drivers/hv/channel.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/sched.h>
  13 #include <linux/wait.h>
  14 #include <linux/mm.h>
  15 #include <linux/slab.h>
  16 #include <linux/module.h>
  17 #include <linux/hyperv.h>
  18 #include <linux/uio.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/set_memory.h>
  21 #include <asm/page.h>
  22 #include <asm/mshyperv.h>
  23
  24 #include "hyperv_vmbus.h"
  25
  26 /*
  27  * hv_gpadl_size - Return the real size of a gpadl, the size that Hyper-V uses
  28  *
  29  * For BUFFER gpadl, Hyper-V uses the exact same size as the guest does.
  30  *
  31  * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the header
  32  * (because of the alignment requirement), however, the hypervisor only
  33  * uses the first HV_HYP_PAGE_SIZE as the header, therefore leaving a
  34  * (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap. And since there are two rings in a
  35  * ringbuffer, the total size for a RING gpadl that Hyper-V uses is the
  36  * total size that the guest uses minus twice of the gap size.
  37  */
  38 static inline u32 hv_gpadl_size(enum hv_gpadl_type type, u32 size)
  39 {
  40         switch (type) {
  41         case HV_GPADL_BUFFER:
  42                 return size;
  43         case HV_GPADL_RING:
  44                 /* The size of a ringbuffer must be page-aligned */
  45                 BUG_ON(size % PAGE_SIZE);
  46                 /*
  47                  * Two things to notice here:
  48                  * 1) We're processing two ring buffers as a unit
  49                  * 2) We're skipping any space larger than HV_HYP_PAGE_SIZE in
  50                  * the first guest-size page of each of the two ring buffers.
  51                  * So we effectively subtract out two guest-size pages, and add
  52                  * back two Hyper-V size pages.
  53                  */
  54                 return size - 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
  55         }
  56         BUG();
  57         return 0;
  58 }
  59
  60 /*
  61  * hv_ring_gpadl_send_hvpgoffset - Calculate the send offset (in unit of
  62  *                                 HV_HYP_PAGE) in a ring gpadl based on the
  63  *                                 offset in the guest
  64  *
  65  * @offset: the offset (in bytes) where the send ringbuffer starts in the
  66  *               virtual address space of the guest
  67  */
  68 static inline u32 hv_ring_gpadl_send_hvpgoffset(u32 offset)
  69 {
  70
  71         /*
  72          * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the
  73          * header (because of the alignment requirement), however, the
  74          * hypervisor only uses the first HV_HYP_PAGE_SIZE as the header,
  75          * therefore leaving a (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap.
  76          *
  77          * And to calculate the effective send offset in gpadl, we need to
  78          * substract this gap.
  79          */
  80         return (offset - (PAGE_SIZE - HV_HYP_PAGE_SIZE)) >> HV_HYP_PAGE_SHIFT;
  81 }
  82
  83 /*
  84  * hv_gpadl_hvpfn - Return the Hyper-V page PFN of the @i th Hyper-V page in
  85  *                  the gpadl
  86  *
  87  * @type: the type of the gpadl
  88  * @kbuffer: the pointer to the gpadl in the guest
  89  * @size: the total size (in bytes) of the gpadl
  90  * @send_offset: the offset (in bytes) where the send ringbuffer starts in the
  91  *               virtual address space of the guest
  92  * @i: the index
  93  */
  94 static inline u64 hv_gpadl_hvpfn(enum hv_gpadl_type type, void *kbuffer,
  95                                  u32 size, u32 send_offset, int i)
  96 {
  97         int send_idx = hv_ring_gpadl_send_hvpgoffset(send_offset);
  98         unsigned long delta = 0UL;
  99
 100         switch (type) {
 101         case HV_GPADL_BUFFER:
 102                 break;
 103         case HV_GPADL_RING:
 104                 if (i == 0)
 105                         delta = 0;
 106                 else if (i <= send_idx)
 107                         delta = PAGE_SIZE - HV_HYP_PAGE_SIZE;
 108                 else
 109                         delta = 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
 110                 break;
 111         default:
 112                 BUG();
 113                 break;
 114         }
 115
 116         return virt_to_hvpfn(kbuffer + delta + (HV_HYP_PAGE_SIZE * i));
 117 }
 118
 119 /*
 120  * vmbus_setevent- Trigger an event notification on the specified
 121  * channel.
 122  */
 123 void vmbus_setevent(struct vmbus_channel *channel)
 124 {
 125         struct hv_monitor_page *monitorpage;
 126
 127         trace_vmbus_setevent(channel);
 128
 129         /*
 130          * For channels marked as in "low latency" mode
 131          * bypass the monitor page mechanism.
 132          */
 133         if (channel->offermsg.monitor_allocated && !channel->low_latency) {
 134                 vmbus_send_interrupt(channel->offermsg.child_relid);
 135
 136                 /* Get the child to parent monitor page */
 137                 monitorpage = vmbus_connection.monitor_pages[1];
 138
 139                 sync_set_bit(channel->monitor_bit,
 140                         (unsigned long *)&monitorpage->trigger_group
 141                                         [channel->monitor_grp].pending);
 142
 143         } else {
 144                 vmbus_set_event(channel);
 145         }
 146 }
 147 EXPORT_SYMBOL_GPL(vmbus_setevent);
 148
 149 /* vmbus_free_ring - drop mapping of ring buffer */
 150 void vmbus_free_ring(struct vmbus_channel *channel)
 151 {
 152         hv_ringbuffer_cleanup(&channel->outbound);
 153         hv_ringbuffer_cleanup(&channel->inbound);
 154
 155         if (channel->ringbuffer_page) {
 156                 __free_pages(channel->ringbuffer_page,
 157                              get_order(channel->ringbuffer_pagecount
 158                                        << PAGE_SHIFT));
 159                 channel->ringbuffer_page = NULL;
 160         }
 161 }
 162 EXPORT_SYMBOL_GPL(vmbus_free_ring);
 163
 164 /* vmbus_alloc_ring - allocate and map pages for ring buffer */
 165 int vmbus_alloc_ring(struct vmbus_channel *newchannel,
 166                      u32 send_size, u32 recv_size)
 167 {
 168         struct page *page;
 169         int order;
 170
 171         if (send_size % PAGE_SIZE || recv_size % PAGE_SIZE)
 172                 return -EINVAL;
 173
 174         /* Allocate the ring buffer */
 175         order = get_order(send_size + recv_size);
 176         page = alloc_pages_node(cpu_to_node(newchannel->target_cpu),
 177                                 GFP_KERNEL|__GFP_ZERO, order);
 178
 179         if (!page)
 180                 page = alloc_pages(GFP_KERNEL|__GFP_ZERO, order);
 181
 182         if (!page)
 183                 return -ENOMEM;
 184
 185         newchannel->ringbuffer_page = page;
 186         newchannel->ringbuffer_pagecount = (send_size + recv_size) >> PAGE_SHIFT;
 187         newchannel->ringbuffer_send_offset = send_size >> PAGE_SHIFT;
 188
 189         return 0;
 190 }
 191 EXPORT_SYMBOL_GPL(vmbus_alloc_ring);
 192
 193 /* Used for Hyper-V Socket: a guest client's connect() to the host */
 194 int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
 195                                   const guid_t *shv_host_servie_id)
 196 {
 197         struct vmbus_channel_tl_connect_request conn_msg;
 198         int ret;
 199
 200         memset(&conn_msg, 0, sizeof(conn_msg));
 201         conn_msg.header.msgtype = CHANNELMSG_TL_CONNECT_REQUEST;
 202         conn_msg.guest_endpoint_id = *shv_guest_servie_id;
 203         conn_msg.host_service_id = *shv_host_servie_id;
 204
 205         ret = vmbus_post_msg(&conn_msg, sizeof(conn_msg), true);
 206
 207         trace_vmbus_send_tl_connect_request(&conn_msg, ret);
 208
 209         return ret;
 210 }
 211 EXPORT_SYMBOL_GPL(vmbus_send_tl_connect_request);
 212
 213 static int send_modifychannel_without_ack(struct vmbus_channel *channel, u32 target_vp)
 214 {
 215         struct vmbus_channel_modifychannel msg;
 216         int ret;
 217
 218         memset(&msg, 0, sizeof(msg));
 219         msg.header.msgtype = CHANNELMSG_MODIFYCHANNEL;
 220         msg.child_relid = channel->offermsg.child_relid;
 221         msg.target_vp = target_vp;
 222
 223         ret = vmbus_post_msg(&msg, sizeof(msg), true);
 224         trace_vmbus_send_modifychannel(&msg, ret);
 225
 226         return ret;
 227 }
 228
 229 static int send_modifychannel_with_ack(struct vmbus_channel *channel, u32 target_vp)
 230 {
 231         struct vmbus_channel_modifychannel *msg;
 232         struct vmbus_channel_msginfo *info;
 233         unsigned long flags;
 234         int ret;
 235
 236         info = kzalloc(sizeof(struct vmbus_channel_msginfo) +
 237                                 sizeof(struct vmbus_channel_modifychannel),
 238                        GFP_KERNEL);
 239         if (!info)
 240                 return -ENOMEM;
 241
 242         init_completion(&info->waitevent);
 243         info->waiting_channel = channel;
 244
 245         msg = (struct vmbus_channel_modifychannel *)info->msg;
 246         msg->header.msgtype = CHANNELMSG_MODIFYCHANNEL;
 247         msg->child_relid = channel->offermsg.child_relid;
 248         msg->target_vp = target_vp;
 249
 250         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 251         list_add_tail(&info->msglistentry, &vmbus_connection.chn_msg_list);
 252         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 253
 254         ret = vmbus_post_msg(msg, sizeof(*msg), true);
 255         trace_vmbus_send_modifychannel(msg, ret);
 256         if (ret != 0) {
 257                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 258                 list_del(&info->msglistentry);
 259                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 260                 goto free_info;
 261         }
 262
 263         /*
 264          * Release channel_mutex; otherwise, vmbus_onoffer_rescind() could block on
 265          * the mutex and be unable to signal the completion.
 266          *
 267          * See the caller target_cpu_store() for information about the usage of the
 268          * mutex.
 269          */
 270         mutex_unlock(&vmbus_connection.channel_mutex);
 271         wait_for_completion(&info->waitevent);
 272         mutex_lock(&vmbus_connection.channel_mutex);
 273
 274         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 275         list_del(&info->msglistentry);
 276         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 277
 278         if (info->response.modify_response.status)
 279                 ret = -EAGAIN;
 280
 281 free_info:
 282         kfree(info);
 283         return ret;
 284 }
 285
 286 /*
 287  * Set/change the vCPU (@target_vp) the channel (@child_relid) will interrupt.
 288  *
 289  * CHANNELMSG_MODIFYCHANNEL messages are aynchronous.  When VMbus version 5.3
 290  * or later is negotiated, Hyper-V always sends an ACK in response to such a
 291  * message.  For VMbus version 5.2 and earlier, it never sends an ACK.  With-
 292  * out an ACK, we can not know when the host will stop interrupting the "old"
 293  * vCPU and start interrupting the "new" vCPU for the given channel.
 294  *
 295  * The CHANNELMSG_MODIFYCHANNEL message type is supported since VMBus version
 296  * VERSION_WIN10_V4_1.
 297  */
 298 int vmbus_send_modifychannel(struct vmbus_channel *channel, u32 target_vp)
 299 {
 300         if (vmbus_proto_version >= VERSION_WIN10_V5_3)
 301                 return send_modifychannel_with_ack(channel, target_vp);
 302         return send_modifychannel_without_ack(channel, target_vp);
 303 }
 304 EXPORT_SYMBOL_GPL(vmbus_send_modifychannel);
 305
 306 /*
 307  * create_gpadl_header - Creates a gpadl for the specified buffer
 308  */
 309 static int create_gpadl_header(enum hv_gpadl_type type, void *kbuffer,
 310                                u32 size, u32 send_offset,
 311                                struct vmbus_channel_msginfo **msginfo)
 312 {
 313         int i;
 314         int pagecount;
 315         struct vmbus_channel_gpadl_header *gpadl_header;
 316         struct vmbus_channel_gpadl_body *gpadl_body;
 317         struct vmbus_channel_msginfo *msgheader;
 318         struct vmbus_channel_msginfo *msgbody = NULL;
 319         u32 msgsize;
 320
 321         int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
 322
 323         pagecount = hv_gpadl_size(type, size) >> HV_HYP_PAGE_SHIFT;
 324
 325         /* do we need a gpadl body msg */
 326         pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
 327                   sizeof(struct vmbus_channel_gpadl_header) -
 328                   sizeof(struct gpa_range);
 329         pfncount = pfnsize / sizeof(u64);
 330
 331         if (pagecount > pfncount) {
 332                 /* we need a gpadl body */
 333                 /* fill in the header */
 334                 msgsize = sizeof(struct vmbus_channel_msginfo) +
 335                           sizeof(struct vmbus_channel_gpadl_header) +
 336                           sizeof(struct gpa_range) + pfncount * sizeof(u64);
 337                 msgheader =  kzalloc(msgsize, GFP_KERNEL);
 338                 if (!msgheader)
 339                         goto nomem;
 340
 341                 INIT_LIST_HEAD(&msgheader->submsglist);
 342                 msgheader->msgsize = msgsize;
 343
 344                 gpadl_header = (struct vmbus_channel_gpadl_header *)
 345                         msgheader->msg;
 346                 gpadl_header->rangecount = 1;
 347                 gpadl_header->range_buflen = sizeof(struct gpa_range) +
 348                                          pagecount * sizeof(u64);
 349                 gpadl_header->range[0].byte_offset = 0;
 350                 gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
 351                 for (i = 0; i < pfncount; i++)
 352                         gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
 353                                 type, kbuffer, size, send_offset, i);
 354                 *msginfo = msgheader;
 355
 356                 pfnsum = pfncount;
 357                 pfnleft = pagecount - pfncount;
 358
 359                 /* how many pfns can we fit */
 360                 pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
 361                           sizeof(struct vmbus_channel_gpadl_body);
 362                 pfncount = pfnsize / sizeof(u64);
 363
 364                 /* fill in the body */
 365                 while (pfnleft) {
 366                         if (pfnleft > pfncount)
 367                                 pfncurr = pfncount;
 368                         else
 369                                 pfncurr = pfnleft;
 370
 371                         msgsize = sizeof(struct vmbus_channel_msginfo) +
 372                                   sizeof(struct vmbus_channel_gpadl_body) +
 373                                   pfncurr * sizeof(u64);
 374                         msgbody = kzalloc(msgsize, GFP_KERNEL);
 375
 376                         if (!msgbody) {
 377                                 struct vmbus_channel_msginfo *pos = NULL;
 378                                 struct vmbus_channel_msginfo *tmp = NULL;
 379                                 /*
 380                                  * Free up all the allocated messages.
 381                                  */
 382                                 list_for_each_entry_safe(pos, tmp,
 383                                         &msgheader->submsglist,
 384                                         msglistentry) {
 385
 386                                         list_del(&pos->msglistentry);
 387                                         kfree(pos);
 388                                 }
 389
 390                                 goto nomem;
 391                         }
 392
 393                         msgbody->msgsize = msgsize;
 394                         gpadl_body =
 395                                 (struct vmbus_channel_gpadl_body *)msgbody->msg;
 396
 397                         /*
 398                          * Gpadl is u32 and we are using a pointer which could
 399                          * be 64-bit
 400                          * This is governed by the guest/host protocol and
 401                          * so the hypervisor guarantees that this is ok.
 402                          */
 403                         for (i = 0; i < pfncurr; i++)
 404                                 gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
 405                                         kbuffer, size, send_offset, pfnsum + i);
 406
 407                         /* add to msg header */
 408                         list_add_tail(&msgbody->msglistentry,
 409                                       &msgheader->submsglist);
 410                         pfnsum += pfncurr;
 411                         pfnleft -= pfncurr;
 412                 }
 413         } else {
 414                 /* everything fits in a header */
 415                 msgsize = sizeof(struct vmbus_channel_msginfo) +
 416                           sizeof(struct vmbus_channel_gpadl_header) +
 417                           sizeof(struct gpa_range) + pagecount * sizeof(u64);
 418                 msgheader = kzalloc(msgsize, GFP_KERNEL);
 419                 if (msgheader == NULL)
 420                         goto nomem;
 421
 422                 INIT_LIST_HEAD(&msgheader->submsglist);
 423                 msgheader->msgsize = msgsize;
 424
 425                 gpadl_header = (struct vmbus_channel_gpadl_header *)
 426                         msgheader->msg;
 427                 gpadl_header->rangecount = 1;
 428                 gpadl_header->range_buflen = sizeof(struct gpa_range) +
 429                                          pagecount * sizeof(u64);
 430                 gpadl_header->range[0].byte_offset = 0;
 431                 gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
 432                 for (i = 0; i < pagecount; i++)
 433                         gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
 434                                 type, kbuffer, size, send_offset, i);
 435
 436                 *msginfo = msgheader;
 437         }
 438
 439         return 0;
 440 nomem:
 441         kfree(msgheader);
 442         kfree(msgbody);
 443         return -ENOMEM;
 444 }
 445
 446 /*
 447  * __vmbus_establish_gpadl - Establish a GPADL for a buffer or ringbuffer
 448  *
 449  * @channel: a channel
 450  * @type: the type of the corresponding GPADL, only meaningful for the guest.
 451  * @kbuffer: from kmalloc or vmalloc
 452  * @size: page-size multiple
 453  * @send_offset: the offset (in bytes) where the send ring buffer starts,
 454  *              should be 0 for BUFFER type gpadl
 455  * @gpadl_handle: some funky thing
 456  */
 457 static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 458                                    enum hv_gpadl_type type, void *kbuffer,
 459                                    u32 size, u32 send_offset,
 460                                    struct vmbus_gpadl *gpadl)
 461 {
 462         struct vmbus_channel_gpadl_header *gpadlmsg;
 463         struct vmbus_channel_gpadl_body *gpadl_body;
 464         struct vmbus_channel_msginfo *msginfo = NULL;
 465         struct vmbus_channel_msginfo *submsginfo, *tmp;
 466         struct list_head *curr;
 467         u32 next_gpadl_handle;
 468         unsigned long flags;
 469         int ret = 0;
 470
 471         next_gpadl_handle =
 472                 (atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
 473
 474         ret = create_gpadl_header(type, kbuffer, size, send_offset, &msginfo);
 475         if (ret)
 476                 return ret;
 477
 478         ret = set_memory_decrypted((unsigned long)kbuffer,
 479                                    PFN_UP(size));
 480         if (ret) {
 481                 dev_warn(&channel->device_obj->device,
 482                          "Failed to set host visibility for new GPADL %d.\n",
 483                          ret);
 484                 return ret;
 485         }
 486
 487         init_completion(&msginfo->waitevent);
 488         msginfo->waiting_channel = channel;
 489
 490         gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo->msg;
 491         gpadlmsg->header.msgtype = CHANNELMSG_GPADL_HEADER;
 492         gpadlmsg->child_relid = channel->offermsg.child_relid;
 493         gpadlmsg->gpadl = next_gpadl_handle;
 494
 495
 496         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 497         list_add_tail(&msginfo->msglistentry,
 498                       &vmbus_connection.chn_msg_list);
 499
 500         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 501
 502         if (channel->rescind) {
 503                 ret = -ENODEV;
 504                 goto cleanup;
 505         }
 506
 507         ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
 508                              sizeof(*msginfo), true);
 509
 510         trace_vmbus_establish_gpadl_header(gpadlmsg, ret);
 511
 512         if (ret != 0)
 513                 goto cleanup;
 514
 515         list_for_each(curr, &msginfo->submsglist) {
 516                 submsginfo = (struct vmbus_channel_msginfo *)curr;
 517                 gpadl_body =
 518                         (struct vmbus_channel_gpadl_body *)submsginfo->msg;
 519
 520                 gpadl_body->header.msgtype =
 521                         CHANNELMSG_GPADL_BODY;
 522                 gpadl_body->gpadl = next_gpadl_handle;
 523
 524                 ret = vmbus_post_msg(gpadl_body,
 525                                      submsginfo->msgsize - sizeof(*submsginfo),
 526                                      true);
 527
 528                 trace_vmbus_establish_gpadl_body(gpadl_body, ret);
 529
 530                 if (ret != 0)
 531                         goto cleanup;
 532
 533         }
 534         wait_for_completion(&msginfo->waitevent);
 535
 536         if (msginfo->response.gpadl_created.creation_status != 0) {
 537                 pr_err("Failed to establish GPADL: err = 0x%x\n",
 538                        msginfo->response.gpadl_created.creation_status);
 539
 540                 ret = -EDQUOT;
 541                 goto cleanup;
 542         }
 543
 544         if (channel->rescind) {
 545                 ret = -ENODEV;
 546                 goto cleanup;
 547         }
 548
 549         /* At this point, we received the gpadl created msg */
 550         gpadl->gpadl_handle = gpadlmsg->gpadl;
 551         gpadl->buffer = kbuffer;
 552         gpadl->size = size;
 553
 554
 555 cleanup:
 556         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 557         list_del(&msginfo->msglistentry);
 558         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 559         list_for_each_entry_safe(submsginfo, tmp, &msginfo->submsglist,
 560                                  msglistentry) {
 561                 kfree(submsginfo);
 562         }
 563
 564         kfree(msginfo);
 565
 566         if (ret)
 567                 set_memory_encrypted((unsigned long)kbuffer,
 568                                      PFN_UP(size));
 569
 570         return ret;
 571 }
 572
 573 /*
 574  * vmbus_establish_gpadl - Establish a GPADL for the specified buffer
 575  *
 576  * @channel: a channel
 577  * @kbuffer: from kmalloc or vmalloc
 578  * @size: page-size multiple
 579  * @gpadl_handle: some funky thing
 580  */
 581 int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
 582                           u32 size, struct vmbus_gpadl *gpadl)
 583 {
 584         return __vmbus_establish_gpadl(channel, HV_GPADL_BUFFER, kbuffer, size,
 585                                        0U, gpadl);
 586 }
 587 EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
 588
 589 /**
 590  * request_arr_init - Allocates memory for the requestor array. Each slot
 591  * keeps track of the next available slot in the array. Initially, each
 592  * slot points to the next one (as in a Linked List). The last slot
 593  * does not point to anything, so its value is U64_MAX by default.
 594  * @size The size of the array
 595  */
 596 static u64 *request_arr_init(u32 size)
 597 {
 598         int i;
 599         u64 *req_arr;
 600
 601         req_arr = kcalloc(size, sizeof(u64), GFP_KERNEL);
 602         if (!req_arr)
 603                 return NULL;
 604
 605         for (i = 0; i < size - 1; i++)
 606                 req_arr[i] = i + 1;
 607
 608         /* Last slot (no more available slots) */
 609         req_arr[i] = U64_MAX;
 610
 611         return req_arr;
 612 }
 613
 614 /*
 615  * vmbus_alloc_requestor - Initializes @rqstor's fields.
 616  * Index 0 is the first free slot
 617  * @size: Size of the requestor array
 618  */
 619 static int vmbus_alloc_requestor(struct vmbus_requestor *rqstor, u32 size)
 620 {
 621         u64 *rqst_arr;
 622         unsigned long *bitmap;
 623
 624         rqst_arr = request_arr_init(size);
 625         if (!rqst_arr)
 626                 return -ENOMEM;
 627
 628         bitmap = bitmap_zalloc(size, GFP_KERNEL);
 629         if (!bitmap) {
 630                 kfree(rqst_arr);
 631                 return -ENOMEM;
 632         }
 633
 634         rqstor->req_arr = rqst_arr;
 635         rqstor->req_bitmap = bitmap;
 636         rqstor->size = size;
 637         rqstor->next_request_id = 0;
 638         spin_lock_init(&rqstor->req_lock);
 639
 640         return 0;
 641 }
 642
 643 /*
 644  * vmbus_free_requestor - Frees memory allocated for @rqstor
 645  * @rqstor: Pointer to the requestor struct
 646  */
 647 static void vmbus_free_requestor(struct vmbus_requestor *rqstor)
 648 {
 649         kfree(rqstor->req_arr);
 650         bitmap_free(rqstor->req_bitmap);
 651 }
 652
 653 static int __vmbus_open(struct vmbus_channel *newchannel,
 654                        void *userdata, u32 userdatalen,
 655                        void (*onchannelcallback)(void *context), void *context)
 656 {
 657         struct vmbus_channel_open_channel *open_msg;
 658         struct vmbus_channel_msginfo *open_info = NULL;
 659         struct page *page = newchannel->ringbuffer_page;
 660         u32 send_pages, recv_pages;
 661         unsigned long flags;
 662         int err;
 663
 664         if (userdatalen > MAX_USER_DEFINED_BYTES)
 665                 return -EINVAL;
 666
 667         send_pages = newchannel->ringbuffer_send_offset;
 668         recv_pages = newchannel->ringbuffer_pagecount - send_pages;
 669
 670         if (newchannel->state != CHANNEL_OPEN_STATE)
 671                 return -EINVAL;
 672
 673         /* Create and init requestor */
 674         if (newchannel->rqstor_size) {
 675                 if (vmbus_alloc_requestor(&newchannel->requestor, newchannel->rqstor_size))
 676                         return -ENOMEM;
 677         }
 678
 679         newchannel->state = CHANNEL_OPENING_STATE;
 680         newchannel->onchannel_callback = onchannelcallback;
 681         newchannel->channel_callback_context = context;
 682
 683         if (!newchannel->max_pkt_size)
 684                 newchannel->max_pkt_size = VMBUS_DEFAULT_MAX_PKT_SIZE;
 685
 686         /* Establish the gpadl for the ring buffer */
 687         newchannel->ringbuffer_gpadlhandle.gpadl_handle = 0;
 688
 689         err = __vmbus_establish_gpadl(newchannel, HV_GPADL_RING,
 690                                       page_address(newchannel->ringbuffer_page),
 691                                       (send_pages + recv_pages) << PAGE_SHIFT,
 692                                       newchannel->ringbuffer_send_offset << PAGE_SHIFT,
 693                                       &newchannel->ringbuffer_gpadlhandle);
 694         if (err)
 695                 goto error_clean_ring;
 696
 697         err = hv_ringbuffer_init(&newchannel->outbound,
 698                                  page, send_pages, 0);
 699         if (err)
 700                 goto error_free_gpadl;
 701
 702         err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
 703                                  recv_pages, newchannel->max_pkt_size);
 704         if (err)
 705                 goto error_free_gpadl;
 706
 707         /* Create and init the channel open message */
 708         open_info = kzalloc(sizeof(*open_info) +
 709                            sizeof(struct vmbus_channel_open_channel),
 710                            GFP_KERNEL);
 711         if (!open_info) {
 712                 err = -ENOMEM;
 713                 goto error_free_gpadl;
 714         }
 715
 716         init_completion(&open_info->waitevent);
 717         open_info->waiting_channel = newchannel;
 718
 719         open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
 720         open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
 721         open_msg->openid = newchannel->offermsg.child_relid;
 722         open_msg->child_relid = newchannel->offermsg.child_relid;
 723         open_msg->ringbuffer_gpadlhandle
 724                 = newchannel->ringbuffer_gpadlhandle.gpadl_handle;
 725         /*
 726          * The unit of ->downstream_ringbuffer_pageoffset is HV_HYP_PAGE and
 727          * the unit of ->ringbuffer_send_offset (i.e. send_pages) is PAGE, so
 728          * here we calculate it into HV_HYP_PAGE.
 729          */
 730         open_msg->downstream_ringbuffer_pageoffset =
 731                 hv_ring_gpadl_send_hvpgoffset(send_pages << PAGE_SHIFT);
 732         open_msg->target_vp = hv_cpu_number_to_vp_number(newchannel->target_cpu);
 733
 734         if (userdatalen)
 735                 memcpy(open_msg->userdata, userdata, userdatalen);
 736
 737         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 738         list_add_tail(&open_info->msglistentry,
 739                       &vmbus_connection.chn_msg_list);
 740         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 741
 742         if (newchannel->rescind) {
 743                 err = -ENODEV;
 744                 goto error_clean_msglist;
 745         }
 746
 747         err = vmbus_post_msg(open_msg,
 748                              sizeof(struct vmbus_channel_open_channel), true);
 749
 750         trace_vmbus_open(open_msg, err);
 751
 752         if (err != 0)
 753                 goto error_clean_msglist;
 754
 755         wait_for_completion(&open_info->waitevent);
 756
 757         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 758         list_del(&open_info->msglistentry);
 759         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 760
 761         if (newchannel->rescind) {
 762                 err = -ENODEV;
 763                 goto error_free_info;
 764         }
 765
 766         if (open_info->response.open_result.status) {
 767                 err = -EAGAIN;
 768                 goto error_free_info;
 769         }
 770
 771         newchannel->state = CHANNEL_OPENED_STATE;
 772         kfree(open_info);
 773         return 0;
 774
 775 error_clean_msglist:
 776         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 777         list_del(&open_info->msglistentry);
 778         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 779 error_free_info:
 780         kfree(open_info);
 781 error_free_gpadl:
 782         vmbus_teardown_gpadl(newchannel, &newchannel->ringbuffer_gpadlhandle);
 783 error_clean_ring:
 784         hv_ringbuffer_cleanup(&newchannel->outbound);
 785         hv_ringbuffer_cleanup(&newchannel->inbound);
 786         vmbus_free_requestor(&newchannel->requestor);
 787         newchannel->state = CHANNEL_OPEN_STATE;
 788         return err;
 789 }
 790
 791 /*
 792  * vmbus_connect_ring - Open the channel but reuse ring buffer
 793  */
 794 int vmbus_connect_ring(struct vmbus_channel *newchannel,
 795                        void (*onchannelcallback)(void *context), void *context)
 796 {
 797         return  __vmbus_open(newchannel, NULL, 0, onchannelcallback, context);
 798 }
 799 EXPORT_SYMBOL_GPL(vmbus_connect_ring);
 800
 801 /*
 802  * vmbus_open - Open the specified channel.
 803  */
 804 int vmbus_open(struct vmbus_channel *newchannel,
 805                u32 send_ringbuffer_size, u32 recv_ringbuffer_size,
 806                void *userdata, u32 userdatalen,
 807                void (*onchannelcallback)(void *context), void *context)
 808 {
 809         int err;
 810
 811         err = vmbus_alloc_ring(newchannel, send_ringbuffer_size,
 812                                recv_ringbuffer_size);
 813         if (err)
 814                 return err;
 815
 816         err = __vmbus_open(newchannel, userdata, userdatalen,
 817                            onchannelcallback, context);
 818         if (err)
 819                 vmbus_free_ring(newchannel);
 820
 821         return err;
 822 }
 823 EXPORT_SYMBOL_GPL(vmbus_open);
 824
 825 /*
 826  * vmbus_teardown_gpadl -Teardown the specified GPADL handle
 827  */
 828 int vmbus_teardown_gpadl(struct vmbus_channel *channel, struct vmbus_gpadl *gpadl)
 829 {
 830         struct vmbus_channel_gpadl_teardown *msg;
 831         struct vmbus_channel_msginfo *info;
 832         unsigned long flags;
 833         int ret;
 834
 835         info = kzalloc(sizeof(*info) +
 836                        sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
 837         if (!info)
 838                 return -ENOMEM;
 839
 840         init_completion(&info->waitevent);
 841         info->waiting_channel = channel;
 842
 843         msg = (struct vmbus_channel_gpadl_teardown *)info->msg;
 844
 845         msg->header.msgtype = CHANNELMSG_GPADL_TEARDOWN;
 846         msg->child_relid = channel->offermsg.child_relid;
 847         msg->gpadl = gpadl->gpadl_handle;
 848
 849         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 850         list_add_tail(&info->msglistentry,
 851                       &vmbus_connection.chn_msg_list);
 852         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 853
 854         if (channel->rescind)
 855                 goto post_msg_err;
 856
 857         ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_gpadl_teardown),
 858                              true);
 859
 860         trace_vmbus_teardown_gpadl(msg, ret);
 861
 862         if (ret)
 863                 goto post_msg_err;
 864
 865         wait_for_completion(&info->waitevent);
 866
 867         gpadl->gpadl_handle = 0;
 868
 869 post_msg_err:
 870         /*
 871          * If the channel has been rescinded;
 872          * we will be awakened by the rescind
 873          * handler; set the error code to zero so we don't leak memory.
 874          */
 875         if (channel->rescind)
 876                 ret = 0;
 877
 878         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 879         list_del(&info->msglistentry);
 880         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
 881
 882         kfree(info);
 883
 884         ret = set_memory_encrypted((unsigned long)gpadl->buffer,
 885                                    PFN_UP(gpadl->size));
 886         if (ret)
 887                 pr_warn("Fail to set mem host visibility in GPADL teardown %d.\n", ret);
 888
 889         return ret;
 890 }
 891 EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
 892
 893 void vmbus_reset_channel_cb(struct vmbus_channel *channel)
 894 {
 895         unsigned long flags;
 896
 897         /*
 898          * vmbus_on_event(), running in the per-channel tasklet, can race
 899          * with vmbus_close_internal() in the case of SMP guest, e.g., when
 900          * the former is accessing channel->inbound.ring_buffer, the latter
 901          * could be freeing the ring_buffer pages, so here we must stop it
 902          * first.
 903          *
 904          * vmbus_chan_sched() might call the netvsc driver callback function
 905          * that ends up scheduling NAPI work that accesses the ring buffer.
 906          * At this point, we have to ensure that any such work is completed
 907          * and that the channel ring buffer is no longer being accessed, cf.
 908          * the calls to napi_disable() in netvsc_device_remove().
 909          */
 910         tasklet_disable(&channel->callback_event);
 911
 912         /* See the inline comments in vmbus_chan_sched(). */
 913         spin_lock_irqsave(&channel->sched_lock, flags);
 914         channel->onchannel_callback = NULL;
 915         spin_unlock_irqrestore(&channel->sched_lock, flags);
 916
 917         channel->sc_creation_callback = NULL;
 918
 919         /* Re-enable tasklet for use on re-open */
 920         tasklet_enable(&channel->callback_event);
 921 }
 922
 923 static int vmbus_close_internal(struct vmbus_channel *channel)
 924 {
 925         struct vmbus_channel_close_channel *msg;
 926         int ret;
 927
 928         vmbus_reset_channel_cb(channel);
 929
 930         /*
 931          * In case a device driver's probe() fails (e.g.,
 932          * util_probe() -> vmbus_open() returns -ENOMEM) and the device is
 933          * rescinded later (e.g., we dynamically disable an Integrated Service
 934          * in Hyper-V Manager), the driver's remove() invokes vmbus_close():
 935          * here we should skip most of the below cleanup work.
 936          */
 937         if (channel->state != CHANNEL_OPENED_STATE)
 938                 return -EINVAL;
 939
 940         channel->state = CHANNEL_OPEN_STATE;
 941
 942         /* Send a closing message */
 943
 944         msg = &channel->close_msg.msg;
 945
 946         msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
 947         msg->child_relid = channel->offermsg.child_relid;
 948
 949         ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_close_channel),
 950                              true);
 951
 952         trace_vmbus_close_internal(msg, ret);
 953
 954         if (ret) {
 955                 pr_err("Close failed: close post msg return is %d\n", ret);
 956                 /*
 957                  * If we failed to post the close msg,
 958                  * it is perhaps better to leak memory.
 959                  */
 960         }
 961
 962         /* Tear down the gpadl for the channel's ring buffer */
 963         else if (channel->ringbuffer_gpadlhandle.gpadl_handle) {
 964                 ret = vmbus_teardown_gpadl(channel, &channel->ringbuffer_gpadlhandle);
 965                 if (ret) {
 966                         pr_err("Close failed: teardown gpadl return %d\n", ret);
 967                         /*
 968                          * If we failed to teardown gpadl,
 969                          * it is perhaps better to leak memory.
 970                          */
 971                 }
 972         }
 973
 974         if (!ret)
 975                 vmbus_free_requestor(&channel->requestor);
 976
 977         return ret;
 978 }
 979
 980 /* disconnect ring - close all channels */
 981 int vmbus_disconnect_ring(struct vmbus_channel *channel)
 982 {
 983         struct vmbus_channel *cur_channel, *tmp;
 984         int ret;
 985
 986         if (channel->primary_channel != NULL)
 987                 return -EINVAL;
 988
 989         list_for_each_entry_safe(cur_channel, tmp, &channel->sc_list, sc_list) {
 990                 if (cur_channel->rescind)
 991                         wait_for_completion(&cur_channel->rescind_event);
 992
 993                 mutex_lock(&vmbus_connection.channel_mutex);
 994                 if (vmbus_close_internal(cur_channel) == 0) {
 995                         vmbus_free_ring(cur_channel);
 996
 997                         if (cur_channel->rescind)
 998                                 hv_process_channel_removal(cur_channel);
 999                 }
1000                 mutex_unlock(&vmbus_connection.channel_mutex);
1001         }
1002
1003         /*
1004          * Now close the primary.
1005          */
1006         mutex_lock(&vmbus_connection.channel_mutex);
1007         ret = vmbus_close_internal(channel);
1008         mutex_unlock(&vmbus_connection.channel_mutex);
1009
1010         return ret;
1011 }
1012 EXPORT_SYMBOL_GPL(vmbus_disconnect_ring);
1013
1014 /*
1015  * vmbus_close - Close the specified channel
1016  */
1017 void vmbus_close(struct vmbus_channel *channel)
1018 {
1019         if (vmbus_disconnect_ring(channel) == 0)
1020                 vmbus_free_ring(channel);
1021 }
1022 EXPORT_SYMBOL_GPL(vmbus_close);
1023
1024 /**
1025  * vmbus_sendpacket_getid() - Send the specified buffer on the given channel
1026  * @channel: Pointer to vmbus_channel structure
1027  * @buffer: Pointer to the buffer you want to send the data from.
1028  * @bufferlen: Maximum size of what the buffer holds.
1029  * @requestid: Identifier of the request
1030  * @trans_id: Identifier of the transaction associated to this request, if
1031  *            the send is successful; undefined, otherwise.
1032  * @type: Type of packet that is being sent e.g. negotiate, time
1033  *        packet etc.
1034  * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
1035  *
1036  * Sends data in @buffer directly to Hyper-V via the vmbus.
1037  * This will send the data unparsed to Hyper-V.
1038  *
1039  * Mainly used by Hyper-V drivers.
1040  */
1041 int vmbus_sendpacket_getid(struct vmbus_channel *channel, void *buffer,
1042                            u32 bufferlen, u64 requestid, u64 *trans_id,
1043                            enum vmbus_packet_type type, u32 flags)
1044 {
1045         struct vmpacket_descriptor desc;
1046         u32 packetlen = sizeof(struct vmpacket_descriptor) + bufferlen;
1047         u32 packetlen_aligned = ALIGN(packetlen, sizeof(u64));
1048         struct kvec bufferlist[3];
1049         u64 aligned_data = 0;
1050         int num_vecs = ((bufferlen != 0) ? 3 : 1);
1051
1052
1053         /* Setup the descriptor */
1054         desc.type = type; /* VmbusPacketTypeDataInBand; */
1055         desc.flags = flags; /* VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; */
1056         /* in 8-bytes granularity */
1057         desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
1058         desc.len8 = (u16)(packetlen_aligned >> 3);
1059         desc.trans_id = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
1060
1061         bufferlist[0].iov_base = &desc;
1062         bufferlist[0].iov_len = sizeof(struct vmpacket_descriptor);
1063         bufferlist[1].iov_base = buffer;
1064         bufferlist[1].iov_len = bufferlen;
1065         bufferlist[2].iov_base = &aligned_data;
1066         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
1067
1068         return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid, trans_id);
1069 }
1070 EXPORT_SYMBOL(vmbus_sendpacket_getid);
1071
1072 /**
1073  * vmbus_sendpacket() - Send the specified buffer on the given channel
1074  * @channel: Pointer to vmbus_channel structure
1075  * @buffer: Pointer to the buffer you want to send the data from.
1076  * @bufferlen: Maximum size of what the buffer holds.
1077  * @requestid: Identifier of the request
1078  * @type: Type of packet that is being sent e.g. negotiate, time
1079  *        packet etc.
1080  * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
1081  *
1082  * Sends data in @buffer directly to Hyper-V via the vmbus.
1083  * This will send the data unparsed to Hyper-V.
1084  *
1085  * Mainly used by Hyper-V drivers.
1086  */
1087 int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
1088                      u32 bufferlen, u64 requestid,
1089                      enum vmbus_packet_type type, u32 flags)
1090 {
1091         return vmbus_sendpacket_getid(channel, buffer, bufferlen,
1092                                       requestid, NULL, type, flags);
1093 }
1094 EXPORT_SYMBOL(vmbus_sendpacket);
1095
1096 /*
1097  * vmbus_sendpacket_pagebuffer - Send a range of single-page buffer
1098  * packets using a GPADL Direct packet type. This interface allows you
1099  * to control notifying the host. This will be useful for sending
1100  * batched data. Also the sender can control the send flags
1101  * explicitly.
1102  */
1103 int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
1104                                 struct hv_page_buffer pagebuffers[],
1105                                 u32 pagecount, void *buffer, u32 bufferlen,
1106                                 u64 requestid)
1107 {
1108         int i;
1109         struct vmbus_channel_packet_page_buffer desc;
1110         u32 descsize;
1111         u32 packetlen;
1112         u32 packetlen_aligned;
1113         struct kvec bufferlist[3];
1114         u64 aligned_data = 0;
1115
1116         if (pagecount > MAX_PAGE_BUFFER_COUNT)
1117                 return -EINVAL;
1118
1119         /*
1120          * Adjust the size down since vmbus_channel_packet_page_buffer is the
1121          * largest size we support
1122          */
1123         descsize = sizeof(struct vmbus_channel_packet_page_buffer) -
1124                           ((MAX_PAGE_BUFFER_COUNT - pagecount) *
1125                           sizeof(struct hv_page_buffer));
1126         packetlen = descsize + bufferlen;
1127         packetlen_aligned = ALIGN(packetlen, sizeof(u64));
1128
1129         /* Setup the descriptor */
1130         desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
1131         desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
1132         desc.dataoffset8 = descsize >> 3; /* in 8-bytes granularity */
1133         desc.length8 = (u16)(packetlen_aligned >> 3);
1134         desc.transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
1135         desc.reserved = 0;
1136         desc.rangecount = pagecount;
1137
1138         for (i = 0; i < pagecount; i++) {
1139                 desc.range[i].len = pagebuffers[i].len;
1140                 desc.range[i].offset = pagebuffers[i].offset;
1141                 desc.range[i].pfn        = pagebuffers[i].pfn;
1142         }
1143
1144         bufferlist[0].iov_base = &desc;
1145         bufferlist[0].iov_len = descsize;
1146         bufferlist[1].iov_base = buffer;
1147         bufferlist[1].iov_len = bufferlen;
1148         bufferlist[2].iov_base = &aligned_data;
1149         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
1150
1151         return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
1152 }
1153 EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
1154
1155 /*
1156  * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
1157  * using a GPADL Direct packet type.
1158  * The buffer includes the vmbus descriptor.
1159  */
1160 int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
1161                               struct vmbus_packet_mpb_array *desc,
1162                               u32 desc_size,
1163                               void *buffer, u32 bufferlen, u64 requestid)
1164 {
1165         u32 packetlen;
1166         u32 packetlen_aligned;
1167         struct kvec bufferlist[3];
1168         u64 aligned_data = 0;
1169
1170         packetlen = desc_size + bufferlen;
1171         packetlen_aligned = ALIGN(packetlen, sizeof(u64));
1172
1173         /* Setup the descriptor */
1174         desc->type = VM_PKT_DATA_USING_GPA_DIRECT;
1175         desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
1176         desc->dataoffset8 = desc_size >> 3; /* in 8-bytes granularity */
1177         desc->length8 = (u16)(packetlen_aligned >> 3);
1178         desc->transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
1179         desc->reserved = 0;
1180         desc->rangecount = 1;
1181
1182         bufferlist[0].iov_base = desc;
1183         bufferlist[0].iov_len = desc_size;
1184         bufferlist[1].iov_base = buffer;
1185         bufferlist[1].iov_len = bufferlen;
1186         bufferlist[2].iov_base = &aligned_data;
1187         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
1188
1189         return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
1190 }
1191 EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
1192
1193 /**
1194  * __vmbus_recvpacket() - Retrieve the user packet on the specified channel
1195  * @channel: Pointer to vmbus_channel structure
1196  * @buffer: Pointer to the buffer you want to receive the data into.
1197  * @bufferlen: Maximum size of what the buffer can hold.
1198  * @buffer_actual_len: The actual size of the data after it was received.
1199  * @requestid: Identifier of the request
1200  * @raw: true means keep the vmpacket_descriptor header in the received data.
1201  *
1202  * Receives directly from the hyper-v vmbus and puts the data it received
1203  * into Buffer. This will receive the data unparsed from hyper-v.
1204  *
1205  * Mainly used by Hyper-V drivers.
1206  */
1207 static inline int
1208 __vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
1209                    u32 bufferlen, u32 *buffer_actual_len, u64 *requestid,
1210                    bool raw)
1211 {
1212         return hv_ringbuffer_read(channel, buffer, bufferlen,
1213                                   buffer_actual_len, requestid, raw);
1214
1215 }
1216
1217 int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
1218                      u32 bufferlen, u32 *buffer_actual_len,
1219                      u64 *requestid)
1220 {
1221         return __vmbus_recvpacket(channel, buffer, bufferlen,
1222                                   buffer_actual_len, requestid, false);
1223 }
1224 EXPORT_SYMBOL(vmbus_recvpacket);
1225
1226 /*
1227  * vmbus_recvpacket_raw - Retrieve the raw packet on the specified channel
1228  */
1229 int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
1230                               u32 bufferlen, u32 *buffer_actual_len,
1231                               u64 *requestid)
1232 {
1233         return __vmbus_recvpacket(channel, buffer, bufferlen,
1234                                   buffer_actual_len, requestid, true);
1235 }
1236 EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
1237
1238 /*
1239  * vmbus_next_request_id - Returns a new request id. It is also
1240  * the index at which the guest memory address is stored.
1241  * Uses a spin lock to avoid race conditions.
1242  * @channel: Pointer to the VMbus channel struct
1243  * @rqst_add: Guest memory address to be stored in the array
1244  */
1245 u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
1246 {
1247         struct vmbus_requestor *rqstor = &channel->requestor;
1248         unsigned long flags;
1249         u64 current_id;
1250
1251         /* Check rqstor has been initialized */
1252         if (!channel->rqstor_size)
1253                 return VMBUS_NO_RQSTOR;
1254
1255         lock_requestor(channel, flags);
1256         current_id = rqstor->next_request_id;
1257
1258         /* Requestor array is full */
1259         if (current_id >= rqstor->size) {
1260                 unlock_requestor(channel, flags);
1261                 return VMBUS_RQST_ERROR;
1262         }
1263
1264         rqstor->next_request_id = rqstor->req_arr[current_id];
1265         rqstor->req_arr[current_id] = rqst_addr;
1266
1267         /* The already held spin lock provides atomicity */
1268         bitmap_set(rqstor->req_bitmap, current_id, 1);
1269
1270         unlock_requestor(channel, flags);
1271
1272         /*
1273          * Cannot return an ID of 0, which is reserved for an unsolicited
1274          * message from Hyper-V; Hyper-V does not acknowledge (respond to)
1275          * VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED requests with ID of
1276          * 0 sent by the guest.
1277          */
1278         return current_id + 1;
1279 }
1280 EXPORT_SYMBOL_GPL(vmbus_next_request_id);
1281
1282 /* As in vmbus_request_addr_match() but without the requestor lock */
1283 u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
1284                                u64 rqst_addr)
1285 {
1286         struct vmbus_requestor *rqstor = &channel->requestor;
1287         u64 req_addr;
1288
1289         /* Check rqstor has been initialized */
1290         if (!channel->rqstor_size)
1291                 return VMBUS_NO_RQSTOR;
1292
1293         /* Hyper-V can send an unsolicited message with ID of 0 */
1294         if (!trans_id)
1295                 return VMBUS_RQST_ERROR;
1296
1297         /* Data corresponding to trans_id is stored at trans_id - 1 */
1298         trans_id--;
1299
1300         /* Invalid trans_id */
1301         if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))
1302                 return VMBUS_RQST_ERROR;
1303
1304         req_addr = rqstor->req_arr[trans_id];
1305         if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {
1306                 rqstor->req_arr[trans_id] = rqstor->next_request_id;
1307                 rqstor->next_request_id = trans_id;
1308
1309                 /* The already held spin lock provides atomicity */
1310                 bitmap_clear(rqstor->req_bitmap, trans_id, 1);
1311         }
1312
1313         return req_addr;
1314 }
1315 EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
1316
1317 /*
1318  * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's
1319  * requestor, provided the memory address stored at @trans_id equals @rqst_addr
1320  * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).
1321  *
1322  * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if
1323  * @trans_id is not contained in the requestor.
1324  *
1325  * Acquires and releases the requestor spin lock.
1326  */
1327 u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
1328                              u64 rqst_addr)
1329 {
1330         unsigned long flags;
1331         u64 req_addr;
1332
1333         lock_requestor(channel, flags);
1334         req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
1335         unlock_requestor(channel, flags);
1336
1337         return req_addr;
1338 }
1339 EXPORT_SYMBOL_GPL(vmbus_request_addr_match);
1340
1341 /*
1342  * vmbus_request_addr - Returns the memory address stored at @trans_id
1343  * in @rqstor. Uses a spin lock to avoid race conditions.
1344  * @channel: Pointer to the VMbus channel struct
1345  * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
1346  * next request id.
1347  */
1348 u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
1349 {
1350         return vmbus_request_addr_match(channel, trans_id, VMBUS_RQST_ADDR_ANY);
1351 }
1352 EXPORT_SYMBOL_GPL(vmbus_request_addr);