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         uuid_le 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 uuid_le *guid)
 175 {
 176         int i;
 177
 178         for (i = 0; i < ARRAY_SIZE(vmbus_unsupported_devs); i++)
 179                 if (!uuid_le_cmp(*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 uuid_le *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 (!uuid_le_cmp(*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         return channel;
 340 }
 341
 342 /*
 343  * free_channel - Release the resources used by the vmbus channel object
 344  */
 345 static void free_channel(struct vmbus_channel *channel)
 346 {
 347         tasklet_kill(&channel->callback_event);
 348
 349         kobject_put(&channel->kobj);
 350 }
 351
 352 static void percpu_channel_enq(void *arg)
 353 {
 354         struct vmbus_channel *channel = arg;
 355         struct hv_per_cpu_context *hv_cpu
 356                 = this_cpu_ptr(hv_context.cpu_context);
 357
 358         list_add_tail_rcu(&channel->percpu_list, &hv_cpu->chan_list);
 359 }
 360
 361 static void percpu_channel_deq(void *arg)
 362 {
 363         struct vmbus_channel *channel = arg;
 364
 365         list_del_rcu(&channel->percpu_list);
 366 }
 367
 368
 369 static void vmbus_release_relid(u32 relid)
 370 {
 371         struct vmbus_channel_relid_released msg;
 372         int ret;
 373
 374         memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
 375         msg.child_relid = relid;
 376         msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
 377         ret = vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released),
 378                              true);
 379
 380         trace_vmbus_release_relid(&msg, ret);
 381 }
 382
 383 void hv_process_channel_removal(struct vmbus_channel *channel)
 384 {
 385         struct vmbus_channel *primary_channel;
 386         unsigned long flags;
 387
 388         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
 389         BUG_ON(!channel->rescind);
 390
 391         if (channel->target_cpu != get_cpu()) {
 392                 put_cpu();
 393                 smp_call_function_single(channel->target_cpu,
 394                                          percpu_channel_deq, channel, true);
 395         } else {
 396                 percpu_channel_deq(channel);
 397                 put_cpu();
 398         }
 399
 400         if (channel->primary_channel == NULL) {
 401                 list_del(&channel->listentry);
 402
 403                 primary_channel = channel;
 404         } else {
 405                 primary_channel = channel->primary_channel;
 406                 spin_lock_irqsave(&primary_channel->lock, flags);
 407                 list_del(&channel->sc_list);
 408                 primary_channel->num_sc--;
 409                 spin_unlock_irqrestore(&primary_channel->lock, flags);
 410         }
 411
 412         /*
 413          * We need to free the bit for init_vp_index() to work in the case
 414          * of sub-channel, when we reload drivers like hv_netvsc.
 415          */
 416         if (channel->affinity_policy == HV_LOCALIZED)
 417                 cpumask_clear_cpu(channel->target_cpu,
 418                                   &primary_channel->alloced_cpus_in_node);
 419
 420         vmbus_release_relid(channel->offermsg.child_relid);
 421
 422         free_channel(channel);
 423 }
 424
 425 void vmbus_free_channels(void)
 426 {
 427         struct vmbus_channel *channel, *tmp;
 428
 429         list_for_each_entry_safe(channel, tmp, &vmbus_connection.chn_list,
 430                 listentry) {
 431                 /* hv_process_channel_removal() needs this */
 432                 channel->rescind = true;
 433
 434                 vmbus_device_unregister(channel->device_obj);
 435         }
 436 }
 437
 438 /* Note: the function can run concurrently for primary/sub channels. */
 439 static void vmbus_add_channel_work(struct work_struct *work)
 440 {
 441         struct vmbus_channel *newchannel =
 442                 container_of(work, struct vmbus_channel, add_channel_work);
 443         struct vmbus_channel *primary_channel = newchannel->primary_channel;
 444         unsigned long flags;
 445         u16 dev_type;
 446         int ret;
 447
 448         dev_type = hv_get_dev_type(newchannel);
 449
 450         init_vp_index(newchannel, dev_type);
 451
 452         if (newchannel->target_cpu != get_cpu()) {
 453                 put_cpu();
 454                 smp_call_function_single(newchannel->target_cpu,
 455                                          percpu_channel_enq,
 456                                          newchannel, true);
 457         } else {
 458                 percpu_channel_enq(newchannel);
 459                 put_cpu();
 460         }
 461
 462         /*
 463          * This state is used to indicate a successful open
 464          * so that when we do close the channel normally, we
 465          * can cleanup properly.
 466          */
 467         newchannel->state = CHANNEL_OPEN_STATE;
 468
 469         if (primary_channel != NULL) {
 470                 /* newchannel is a sub-channel. */
 471                 struct hv_device *dev = primary_channel->device_obj;
 472
 473                 if (vmbus_add_channel_kobj(dev, newchannel))
 474                         goto err_deq_chan;
 475
 476                 if (primary_channel->sc_creation_callback != NULL)
 477                         primary_channel->sc_creation_callback(newchannel);
 478
 479                 newchannel->probe_done = true;
 480                 return;
 481         }
 482
 483         /*
 484          * Start the process of binding the primary channel to the driver
 485          */
 486         newchannel->device_obj = vmbus_device_create(
 487                 &newchannel->offermsg.offer.if_type,
 488                 &newchannel->offermsg.offer.if_instance,
 489                 newchannel);
 490         if (!newchannel->device_obj)
 491                 goto err_deq_chan;
 492
 493         newchannel->device_obj->device_id = dev_type;
 494         /*
 495          * Add the new device to the bus. This will kick off device-driver
 496          * binding which eventually invokes the device driver's AddDevice()
 497          * method.
 498          */
 499         ret = vmbus_device_register(newchannel->device_obj);
 500
 501         if (ret != 0) {
 502                 pr_err("unable to add child device object (relid %d)\n",
 503                         newchannel->offermsg.child_relid);
 504                 kfree(newchannel->device_obj);
 505                 goto err_deq_chan;
 506         }
 507
 508         newchannel->probe_done = true;
 509         return;
 510
 511 err_deq_chan:
 512         mutex_lock(&vmbus_connection.channel_mutex);
 513
 514         /*
 515          * We need to set the flag, otherwise
 516          * vmbus_onoffer_rescind() can be blocked.
 517          */
 518         newchannel->probe_done = true;
 519
 520         if (primary_channel == NULL) {
 521                 list_del(&newchannel->listentry);
 522         } else {
 523                 spin_lock_irqsave(&primary_channel->lock, flags);
 524                 list_del(&newchannel->sc_list);
 525                 spin_unlock_irqrestore(&primary_channel->lock, flags);
 526         }
 527
 528         mutex_unlock(&vmbus_connection.channel_mutex);
 529
 530         if (newchannel->target_cpu != get_cpu()) {
 531                 put_cpu();
 532                 smp_call_function_single(newchannel->target_cpu,
 533                                          percpu_channel_deq,
 534                                          newchannel, true);
 535         } else {
 536                 percpu_channel_deq(newchannel);
 537                 put_cpu();
 538         }
 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         unsigned long flags;
 554         bool fnew = true;
 555
 556         mutex_lock(&vmbus_connection.channel_mutex);
 557
 558         /*
 559          * Now that we have acquired the channel_mutex,
 560          * we can release the potentially racing rescind thread.
 561          */
 562         atomic_dec(&vmbus_connection.offer_in_progress);
 563
 564         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 565                 if (!uuid_le_cmp(channel->offermsg.offer.if_type,
 566                                  newchannel->offermsg.offer.if_type) &&
 567                     !uuid_le_cmp(channel->offermsg.offer.if_instance,
 568                                  newchannel->offermsg.offer.if_instance)) {
 569                         fnew = false;
 570                         break;
 571                 }
 572         }
 573
 574         if (fnew)
 575                 list_add_tail(&newchannel->listentry,
 576                               &vmbus_connection.chn_list);
 577         else {
 578                 /*
 579                  * Check to see if this is a valid sub-channel.
 580                  */
 581                 if (newchannel->offermsg.offer.sub_channel_index == 0) {
 582                         mutex_unlock(&vmbus_connection.channel_mutex);
 583                         /*
 584                          * Don't call free_channel(), because newchannel->kobj
 585                          * is not initialized yet.
 586                          */
 587                         kfree(newchannel);
 588                         WARN_ON_ONCE(1);
 589                         return;
 590                 }
 591                 /*
 592                  * Process the sub-channel.
 593                  */
 594                 newchannel->primary_channel = channel;
 595                 spin_lock_irqsave(&channel->lock, flags);
 596                 list_add_tail(&newchannel->sc_list, &channel->sc_list);
 597                 spin_unlock_irqrestore(&channel->lock, flags);
 598         }
 599
 600         mutex_unlock(&vmbus_connection.channel_mutex);
 601
 602         /*
 603          * vmbus_process_offer() mustn't call channel->sc_creation_callback()
 604          * directly for sub-channels, because sc_creation_callback() ->
 605          * vmbus_open() may never get the host's response to the
 606          * OPEN_CHANNEL message (the host may rescind a channel at any time,
 607          * e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind()
 608          * may not wake up the vmbus_open() as it's blocked due to a non-zero
 609          * vmbus_connection.offer_in_progress, and finally we have a deadlock.
 610          *
 611          * The above is also true for primary channels, if the related device
 612          * drivers use sync probing mode by default.
 613          *
 614          * And, usually the handling of primary channels and sub-channels can
 615          * depend on each other, so we should offload them to different
 616          * workqueues to avoid possible deadlock, e.g. in sync-probing mode,
 617          * NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() ->
 618          * rtnl_lock(), and causes deadlock: the former gets the rtnl_lock
 619          * and waits for all the sub-channels to appear, but the latter
 620          * can't get the rtnl_lock and this blocks the handling of
 621          * sub-channels.
 622          */
 623         INIT_WORK(&newchannel->add_channel_work, vmbus_add_channel_work);
 624         wq = fnew ? vmbus_connection.handle_primary_chan_wq :
 625                     vmbus_connection.handle_sub_chan_wq;
 626         queue_work(wq, &newchannel->add_channel_work);
 627 }
 628
 629 /*
 630  * We use this state to statically distribute the channel interrupt load.
 631  */
 632 static int next_numa_node_id;
 633 /*
 634  * init_vp_index() accesses global variables like next_numa_node_id, and
 635  * it can run concurrently for primary channels and sub-channels: see
 636  * vmbus_process_offer(), so we need the lock to protect the global
 637  * variables.
 638  */
 639 static DEFINE_SPINLOCK(bind_channel_to_cpu_lock);
 640
 641 /*
 642  * Starting with Win8, we can statically distribute the incoming
 643  * channel interrupt load by binding a channel to VCPU.
 644  * We distribute the interrupt loads to one or more NUMA nodes based on
 645  * the channel's affinity_policy.
 646  *
 647  * For pre-win8 hosts or non-performance critical channels we assign the
 648  * first CPU in the first NUMA node.
 649  */
 650 static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
 651 {
 652         u32 cur_cpu;
 653         bool perf_chn = vmbus_devs[dev_type].perf_device;
 654         struct vmbus_channel *primary = channel->primary_channel;
 655         int next_node;
 656         cpumask_var_t available_mask;
 657         struct cpumask *alloced_mask;
 658
 659         if ((vmbus_proto_version == VERSION_WS2008) ||
 660             (vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
 661             !alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
 662                 /*
 663                  * Prior to win8, all channel interrupts are
 664                  * delivered on cpu 0.
 665                  * Also if the channel is not a performance critical
 666                  * channel, bind it to cpu 0.
 667                  * In case alloc_cpumask_var() fails, bind it to cpu 0.
 668                  */
 669                 channel->numa_node = 0;
 670                 channel->target_cpu = 0;
 671                 channel->target_vp = hv_cpu_number_to_vp_number(0);
 672                 return;
 673         }
 674
 675         spin_lock(&bind_channel_to_cpu_lock);
 676
 677         /*
 678          * Based on the channel affinity policy, we will assign the NUMA
 679          * nodes.
 680          */
 681
 682         if ((channel->affinity_policy == HV_BALANCED) || (!primary)) {
 683                 while (true) {
 684                         next_node = next_numa_node_id++;
 685                         if (next_node == nr_node_ids) {
 686                                 next_node = next_numa_node_id = 0;
 687                                 continue;
 688                         }
 689                         if (cpumask_empty(cpumask_of_node(next_node)))
 690                                 continue;
 691                         break;
 692                 }
 693                 channel->numa_node = next_node;
 694                 primary = channel;
 695         }
 696         alloced_mask = &hv_context.hv_numa_map[primary->numa_node];
 697
 698         if (cpumask_weight(alloced_mask) ==
 699             cpumask_weight(cpumask_of_node(primary->numa_node))) {
 700                 /*
 701                  * We have cycled through all the CPUs in the node;
 702                  * reset the alloced map.
 703                  */
 704                 cpumask_clear(alloced_mask);
 705         }
 706
 707         cpumask_xor(available_mask, alloced_mask,
 708                     cpumask_of_node(primary->numa_node));
 709
 710         cur_cpu = -1;
 711
 712         if (primary->affinity_policy == HV_LOCALIZED) {
 713                 /*
 714                  * Normally Hyper-V host doesn't create more subchannels
 715                  * than there are VCPUs on the node but it is possible when not
 716                  * all present VCPUs on the node are initialized by guest.
 717                  * Clear the alloced_cpus_in_node to start over.
 718                  */
 719                 if (cpumask_equal(&primary->alloced_cpus_in_node,
 720                                   cpumask_of_node(primary->numa_node)))
 721                         cpumask_clear(&primary->alloced_cpus_in_node);
 722         }
 723
 724         while (true) {
 725                 cur_cpu = cpumask_next(cur_cpu, available_mask);
 726                 if (cur_cpu >= nr_cpu_ids) {
 727                         cur_cpu = -1;
 728                         cpumask_copy(available_mask,
 729                                      cpumask_of_node(primary->numa_node));
 730                         continue;
 731                 }
 732
 733                 if (primary->affinity_policy == HV_LOCALIZED) {
 734                         /*
 735                          * NOTE: in the case of sub-channel, we clear the
 736                          * sub-channel related bit(s) in
 737                          * primary->alloced_cpus_in_node in
 738                          * hv_process_channel_removal(), so when we
 739                          * reload drivers like hv_netvsc in SMP guest, here
 740                          * we're able to re-allocate
 741                          * bit from primary->alloced_cpus_in_node.
 742                          */
 743                         if (!cpumask_test_cpu(cur_cpu,
 744                                               &primary->alloced_cpus_in_node)) {
 745                                 cpumask_set_cpu(cur_cpu,
 746                                                 &primary->alloced_cpus_in_node);
 747                                 cpumask_set_cpu(cur_cpu, alloced_mask);
 748                                 break;
 749                         }
 750                 } else {
 751                         cpumask_set_cpu(cur_cpu, alloced_mask);
 752                         break;
 753                 }
 754         }
 755
 756         channel->target_cpu = cur_cpu;
 757         channel->target_vp = hv_cpu_number_to_vp_number(cur_cpu);
 758
 759         spin_unlock(&bind_channel_to_cpu_lock);
 760
 761         free_cpumask_var(available_mask);
 762 }
 763
 764 static void vmbus_wait_for_unload(void)
 765 {
 766         int cpu;
 767         void *page_addr;
 768         struct hv_message *msg;
 769         struct vmbus_channel_message_header *hdr;
 770         u32 message_type;
 771
 772         /*
 773          * CHANNELMSG_UNLOAD_RESPONSE is always delivered to the CPU which was
 774          * used for initial contact or to CPU0 depending on host version. When
 775          * we're crashing on a different CPU let's hope that IRQ handler on
 776          * the cpu which receives CHANNELMSG_UNLOAD_RESPONSE is still
 777          * functional and vmbus_unload_response() will complete
 778          * vmbus_connection.unload_event. If not, the last thing we can do is
 779          * read message pages for all CPUs directly.
 780          */
 781         while (1) {
 782                 if (completion_done(&vmbus_connection.unload_event))
 783                         break;
 784
 785                 for_each_online_cpu(cpu) {
 786                         struct hv_per_cpu_context *hv_cpu
 787                                 = per_cpu_ptr(hv_context.cpu_context, cpu);
 788
 789                         page_addr = hv_cpu->synic_message_page;
 790                         msg = (struct hv_message *)page_addr
 791                                 + VMBUS_MESSAGE_SINT;
 792
 793                         message_type = READ_ONCE(msg->header.message_type);
 794                         if (message_type == HVMSG_NONE)
 795                                 continue;
 796
 797                         hdr = (struct vmbus_channel_message_header *)
 798                                 msg->u.payload;
 799
 800                         if (hdr->msgtype == CHANNELMSG_UNLOAD_RESPONSE)
 801                                 complete(&vmbus_connection.unload_event);
 802
 803                         vmbus_signal_eom(msg, message_type);
 804                 }
 805
 806                 mdelay(10);
 807         }
 808
 809         /*
 810          * We're crashing and already got the UNLOAD_RESPONSE, cleanup all
 811          * maybe-pending messages on all CPUs to be able to receive new
 812          * messages after we reconnect.
 813          */
 814         for_each_online_cpu(cpu) {
 815                 struct hv_per_cpu_context *hv_cpu
 816                         = per_cpu_ptr(hv_context.cpu_context, cpu);
 817
 818                 page_addr = hv_cpu->synic_message_page;
 819                 msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
 820                 msg->header.message_type = HVMSG_NONE;
 821         }
 822 }
 823
 824 /*
 825  * vmbus_unload_response - Handler for the unload response.
 826  */
 827 static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
 828 {
 829         /*
 830          * This is a global event; just wakeup the waiting thread.
 831          * Once we successfully unload, we can cleanup the monitor state.
 832          */
 833         complete(&vmbus_connection.unload_event);
 834 }
 835
 836 void vmbus_initiate_unload(bool crash)
 837 {
 838         struct vmbus_channel_message_header hdr;
 839
 840         /* Pre-Win2012R2 hosts don't support reconnect */
 841         if (vmbus_proto_version < VERSION_WIN8_1)
 842                 return;
 843
 844         init_completion(&vmbus_connection.unload_event);
 845         memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
 846         hdr.msgtype = CHANNELMSG_UNLOAD;
 847         vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header),
 848                        !crash);
 849
 850         /*
 851          * vmbus_initiate_unload() is also called on crash and the crash can be
 852          * happening in an interrupt context, where scheduling is impossible.
 853          */
 854         if (!crash)
 855                 wait_for_completion(&vmbus_connection.unload_event);
 856         else
 857                 vmbus_wait_for_unload();
 858 }
 859
 860 /*
 861  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
 862  *
 863  */
 864 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 865 {
 866         struct vmbus_channel_offer_channel *offer;
 867         struct vmbus_channel *newchannel;
 868
 869         offer = (struct vmbus_channel_offer_channel *)hdr;
 870
 871         trace_vmbus_onoffer(offer);
 872
 873         /* Allocate the channel object and save this offer. */
 874         newchannel = alloc_channel();
 875         if (!newchannel) {
 876                 vmbus_release_relid(offer->child_relid);
 877                 atomic_dec(&vmbus_connection.offer_in_progress);
 878                 pr_err("Unable to allocate channel object\n");
 879                 return;
 880         }
 881
 882         /*
 883          * Setup state for signalling the host.
 884          */
 885         newchannel->sig_event = VMBUS_EVENT_CONNECTION_ID;
 886
 887         if (vmbus_proto_version != VERSION_WS2008) {
 888                 newchannel->is_dedicated_interrupt =
 889                                 (offer->is_dedicated_interrupt != 0);
 890                 newchannel->sig_event = offer->connection_id;
 891         }
 892
 893         memcpy(&newchannel->offermsg, offer,
 894                sizeof(struct vmbus_channel_offer_channel));
 895         newchannel->monitor_grp = (u8)offer->monitorid / 32;
 896         newchannel->monitor_bit = (u8)offer->monitorid % 32;
 897
 898         vmbus_process_offer(newchannel);
 899 }
 900
 901 /*
 902  * vmbus_onoffer_rescind - Rescind offer handler.
 903  *
 904  * We queue a work item to process this offer synchronously
 905  */
 906 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 907 {
 908         struct vmbus_channel_rescind_offer *rescind;
 909         struct vmbus_channel *channel;
 910         struct device *dev;
 911
 912         rescind = (struct vmbus_channel_rescind_offer *)hdr;
 913
 914         trace_vmbus_onoffer_rescind(rescind);
 915
 916         /*
 917          * The offer msg and the corresponding rescind msg
 918          * from the host are guranteed to be ordered -
 919          * offer comes in first and then the rescind.
 920          * Since we process these events in work elements,
 921          * and with preemption, we may end up processing
 922          * the events out of order. Given that we handle these
 923          * work elements on the same CPU, this is possible only
 924          * in the case of preemption. In any case wait here
 925          * until the offer processing has moved beyond the
 926          * point where the channel is discoverable.
 927          */
 928
 929         while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
 930                 /*
 931                  * We wait here until any channel offer is currently
 932                  * being processed.
 933                  */
 934                 msleep(1);
 935         }
 936
 937         mutex_lock(&vmbus_connection.channel_mutex);
 938         channel = relid2channel(rescind->child_relid);
 939         mutex_unlock(&vmbus_connection.channel_mutex);
 940
 941         if (channel == NULL) {
 942                 /*
 943                  * We failed in processing the offer message;
 944                  * we would have cleaned up the relid in that
 945                  * failure path.
 946                  */
 947                 return;
 948         }
 949
 950         /*
 951          * Before setting channel->rescind in vmbus_rescind_cleanup(), we
 952          * should make sure the channel callback is not running any more.
 953          */
 954         vmbus_reset_channel_cb(channel);
 955
 956         /*
 957          * Now wait for offer handling to complete.
 958          */
 959         vmbus_rescind_cleanup(channel);
 960         while (READ_ONCE(channel->probe_done) == false) {
 961                 /*
 962                  * We wait here until any channel offer is currently
 963                  * being processed.
 964                  */
 965                 msleep(1);
 966         }
 967
 968         /*
 969          * At this point, the rescind handling can proceed safely.
 970          */
 971
 972         if (channel->device_obj) {
 973                 if (channel->chn_rescind_callback) {
 974                         channel->chn_rescind_callback(channel);
 975                         return;
 976                 }
 977                 /*
 978                  * We will have to unregister this device from the
 979                  * driver core.
 980                  */
 981                 dev = get_device(&channel->device_obj->device);
 982                 if (dev) {
 983                         vmbus_device_unregister(channel->device_obj);
 984                         put_device(dev);
 985                 }
 986         }
 987         if (channel->primary_channel != NULL) {
 988                 /*
 989                  * Sub-channel is being rescinded. Following is the channel
 990                  * close sequence when initiated from the driveri (refer to
 991                  * vmbus_close() for details):
 992                  * 1. Close all sub-channels first
 993                  * 2. Then close the primary channel.
 994                  */
 995                 mutex_lock(&vmbus_connection.channel_mutex);
 996                 if (channel->state == CHANNEL_OPEN_STATE) {
 997                         /*
 998                          * The channel is currently not open;
 999                          * it is safe for us to cleanup the channel.
1000                          */
1001                         hv_process_channel_removal(channel);
1002                 } else {
1003                         complete(&channel->rescind_event);
1004                 }
1005                 mutex_unlock(&vmbus_connection.channel_mutex);
1006         }
1007 }
1008
1009 void vmbus_hvsock_device_unregister(struct vmbus_channel *channel)
1010 {
1011         BUG_ON(!is_hvsock_channel(channel));
1012
1013         /* We always get a rescind msg when a connection is closed. */
1014         while (!READ_ONCE(channel->probe_done) || !READ_ONCE(channel->rescind))
1015                 msleep(1);
1016
1017         vmbus_device_unregister(channel->device_obj);
1018 }
1019 EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister);
1020
1021
1022 /*
1023  * vmbus_onoffers_delivered -
1024  * This is invoked when all offers have been delivered.
1025  *
1026  * Nothing to do here.
1027  */
1028 static void vmbus_onoffers_delivered(
1029                         struct vmbus_channel_message_header *hdr)
1030 {
1031 }
1032
1033 /*
1034  * vmbus_onopen_result - Open result handler.
1035  *
1036  * This is invoked when we received a response to our channel open request.
1037  * Find the matching request, copy the response and signal the requesting
1038  * thread.
1039  */
1040 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
1041 {
1042         struct vmbus_channel_open_result *result;
1043         struct vmbus_channel_msginfo *msginfo;
1044         struct vmbus_channel_message_header *requestheader;
1045         struct vmbus_channel_open_channel *openmsg;
1046         unsigned long flags;
1047
1048         result = (struct vmbus_channel_open_result *)hdr;
1049
1050         trace_vmbus_onopen_result(result);
1051
1052         /*
1053          * Find the open msg, copy the result and signal/unblock the wait event
1054          */
1055         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1056
1057         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1058                                 msglistentry) {
1059                 requestheader =
1060                         (struct vmbus_channel_message_header *)msginfo->msg;
1061
1062                 if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
1063                         openmsg =
1064                         (struct vmbus_channel_open_channel *)msginfo->msg;
1065                         if (openmsg->child_relid == result->child_relid &&
1066                             openmsg->openid == result->openid) {
1067                                 memcpy(&msginfo->response.open_result,
1068                                        result,
1069                                        sizeof(
1070                                         struct vmbus_channel_open_result));
1071                                 complete(&msginfo->waitevent);
1072                                 break;
1073                         }
1074                 }
1075         }
1076         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1077 }
1078
1079 /*
1080  * vmbus_ongpadl_created - GPADL created handler.
1081  *
1082  * This is invoked when we received a response to our gpadl create request.
1083  * Find the matching request, copy the response and signal the requesting
1084  * thread.
1085  */
1086 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
1087 {
1088         struct vmbus_channel_gpadl_created *gpadlcreated;
1089         struct vmbus_channel_msginfo *msginfo;
1090         struct vmbus_channel_message_header *requestheader;
1091         struct vmbus_channel_gpadl_header *gpadlheader;
1092         unsigned long flags;
1093
1094         gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
1095
1096         trace_vmbus_ongpadl_created(gpadlcreated);
1097
1098         /*
1099          * Find the establish msg, copy the result and signal/unblock the wait
1100          * event
1101          */
1102         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1103
1104         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1105                                 msglistentry) {
1106                 requestheader =
1107                         (struct vmbus_channel_message_header *)msginfo->msg;
1108
1109                 if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
1110                         gpadlheader =
1111                         (struct vmbus_channel_gpadl_header *)requestheader;
1112
1113                         if ((gpadlcreated->child_relid ==
1114                              gpadlheader->child_relid) &&
1115                             (gpadlcreated->gpadl == gpadlheader->gpadl)) {
1116                                 memcpy(&msginfo->response.gpadl_created,
1117                                        gpadlcreated,
1118                                        sizeof(
1119                                         struct vmbus_channel_gpadl_created));
1120                                 complete(&msginfo->waitevent);
1121                                 break;
1122                         }
1123                 }
1124         }
1125         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1126 }
1127
1128 /*
1129  * vmbus_ongpadl_torndown - GPADL torndown handler.
1130  *
1131  * This is invoked when we received a response to our gpadl teardown request.
1132  * Find the matching request, copy the response and signal the requesting
1133  * thread.
1134  */
1135 static void vmbus_ongpadl_torndown(
1136                         struct vmbus_channel_message_header *hdr)
1137 {
1138         struct vmbus_channel_gpadl_torndown *gpadl_torndown;
1139         struct vmbus_channel_msginfo *msginfo;
1140         struct vmbus_channel_message_header *requestheader;
1141         struct vmbus_channel_gpadl_teardown *gpadl_teardown;
1142         unsigned long flags;
1143
1144         gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
1145
1146         trace_vmbus_ongpadl_torndown(gpadl_torndown);
1147
1148         /*
1149          * Find the open msg, copy the result and signal/unblock the wait event
1150          */
1151         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1152
1153         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1154                                 msglistentry) {
1155                 requestheader =
1156                         (struct vmbus_channel_message_header *)msginfo->msg;
1157
1158                 if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
1159                         gpadl_teardown =
1160                         (struct vmbus_channel_gpadl_teardown *)requestheader;
1161
1162                         if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
1163                                 memcpy(&msginfo->response.gpadl_torndown,
1164                                        gpadl_torndown,
1165                                        sizeof(
1166                                         struct vmbus_channel_gpadl_torndown));
1167                                 complete(&msginfo->waitevent);
1168                                 break;
1169                         }
1170                 }
1171         }
1172         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1173 }
1174
1175 /*
1176  * vmbus_onversion_response - Version response handler
1177  *
1178  * This is invoked when we received a response to our initiate contact request.
1179  * Find the matching request, copy the response and signal the requesting
1180  * thread.
1181  */
1182 static void vmbus_onversion_response(
1183                 struct vmbus_channel_message_header *hdr)
1184 {
1185         struct vmbus_channel_msginfo *msginfo;
1186         struct vmbus_channel_message_header *requestheader;
1187         struct vmbus_channel_version_response *version_response;
1188         unsigned long flags;
1189
1190         version_response = (struct vmbus_channel_version_response *)hdr;
1191
1192         trace_vmbus_onversion_response(version_response);
1193
1194         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
1195
1196         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
1197                                 msglistentry) {
1198                 requestheader =
1199                         (struct vmbus_channel_message_header *)msginfo->msg;
1200
1201                 if (requestheader->msgtype ==
1202                     CHANNELMSG_INITIATE_CONTACT) {
1203                         memcpy(&msginfo->response.version_response,
1204                               version_response,
1205                               sizeof(struct vmbus_channel_version_response));
1206                         complete(&msginfo->waitevent);
1207                 }
1208         }
1209         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
1210 }
1211
1212 /* Channel message dispatch table */
1213 const struct vmbus_channel_message_table_entry
1214 channel_message_table[CHANNELMSG_COUNT] = {
1215         { CHANNELMSG_INVALID,                   0, NULL },
1216         { CHANNELMSG_OFFERCHANNEL,              0, vmbus_onoffer },
1217         { CHANNELMSG_RESCIND_CHANNELOFFER,      0, vmbus_onoffer_rescind },
1218         { CHANNELMSG_REQUESTOFFERS,             0, NULL },
1219         { CHANNELMSG_ALLOFFERS_DELIVERED,       1, vmbus_onoffers_delivered },
1220         { CHANNELMSG_OPENCHANNEL,               0, NULL },
1221         { CHANNELMSG_OPENCHANNEL_RESULT,        1, vmbus_onopen_result },
1222         { CHANNELMSG_CLOSECHANNEL,              0, NULL },
1223         { CHANNELMSG_GPADL_HEADER,              0, NULL },
1224         { CHANNELMSG_GPADL_BODY,                0, NULL },
1225         { CHANNELMSG_GPADL_CREATED,             1, vmbus_ongpadl_created },
1226         { CHANNELMSG_GPADL_TEARDOWN,            0, NULL },
1227         { CHANNELMSG_GPADL_TORNDOWN,            1, vmbus_ongpadl_torndown },
1228         { CHANNELMSG_RELID_RELEASED,            0, NULL },
1229         { CHANNELMSG_INITIATE_CONTACT,          0, NULL },
1230         { CHANNELMSG_VERSION_RESPONSE,          1, vmbus_onversion_response },
1231         { CHANNELMSG_UNLOAD,                    0, NULL },
1232         { CHANNELMSG_UNLOAD_RESPONSE,           1, vmbus_unload_response },
1233         { CHANNELMSG_18,                        0, NULL },
1234         { CHANNELMSG_19,                        0, NULL },
1235         { CHANNELMSG_20,                        0, NULL },
1236         { CHANNELMSG_TL_CONNECT_REQUEST,        0, NULL },
1237 };
1238
1239 /*
1240  * vmbus_onmessage - Handler for channel protocol messages.
1241  *
1242  * This is invoked in the vmbus worker thread context.
1243  */
1244 void vmbus_onmessage(void *context)
1245 {
1246         struct hv_message *msg = context;
1247         struct vmbus_channel_message_header *hdr;
1248         int size;
1249
1250         hdr = (struct vmbus_channel_message_header *)msg->u.payload;
1251         size = msg->header.payload_size;
1252
1253         trace_vmbus_on_message(hdr);
1254
1255         if (hdr->msgtype >= CHANNELMSG_COUNT) {
1256                 pr_err("Received invalid channel message type %d size %d\n",
1257                            hdr->msgtype, size);
1258                 print_hex_dump_bytes("", DUMP_PREFIX_NONE,
1259                                      (unsigned char *)msg->u.payload, size);
1260                 return;
1261         }
1262
1263         if (channel_message_table[hdr->msgtype].message_handler)
1264                 channel_message_table[hdr->msgtype].message_handler(hdr);
1265         else
1266                 pr_err("Unhandled channel message type %d\n", hdr->msgtype);
1267 }
1268
1269 /*
1270  * vmbus_request_offers - Send a request to get all our pending offers.
1271  */
1272 int vmbus_request_offers(void)
1273 {
1274         struct vmbus_channel_message_header *msg;
1275         struct vmbus_channel_msginfo *msginfo;
1276         int ret;
1277
1278         msginfo = kmalloc(sizeof(*msginfo) +
1279                           sizeof(struct vmbus_channel_message_header),
1280                           GFP_KERNEL);
1281         if (!msginfo)
1282                 return -ENOMEM;
1283
1284         msg = (struct vmbus_channel_message_header *)msginfo->msg;
1285
1286         msg->msgtype = CHANNELMSG_REQUESTOFFERS;
1287
1288         ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_message_header),
1289                              true);
1290
1291         trace_vmbus_request_offers(ret);
1292
1293         if (ret != 0) {
1294                 pr_err("Unable to request offers - %d\n", ret);
1295
1296                 goto cleanup;
1297         }
1298
1299 cleanup:
1300         kfree(msginfo);
1301
1302         return ret;
1303 }
1304
1305 /*
1306  * Retrieve the (sub) channel on which to send an outgoing request.
1307  * When a primary channel has multiple sub-channels, we try to
1308  * distribute the load equally amongst all available channels.
1309  */
1310 struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary)
1311 {
1312         struct list_head *cur, *tmp;
1313         int cur_cpu;
1314         struct vmbus_channel *cur_channel;
1315         struct vmbus_channel *outgoing_channel = primary;
1316         int next_channel;
1317         int i = 1;
1318
1319         if (list_empty(&primary->sc_list))
1320                 return outgoing_channel;
1321
1322         next_channel = primary->next_oc++;
1323
1324         if (next_channel > (primary->num_sc)) {
1325                 primary->next_oc = 0;
1326                 return outgoing_channel;
1327         }
1328
1329         cur_cpu = hv_cpu_number_to_vp_number(smp_processor_id());
1330         list_for_each_safe(cur, tmp, &primary->sc_list) {
1331                 cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
1332                 if (cur_channel->state != CHANNEL_OPENED_STATE)
1333                         continue;
1334
1335                 if (cur_channel->target_vp == cur_cpu)
1336                         return cur_channel;
1337
1338                 if (i == next_channel)
1339                         return cur_channel;
1340
1341                 i++;
1342         }
1343
1344         return outgoing_channel;
1345 }
1346 EXPORT_SYMBOL_GPL(vmbus_get_outgoing_channel);
1347
1348 static void invoke_sc_cb(struct vmbus_channel *primary_channel)
1349 {
1350         struct list_head *cur, *tmp;
1351         struct vmbus_channel *cur_channel;
1352
1353         if (primary_channel->sc_creation_callback == NULL)
1354                 return;
1355
1356         list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
1357                 cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
1358
1359                 primary_channel->sc_creation_callback(cur_channel);
1360         }
1361 }
1362
1363 void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
1364                                 void (*sc_cr_cb)(struct vmbus_channel *new_sc))
1365 {
1366         primary_channel->sc_creation_callback = sc_cr_cb;
1367 }
1368 EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
1369
1370 bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
1371 {
1372         bool ret;
1373
1374         ret = !list_empty(&primary->sc_list);
1375
1376         if (ret) {
1377                 /*
1378                  * Invoke the callback on sub-channel creation.
1379                  * This will present a uniform interface to the
1380                  * clients.
1381                  */
1382                 invoke_sc_cb(primary);
1383         }
1384
1385         return ret;
1386 }
1387 EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);
1388
1389 void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel,
1390                 void (*chn_rescind_cb)(struct vmbus_channel *))
1391 {
1392         channel->chn_rescind_callback = chn_rescind_cb;
1393 }
1394 EXPORT_SYMBOL_GPL(vmbus_set_chn_rescind_callback);