg;
1067                         if (openmsg->child_relid == result->child_relid &&
1068                             openmsg->openid == result->openid) {
1069                                 memcpy(&msginfo->response.open_result,
1070                                        result,
1071                                        sizeof(
1072                                         struct vmbus_channel_open_result));
1073                                 complete(&msginfo->waitevent);
1074                                 break;
1075                         }
1076                 }
1077         }
1078         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1079 }
1080
1081 /*
1082  * vmbus_ongpadl_created - GPADL created handler.
1083  *
1084  * This is invoked when we received a response to our gpadl create request.
1085  * Find the matching request, copy the response and signal the requesting
1086  * thread.
1087  */
1088 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
1089 {
1090         struct vmbus_channel_gpadl_created *gpadlcreated;
1091         struct vmbus_channel_msginfo *msginfo;
1092         struct vmbus_channel_message_header *requestheader;
1093         struct vmbus_channel_gpadl_header *gpadlheader;
1094         unsigned long flags;
1095
1096         gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
1097
1098         trace_vmbus_ongpadl_created(gpadlcreated);
1099
1100         /*
1101          * Find the establish msg, copy the result and signal/unblock the wait
1102          * event
1103          */
1104         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1105
1106         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1107                                 msglistentry) {
1108                 requestheader =
1109                         (struct vmbus_channel_message_header *)msginfo->msg;
1110
1111                 if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
1112                         gpadlheader =
1113                         (struct vmbus_channel_gpadl_header *)requestheader;
1114
1115                         if ((gpadlcreated->child_relid ==
1116                              gpadlheader->child_relid) &&
1117                             (gpadlcreated->gpadl == gpadlheader->gpadl)) {
1118                                 memcpy(&msginfo->response.gpadl_created,
1119                                        gpadlcreated,
1120                                        sizeof(
1121                                         struct vmbus_channel_gpadl_created));
1122                                 complete(&msginfo->waitevent);
1123                                 break;
1124                         }
1125                 }
1126         }
1127         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1128 }
1129
1130 /*
1131  * vmbus_ongpadl_torndown - GPADL torndown handler.
1132  *
1133  * This is invoked when we received a response to our gpadl teardown request.
1134  * Find the matching request, copy the response and signal the requesting
1135  * thread.
1136  */
1137 static void vmbus_ongpadl_torndown(
1138                         struct vmbus_channel_message_header *hdr)
1139 {
1140         struct vmbus_channel_gpadl_torndown *gpadl_torndown;
1141         struct vmbus_channel_msginfo *msginfo;
1142         struct vmbus_channel_message_header *requestheader;
1143         struct vmbus_channel_gpadl_teardown *gpadl_teardown;
1144         unsigned long flags;
1145
1146         gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
1147
1148         trace_vmbus_ongpadl_torndown(gpadl_torndown);
1149
1150         /*
1151          * Find the open msg, copy the result and signal/unblock the wait event
1152          */
1153         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1154
1155         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1156                                 msglistentry) {
1157                 requestheader =
1158                         (struct vmbus_channel_message_header *)msginfo->msg;
1159
1160                 if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
1161                         gpadl_teardown =
1162                         (struct vmbus_channel_gpadl_teardown *)requestheader;
1163
1164                         if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
1165                                 memcpy(&msginfo->response.gpadl_torndown,
1166                                        gpadl_torndown,
1167                                        sizeof(
1168                                         struct vmbus_channel_gpadl_torndown));
1169                                 complete(&msginfo->waitevent);
1170                                 break;
1171                         }
1172                 }
1173         }
1174         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1175 }
1176
1177 /*
1178  * vmbus_onversion_response - Version response handler
1179  *
1180  * This is invoked when we received a response to our initiate contact request.
1181  * Find the matching request, copy the response and signal the requesting
1182  * thread.
1183  */
1184 static void vmbus_onversion_response(
1185                 struct vmbus_channel_message_header *hdr)
1186 {
1187         struct vmbus_channel_msginfo *msginfo;
1188         struct vmbus_channel_message_header *requestheader;
1189         struct vmbus_channel_version_response *version_response;
1190         unsigned long flags;
1191
1192         version_response = (struct vmbus_channel_version_response *)hdr;
1193
1194         trace_vmbus_onversion_response(version_response);
1195
1196         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1197
1198         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1199                                 msglistentry) {
1200                 requestheader =
1201                         (struct vmbus_channel_message_header *)msginfo->msg;
1202
1203                 if (requestheader->msgtype ==
1204                     CHANNELMSG_INITIATE_CONTACT) {
1205                         memcpy(&msginfo->response.version_response,
1206                               version_response,
1207                               sizeof(struct vmbus_channel_version_response));
1208                         complete(&msginfo->waitevent);
1209                 }
1210         }
1211         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1212 }
1213
1214 /* Channel message dispatch table */
1215 const struct vmbus_channel_message_table_entry
1216 channel_message_table[CHANNELMSG_COUNT] = {
1217         { CHANNELMSG_INVALID,                   0, NULL },
1218         { CHANNELMSG_OFFERCHANNEL,              0, vmbus_onoffer },
1219         { CHANNELMSG_RESCIND_CHANNELOFFER,      0, vmbus_onoffer_rescind },
1220         { CHANNELMSG_REQUESTOFFERS,             0, NULL },
1221         { CHANNELMSG_ALLOFFERS_DELIVERED,       1, vmbus_onoffers_delivered },
1222         { CHANNELMSG_OPENCHANNEL,               0, NULL },
1223         { CHANNELMSG_OPENCHANNEL_RESULT,        1, vmbus_onopen_result },
1224         { CHANNELMSG_CLOSECHANNEL,              0, NULL },
1225         { CHANNELMSG_GPADL_HEADER,              0, NULL },
1226         { CHANNELMSG_GPADL_BODY,                0, NULL },
1227         { CHANNELMSG_GPADL_CREATED,             1, vmbus_ongpadl_created },
1228         { CHANNELMSG_GPADL_TEARDOWN,            0, NULL },
1229         { CHANNELMSG_GPADL_TORNDOWN,            1, vmbus_ongpadl_torndown },
1230         { CHANNELMSG_RELID_RELEASED,            0, NULL },
1231         { CHANNELMSG_INITIATE_CONTACT,          0, NULL },
1232         { CHANNELMSG_VERSION_RESPONSE,          1, vmbus_onversion_response },
1233         { CHANNELMSG_UNLOAD,                    0, NULL },
1234         { CHANNELMSG_UNLOAD_RESPONSE,           1, vmbus_unload_response },
1235         { CHANNELMSG_18,                        0, NULL },
1236         { CHANNELMSG_19,                        0, NULL },
1237         { CHANNELMSG_20,                        0, NULL },
1238         { CHANNELMSG_TL_CONNECT_REQUEST,        0, NULL },
1239 };
1240
1241 /*
1242  * vmbus_onmessage - Handler for channel protocol messages.
1243  *
1244  * This is invoked in the vmbus worker thread context.
1245  */
1246 void vmbus_onmessage(void *context)
1247 {
1248         struct hv_message *msg = context;
1249         struct vmbus_channel_message_header *hdr;
1250         int size;
1251
1252         hdr = (struct vmbus_channel_message_header *)msg->u.payload;
1253         size = msg->header.payload_size;
1254
1255         trace_vmbus_on_message(hdr);
1256
1257         if (hdr->msgtype >= CHANNELMSG_COUNT) {
1258                 pr_err("Received invalid channel message type %d size %d\n",
1259                            hdr->msgtype, size);
1260                 print_hex_dump_bytes("", DUMP_PREFIX_NONE,
1261                                      (unsigned char *)msg->u.payload, size);
1262                 return;
1263         }
1264
1265         if (channel_message_table[hdr->msgtype].message_handler)
1266                 channel_message_table[hdr->msgtype].message_handler(hdr);
1267         else
1268                 pr_err("Unhandled channel message type %d\n", hdr->msgtype);
1269 }
1270
1271 /*
1272  * vmbus_request_offers - Send a request to get all our pending offers.
1273  */
1274 int vmbus_request_offers(void)
1275 {
1276         struct vmbus_channel_message_header *msg;
1277         struct vmbus_channel_msginfo *msginfo;
1278         int ret;
1279
1280         msginfo = kmalloc(sizeof(*msginfo) +
1281                           sizeof(struct vmbus_channel_message_header),
1282                           GFP_KERNEL);
1283         if (!msginfo)
1284                 return -ENOMEM;
1285
1286         msg = (struct vmbus_channel_message_header *)msginfo->msg;
1287
1288         msg->msgtype = CHANNELMSG_REQUESTOFFERS;
1289
1290         ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_message_header),
1291                              true);
1292
1293         trace_vmbus_request_offers(ret);
1294
1295         if (ret != 0) {
1296                 pr_err("Unable to request offers - %d\n", ret);
1297
1298                 goto cleanup;
1299         }
1300
1301 cleanup:
1302         kfree(msginfo);
1303
1304         return ret;
1305 }
1306
1307 static void invoke_sc_cb(struct vmbus_channel *primary_channel)
1308 {
1309         struct list_head *cur, *tmp;
1310         struct vmbus_channel *cur_channel;
1311
1312         if (primary_channel->sc_creation_callback == NULL)
1313                 return;
1314
1315         list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
1316                 cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
1317
1318                 primary_channel->sc_creation_callback(cur_channel);
1319         }
1320 }
1321
1322 void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
1323                                 void (*sc_cr_cb)(struct vmbus_channel *new_sc))
1324 {
1325         primary_channel->sc_creation_callback = sc_cr_cb;
1326 }
1327 EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
1328
1329 bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
1330 {
1331         bool ret;
1332
1333         ret = !list_empty(&primary->sc_list);
1334
1335         if (ret) {
1336                 /*
1337                  * Invoke the callback on sub-channel creation.
1338                  * This will present a uniform interface to the
1339                  * clients.
1340                  */
1341                 invoke_sc_cb(primary);
1342         }
1343
1344         return ret;
1345 }
1346 EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);
1347
1348 void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel,
1349                 void (*chn_rescind_cb)(struct vmbus_channel *))
1350 {
1351         channel->chn_rescind_callback = chn_rescind_cb;
1352 }
1353 EXPORT_SYMBOL_GPL(vmbus_set_chn_rescind_callback);