drivers/hv/channel_mgmt.c

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