drivers/hv/hv_balloon.c

   1 /*
   2  * Copyright (c) 2012, Microsoft Corporation.
   3  *
   4  * Author:
   5  *   K. Y. Srinivasan <kys@microsoft.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published
   9  * by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  14  * NON INFRINGEMENT.  See the GNU General Public License for more
  15  * details.
  16  *
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/kernel.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/mman.h>
  24 #include <linux/delay.h>
  25 #include <linux/init.h>
  26 #include <linux/module.h>
  27 #include <linux/slab.h>
  28 #include <linux/kthread.h>
  29 #include <linux/completion.h>
  30 #include <linux/memory_hotplug.h>
  31 #include <linux/memory.h>
  32 #include <linux/notifier.h>
  33 #include <linux/percpu_counter.h>
  34
  35 #include <linux/hyperv.h>
  36
  37 #define CREATE_TRACE_POINTS
  38 #include "hv_trace_balloon.h"
  39
  40 /*
  41  * We begin with definitions supporting the Dynamic Memory protocol
  42  * with the host.
  43  *
  44  * Begin protocol definitions.
  45  */
  46
  47
  48
  49 /*
  50  * Protocol versions. The low word is the minor version, the high word the major
  51  * version.
  52  *
  53  * History:
  54  * Initial version 1.0
  55  * Changed to 0.1 on 2009/03/25
  56  * Changes to 0.2 on 2009/05/14
  57  * Changes to 0.3 on 2009/12/03
  58  * Changed to 1.0 on 2011/04/05
  59  */
  60
  61 #define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
  62 #define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
  63 #define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)
  64
  65 enum {
  66         DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
  67         DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
  68         DYNMEM_PROTOCOL_VERSION_3 = DYNMEM_MAKE_VERSION(2, 0),
  69
  70         DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
  71         DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
  72         DYNMEM_PROTOCOL_VERSION_WIN10 = DYNMEM_PROTOCOL_VERSION_3,
  73
  74         DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN10
  75 };
  76
  77
  78
  79 /*
  80  * Message Types
  81  */
  82
  83 enum dm_message_type {
  84         /*
  85          * Version 0.3
  86          */
  87         DM_ERROR                        = 0,
  88         DM_VERSION_REQUEST              = 1,
  89         DM_VERSION_RESPONSE             = 2,
  90         DM_CAPABILITIES_REPORT          = 3,
  91         DM_CAPABILITIES_RESPONSE        = 4,
  92         DM_STATUS_REPORT                = 5,
  93         DM_BALLOON_REQUEST              = 6,
  94         DM_BALLOON_RESPONSE             = 7,
  95         DM_UNBALLOON_REQUEST            = 8,
  96         DM_UNBALLOON_RESPONSE           = 9,
  97         DM_MEM_HOT_ADD_REQUEST          = 10,
  98         DM_MEM_HOT_ADD_RESPONSE         = 11,
  99         DM_VERSION_03_MAX               = 11,
 100         /*
 101          * Version 1.0.
 102          */
 103         DM_INFO_MESSAGE                 = 12,
 104         DM_VERSION_1_MAX                = 12
 105 };
 106
 107
 108 /*
 109  * Structures defining the dynamic memory management
 110  * protocol.
 111  */
 112
 113 union dm_version {
 114         struct {
 115                 __u16 minor_version;
 116                 __u16 major_version;
 117         };
 118         __u32 version;
 119 } __packed;
 120
 121
 122 union dm_caps {
 123         struct {
 124                 __u64 balloon:1;
 125                 __u64 hot_add:1;
 126                 /*
 127                  * To support guests that may have alignment
 128                  * limitations on hot-add, the guest can specify
 129                  * its alignment requirements; a value of n
 130                  * represents an alignment of 2^n in mega bytes.
 131                  */
 132                 __u64 hot_add_alignment:4;
 133                 __u64 reservedz:58;
 134         } cap_bits;
 135         __u64 caps;
 136 } __packed;
 137
 138 union dm_mem_page_range {
 139         struct  {
 140                 /*
 141                  * The PFN number of the first page in the range.
 142                  * 40 bits is the architectural limit of a PFN
 143                  * number for AMD64.
 144                  */
 145                 __u64 start_page:40;
 146                 /*
 147                  * The number of pages in the range.
 148                  */
 149                 __u64 page_cnt:24;
 150         } finfo;
 151         __u64  page_range;
 152 } __packed;
 153
 154
 155
 156 /*
 157  * The header for all dynamic memory messages:
 158  *
 159  * type: Type of the message.
 160  * size: Size of the message in bytes; including the header.
 161  * trans_id: The guest is responsible for manufacturing this ID.
 162  */
 163
 164 struct dm_header {
 165         __u16 type;
 166         __u16 size;
 167         __u32 trans_id;
 168 } __packed;
 169
 170 /*
 171  * A generic message format for dynamic memory.
 172  * Specific message formats are defined later in the file.
 173  */
 174
 175 struct dm_message {
 176         struct dm_header hdr;
 177         __u8 data[]; /* enclosed message */
 178 } __packed;
 179
 180
 181 /*
 182  * Specific message types supporting the dynamic memory protocol.
 183  */
 184
 185 /*
 186  * Version negotiation message. Sent from the guest to the host.
 187  * The guest is free to try different versions until the host
 188  * accepts the version.
 189  *
 190  * dm_version: The protocol version requested.
 191  * is_last_attempt: If TRUE, this is the last version guest will request.
 192  * reservedz: Reserved field, set to zero.
 193  */
 194
 195 struct dm_version_request {
 196         struct dm_header hdr;
 197         union dm_version version;
 198         __u32 is_last_attempt:1;
 199         __u32 reservedz:31;
 200 } __packed;
 201
 202 /*
 203  * Version response message; Host to Guest and indicates
 204  * if the host has accepted the version sent by the guest.
 205  *
 206  * is_accepted: If TRUE, host has accepted the version and the guest
 207  * should proceed to the next stage of the protocol. FALSE indicates that
 208  * guest should re-try with a different version.
 209  *
 210  * reservedz: Reserved field, set to zero.
 211  */
 212
 213 struct dm_version_response {
 214         struct dm_header hdr;
 215         __u64 is_accepted:1;
 216         __u64 reservedz:63;
 217 } __packed;
 218
 219 /*
 220  * Message reporting capabilities. This is sent from the guest to the
 221  * host.
 222  */
 223
 224 struct dm_capabilities {
 225         struct dm_header hdr;
 226         union dm_caps caps;
 227         __u64 min_page_cnt;
 228         __u64 max_page_number;
 229 } __packed;
 230
 231 /*
 232  * Response to the capabilities message. This is sent from the host to the
 233  * guest. This message notifies if the host has accepted the guest's
 234  * capabilities. If the host has not accepted, the guest must shutdown
 235  * the service.
 236  *
 237  * is_accepted: Indicates if the host has accepted guest's capabilities.
 238  * reservedz: Must be 0.
 239  */
 240
 241 struct dm_capabilities_resp_msg {
 242         struct dm_header hdr;
 243         __u64 is_accepted:1;
 244         __u64 reservedz:63;
 245 } __packed;
 246
 247 /*
 248  * This message is used to report memory pressure from the guest.
 249  * This message is not part of any transaction and there is no
 250  * response to this message.
 251  *
 252  * num_avail: Available memory in pages.
 253  * num_committed: Committed memory in pages.
 254  * page_file_size: The accumulated size of all page files
 255  *                 in the system in pages.
 256  * zero_free: The nunber of zero and free pages.
 257  * page_file_writes: The writes to the page file in pages.
 258  * io_diff: An indicator of file cache efficiency or page file activity,
 259  *          calculated as File Cache Page Fault Count - Page Read Count.
 260  *          This value is in pages.
 261  *
 262  * Some of these metrics are Windows specific and fortunately
 263  * the algorithm on the host side that computes the guest memory
 264  * pressure only uses num_committed value.
 265  */
 266
 267 struct dm_status {
 268         struct dm_header hdr;
 269         __u64 num_avail;
 270         __u64 num_committed;
 271         __u64 page_file_size;
 272         __u64 zero_free;
 273         __u32 page_file_writes;
 274         __u32 io_diff;
 275 } __packed;
 276
 277
 278 /*
 279  * Message to ask the guest to allocate memory - balloon up message.
 280  * This message is sent from the host to the guest. The guest may not be
 281  * able to allocate as much memory as requested.
 282  *
 283  * num_pages: number of pages to allocate.
 284  */
 285
 286 struct dm_balloon {
 287         struct dm_header hdr;
 288         __u32 num_pages;
 289         __u32 reservedz;
 290 } __packed;
 291
 292
 293 /*
 294  * Balloon response message; this message is sent from the guest
 295  * to the host in response to the balloon message.
 296  *
 297  * reservedz: Reserved; must be set to zero.
 298  * more_pages: If FALSE, this is the last message of the transaction.
 299  * if TRUE there will atleast one more message from the guest.
 300  *
 301  * range_count: The number of ranges in the range array.
 302  *
 303  * range_array: An array of page ranges returned to the host.
 304  *
 305  */
 306
 307 struct dm_balloon_response {
 308         struct dm_header hdr;
 309         __u32 reservedz;
 310         __u32 more_pages:1;
 311         __u32 range_count:31;
 312         union dm_mem_page_range range_array[];
 313 } __packed;
 314
 315 /*
 316  * Un-balloon message; this message is sent from the host
 317  * to the guest to give guest more memory.
 318  *
 319  * more_pages: If FALSE, this is the last message of the transaction.
 320  * if TRUE there will atleast one more message from the guest.
 321  *
 322  * reservedz: Reserved; must be set to zero.
 323  *
 324  * range_count: The number of ranges in the range array.
 325  *
 326  * range_array: An array of page ranges returned to the host.
 327  *
 328  */
 329
 330 struct dm_unballoon_request {
 331         struct dm_header hdr;
 332         __u32 more_pages:1;
 333         __u32 reservedz:31;
 334         __u32 range_count;
 335         union dm_mem_page_range range_array[];
 336 } __packed;
 337
 338 /*
 339  * Un-balloon response message; this message is sent from the guest
 340  * to the host in response to an unballoon request.
 341  *
 342  */
 343
 344 struct dm_unballoon_response {
 345         struct dm_header hdr;
 346 } __packed;
 347
 348
 349 /*
 350  * Hot add request message. Message sent from the host to the guest.
 351  *
 352  * mem_range: Memory range to hot add.
 353  *
 354  * On Linux we currently don't support this since we cannot hot add
 355  * arbitrary granularity of memory.
 356  */
 357
 358 struct dm_hot_add {
 359         struct dm_header hdr;
 360         union dm_mem_page_range range;
 361 } __packed;
 362
 363 /*
 364  * Hot add response message.
 365  * This message is sent by the guest to report the status of a hot add request.
 366  * If page_count is less than the requested page count, then the host should
 367  * assume all further hot add requests will fail, since this indicates that
 368  * the guest has hit an upper physical memory barrier.
 369  *
 370  * Hot adds may also fail due to low resources; in this case, the guest must
 371  * not complete this message until the hot add can succeed, and the host must
 372  * not send a new hot add request until the response is sent.
 373  * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
 374  * times it fails the request.
 375  *
 376  *
 377  * page_count: number of pages that were successfully hot added.
 378  *
 379  * result: result of the operation 1: success, 0: failure.
 380  *
 381  */
 382
 383 struct dm_hot_add_response {
 384         struct dm_header hdr;
 385         __u32 page_count;
 386         __u32 result;
 387 } __packed;
 388
 389 /*
 390  * Types of information sent from host to the guest.
 391  */
 392
 393 enum dm_info_type {
 394         INFO_TYPE_MAX_PAGE_CNT = 0,
 395         MAX_INFO_TYPE
 396 };
 397
 398
 399 /*
 400  * Header for the information message.
 401  */
 402
 403 struct dm_info_header {
 404         enum dm_info_type type;
 405         __u32 data_size;
 406 } __packed;
 407
 408 /*
 409  * This message is sent from the host to the guest to pass
 410  * some relevant information (win8 addition).
 411  *
 412  * reserved: no used.
 413  * info_size: size of the information blob.
 414  * info: information blob.
 415  */
 416
 417 struct dm_info_msg {
 418         struct dm_header hdr;
 419         __u32 reserved;
 420         __u32 info_size;
 421         __u8  info[];
 422 };
 423
 424 /*
 425  * End protocol definitions.
 426  */
 427
 428 /*
 429  * State to manage hot adding memory into the guest.
 430  * The range start_pfn : end_pfn specifies the range
 431  * that the host has asked us to hot add. The range
 432  * start_pfn : ha_end_pfn specifies the range that we have
 433  * currently hot added. We hot add in multiples of 128M
 434  * chunks; it is possible that we may not be able to bring
 435  * online all the pages in the region. The range
 436  * covered_start_pfn:covered_end_pfn defines the pages that can
 437  * be brough online.
 438  */
 439
 440 struct hv_hotadd_state {
 441         struct list_head list;
 442         unsigned long start_pfn;
 443         unsigned long covered_start_pfn;
 444         unsigned long covered_end_pfn;
 445         unsigned long ha_end_pfn;
 446         unsigned long end_pfn;
 447         /*
 448          * A list of gaps.
 449          */
 450         struct list_head gap_list;
 451 };
 452
 453 struct hv_hotadd_gap {
 454         struct list_head list;
 455         unsigned long start_pfn;
 456         unsigned long end_pfn;
 457 };
 458
 459 struct balloon_state {
 460         __u32 num_pages;
 461         struct work_struct wrk;
 462 };
 463
 464 struct hot_add_wrk {
 465         union dm_mem_page_range ha_page_range;
 466         union dm_mem_page_range ha_region_range;
 467         struct work_struct wrk;
 468 };
 469
 470 static bool hot_add = true;
 471 static bool do_hot_add;
 472 /*
 473  * Delay reporting memory pressure by
 474  * the specified number of seconds.
 475  */
 476 static uint pressure_report_delay = 45;
 477
 478 /*
 479  * The last time we posted a pressure report to host.
 480  */
 481 static unsigned long last_post_time;
 482
 483 module_param(hot_add, bool, (S_IRUGO | S_IWUSR));
 484 MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");
 485
 486 module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR));
 487 MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
 488 static atomic_t trans_id = ATOMIC_INIT(0);
 489
 490 static int dm_ring_size = (5 * PAGE_SIZE);
 491
 492 /*
 493  * Driver specific state.
 494  */
 495
 496 enum hv_dm_state {
 497         DM_INITIALIZING = 0,
 498         DM_INITIALIZED,
 499         DM_BALLOON_UP,
 500         DM_BALLOON_DOWN,
 501         DM_HOT_ADD,
 502         DM_INIT_ERROR
 503 };
 504
 505
 506 static __u8 recv_buffer[PAGE_SIZE];
 507 static __u8 *send_buffer;
 508 #define PAGES_IN_2M     512
 509 #define HA_CHUNK (32 * 1024)
 510
 511 struct hv_dynmem_device {
 512         struct hv_device *dev;
 513         enum hv_dm_state state;
 514         struct completion host_event;
 515         struct completion config_event;
 516
 517         /*
 518          * Number of pages we have currently ballooned out.
 519          */
 520         unsigned int num_pages_ballooned;
 521         unsigned int num_pages_onlined;
 522         unsigned int num_pages_added;
 523
 524         /*
 525          * State to manage the ballooning (up) operation.
 526          */
 527         struct balloon_state balloon_wrk;
 528
 529         /*
 530          * State to execute the "hot-add" operation.
 531          */
 532         struct hot_add_wrk ha_wrk;
 533
 534         /*
 535          * This state tracks if the host has specified a hot-add
 536          * region.
 537          */
 538         bool host_specified_ha_region;
 539
 540         /*
 541          * State to synchronize hot-add.
 542          */
 543         struct completion  ol_waitevent;
 544         bool ha_waiting;
 545         /*
 546          * This thread handles hot-add
 547          * requests from the host as well as notifying
 548          * the host with regards to memory pressure in
 549          * the guest.
 550          */
 551         struct task_struct *thread;
 552
 553         /*
 554          * Protects ha_region_list, num_pages_onlined counter and individual
 555          * regions from ha_region_list.
 556          */
 557         spinlock_t ha_lock;
 558
 559         /*
 560          * A list of hot-add regions.
 561          */
 562         struct list_head ha_region_list;
 563
 564         /*
 565          * We start with the highest version we can support
 566          * and downgrade based on the host; we save here the
 567          * next version to try.
 568          */
 569         __u32 next_version;
 570
 571         /*
 572          * The negotiated version agreed by host.
 573          */
 574         __u32 version;
 575 };
 576
 577 static struct hv_dynmem_device dm_device;
 578
 579 static void post_status(struct hv_dynmem_device *dm);
 580
 581 #ifdef CONFIG_MEMORY_HOTPLUG
 582 static inline bool has_pfn_is_backed(struct hv_hotadd_state *has,
 583                                      unsigned long pfn)
 584 {
 585         struct hv_hotadd_gap *gap;
 586
 587         /* The page is not backed. */
 588         if ((pfn < has->covered_start_pfn) || (pfn >= has->covered_end_pfn))
 589                 return false;
 590
 591         /* Check for gaps. */
 592         list_for_each_entry(gap, &has->gap_list, list) {
 593                 if ((pfn >= gap->start_pfn) && (pfn < gap->end_pfn))
 594                         return false;
 595         }
 596
 597         return true;
 598 }
 599
 600 static unsigned long hv_page_offline_check(unsigned long start_pfn,
 601                                            unsigned long nr_pages)
 602 {
 603         unsigned long pfn = start_pfn, count = 0;
 604         struct hv_hotadd_state *has;
 605         bool found;
 606
 607         while (pfn < start_pfn + nr_pages) {
 608                 /*
 609                  * Search for HAS which covers the pfn and when we find one
 610                  * count how many consequitive PFNs are covered.
 611                  */
 612                 found = false;
 613                 list_for_each_entry(has, &dm_device.ha_region_list, list) {
 614                         while ((pfn >= has->start_pfn) &&
 615                                (pfn < has->end_pfn) &&
 616                                (pfn < start_pfn + nr_pages)) {
 617                                 found = true;
 618                                 if (has_pfn_is_backed(has, pfn))
 619                                         count++;
 620                                 pfn++;
 621                         }
 622                 }
 623
 624                 /*
 625                  * This PFN is not in any HAS (e.g. we're offlining a region
 626                  * which was present at boot), no need to account for it. Go
 627                  * to the next one.
 628                  */
 629                 if (!found)
 630                         pfn++;
 631         }
 632
 633         return count;
 634 }
 635
 636 static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
 637                               void *v)
 638 {
 639         struct memory_notify *mem = (struct memory_notify *)v;
 640         unsigned long flags, pfn_count;
 641
 642         switch (val) {
 643         case MEM_ONLINE:
 644         case MEM_CANCEL_ONLINE:
 645                 if (dm_device.ha_waiting) {
 646                         dm_device.ha_waiting = false;
 647                         complete(&dm_device.ol_waitevent);
 648                 }
 649                 break;
 650
 651         case MEM_OFFLINE:
 652                 spin_lock_irqsave(&dm_device.ha_lock, flags);
 653                 pfn_count = hv_page_offline_check(mem->start_pfn,
 654                                                   mem->nr_pages);
 655                 if (pfn_count <= dm_device.num_pages_onlined) {
 656                         dm_device.num_pages_onlined -= pfn_count;
 657                 } else {
 658                         /*
 659                          * We're offlining more pages than we managed to online.
 660                          * This is unexpected. In any case don't let
 661                          * num_pages_onlined wrap around zero.
 662                          */
 663                         WARN_ON_ONCE(1);
 664                         dm_device.num_pages_onlined = 0;
 665                 }
 666                 spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 667                 break;
 668         case MEM_GOING_ONLINE:
 669         case MEM_GOING_OFFLINE:
 670         case MEM_CANCEL_OFFLINE:
 671                 break;
 672         }
 673         return NOTIFY_OK;
 674 }
 675
 676 static struct notifier_block hv_memory_nb = {
 677         .notifier_call = hv_memory_notifier,
 678         .priority = 0
 679 };
 680
 681 /* Check if the particular page is backed and can be onlined and online it. */
 682 static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
 683 {
 684         if (!has_pfn_is_backed(has, page_to_pfn(pg)))
 685                 return;
 686
 687         /* This frame is currently backed; online the page. */
 688         __online_page_set_limits(pg);
 689         __online_page_increment_counters(pg);
 690         __online_page_free(pg);
 691
 692         lockdep_assert_held(&dm_device.ha_lock);
 693         dm_device.num_pages_onlined++;
 694 }
 695
 696 static void hv_bring_pgs_online(struct hv_hotadd_state *has,
 697                                 unsigned long start_pfn, unsigned long size)
 698 {
 699         int i;
 700
 701         pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
 702         for (i = 0; i < size; i++)
 703                 hv_page_online_one(has, pfn_to_page(start_pfn + i));
 704 }
 705
 706 static void hv_mem_hot_add(unsigned long start, unsigned long size,
 707                                 unsigned long pfn_count,
 708                                 struct hv_hotadd_state *has)
 709 {
 710         int ret = 0;
 711         int i, nid;
 712         unsigned long start_pfn;
 713         unsigned long processed_pfn;
 714         unsigned long total_pfn = pfn_count;
 715         unsigned long flags;
 716
 717         for (i = 0; i < (size/HA_CHUNK); i++) {
 718                 start_pfn = start + (i * HA_CHUNK);
 719
 720                 spin_lock_irqsave(&dm_device.ha_lock, flags);
 721                 has->ha_end_pfn +=  HA_CHUNK;
 722
 723                 if (total_pfn > HA_CHUNK) {
 724                         processed_pfn = HA_CHUNK;
 725                         total_pfn -= HA_CHUNK;
 726                 } else {
 727                         processed_pfn = total_pfn;
 728                         total_pfn = 0;
 729                 }
 730
 731                 has->covered_end_pfn +=  processed_pfn;
 732                 spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 733
 734                 init_completion(&dm_device.ol_waitevent);
 735                 dm_device.ha_waiting = !memhp_auto_online;
 736
 737                 nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
 738                 ret = add_memory(nid, PFN_PHYS((start_pfn)),
 739                                 (HA_CHUNK << PAGE_SHIFT));
 740
 741                 if (ret) {
 742                         pr_err("hot_add memory failed error is %d\n", ret);
 743                         if (ret == -EEXIST) {
 744                                 /*
 745                                  * This error indicates that the error
 746                                  * is not a transient failure. This is the
 747                                  * case where the guest's physical address map
 748                                  * precludes hot adding memory. Stop all further
 749                                  * memory hot-add.
 750                                  */
 751                                 do_hot_add = false;
 752                         }
 753                         spin_lock_irqsave(&dm_device.ha_lock, flags);
 754                         has->ha_end_pfn -= HA_CHUNK;
 755                         has->covered_end_pfn -=  processed_pfn;
 756                         spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 757                         break;
 758                 }
 759
 760                 /*
 761                  * Wait for the memory block to be onlined when memory onlining
 762                  * is done outside of kernel (memhp_auto_online). Since the hot
 763                  * add has succeeded, it is ok to proceed even if the pages in
 764                  * the hot added region have not been "onlined" within the
 765                  * allowed time.
 766                  */
 767                 if (dm_device.ha_waiting)
 768                         wait_for_completion_timeout(&dm_device.ol_waitevent,
 769                                                     5*HZ);
 770                 post_status(&dm_device);
 771         }
 772 }
 773
 774 static void hv_online_page(struct page *pg)
 775 {
 776         struct hv_hotadd_state *has;
 777         unsigned long flags;
 778         unsigned long pfn = page_to_pfn(pg);
 779
 780         spin_lock_irqsave(&dm_device.ha_lock, flags);
 781         list_for_each_entry(has, &dm_device.ha_region_list, list) {
 782                 /* The page belongs to a different HAS. */
 783                 if ((pfn < has->start_pfn) || (pfn >= has->end_pfn))
 784                         continue;
 785
 786                 hv_page_online_one(has, pg);
 787                 break;
 788         }
 789         spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 790 }
 791
 792 static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
 793 {
 794         struct hv_hotadd_state *has;
 795         struct hv_hotadd_gap *gap;
 796         unsigned long residual, new_inc;
 797         int ret = 0;
 798         unsigned long flags;
 799
 800         spin_lock_irqsave(&dm_device.ha_lock, flags);
 801         list_for_each_entry(has, &dm_device.ha_region_list, list) {
 802                 /*
 803                  * If the pfn range we are dealing with is not in the current
 804                  * "hot add block", move on.
 805                  */
 806                 if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
 807                         continue;
 808
 809                 /*
 810                  * If the current start pfn is not where the covered_end
 811                  * is, create a gap and update covered_end_pfn.
 812                  */
 813                 if (has->covered_end_pfn != start_pfn) {
 814                         gap = kzalloc(sizeof(struct hv_hotadd_gap), GFP_ATOMIC);
 815                         if (!gap) {
 816                                 ret = -ENOMEM;
 817                                 break;
 818                         }
 819
 820                         INIT_LIST_HEAD(&gap->list);
 821                         gap->start_pfn = has->covered_end_pfn;
 822                         gap->end_pfn = start_pfn;
 823                         list_add_tail(&gap->list, &has->gap_list);
 824
 825                         has->covered_end_pfn = start_pfn;
 826                 }
 827
 828                 /*
 829                  * If the current hot add-request extends beyond
 830                  * our current limit; extend it.
 831                  */
 832                 if ((start_pfn + pfn_cnt) > has->end_pfn) {
 833                         residual = (start_pfn + pfn_cnt - has->end_pfn);
 834                         /*
 835                          * Extend the region by multiples of HA_CHUNK.
 836                          */
 837                         new_inc = (residual / HA_CHUNK) * HA_CHUNK;
 838                         if (residual % HA_CHUNK)
 839                                 new_inc += HA_CHUNK;
 840
 841                         has->end_pfn += new_inc;
 842                 }
 843
 844                 ret = 1;
 845                 break;
 846         }
 847         spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 848
 849         return ret;
 850 }
 851
 852 static unsigned long handle_pg_range(unsigned long pg_start,
 853                                         unsigned long pg_count)
 854 {
 855         unsigned long start_pfn = pg_start;
 856         unsigned long pfn_cnt = pg_count;
 857         unsigned long size;
 858         struct hv_hotadd_state *has;
 859         unsigned long pgs_ol = 0;
 860         unsigned long old_covered_state;
 861         unsigned long res = 0, flags;
 862
 863         pr_debug("Hot adding %lu pages starting at pfn 0x%lx.\n", pg_count,
 864                 pg_start);
 865
 866         spin_lock_irqsave(&dm_device.ha_lock, flags);
 867         list_for_each_entry(has, &dm_device.ha_region_list, list) {
 868                 /*
 869                  * If the pfn range we are dealing with is not in the current
 870                  * "hot add block", move on.
 871                  */
 872                 if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
 873                         continue;
 874
 875                 old_covered_state = has->covered_end_pfn;
 876
 877                 if (start_pfn < has->ha_end_pfn) {
 878                         /*
 879                          * This is the case where we are backing pages
 880                          * in an already hot added region. Bring
 881                          * these pages online first.
 882                          */
 883                         pgs_ol = has->ha_end_pfn - start_pfn;
 884                         if (pgs_ol > pfn_cnt)
 885                                 pgs_ol = pfn_cnt;
 886
 887                         has->covered_end_pfn +=  pgs_ol;
 888                         pfn_cnt -= pgs_ol;
 889                         /*
 890                          * Check if the corresponding memory block is already
 891                          * online by checking its last previously backed page.
 892                          * In case it is we need to bring rest (which was not
 893                          * backed previously) online too.
 894                          */
 895                         if (start_pfn > has->start_pfn &&
 896                             !PageReserved(pfn_to_page(start_pfn - 1)))
 897                                 hv_bring_pgs_online(has, start_pfn, pgs_ol);
 898
 899                 }
 900
 901                 if ((has->ha_end_pfn < has->end_pfn) && (pfn_cnt > 0)) {
 902                         /*
 903                          * We have some residual hot add range
 904                          * that needs to be hot added; hot add
 905                          * it now. Hot add a multiple of
 906                          * of HA_CHUNK that fully covers the pages
 907                          * we have.
 908                          */
 909                         size = (has->end_pfn - has->ha_end_pfn);
 910                         if (pfn_cnt <= size) {
 911                                 size = ((pfn_cnt / HA_CHUNK) * HA_CHUNK);
 912                                 if (pfn_cnt % HA_CHUNK)
 913                                         size += HA_CHUNK;
 914                         } else {
 915                                 pfn_cnt = size;
 916                         }
 917                         spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 918                         hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has);
 919                         spin_lock_irqsave(&dm_device.ha_lock, flags);
 920                 }
 921                 /*
 922                  * If we managed to online any pages that were given to us,
 923                  * we declare success.
 924                  */
 925                 res = has->covered_end_pfn - old_covered_state;
 926                 break;
 927         }
 928         spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 929
 930         return res;
 931 }
 932
 933 static unsigned long process_hot_add(unsigned long pg_start,
 934                                         unsigned long pfn_cnt,
 935                                         unsigned long rg_start,
 936                                         unsigned long rg_size)
 937 {
 938         struct hv_hotadd_state *ha_region = NULL;
 939         int covered;
 940         unsigned long flags;
 941
 942         if (pfn_cnt == 0)
 943                 return 0;
 944
 945         if (!dm_device.host_specified_ha_region) {
 946                 covered = pfn_covered(pg_start, pfn_cnt);
 947                 if (covered < 0)
 948                         return 0;
 949
 950                 if (covered)
 951                         goto do_pg_range;
 952         }
 953
 954         /*
 955          * If the host has specified a hot-add range; deal with it first.
 956          */
 957
 958         if (rg_size != 0) {
 959                 ha_region = kzalloc(sizeof(struct hv_hotadd_state), GFP_KERNEL);
 960                 if (!ha_region)
 961                         return 0;
 962
 963                 INIT_LIST_HEAD(&ha_region->list);
 964                 INIT_LIST_HEAD(&ha_region->gap_list);
 965
 966                 ha_region->start_pfn = rg_start;
 967                 ha_region->ha_end_pfn = rg_start;
 968                 ha_region->covered_start_pfn = pg_start;
 969                 ha_region->covered_end_pfn = pg_start;
 970                 ha_region->end_pfn = rg_start + rg_size;
 971
 972                 spin_lock_irqsave(&dm_device.ha_lock, flags);
 973                 list_add_tail(&ha_region->list, &dm_device.ha_region_list);
 974                 spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 975         }
 976
 977 do_pg_range:
 978         /*
 979          * Process the page range specified; bringing them
 980          * online if possible.
 981          */
 982         return handle_pg_range(pg_start, pfn_cnt);
 983 }
 984
 985 #endif
 986
 987 static void hot_add_req(struct work_struct *dummy)
 988 {
 989         struct dm_hot_add_response resp;
 990 #ifdef CONFIG_MEMORY_HOTPLUG
 991         unsigned long pg_start, pfn_cnt;
 992         unsigned long rg_start, rg_sz;
 993 #endif
 994         struct hv_dynmem_device *dm = &dm_device;
 995
 996         memset(&resp, 0, sizeof(struct dm_hot_add_response));
 997         resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
 998         resp.hdr.size = sizeof(struct dm_hot_add_response);
 999
1000 #ifdef CONFIG_MEMORY_HOTPLUG
1001         pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
1002         pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
1003
1004         rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
1005         rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;
1006
1007         if ((rg_start == 0) && (!dm->host_specified_ha_region)) {
1008                 unsigned long region_size;
1009                 unsigned long region_start;
1010
1011                 /*
1012                  * The host has not specified the hot-add region.
1013                  * Based on the hot-add page range being specified,
1014                  * compute a hot-add region that can cover the pages
1015                  * that need to be hot-added while ensuring the alignment
1016                  * and size requirements of Linux as it relates to hot-add.
1017                  */
1018                 region_start = pg_start;
1019                 region_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
1020                 if (pfn_cnt % HA_CHUNK)
1021                         region_size += HA_CHUNK;
1022
1023                 region_start = (pg_start / HA_CHUNK) * HA_CHUNK;
1024
1025                 rg_start = region_start;
1026                 rg_sz = region_size;
1027         }
1028
1029         if (do_hot_add)
1030                 resp.page_count = process_hot_add(pg_start, pfn_cnt,
1031                                                 rg_start, rg_sz);
1032
1033         dm->num_pages_added += resp.page_count;
1034 #endif
1035         /*
1036          * The result field of the response structure has the
1037          * following semantics:
1038          *
1039          * 1. If all or some pages hot-added: Guest should return success.
1040          *
1041          * 2. If no pages could be hot-added:
1042          *
1043          * If the guest returns success, then the host
1044          * will not attempt any further hot-add operations. This
1045          * signifies a permanent failure.
1046          *
1047          * If the guest returns failure, then this failure will be
1048          * treated as a transient failure and the host may retry the
1049          * hot-add operation after some delay.
1050          */
1051         if (resp.page_count > 0)
1052                 resp.result = 1;
1053         else if (!do_hot_add)
1054                 resp.result = 1;
1055         else
1056                 resp.result = 0;
1057
1058         if (!do_hot_add || (resp.page_count == 0))
1059                 pr_err("Memory hot add failed\n");
1060
1061         dm->state = DM_INITIALIZED;
1062         resp.hdr.trans_id = atomic_inc_return(&trans_id);
1063         vmbus_sendpacket(dm->dev->channel, &resp,
1064                         sizeof(struct dm_hot_add_response),
1065                         (unsigned long)NULL,
1066                         VM_PKT_DATA_INBAND, 0);
1067 }
1068
1069 static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
1070 {
1071         struct dm_info_header *info_hdr;
1072
1073         info_hdr = (struct dm_info_header *)msg->info;
1074
1075         switch (info_hdr->type) {
1076         case INFO_TYPE_MAX_PAGE_CNT:
1077                 if (info_hdr->data_size == sizeof(__u64)) {
1078                         __u64 *max_page_count = (__u64 *)&info_hdr[1];
1079
1080                         pr_info("Max. dynamic memory size: %llu MB\n",
1081                                 (*max_page_count) >> (20 - PAGE_SHIFT));
1082                 }
1083
1084                 break;
1085         default:
1086                 pr_warn("Received Unknown type: %d\n", info_hdr->type);
1087         }
1088 }
1089
1090 static unsigned long compute_balloon_floor(void)
1091 {
1092         unsigned long min_pages;
1093         unsigned long nr_pages = totalram_pages();
1094 #define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
1095         /* Simple continuous piecewiese linear function:
1096          *  max MiB -> min MiB  gradient
1097          *       0         0
1098          *      16        16
1099          *      32        24
1100          *     128        72    (1/2)
1101          *     512       168    (1/4)
1102          *    2048       360    (1/8)
1103          *    8192       744    (1/16)
1104          *   32768      1512    (1/32)
1105          */
1106         if (nr_pages < MB2PAGES(128))
1107                 min_pages = MB2PAGES(8) + (nr_pages >> 1);
1108         else if (nr_pages < MB2PAGES(512))
1109                 min_pages = MB2PAGES(40) + (nr_pages >> 2);
1110         else if (nr_pages < MB2PAGES(2048))
1111                 min_pages = MB2PAGES(104) + (nr_pages >> 3);
1112         else if (nr_pages < MB2PAGES(8192))
1113                 min_pages = MB2PAGES(232) + (nr_pages >> 4);
1114         else
1115                 min_pages = MB2PAGES(488) + (nr_pages >> 5);
1116 #undef MB2PAGES
1117         return min_pages;
1118 }
1119
1120 /*
1121  * Post our status as it relates memory pressure to the
1122  * host. Host expects the guests to post this status
1123  * periodically at 1 second intervals.
1124  *
1125  * The metrics specified in this protocol are very Windows
1126  * specific and so we cook up numbers here to convey our memory
1127  * pressure.
1128  */
1129
1130 static void post_status(struct hv_dynmem_device *dm)
1131 {
1132         struct dm_status status;
1133         unsigned long now = jiffies;
1134         unsigned long last_post = last_post_time;
1135
1136         if (pressure_report_delay > 0) {
1137                 --pressure_report_delay;
1138                 return;
1139         }
1140
1141         if (!time_after(now, (last_post_time + HZ)))
1142                 return;
1143
1144         memset(&status, 0, sizeof(struct dm_status));
1145         status.hdr.type = DM_STATUS_REPORT;
1146         status.hdr.size = sizeof(struct dm_status);
1147         status.hdr.trans_id = atomic_inc_return(&trans_id);
1148
1149         /*
1150          * The host expects the guest to report free and committed memory.
1151          * Furthermore, the host expects the pressure information to include
1152          * the ballooned out pages. For a given amount of memory that we are
1153          * managing we need to compute a floor below which we should not
1154          * balloon. Compute this and add it to the pressure report.
1155          * We also need to report all offline pages (num_pages_added -
1156          * num_pages_onlined) as committed to the host, otherwise it can try
1157          * asking us to balloon them out.
1158          */
1159         status.num_avail = si_mem_available();
1160         status.num_committed = vm_memory_committed() +
1161                 dm->num_pages_ballooned +
1162                 (dm->num_pages_added > dm->num_pages_onlined ?
1163                  dm->num_pages_added - dm->num_pages_onlined : 0) +
1164                 compute_balloon_floor();
1165
1166         trace_balloon_status(status.num_avail, status.num_committed,
1167                              vm_memory_committed(), dm->num_pages_ballooned,
1168                              dm->num_pages_added, dm->num_pages_onlined);
1169         /*
1170          * If our transaction ID is no longer current, just don't
1171          * send the status. This can happen if we were interrupted
1172          * after we picked our transaction ID.
1173          */
1174         if (status.hdr.trans_id != atomic_read(&trans_id))
1175                 return;
1176
1177         /*
1178          * If the last post time that we sampled has changed,
1179          * we have raced, don't post the status.
1180          */
1181         if (last_post != last_post_time)
1182                 return;
1183
1184         last_post_time = jiffies;
1185         vmbus_sendpacket(dm->dev->channel, &status,
1186                                 sizeof(struct dm_status),
1187                                 (unsigned long)NULL,
1188                                 VM_PKT_DATA_INBAND, 0);
1189
1190 }
1191
1192 static void free_balloon_pages(struct hv_dynmem_device *dm,
1193                          union dm_mem_page_range *range_array)
1194 {
1195         int num_pages = range_array->finfo.page_cnt;
1196         __u64 start_frame = range_array->finfo.start_page;
1197         struct page *pg;
1198         int i;
1199
1200         for (i = 0; i < num_pages; i++) {
1201                 pg = pfn_to_page(i + start_frame);
1202                 __free_page(pg);
1203                 dm->num_pages_ballooned--;
1204         }
1205 }
1206
1207
1208
1209 static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
1210                                         unsigned int num_pages,
1211                                         struct dm_balloon_response *bl_resp,
1212                                         int alloc_unit)
1213 {
1214         unsigned int i = 0;
1215         struct page *pg;
1216
1217         if (num_pages < alloc_unit)
1218                 return 0;
1219
1220         for (i = 0; (i * alloc_unit) < num_pages; i++) {
1221                 if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
1222                         PAGE_SIZE)
1223                         return i * alloc_unit;
1224
1225                 /*
1226                  * We execute this code in a thread context. Furthermore,
1227                  * we don't want the kernel to try too hard.
1228                  */
1229                 pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
1230                                 __GFP_NOMEMALLOC | __GFP_NOWARN,
1231                                 get_order(alloc_unit << PAGE_SHIFT));
1232
1233                 if (!pg)
1234                         return i * alloc_unit;
1235
1236                 dm->num_pages_ballooned += alloc_unit;
1237
1238                 /*
1239                  * If we allocatted 2M pages; split them so we
1240                  * can free them in any order we get.
1241                  */
1242
1243                 if (alloc_unit != 1)
1244                         split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
1245
1246                 bl_resp->range_count++;
1247                 bl_resp->range_array[i].finfo.start_page =
1248                         page_to_pfn(pg);
1249                 bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
1250                 bl_resp->hdr.size += sizeof(union dm_mem_page_range);
1251
1252         }
1253
1254         return num_pages;
1255 }
1256
1257 static void balloon_up(struct work_struct *dummy)
1258 {
1259         unsigned int num_pages = dm_device.balloon_wrk.num_pages;
1260         unsigned int num_ballooned = 0;
1261         struct dm_balloon_response *bl_resp;
1262         int alloc_unit;
1263         int ret;
1264         bool done = false;
1265         int i;
1266         long avail_pages;
1267         unsigned long floor;
1268
1269         /* The host balloons pages in 2M granularity. */
1270         WARN_ON_ONCE(num_pages % PAGES_IN_2M != 0);
1271
1272         /*
1273          * We will attempt 2M allocations. However, if we fail to
1274          * allocate 2M chunks, we will go back to 4k allocations.
1275          */
1276         alloc_unit = 512;
1277
1278         avail_pages = si_mem_available();
1279         floor = compute_balloon_floor();
1280
1281         /* Refuse to balloon below the floor, keep the 2M granularity. */
1282         if (avail_pages < num_pages || avail_pages - num_pages < floor) {
1283                 pr_warn("Balloon request will be partially fulfilled. %s\n",
1284                         avail_pages < num_pages ? "Not enough memory." :
1285                         "Balloon floor reached.");
1286
1287                 num_pages = avail_pages > floor ? (avail_pages - floor) : 0;
1288                 num_pages -= num_pages % PAGES_IN_2M;
1289         }
1290
1291         while (!done) {
1292                 bl_resp = (struct dm_balloon_response *)send_buffer;
1293                 memset(send_buffer, 0, PAGE_SIZE);
1294                 bl_resp->hdr.type = DM_BALLOON_RESPONSE;
1295                 bl_resp->hdr.size = sizeof(struct dm_balloon_response);
1296                 bl_resp->more_pages = 1;
1297
1298                 num_pages -= num_ballooned;
1299                 num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
1300                                                     bl_resp, alloc_unit);
1301
1302                 if (alloc_unit != 1 && num_ballooned == 0) {
1303                         alloc_unit = 1;
1304                         continue;
1305                 }
1306
1307                 if (num_ballooned == 0 || num_ballooned == num_pages) {
1308                         pr_debug("Ballooned %u out of %u requested pages.\n",
1309                                 num_pages, dm_device.balloon_wrk.num_pages);
1310
1311                         bl_resp->more_pages = 0;
1312                         done = true;
1313                         dm_device.state = DM_INITIALIZED;
1314                 }
1315
1316                 /*
1317                  * We are pushing a lot of data through the channel;
1318                  * deal with transient failures caused because of the
1319                  * lack of space in the ring buffer.
1320                  */
1321
1322                 do {
1323                         bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
1324                         ret = vmbus_sendpacket(dm_device.dev->channel,
1325                                                 bl_resp,
1326                                                 bl_resp->hdr.size,
1327                                                 (unsigned long)NULL,
1328                                                 VM_PKT_DATA_INBAND, 0);
1329
1330                         if (ret == -EAGAIN)
1331                                 msleep(20);
1332                         post_status(&dm_device);
1333                 } while (ret == -EAGAIN);
1334
1335                 if (ret) {
1336                         /*
1337                          * Free up the memory we allocatted.
1338                          */
1339                         pr_err("Balloon response failed\n");
1340
1341                         for (i = 0; i < bl_resp->range_count; i++)
1342                                 free_balloon_pages(&dm_device,
1343                                                  &bl_resp->range_array[i]);
1344
1345                         done = true;
1346                 }
1347         }
1348
1349 }
1350
1351 static void balloon_down(struct hv_dynmem_device *dm,
1352                         struct dm_unballoon_request *req)
1353 {
1354         union dm_mem_page_range *range_array = req->range_array;
1355         int range_count = req->range_count;
1356         struct dm_unballoon_response resp;
1357         int i;
1358         unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
1359
1360         for (i = 0; i < range_count; i++) {
1361                 free_balloon_pages(dm, &range_array[i]);
1362                 complete(&dm_device.config_event);
1363         }
1364
1365         pr_debug("Freed %u ballooned pages.\n",
1366                 prev_pages_ballooned - dm->num_pages_ballooned);
1367
1368         if (req->more_pages == 1)
1369                 return;
1370
1371         memset(&resp, 0, sizeof(struct dm_unballoon_response));
1372         resp.hdr.type = DM_UNBALLOON_RESPONSE;
1373         resp.hdr.trans_id = atomic_inc_return(&trans_id);
1374         resp.hdr.size = sizeof(struct dm_unballoon_response);
1375
1376         vmbus_sendpacket(dm_device.dev->channel, &resp,
1377                                 sizeof(struct dm_unballoon_response),
1378                                 (unsigned long)NULL,
1379                                 VM_PKT_DATA_INBAND, 0);
1380
1381         dm->state = DM_INITIALIZED;
1382 }
1383
1384 static void balloon_onchannelcallback(void *context);
1385
1386 static int dm_thread_func(void *dm_dev)
1387 {
1388         struct hv_dynmem_device *dm = dm_dev;
1389
1390         while (!kthread_should_stop()) {
1391                 wait_for_completion_interruptible_timeout(
1392                                                 &dm_device.config_event, 1*HZ);
1393                 /*
1394                  * The host expects us to post information on the memory
1395                  * pressure every second.
1396                  */
1397                 reinit_completion(&dm_device.config_event);
1398                 post_status(dm);
1399         }
1400
1401         return 0;
1402 }
1403
1404
1405 static void version_resp(struct hv_dynmem_device *dm,
1406                         struct dm_version_response *vresp)
1407 {
1408         struct dm_version_request version_req;
1409         int ret;
1410
1411         if (vresp->is_accepted) {
1412                 /*
1413                  * We are done; wakeup the
1414                  * context waiting for version
1415                  * negotiation.
1416                  */
1417                 complete(&dm->host_event);
1418                 return;
1419         }
1420         /*
1421          * If there are more versions to try, continue
1422          * with negotiations; if not
1423          * shutdown the service since we are not able
1424          * to negotiate a suitable version number
1425          * with the host.
1426          */
1427         if (dm->next_version == 0)
1428                 goto version_error;
1429
1430         memset(&version_req, 0, sizeof(struct dm_version_request));
1431         version_req.hdr.type = DM_VERSION_REQUEST;
1432         version_req.hdr.size = sizeof(struct dm_version_request);
1433         version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1434         version_req.version.version = dm->next_version;
1435         dm->version = version_req.version.version;
1436
1437         /*
1438          * Set the next version to try in case current version fails.
1439          * Win7 protocol ought to be the last one to try.
1440          */
1441         switch (version_req.version.version) {
1442         case DYNMEM_PROTOCOL_VERSION_WIN8:
1443                 dm->next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
1444                 version_req.is_last_attempt = 0;
1445                 break;
1446         default:
1447                 dm->next_version = 0;
1448                 version_req.is_last_attempt = 1;
1449         }
1450
1451         ret = vmbus_sendpacket(dm->dev->channel, &version_req,
1452                                 sizeof(struct dm_version_request),
1453                                 (unsigned long)NULL,
1454                                 VM_PKT_DATA_INBAND, 0);
1455
1456         if (ret)
1457                 goto version_error;
1458
1459         return;
1460
1461 version_error:
1462         dm->state = DM_INIT_ERROR;
1463         complete(&dm->host_event);
1464 }
1465
1466 static void cap_resp(struct hv_dynmem_device *dm,
1467                         struct dm_capabilities_resp_msg *cap_resp)
1468 {
1469         if (!cap_resp->is_accepted) {
1470                 pr_err("Capabilities not accepted by host\n");
1471                 dm->state = DM_INIT_ERROR;
1472         }
1473         complete(&dm->host_event);
1474 }
1475
1476 static void balloon_onchannelcallback(void *context)
1477 {
1478         struct hv_device *dev = context;
1479         u32 recvlen;
1480         u64 requestid;
1481         struct dm_message *dm_msg;
1482         struct dm_header *dm_hdr;
1483         struct hv_dynmem_device *dm = hv_get_drvdata(dev);
1484         struct dm_balloon *bal_msg;
1485         struct dm_hot_add *ha_msg;
1486         union dm_mem_page_range *ha_pg_range;
1487         union dm_mem_page_range *ha_region;
1488
1489         memset(recv_buffer, 0, sizeof(recv_buffer));
1490         vmbus_recvpacket(dev->channel, recv_buffer,
1491                          PAGE_SIZE, &recvlen, &requestid);
1492
1493         if (recvlen > 0) {
1494                 dm_msg = (struct dm_message *)recv_buffer;
1495                 dm_hdr = &dm_msg->hdr;
1496
1497                 switch (dm_hdr->type) {
1498                 case DM_VERSION_RESPONSE:
1499                         version_resp(dm,
1500                                  (struct dm_version_response *)dm_msg);
1501                         break;
1502
1503                 case DM_CAPABILITIES_RESPONSE:
1504                         cap_resp(dm,
1505                                  (struct dm_capabilities_resp_msg *)dm_msg);
1506                         break;
1507
1508                 case DM_BALLOON_REQUEST:
1509                         if (dm->state == DM_BALLOON_UP)
1510                                 pr_warn("Currently ballooning\n");
1511                         bal_msg = (struct dm_balloon *)recv_buffer;
1512                         dm->state = DM_BALLOON_UP;
1513                         dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
1514                         schedule_work(&dm_device.balloon_wrk.wrk);
1515                         break;
1516
1517                 case DM_UNBALLOON_REQUEST:
1518                         dm->state = DM_BALLOON_DOWN;
1519                         balloon_down(dm,
1520                                  (struct dm_unballoon_request *)recv_buffer);
1521                         break;
1522
1523                 case DM_MEM_HOT_ADD_REQUEST:
1524                         if (dm->state == DM_HOT_ADD)
1525                                 pr_warn("Currently hot-adding\n");
1526                         dm->state = DM_HOT_ADD;
1527                         ha_msg = (struct dm_hot_add *)recv_buffer;
1528                         if (ha_msg->hdr.size == sizeof(struct dm_hot_add)) {
1529                                 /*
1530                                  * This is a normal hot-add request specifying
1531                                  * hot-add memory.
1532                                  */
1533                                 dm->host_specified_ha_region = false;
1534                                 ha_pg_range = &ha_msg->range;
1535                                 dm->ha_wrk.ha_page_range = *ha_pg_range;
1536                                 dm->ha_wrk.ha_region_range.page_range = 0;
1537                         } else {
1538                                 /*
1539                                  * Host is specifying that we first hot-add
1540                                  * a region and then partially populate this
1541                                  * region.
1542                                  */
1543                                 dm->host_specified_ha_region = true;
1544                                 ha_pg_range = &ha_msg->range;
1545                                 ha_region = &ha_pg_range[1];
1546                                 dm->ha_wrk.ha_page_range = *ha_pg_range;
1547                                 dm->ha_wrk.ha_region_range = *ha_region;
1548                         }
1549                         schedule_work(&dm_device.ha_wrk.wrk);
1550                         break;
1551
1552                 case DM_INFO_MESSAGE:
1553                         process_info(dm, (struct dm_info_msg *)dm_msg);
1554                         break;
1555
1556                 default:
1557                         pr_warn("Unhandled message: type: %d\n", dm_hdr->type);
1558
1559                 }
1560         }
1561
1562 }
1563
1564 static int balloon_probe(struct hv_device *dev,
1565                         const struct hv_vmbus_device_id *dev_id)
1566 {
1567         int ret;
1568         unsigned long t;
1569         struct dm_version_request version_req;
1570         struct dm_capabilities cap_msg;
1571
1572 #ifdef CONFIG_MEMORY_HOTPLUG
1573         do_hot_add = hot_add;
1574 #else
1575         do_hot_add = false;
1576 #endif
1577
1578         /*
1579          * First allocate a send buffer.
1580          */
1581
1582         send_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
1583         if (!send_buffer)
1584                 return -ENOMEM;
1585
1586         ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
1587                         balloon_onchannelcallback, dev);
1588
1589         if (ret)
1590                 goto probe_error0;
1591
1592         dm_device.dev = dev;
1593         dm_device.state = DM_INITIALIZING;
1594         dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN8;
1595         init_completion(&dm_device.host_event);
1596         init_completion(&dm_device.config_event);
1597         INIT_LIST_HEAD(&dm_device.ha_region_list);
1598         spin_lock_init(&dm_device.ha_lock);
1599         INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
1600         INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
1601         dm_device.host_specified_ha_region = false;
1602
1603         dm_device.thread =
1604                  kthread_run(dm_thread_func, &dm_device, "hv_balloon");
1605         if (IS_ERR(dm_device.thread)) {
1606                 ret = PTR_ERR(dm_device.thread);
1607                 goto probe_error1;
1608         }
1609
1610 #ifdef CONFIG_MEMORY_HOTPLUG
1611         set_online_page_callback(&hv_online_page);
1612         register_memory_notifier(&hv_memory_nb);
1613 #endif
1614
1615         hv_set_drvdata(dev, &dm_device);
1616         /*
1617          * Initiate the hand shake with the host and negotiate
1618          * a version that the host can support. We start with the
1619          * highest version number and go down if the host cannot
1620          * support it.
1621          */
1622         memset(&version_req, 0, sizeof(struct dm_version_request));
1623         version_req.hdr.type = DM_VERSION_REQUEST;
1624         version_req.hdr.size = sizeof(struct dm_version_request);
1625         version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1626         version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN10;
1627         version_req.is_last_attempt = 0;
1628         dm_device.version = version_req.version.version;
1629
1630         ret = vmbus_sendpacket(dev->channel, &version_req,
1631                                 sizeof(struct dm_version_request),
1632                                 (unsigned long)NULL,
1633                                 VM_PKT_DATA_INBAND, 0);
1634         if (ret)
1635                 goto probe_error2;
1636
1637         t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
1638         if (t == 0) {
1639                 ret = -ETIMEDOUT;
1640                 goto probe_error2;
1641         }
1642
1643         /*
1644          * If we could not negotiate a compatible version with the host
1645          * fail the probe function.
1646          */
1647         if (dm_device.state == DM_INIT_ERROR) {
1648                 ret = -ETIMEDOUT;
1649                 goto probe_error2;
1650         }
1651
1652         pr_info("Using Dynamic Memory protocol version %u.%u\n",
1653                 DYNMEM_MAJOR_VERSION(dm_device.version),
1654                 DYNMEM_MINOR_VERSION(dm_device.version));
1655
1656         /*
1657          * Now submit our capabilities to the host.
1658          */
1659         memset(&cap_msg, 0, sizeof(struct dm_capabilities));
1660         cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
1661         cap_msg.hdr.size = sizeof(struct dm_capabilities);
1662         cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);
1663
1664         cap_msg.caps.cap_bits.balloon = 1;
1665         cap_msg.caps.cap_bits.hot_add = 1;
1666
1667         /*
1668          * Specify our alignment requirements as it relates
1669          * memory hot-add. Specify 128MB alignment.
1670          */
1671         cap_msg.caps.cap_bits.hot_add_alignment = 7;
1672
1673         /*
1674          * Currently the host does not use these
1675          * values and we set them to what is done in the
1676          * Windows driver.
1677          */
1678         cap_msg.min_page_cnt = 0;
1679         cap_msg.max_page_number = -1;
1680
1681         ret = vmbus_sendpacket(dev->channel, &cap_msg,
1682                                 sizeof(struct dm_capabilities),
1683                                 (unsigned long)NULL,
1684                                 VM_PKT_DATA_INBAND, 0);
1685         if (ret)
1686                 goto probe_error2;
1687
1688         t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
1689         if (t == 0) {
1690                 ret = -ETIMEDOUT;
1691                 goto probe_error2;
1692         }
1693
1694         /*
1695          * If the host does not like our capabilities,
1696          * fail the probe function.
1697          */
1698         if (dm_device.state == DM_INIT_ERROR) {
1699                 ret = -ETIMEDOUT;
1700                 goto probe_error2;
1701         }
1702
1703         dm_device.state = DM_INITIALIZED;
1704         last_post_time = jiffies;
1705
1706         return 0;
1707
1708 probe_error2:
1709 #ifdef CONFIG_MEMORY_HOTPLUG
1710         restore_online_page_callback(&hv_online_page);
1711 #endif
1712         kthread_stop(dm_device.thread);
1713
1714 probe_error1:
1715         vmbus_close(dev->channel);
1716 probe_error0:
1717         kfree(send_buffer);
1718         return ret;
1719 }
1720
1721 static int balloon_remove(struct hv_device *dev)
1722 {
1723         struct hv_dynmem_device *dm = hv_get_drvdata(dev);
1724         struct hv_hotadd_state *has, *tmp;
1725         struct hv_hotadd_gap *gap, *tmp_gap;
1726         unsigned long flags;
1727
1728         if (dm->num_pages_ballooned != 0)
1729                 pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
1730
1731         cancel_work_sync(&dm->balloon_wrk.wrk);
1732         cancel_work_sync(&dm->ha_wrk.wrk);
1733
1734         vmbus_close(dev->channel);
1735         kthread_stop(dm->thread);
1736         kfree(send_buffer);
1737 #ifdef CONFIG_MEMORY_HOTPLUG
1738         restore_online_page_callback(&hv_online_page);
1739         unregister_memory_notifier(&hv_memory_nb);
1740 #endif
1741         spin_lock_irqsave(&dm_device.ha_lock, flags);
1742         list_for_each_entry_safe(has, tmp, &dm->ha_region_list, list) {
1743                 list_for_each_entry_safe(gap, tmp_gap, &has->gap_list, list) {
1744                         list_del(&gap->list);
1745                         kfree(gap);
1746                 }
1747                 list_del(&has->list);
1748                 kfree(has);
1749         }
1750         spin_unlock_irqrestore(&dm_device.ha_lock, flags);
1751
1752         return 0;
1753 }
1754
1755 static const struct hv_vmbus_device_id id_table[] = {
1756         /* Dynamic Memory Class ID */
1757         /* 525074DC-8985-46e2-8057-A307DC18A502 */
1758         { HV_DM_GUID, },
1759         { },
1760 };
1761
1762 MODULE_DEVICE_TABLE(vmbus, id_table);
1763
1764 static  struct hv_driver balloon_drv = {
1765         .name = "hv_balloon",
1766         .id_table = id_table,
1767         .probe =  balloon_probe,
1768         .remove =  balloon_remove,
1769         .driver = {
1770                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
1771         },
1772 };
1773
1774 static int __init init_balloon_drv(void)
1775 {
1776
1777         return vmbus_driver_register(&balloon_drv);
1778 }
1779
1780 module_init(init_balloon_drv);
1781
1782 MODULE_DESCRIPTION("Hyper-V Balloon");
1783 MODULE_LICENSE("GPL");