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/sched.h>
  25 #include <linux/wait.h>
  26 #include <linux/mm.h>
  27 #include <linux/slab.h>
  28 #include <linux/list.h>
  29 #include <linux/module.h>
  30 #include <linux/completion.h>
  31 #include <linux/hyperv.h>
  32
  33 #include "hyperv_vmbus.h"
  34
  35 struct vmbus_channel_message_table_entry {
  36         enum vmbus_channel_message_type message_type;
  37         void (*message_handler)(struct vmbus_channel_message_header *msg);
  38 };
  39
  40
  41 /**
  42  * vmbus_prep_negotiate_resp() - Create default response for Hyper-V Negotiate message
  43  * @icmsghdrp: Pointer to msg header structure
  44  * @icmsg_negotiate: Pointer to negotiate message structure
  45  * @buf: Raw buffer channel data
  46  *
  47  * @icmsghdrp is of type &struct icmsg_hdr.
  48  * @negop is of type &struct icmsg_negotiate.
  49  * Set up and fill in default negotiate response message.
  50  *
  51  * The fw_version specifies the  framework version that
  52  * we can support and srv_version specifies the service
  53  * version we can support.
  54  *
  55  * Mainly used by Hyper-V drivers.
  56  */
  57 bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp,
  58                                 struct icmsg_negotiate *negop, u8 *buf,
  59                                 int fw_version, int srv_version)
  60 {
  61         int icframe_major, icframe_minor;
  62         int icmsg_major, icmsg_minor;
  63         int fw_major, fw_minor;
  64         int srv_major, srv_minor;
  65         int i;
  66         bool found_match = false;
  67
  68         icmsghdrp->icmsgsize = 0x10;
  69         fw_major = (fw_version >> 16);
  70         fw_minor = (fw_version & 0xFFFF);
  71
  72         srv_major = (srv_version >> 16);
  73         srv_minor = (srv_version & 0xFFFF);
  74
  75         negop = (struct icmsg_negotiate *)&buf[
  76                 sizeof(struct vmbuspipe_hdr) +
  77                 sizeof(struct icmsg_hdr)];
  78
  79         icframe_major = negop->icframe_vercnt;
  80         icframe_minor = 0;
  81
  82         icmsg_major = negop->icmsg_vercnt;
  83         icmsg_minor = 0;
  84
  85         /*
  86          * Select the framework version number we will
  87          * support.
  88          */
  89
  90         for (i = 0; i < negop->icframe_vercnt; i++) {
  91                 if ((negop->icversion_data[i].major == fw_major) &&
  92                    (negop->icversion_data[i].minor == fw_minor)) {
  93                         icframe_major = negop->icversion_data[i].major;
  94                         icframe_minor = negop->icversion_data[i].minor;
  95                         found_match = true;
  96                 }
  97         }
  98
  99         if (!found_match)
 100                 goto fw_error;
 101
 102         found_match = false;
 103
 104         for (i = negop->icframe_vercnt;
 105                  (i < negop->icframe_vercnt + negop->icmsg_vercnt); i++) {
 106                 if ((negop->icversion_data[i].major == srv_major) &&
 107                    (negop->icversion_data[i].minor == srv_minor)) {
 108                         icmsg_major = negop->icversion_data[i].major;
 109                         icmsg_minor = negop->icversion_data[i].minor;
 110                         found_match = true;
 111                 }
 112         }
 113
 114         /*
 115          * Respond with the framework and service
 116          * version numbers we can support.
 117          */
 118
 119 fw_error:
 120         if (!found_match) {
 121                 negop->icframe_vercnt = 0;
 122                 negop->icmsg_vercnt = 0;
 123         } else {
 124                 negop->icframe_vercnt = 1;
 125                 negop->icmsg_vercnt = 1;
 126         }
 127
 128         negop->icversion_data[0].major = icframe_major;
 129         negop->icversion_data[0].minor = icframe_minor;
 130         negop->icversion_data[1].major = icmsg_major;
 131         negop->icversion_data[1].minor = icmsg_minor;
 132         return found_match;
 133 }
 134
 135 EXPORT_SYMBOL_GPL(vmbus_prep_negotiate_resp);
 136
 137 /*
 138  * alloc_channel - Allocate and initialize a vmbus channel object
 139  */
 140 static struct vmbus_channel *alloc_channel(void)
 141 {
 142         struct vmbus_channel *channel;
 143
 144         channel = kzalloc(sizeof(*channel), GFP_ATOMIC);
 145         if (!channel)
 146                 return NULL;
 147
 148         spin_lock_init(&channel->inbound_lock);
 149         spin_lock_init(&channel->sc_lock);
 150
 151         INIT_LIST_HEAD(&channel->sc_list);
 152         INIT_LIST_HEAD(&channel->percpu_list);
 153
 154         channel->controlwq = create_workqueue("hv_vmbus_ctl");
 155         if (!channel->controlwq) {
 156                 kfree(channel);
 157                 return NULL;
 158         }
 159
 160         return channel;
 161 }
 162
 163 /*
 164  * release_hannel - Release the vmbus channel object itself
 165  */
 166 static void release_channel(struct work_struct *work)
 167 {
 168         struct vmbus_channel *channel = container_of(work,
 169                                                      struct vmbus_channel,
 170                                                      work);
 171
 172         destroy_workqueue(channel->controlwq);
 173
 174         kfree(channel);
 175 }
 176
 177 /*
 178  * free_channel - Release the resources used by the vmbus channel object
 179  */
 180 static void free_channel(struct vmbus_channel *channel)
 181 {
 182
 183         /*
 184          * We have to release the channel's workqueue/thread in the vmbus's
 185          * workqueue/thread context
 186          * ie we can't destroy ourselves.
 187          */
 188         INIT_WORK(&channel->work, release_channel);
 189         queue_work(vmbus_connection.work_queue, &channel->work);
 190 }
 191
 192 static void percpu_channel_enq(void *arg)
 193 {
 194         struct vmbus_channel *channel = arg;
 195         int cpu = smp_processor_id();
 196
 197         list_add_tail(&channel->percpu_list, &hv_context.percpu_list[cpu]);
 198 }
 199
 200 static void percpu_channel_deq(void *arg)
 201 {
 202         struct vmbus_channel *channel = arg;
 203
 204         list_del(&channel->percpu_list);
 205 }
 206
 207 /*
 208  * vmbus_process_rescind_offer -
 209  * Rescind the offer by initiating a device removal
 210  */
 211 static void vmbus_process_rescind_offer(struct work_struct *work)
 212 {
 213         struct vmbus_channel *channel = container_of(work,
 214                                                      struct vmbus_channel,
 215                                                      work);
 216         unsigned long flags;
 217         struct vmbus_channel *primary_channel;
 218         struct vmbus_channel_relid_released msg;
 219
 220         if (channel->device_obj)
 221                 vmbus_device_unregister(channel->device_obj);
 222         memset(&msg, 0, sizeof(struct vmbus_channel_relid_released));
 223         msg.child_relid = channel->offermsg.child_relid;
 224         msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
 225         vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));
 226
 227         if (channel->target_cpu != smp_processor_id())
 228                 smp_call_function_single(channel->target_cpu,
 229                                          percpu_channel_deq, channel, true);
 230         else
 231                 percpu_channel_deq(channel);
 232
 233         if (channel->primary_channel == NULL) {
 234                 spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 235                 list_del(&channel->listentry);
 236                 spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 237         } else {
 238                 primary_channel = channel->primary_channel;
 239                 spin_lock_irqsave(&primary_channel->sc_lock, flags);
 240                 list_del(&channel->sc_list);
 241                 spin_unlock_irqrestore(&primary_channel->sc_lock, flags);
 242         }
 243         free_channel(channel);
 244 }
 245
 246 void vmbus_free_channels(void)
 247 {
 248         struct vmbus_channel *channel;
 249
 250         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 251                 vmbus_device_unregister(channel->device_obj);
 252                 kfree(channel->device_obj);
 253                 free_channel(channel);
 254         }
 255 }
 256
 257 /*
 258  * vmbus_process_offer - Process the offer by creating a channel/device
 259  * associated with this offer
 260  */
 261 static void vmbus_process_offer(struct work_struct *work)
 262 {
 263         struct vmbus_channel *newchannel = container_of(work,
 264                                                         struct vmbus_channel,
 265                                                         work);
 266         struct vmbus_channel *channel;
 267         bool fnew = true;
 268         bool enq = false;
 269         int ret;
 270         unsigned long flags;
 271
 272         /* The next possible work is rescind handling */
 273         INIT_WORK(&newchannel->work, vmbus_process_rescind_offer);
 274
 275         /* Make sure this is a new offer */
 276         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 277
 278         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 279                 if (!uuid_le_cmp(channel->offermsg.offer.if_type,
 280                         newchannel->offermsg.offer.if_type) &&
 281                         !uuid_le_cmp(channel->offermsg.offer.if_instance,
 282                                 newchannel->offermsg.offer.if_instance)) {
 283                         fnew = false;
 284                         break;
 285                 }
 286         }
 287
 288         if (fnew) {
 289                 list_add_tail(&newchannel->listentry,
 290                               &vmbus_connection.chn_list);
 291                 enq = true;
 292         }
 293
 294         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 295
 296         if (enq) {
 297                 if (newchannel->target_cpu != smp_processor_id())
 298                         smp_call_function_single(newchannel->target_cpu,
 299                                                  percpu_channel_enq,
 300                                                  newchannel, true);
 301                 else
 302                         percpu_channel_enq(newchannel);
 303         }
 304         if (!fnew) {
 305                 /*
 306                  * Check to see if this is a sub-channel.
 307                  */
 308                 if (newchannel->offermsg.offer.sub_channel_index != 0) {
 309                         /*
 310                          * Process the sub-channel.
 311                          */
 312                         newchannel->primary_channel = channel;
 313                         spin_lock_irqsave(&channel->sc_lock, flags);
 314                         list_add_tail(&newchannel->sc_list, &channel->sc_list);
 315                         spin_unlock_irqrestore(&channel->sc_lock, flags);
 316
 317                         if (newchannel->target_cpu != smp_processor_id())
 318                                 smp_call_function_single(newchannel->target_cpu,
 319                                                          percpu_channel_enq,
 320                                                          newchannel, true);
 321                         else
 322                                 percpu_channel_enq(newchannel);
 323
 324                         newchannel->state = CHANNEL_OPEN_STATE;
 325                         if (channel->sc_creation_callback != NULL)
 326                                 channel->sc_creation_callback(newchannel);
 327
 328                         return;
 329                 }
 330
 331                 free_channel(newchannel);
 332                 return;
 333         }
 334
 335         /*
 336          * This state is used to indicate a successful open
 337          * so that when we do close the channel normally, we
 338          * can cleanup properly
 339          */
 340         newchannel->state = CHANNEL_OPEN_STATE;
 341
 342         /*
 343          * Start the process of binding this offer to the driver
 344          * We need to set the DeviceObject field before calling
 345          * vmbus_child_dev_add()
 346          */
 347         newchannel->device_obj = vmbus_device_create(
 348                 &newchannel->offermsg.offer.if_type,
 349                 &newchannel->offermsg.offer.if_instance,
 350                 newchannel);
 351
 352         /*
 353          * Add the new device to the bus. This will kick off device-driver
 354          * binding which eventually invokes the device driver's AddDevice()
 355          * method.
 356          */
 357         ret = vmbus_device_register(newchannel->device_obj);
 358         if (ret != 0) {
 359                 pr_err("unable to add child device object (relid %d)\n",
 360                            newchannel->offermsg.child_relid);
 361
 362                 spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
 363                 list_del(&newchannel->listentry);
 364                 spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 365                 kfree(newchannel->device_obj);
 366
 367                 free_channel(newchannel);
 368         }
 369 }
 370
 371 enum {
 372         IDE = 0,
 373         SCSI,
 374         NIC,
 375         MAX_PERF_CHN,
 376 };
 377
 378 /*
 379  * This is an array of device_ids (device types) that are performance critical.
 380  * We attempt to distribute the interrupt load for these devices across
 381  * all available CPUs.
 382  */
 383 static const struct hv_vmbus_device_id hp_devs[] = {
 384         /* IDE */
 385         { HV_IDE_GUID, },
 386         /* Storage - SCSI */
 387         { HV_SCSI_GUID, },
 388         /* Network */
 389         { HV_NIC_GUID, },
 390 };
 391
 392
 393 /*
 394  * We use this state to statically distribute the channel interrupt load.
 395  */
 396 static u32  next_vp;
 397
 398 /*
 399  * Starting with Win8, we can statically distribute the incoming
 400  * channel interrupt load by binding a channel to VCPU. We
 401  * implement here a simple round robin scheme for distributing
 402  * the interrupt load.
 403  * We will bind channels that are not performance critical to cpu 0 and
 404  * performance critical channels (IDE, SCSI and Network) will be uniformly
 405  * distributed across all available CPUs.
 406  */
 407 static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_guid)
 408 {
 409         u32 cur_cpu;
 410         int i;
 411         bool perf_chn = false;
 412         u32 max_cpus = num_online_cpus();
 413
 414         for (i = IDE; i < MAX_PERF_CHN; i++) {
 415                 if (!memcmp(type_guid->b, hp_devs[i].guid,
 416                                  sizeof(uuid_le))) {
 417                         perf_chn = true;
 418                         break;
 419                 }
 420         }
 421         if ((vmbus_proto_version == VERSION_WS2008) ||
 422             (vmbus_proto_version == VERSION_WIN7) || (!perf_chn)) {
 423                 /*
 424                  * Prior to win8, all channel interrupts are
 425                  * delivered on cpu 0.
 426                  * Also if the channel is not a performance critical
 427                  * channel, bind it to cpu 0.
 428                  */
 429                 channel->target_cpu = 0;
 430                 channel->target_vp = 0;
 431                 return;
 432         }
 433         cur_cpu = (++next_vp % max_cpus);
 434         channel->target_cpu = cur_cpu;
 435         channel->target_vp = hv_context.vp_index[cur_cpu];
 436 }
 437
 438 /*
 439  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
 440  *
 441  */
 442 static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
 443 {
 444         struct vmbus_channel_offer_channel *offer;
 445         struct vmbus_channel *newchannel;
 446
 447         offer = (struct vmbus_channel_offer_channel *)hdr;
 448
 449         /* Allocate the channel object and save this offer. */
 450         newchannel = alloc_channel();
 451         if (!newchannel) {
 452                 pr_err("Unable to allocate channel object\n");
 453                 return;
 454         }
 455
 456         /*
 457          * By default we setup state to enable batched
 458          * reading. A specific service can choose to
 459          * disable this prior to opening the channel.
 460          */
 461         newchannel->batched_reading = true;
 462
 463         /*
 464          * Setup state for signalling the host.
 465          */
 466         newchannel->sig_event = (struct hv_input_signal_event *)
 467                                 (ALIGN((unsigned long)
 468                                 &newchannel->sig_buf,
 469                                 HV_HYPERCALL_PARAM_ALIGN));
 470
 471         newchannel->sig_event->connectionid.asu32 = 0;
 472         newchannel->sig_event->connectionid.u.id = VMBUS_EVENT_CONNECTION_ID;
 473         newchannel->sig_event->flag_number = 0;
 474         newchannel->sig_event->rsvdz = 0;
 475
 476         if (vmbus_proto_version != VERSION_WS2008) {
 477                 newchannel->is_dedicated_interrupt =
 478                                 (offer->is_dedicated_interrupt != 0);
 479                 newchannel->sig_event->connectionid.u.id =
 480                                 offer->connection_id;
 481         }
 482
 483         init_vp_index(newchannel, &offer->offer.if_type);
 484
 485         memcpy(&newchannel->offermsg, offer,
 486                sizeof(struct vmbus_channel_offer_channel));
 487         newchannel->monitor_grp = (u8)offer->monitorid / 32;
 488         newchannel->monitor_bit = (u8)offer->monitorid % 32;
 489
 490         INIT_WORK(&newchannel->work, vmbus_process_offer);
 491         queue_work(newchannel->controlwq, &newchannel->work);
 492 }
 493
 494 /*
 495  * vmbus_onoffer_rescind - Rescind offer handler.
 496  *
 497  * We queue a work item to process this offer synchronously
 498  */
 499 static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 500 {
 501         struct vmbus_channel_rescind_offer *rescind;
 502         struct vmbus_channel *channel;
 503
 504         rescind = (struct vmbus_channel_rescind_offer *)hdr;
 505         channel = relid2channel(rescind->child_relid);
 506
 507         if (channel == NULL)
 508                 /* Just return here, no channel found */
 509                 return;
 510
 511         /* work is initialized for vmbus_process_rescind_offer() from
 512          * vmbus_process_offer() where the channel got created */
 513         queue_work(channel->controlwq, &channel->work);
 514 }
 515
 516 /*
 517  * vmbus_onoffers_delivered -
 518  * This is invoked when all offers have been delivered.
 519  *
 520  * Nothing to do here.
 521  */
 522 static void vmbus_onoffers_delivered(
 523                         struct vmbus_channel_message_header *hdr)
 524 {
 525 }
 526
 527 /*
 528  * vmbus_onopen_result - Open result handler.
 529  *
 530  * This is invoked when we received a response to our channel open request.
 531  * Find the matching request, copy the response and signal the requesting
 532  * thread.
 533  */
 534 static void vmbus_onopen_result(struct vmbus_channel_message_header *hdr)
 535 {
 536         struct vmbus_channel_open_result *result;
 537         struct vmbus_channel_msginfo *msginfo;
 538         struct vmbus_channel_message_header *requestheader;
 539         struct vmbus_channel_open_channel *openmsg;
 540         unsigned long flags;
 541
 542         result = (struct vmbus_channel_open_result *)hdr;
 543
 544         /*
 545          * Find the open msg, copy the result and signal/unblock the wait event
 546          */
 547         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 548
 549         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 550                                 msglistentry) {
 551                 requestheader =
 552                         (struct vmbus_channel_message_header *)msginfo->msg;
 553
 554                 if (requestheader->msgtype == CHANNELMSG_OPENCHANNEL) {
 555                         openmsg =
 556                         (struct vmbus_channel_open_channel *)msginfo->msg;
 557                         if (openmsg->child_relid == result->child_relid &&
 558                             openmsg->openid == result->openid) {
 559                                 memcpy(&msginfo->response.open_result,
 560                                        result,
 561                                        sizeof(
 562                                         struct vmbus_channel_open_result));
 563                                 complete(&msginfo->waitevent);
 564                                 break;
 565                         }
 566                 }
 567         }
 568         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 569 }
 570
 571 /*
 572  * vmbus_ongpadl_created - GPADL created handler.
 573  *
 574  * This is invoked when we received a response to our gpadl create request.
 575  * Find the matching request, copy the response and signal the requesting
 576  * thread.
 577  */
 578 static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
 579 {
 580         struct vmbus_channel_gpadl_created *gpadlcreated;
 581         struct vmbus_channel_msginfo *msginfo;
 582         struct vmbus_channel_message_header *requestheader;
 583         struct vmbus_channel_gpadl_header *gpadlheader;
 584         unsigned long flags;
 585
 586         gpadlcreated = (struct vmbus_channel_gpadl_created *)hdr;
 587
 588         /*
 589          * Find the establish msg, copy the result and signal/unblock the wait
 590          * event
 591          */
 592         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 593
 594         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 595                                 msglistentry) {
 596                 requestheader =
 597                         (struct vmbus_channel_message_header *)msginfo->msg;
 598
 599                 if (requestheader->msgtype == CHANNELMSG_GPADL_HEADER) {
 600                         gpadlheader =
 601                         (struct vmbus_channel_gpadl_header *)requestheader;
 602
 603                         if ((gpadlcreated->child_relid ==
 604                              gpadlheader->child_relid) &&
 605                             (gpadlcreated->gpadl == gpadlheader->gpadl)) {
 606                                 memcpy(&msginfo->response.gpadl_created,
 607                                        gpadlcreated,
 608                                        sizeof(
 609                                         struct vmbus_channel_gpadl_created));
 610                                 complete(&msginfo->waitevent);
 611                                 break;
 612                         }
 613                 }
 614         }
 615         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 616 }
 617
 618 /*
 619  * vmbus_ongpadl_torndown - GPADL torndown handler.
 620  *
 621  * This is invoked when we received a response to our gpadl teardown request.
 622  * Find the matching request, copy the response and signal the requesting
 623  * thread.
 624  */
 625 static void vmbus_ongpadl_torndown(
 626                         struct vmbus_channel_message_header *hdr)
 627 {
 628         struct vmbus_channel_gpadl_torndown *gpadl_torndown;
 629         struct vmbus_channel_msginfo *msginfo;
 630         struct vmbus_channel_message_header *requestheader;
 631         struct vmbus_channel_gpadl_teardown *gpadl_teardown;
 632         unsigned long flags;
 633
 634         gpadl_torndown = (struct vmbus_channel_gpadl_torndown *)hdr;
 635
 636         /*
 637          * Find the open msg, copy the result and signal/unblock the wait event
 638          */
 639         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 640
 641         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 642                                 msglistentry) {
 643                 requestheader =
 644                         (struct vmbus_channel_message_header *)msginfo->msg;
 645
 646                 if (requestheader->msgtype == CHANNELMSG_GPADL_TEARDOWN) {
 647                         gpadl_teardown =
 648                         (struct vmbus_channel_gpadl_teardown *)requestheader;
 649
 650                         if (gpadl_torndown->gpadl == gpadl_teardown->gpadl) {
 651                                 memcpy(&msginfo->response.gpadl_torndown,
 652                                        gpadl_torndown,
 653                                        sizeof(
 654                                         struct vmbus_channel_gpadl_torndown));
 655                                 complete(&msginfo->waitevent);
 656                                 break;
 657                         }
 658                 }
 659         }
 660         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 661 }
 662
 663 /*
 664  * vmbus_onversion_response - Version response handler
 665  *
 666  * This is invoked when we received a response to our initiate contact request.
 667  * Find the matching request, copy the response and signal the requesting
 668  * thread.
 669  */
 670 static void vmbus_onversion_response(
 671                 struct vmbus_channel_message_header *hdr)
 672 {
 673         struct vmbus_channel_msginfo *msginfo;
 674         struct vmbus_channel_message_header *requestheader;
 675         struct vmbus_channel_version_response *version_response;
 676         unsigned long flags;
 677
 678         version_response = (struct vmbus_channel_version_response *)hdr;
 679         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 680
 681         list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
 682                                 msglistentry) {
 683                 requestheader =
 684                         (struct vmbus_channel_message_header *)msginfo->msg;
 685
 686                 if (requestheader->msgtype ==
 687                     CHANNELMSG_INITIATE_CONTACT) {
 688                         memcpy(&msginfo->response.version_response,
 689                               version_response,
 690                               sizeof(struct vmbus_channel_version_response));
 691                         complete(&msginfo->waitevent);
 692                 }
 693         }
 694         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 695 }
 696
 697 /* Channel message dispatch table */
 698 static struct vmbus_channel_message_table_entry
 699         channel_message_table[CHANNELMSG_COUNT] = {
 700         {CHANNELMSG_INVALID,                    NULL},
 701         {CHANNELMSG_OFFERCHANNEL,               vmbus_onoffer},
 702         {CHANNELMSG_RESCIND_CHANNELOFFER,       vmbus_onoffer_rescind},
 703         {CHANNELMSG_REQUESTOFFERS,              NULL},
 704         {CHANNELMSG_ALLOFFERS_DELIVERED,        vmbus_onoffers_delivered},
 705         {CHANNELMSG_OPENCHANNEL,                NULL},
 706         {CHANNELMSG_OPENCHANNEL_RESULT, vmbus_onopen_result},
 707         {CHANNELMSG_CLOSECHANNEL,               NULL},
 708         {CHANNELMSG_GPADL_HEADER,               NULL},
 709         {CHANNELMSG_GPADL_BODY,         NULL},
 710         {CHANNELMSG_GPADL_CREATED,              vmbus_ongpadl_created},
 711         {CHANNELMSG_GPADL_TEARDOWN,             NULL},
 712         {CHANNELMSG_GPADL_TORNDOWN,             vmbus_ongpadl_torndown},
 713         {CHANNELMSG_RELID_RELEASED,             NULL},
 714         {CHANNELMSG_INITIATE_CONTACT,           NULL},
 715         {CHANNELMSG_VERSION_RESPONSE,           vmbus_onversion_response},
 716         {CHANNELMSG_UNLOAD,                     NULL},
 717 };
 718
 719 /*
 720  * vmbus_onmessage - Handler for channel protocol messages.
 721  *
 722  * This is invoked in the vmbus worker thread context.
 723  */
 724 void vmbus_onmessage(void *context)
 725 {
 726         struct hv_message *msg = context;
 727         struct vmbus_channel_message_header *hdr;
 728         int size;
 729
 730         hdr = (struct vmbus_channel_message_header *)msg->u.payload;
 731         size = msg->header.payload_size;
 732
 733         if (hdr->msgtype >= CHANNELMSG_COUNT) {
 734                 pr_err("Received invalid channel message type %d size %d\n",
 735                            hdr->msgtype, size);
 736                 print_hex_dump_bytes("", DUMP_PREFIX_NONE,
 737                                      (unsigned char *)msg->u.payload, size);
 738                 return;
 739         }
 740
 741         if (channel_message_table[hdr->msgtype].message_handler)
 742                 channel_message_table[hdr->msgtype].message_handler(hdr);
 743         else
 744                 pr_err("Unhandled channel message type %d\n", hdr->msgtype);
 745 }
 746
 747 /*
 748  * vmbus_request_offers - Send a request to get all our pending offers.
 749  */
 750 int vmbus_request_offers(void)
 751 {
 752         struct vmbus_channel_message_header *msg;
 753         struct vmbus_channel_msginfo *msginfo;
 754         int ret, t;
 755
 756         msginfo = kmalloc(sizeof(*msginfo) +
 757                           sizeof(struct vmbus_channel_message_header),
 758                           GFP_KERNEL);
 759         if (!msginfo)
 760                 return -ENOMEM;
 761
 762         init_completion(&msginfo->waitevent);
 763
 764         msg = (struct vmbus_channel_message_header *)msginfo->msg;
 765
 766         msg->msgtype = CHANNELMSG_REQUESTOFFERS;
 767
 768
 769         ret = vmbus_post_msg(msg,
 770                                sizeof(struct vmbus_channel_message_header));
 771         if (ret != 0) {
 772                 pr_err("Unable to request offers - %d\n", ret);
 773
 774                 goto cleanup;
 775         }
 776
 777         t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
 778         if (t == 0) {
 779                 ret = -ETIMEDOUT;
 780                 goto cleanup;
 781         }
 782
 783
 784
 785 cleanup:
 786         kfree(msginfo);
 787
 788         return ret;
 789 }
 790
 791 /*
 792  * Retrieve the (sub) channel on which to send an outgoing request.
 793  * When a primary channel has multiple sub-channels, we choose a
 794  * channel whose VCPU binding is closest to the VCPU on which
 795  * this call is being made.
 796  */
 797 struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary)
 798 {
 799         struct list_head *cur, *tmp;
 800         int cur_cpu = hv_context.vp_index[smp_processor_id()];
 801         struct vmbus_channel *cur_channel;
 802         struct vmbus_channel *outgoing_channel = primary;
 803         int cpu_distance, new_cpu_distance;
 804
 805         if (list_empty(&primary->sc_list))
 806                 return outgoing_channel;
 807
 808         list_for_each_safe(cur, tmp, &primary->sc_list) {
 809                 cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
 810                 if (cur_channel->state != CHANNEL_OPENED_STATE)
 811                         continue;
 812
 813                 if (cur_channel->target_vp == cur_cpu)
 814                         return cur_channel;
 815
 816                 cpu_distance = ((outgoing_channel->target_vp > cur_cpu) ?
 817                                 (outgoing_channel->target_vp - cur_cpu) :
 818                                 (cur_cpu - outgoing_channel->target_vp));
 819
 820                 new_cpu_distance = ((cur_channel->target_vp > cur_cpu) ?
 821                                 (cur_channel->target_vp - cur_cpu) :
 822                                 (cur_cpu - cur_channel->target_vp));
 823
 824                 if (cpu_distance < new_cpu_distance)
 825                         continue;
 826
 827                 outgoing_channel = cur_channel;
 828         }
 829
 830         return outgoing_channel;
 831 }
 832 EXPORT_SYMBOL_GPL(vmbus_get_outgoing_channel);
 833
 834 static void invoke_sc_cb(struct vmbus_channel *primary_channel)
 835 {
 836         struct list_head *cur, *tmp;
 837         struct vmbus_channel *cur_channel;
 838
 839         if (primary_channel->sc_creation_callback == NULL)
 840                 return;
 841
 842         list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
 843                 cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
 844
 845                 primary_channel->sc_creation_callback(cur_channel);
 846         }
 847 }
 848
 849 void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
 850                                 void (*sc_cr_cb)(struct vmbus_channel *new_sc))
 851 {
 852         primary_channel->sc_creation_callback = sc_cr_cb;
 853 }
 854 EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
 855
 856 bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
 857 {
 858         bool ret;
 859
 860         ret = !list_empty(&primary->sc_list);
 861
 862         if (ret) {
 863                 /*
 864                  * Invoke the callback on sub-channel creation.
 865                  * This will present a uniform interface to the
 866                  * clients.
 867                  */
 868                 invoke_sc_cb(primary);
 869         }
 870
 871         return ret;
 872 }
 873 EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);