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