linux/drivers/hv/hv_balloon.c
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   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/mman.h>
  23#include <linux/delay.h>
  24#include <linux/init.h>
  25#include <linux/module.h>
  26#include <linux/slab.h>
  27#include <linux/kthread.h>
  28#include <linux/completion.h>
  29#include <linux/memory_hotplug.h>
  30#include <linux/memory.h>
  31#include <linux/notifier.h>
  32#include <linux/percpu_counter.h>
  33
  34#include <linux/hyperv.h>
  35
  36/*
  37 * We begin with definitions supporting the Dynamic Memory protocol
  38 * with the host.
  39 *
  40 * Begin protocol definitions.
  41 */
  42
  43
  44
  45/*
  46 * Protocol versions. The low word is the minor version, the high word the major
  47 * version.
  48 *
  49 * History:
  50 * Initial version 1.0
  51 * Changed to 0.1 on 2009/03/25
  52 * Changes to 0.2 on 2009/05/14
  53 * Changes to 0.3 on 2009/12/03
  54 * Changed to 1.0 on 2011/04/05
  55 */
  56
  57#define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
  58#define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
  59#define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)
  60
  61enum {
  62        DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
  63        DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
  64
  65        DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
  66        DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
  67
  68        DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN8
  69};
  70
  71
  72
  73/*
  74 * Message Types
  75 */
  76
  77enum dm_message_type {
  78        /*
  79         * Version 0.3
  80         */
  81        DM_ERROR                        = 0,
  82        DM_VERSION_REQUEST              = 1,
  83        DM_VERSION_RESPONSE             = 2,
  84        DM_CAPABILITIES_REPORT          = 3,
  85        DM_CAPABILITIES_RESPONSE        = 4,
  86        DM_STATUS_REPORT                = 5,
  87        DM_BALLOON_REQUEST              = 6,
  88        DM_BALLOON_RESPONSE             = 7,
  89        DM_UNBALLOON_REQUEST            = 8,
  90        DM_UNBALLOON_RESPONSE           = 9,
  91        DM_MEM_HOT_ADD_REQUEST          = 10,
  92        DM_MEM_HOT_ADD_RESPONSE         = 11,
  93        DM_VERSION_03_MAX               = 11,
  94        /*
  95         * Version 1.0.
  96         */
  97        DM_INFO_MESSAGE                 = 12,
  98        DM_VERSION_1_MAX                = 12
  99};
 100
 101
 102/*
 103 * Structures defining the dynamic memory management
 104 * protocol.
 105 */
 106
 107union dm_version {
 108        struct {
 109                __u16 minor_version;
 110                __u16 major_version;
 111        };
 112        __u32 version;
 113} __packed;
 114
 115
 116union dm_caps {
 117        struct {
 118                __u64 balloon:1;
 119                __u64 hot_add:1;
 120                /*
 121                 * To support guests that may have alignment
 122                 * limitations on hot-add, the guest can specify
 123                 * its alignment requirements; a value of n
 124                 * represents an alignment of 2^n in mega bytes.
 125                 */
 126                __u64 hot_add_alignment:4;
 127                __u64 reservedz:58;
 128        } cap_bits;
 129        __u64 caps;
 130} __packed;
 131
 132union dm_mem_page_range {
 133        struct  {
 134                /*
 135                 * The PFN number of the first page in the range.
 136                 * 40 bits is the architectural limit of a PFN
 137                 * number for AMD64.
 138                 */
 139                __u64 start_page:40;
 140                /*
 141                 * The number of pages in the range.
 142                 */
 143                __u64 page_cnt:24;
 144        } finfo;
 145        __u64  page_range;
 146} __packed;
 147
 148
 149
 150/*
 151 * The header for all dynamic memory messages:
 152 *
 153 * type: Type of the message.
 154 * size: Size of the message in bytes; including the header.
 155 * trans_id: The guest is responsible for manufacturing this ID.
 156 */
 157
 158struct dm_header {
 159        __u16 type;
 160        __u16 size;
 161        __u32 trans_id;
 162} __packed;
 163
 164/*
 165 * A generic message format for dynamic memory.
 166 * Specific message formats are defined later in the file.
 167 */
 168
 169struct dm_message {
 170        struct dm_header hdr;
 171        __u8 data[]; /* enclosed message */
 172} __packed;
 173
 174
 175/*
 176 * Specific message types supporting the dynamic memory protocol.
 177 */
 178
 179/*
 180 * Version negotiation message. Sent from the guest to the host.
 181 * The guest is free to try different versions until the host
 182 * accepts the version.
 183 *
 184 * dm_version: The protocol version requested.
 185 * is_last_attempt: If TRUE, this is the last version guest will request.
 186 * reservedz: Reserved field, set to zero.
 187 */
 188
 189struct dm_version_request {
 190        struct dm_header hdr;
 191        union dm_version version;
 192        __u32 is_last_attempt:1;
 193        __u32 reservedz:31;
 194} __packed;
 195
 196/*
 197 * Version response message; Host to Guest and indicates
 198 * if the host has accepted the version sent by the guest.
 199 *
 200 * is_accepted: If TRUE, host has accepted the version and the guest
 201 * should proceed to the next stage of the protocol. FALSE indicates that
 202 * guest should re-try with a different version.
 203 *
 204 * reservedz: Reserved field, set to zero.
 205 */
 206
 207struct dm_version_response {
 208        struct dm_header hdr;
 209        __u64 is_accepted:1;
 210        __u64 reservedz:63;
 211} __packed;
 212
 213/*
 214 * Message reporting capabilities. This is sent from the guest to the
 215 * host.
 216 */
 217
 218struct dm_capabilities {
 219        struct dm_header hdr;
 220        union dm_caps caps;
 221        __u64 min_page_cnt;
 222        __u64 max_page_number;
 223} __packed;
 224
 225/*
 226 * Response to the capabilities message. This is sent from the host to the
 227 * guest. This message notifies if the host has accepted the guest's
 228 * capabilities. If the host has not accepted, the guest must shutdown
 229 * the service.
 230 *
 231 * is_accepted: Indicates if the host has accepted guest's capabilities.
 232 * reservedz: Must be 0.
 233 */
 234
 235struct dm_capabilities_resp_msg {
 236        struct dm_header hdr;
 237        __u64 is_accepted:1;
 238        __u64 reservedz:63;
 239} __packed;
 240
 241/*
 242 * This message is used to report memory pressure from the guest.
 243 * This message is not part of any transaction and there is no
 244 * response to this message.
 245 *
 246 * num_avail: Available memory in pages.
 247 * num_committed: Committed memory in pages.
 248 * page_file_size: The accumulated size of all page files
 249 *                 in the system in pages.
 250 * zero_free: The nunber of zero and free pages.
 251 * page_file_writes: The writes to the page file in pages.
 252 * io_diff: An indicator of file cache efficiency or page file activity,
 253 *          calculated as File Cache Page Fault Count - Page Read Count.
 254 *          This value is in pages.
 255 *
 256 * Some of these metrics are Windows specific and fortunately
 257 * the algorithm on the host side that computes the guest memory
 258 * pressure only uses num_committed value.
 259 */
 260
 261struct dm_status {
 262        struct dm_header hdr;
 263        __u64 num_avail;
 264        __u64 num_committed;
 265        __u64 page_file_size;
 266        __u64 zero_free;
 267        __u32 page_file_writes;
 268        __u32 io_diff;
 269} __packed;
 270
 271
 272/*
 273 * Message to ask the guest to allocate memory - balloon up message.
 274 * This message is sent from the host to the guest. The guest may not be
 275 * able to allocate as much memory as requested.
 276 *
 277 * num_pages: number of pages to allocate.
 278 */
 279
 280struct dm_balloon {
 281        struct dm_header hdr;
 282        __u32 num_pages;
 283        __u32 reservedz;
 284} __packed;
 285
 286
 287/*
 288 * Balloon response message; this message is sent from the guest
 289 * to the host in response to the balloon message.
 290 *
 291 * reservedz: Reserved; must be set to zero.
 292 * more_pages: If FALSE, this is the last message of the transaction.
 293 * if TRUE there will atleast one more message from the guest.
 294 *
 295 * range_count: The number of ranges in the range array.
 296 *
 297 * range_array: An array of page ranges returned to the host.
 298 *
 299 */
 300
 301struct dm_balloon_response {
 302        struct dm_header hdr;
 303        __u32 reservedz;
 304        __u32 more_pages:1;
 305        __u32 range_count:31;
 306        union dm_mem_page_range range_array[];
 307} __packed;
 308
 309/*
 310 * Un-balloon message; this message is sent from the host
 311 * to the guest to give guest more memory.
 312 *
 313 * more_pages: If FALSE, this is the last message of the transaction.
 314 * if TRUE there will atleast one more message from the guest.
 315 *
 316 * reservedz: Reserved; must be set to zero.
 317 *
 318 * range_count: The number of ranges in the range array.
 319 *
 320 * range_array: An array of page ranges returned to the host.
 321 *
 322 */
 323
 324struct dm_unballoon_request {
 325        struct dm_header hdr;
 326        __u32 more_pages:1;
 327        __u32 reservedz:31;
 328        __u32 range_count;
 329        union dm_mem_page_range range_array[];
 330} __packed;
 331
 332/*
 333 * Un-balloon response message; this message is sent from the guest
 334 * to the host in response to an unballoon request.
 335 *
 336 */
 337
 338struct dm_unballoon_response {
 339        struct dm_header hdr;
 340} __packed;
 341
 342
 343/*
 344 * Hot add request message. Message sent from the host to the guest.
 345 *
 346 * mem_range: Memory range to hot add.
 347 *
 348 * On Linux we currently don't support this since we cannot hot add
 349 * arbitrary granularity of memory.
 350 */
 351
 352struct dm_hot_add {
 353        struct dm_header hdr;
 354        union dm_mem_page_range range;
 355} __packed;
 356
 357/*
 358 * Hot add response message.
 359 * This message is sent by the guest to report the status of a hot add request.
 360 * If page_count is less than the requested page count, then the host should
 361 * assume all further hot add requests will fail, since this indicates that
 362 * the guest has hit an upper physical memory barrier.
 363 *
 364 * Hot adds may also fail due to low resources; in this case, the guest must
 365 * not complete this message until the hot add can succeed, and the host must
 366 * not send a new hot add request until the response is sent.
 367 * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
 368 * times it fails the request.
 369 *
 370 *
 371 * page_count: number of pages that were successfully hot added.
 372 *
 373 * result: result of the operation 1: success, 0: failure.
 374 *
 375 */
 376
 377struct dm_hot_add_response {
 378        struct dm_header hdr;
 379        __u32 page_count;
 380        __u32 result;
 381} __packed;
 382
 383/*
 384 * Types of information sent from host to the guest.
 385 */
 386
 387enum dm_info_type {
 388        INFO_TYPE_MAX_PAGE_CNT = 0,
 389        MAX_INFO_TYPE
 390};
 391
 392
 393/*
 394 * Header for the information message.
 395 */
 396
 397struct dm_info_header {
 398        enum dm_info_type type;
 399        __u32 data_size;
 400} __packed;
 401
 402/*
 403 * This message is sent from the host to the guest to pass
 404 * some relevant information (win8 addition).
 405 *
 406 * reserved: no used.
 407 * info_size: size of the information blob.
 408 * info: information blob.
 409 */
 410
 411struct dm_info_msg {
 412        struct dm_header hdr;
 413        __u32 reserved;
 414        __u32 info_size;
 415        __u8  info[];
 416};
 417
 418/*
 419 * End protocol definitions.
 420 */
 421
 422/*
 423 * State to manage hot adding memory into the guest.
 424 * The range start_pfn : end_pfn specifies the range
 425 * that the host has asked us to hot add. The range
 426 * start_pfn : ha_end_pfn specifies the range that we have
 427 * currently hot added. We hot add in multiples of 128M
 428 * chunks; it is possible that we may not be able to bring
 429 * online all the pages in the region. The range
 430 * covered_start_pfn : covered_end_pfn defines the pages that can
 431 * be brough online.
 432 */
 433
 434struct hv_hotadd_state {
 435        struct list_head list;
 436        unsigned long start_pfn;
 437        unsigned long covered_start_pfn;
 438        unsigned long covered_end_pfn;
 439        unsigned long ha_end_pfn;
 440        unsigned long end_pfn;
 441};
 442
 443struct balloon_state {
 444        __u32 num_pages;
 445        struct work_struct wrk;
 446};
 447
 448struct hot_add_wrk {
 449        union dm_mem_page_range ha_page_range;
 450        union dm_mem_page_range ha_region_range;
 451        struct work_struct wrk;
 452};
 453
 454static bool hot_add = true;
 455static bool do_hot_add;
 456/*
 457 * Delay reporting memory pressure by
 458 * the specified number of seconds.
 459 */
 460static uint pressure_report_delay = 45;
 461
 462module_param(hot_add, bool, (S_IRUGO | S_IWUSR));
 463MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");
 464
 465module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR));
 466MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
 467static atomic_t trans_id = ATOMIC_INIT(0);
 468
 469static int dm_ring_size = (5 * PAGE_SIZE);
 470
 471/*
 472 * Driver specific state.
 473 */
 474
 475enum hv_dm_state {
 476        DM_INITIALIZING = 0,
 477        DM_INITIALIZED,
 478        DM_BALLOON_UP,
 479        DM_BALLOON_DOWN,
 480        DM_HOT_ADD,
 481        DM_INIT_ERROR
 482};
 483
 484
 485static __u8 recv_buffer[PAGE_SIZE];
 486static __u8 *send_buffer;
 487#define PAGES_IN_2M     512
 488#define HA_CHUNK (32 * 1024)
 489
 490struct hv_dynmem_device {
 491        struct hv_device *dev;
 492        enum hv_dm_state state;
 493        struct completion host_event;
 494        struct completion config_event;
 495
 496        /*
 497         * Number of pages we have currently ballooned out.
 498         */
 499        unsigned int num_pages_ballooned;
 500
 501        /*
 502         * State to manage the ballooning (up) operation.
 503         */
 504        struct balloon_state balloon_wrk;
 505
 506        /*
 507         * State to execute the "hot-add" operation.
 508         */
 509        struct hot_add_wrk ha_wrk;
 510
 511        /*
 512         * This state tracks if the host has specified a hot-add
 513         * region.
 514         */
 515        bool host_specified_ha_region;
 516
 517        /*
 518         * State to synchronize hot-add.
 519         */
 520        struct completion  ol_waitevent;
 521        bool ha_waiting;
 522        /*
 523         * This thread handles hot-add
 524         * requests from the host as well as notifying
 525         * the host with regards to memory pressure in
 526         * the guest.
 527         */
 528        struct task_struct *thread;
 529
 530        /*
 531         * A list of hot-add regions.
 532         */
 533        struct list_head ha_region_list;
 534
 535        /*
 536         * We start with the highest version we can support
 537         * and downgrade based on the host; we save here the
 538         * next version to try.
 539         */
 540        __u32 next_version;
 541};
 542
 543static struct hv_dynmem_device dm_device;
 544
 545#ifdef CONFIG_MEMORY_HOTPLUG
 546
 547static void hv_bring_pgs_online(unsigned long start_pfn, unsigned long size)
 548{
 549        int i;
 550
 551        for (i = 0; i < size; i++) {
 552                struct page *pg;
 553                pg = pfn_to_page(start_pfn + i);
 554                __online_page_set_limits(pg);
 555                __online_page_increment_counters(pg);
 556                __online_page_free(pg);
 557        }
 558}
 559
 560static void hv_mem_hot_add(unsigned long start, unsigned long size,
 561                                unsigned long pfn_count,
 562                                struct hv_hotadd_state *has)
 563{
 564        int ret = 0;
 565        int i, nid;
 566        unsigned long start_pfn;
 567        unsigned long processed_pfn;
 568        unsigned long total_pfn = pfn_count;
 569
 570        for (i = 0; i < (size/HA_CHUNK); i++) {
 571                start_pfn = start + (i * HA_CHUNK);
 572                has->ha_end_pfn +=  HA_CHUNK;
 573
 574                if (total_pfn > HA_CHUNK) {
 575                        processed_pfn = HA_CHUNK;
 576                        total_pfn -= HA_CHUNK;
 577                } else {
 578                        processed_pfn = total_pfn;
 579                        total_pfn = 0;
 580                }
 581
 582                has->covered_end_pfn +=  processed_pfn;
 583
 584                init_completion(&dm_device.ol_waitevent);
 585                dm_device.ha_waiting = true;
 586
 587                nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
 588                ret = add_memory(nid, PFN_PHYS((start_pfn)),
 589                                (HA_CHUNK << PAGE_SHIFT));
 590
 591                if (ret) {
 592                        pr_info("hot_add memory failed error is %d\n", ret);
 593                        if (ret == -EEXIST) {
 594                                /*
 595                                 * This error indicates that the error
 596                                 * is not a transient failure. This is the
 597                                 * case where the guest's physical address map
 598                                 * precludes hot adding memory. Stop all further
 599                                 * memory hot-add.
 600                                 */
 601                                do_hot_add = false;
 602                        }
 603                        has->ha_end_pfn -= HA_CHUNK;
 604                        has->covered_end_pfn -=  processed_pfn;
 605                        break;
 606                }
 607
 608                /*
 609                 * Wait for the memory block to be onlined.
 610                 * Since the hot add has succeeded, it is ok to
 611                 * proceed even if the pages in the hot added region
 612                 * have not been "onlined" within the allowed time.
 613                 */
 614                wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
 615
 616        }
 617
 618        return;
 619}
 620
 621static void hv_online_page(struct page *pg)
 622{
 623        struct list_head *cur;
 624        struct hv_hotadd_state *has;
 625        unsigned long cur_start_pgp;
 626        unsigned long cur_end_pgp;
 627
 628        if (dm_device.ha_waiting) {
 629                dm_device.ha_waiting = false;
 630                complete(&dm_device.ol_waitevent);
 631        }
 632
 633        list_for_each(cur, &dm_device.ha_region_list) {
 634                has = list_entry(cur, struct hv_hotadd_state, list);
 635                cur_start_pgp = (unsigned long)
 636                                pfn_to_page(has->covered_start_pfn);
 637                cur_end_pgp = (unsigned long)pfn_to_page(has->covered_end_pfn);
 638
 639                if (((unsigned long)pg >= cur_start_pgp) &&
 640                        ((unsigned long)pg < cur_end_pgp)) {
 641                        /*
 642                         * This frame is currently backed; online the
 643                         * page.
 644                         */
 645                        __online_page_set_limits(pg);
 646                        __online_page_increment_counters(pg);
 647                        __online_page_free(pg);
 648                        has->covered_start_pfn++;
 649                }
 650        }
 651}
 652
 653static bool pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
 654{
 655        struct list_head *cur;
 656        struct hv_hotadd_state *has;
 657        unsigned long residual, new_inc;
 658
 659        if (list_empty(&dm_device.ha_region_list))
 660                return false;
 661
 662        list_for_each(cur, &dm_device.ha_region_list) {
 663                has = list_entry(cur, struct hv_hotadd_state, list);
 664
 665                /*
 666                 * If the pfn range we are dealing with is not in the current
 667                 * "hot add block", move on.
 668                 */
 669                if ((start_pfn >= has->end_pfn))
 670                        continue;
 671                /*
 672                 * If the current hot add-request extends beyond
 673                 * our current limit; extend it.
 674                 */
 675                if ((start_pfn + pfn_cnt) > has->end_pfn) {
 676                        residual = (start_pfn + pfn_cnt - has->end_pfn);
 677                        /*
 678                         * Extend the region by multiples of HA_CHUNK.
 679                         */
 680                        new_inc = (residual / HA_CHUNK) * HA_CHUNK;
 681                        if (residual % HA_CHUNK)
 682                                new_inc += HA_CHUNK;
 683
 684                        has->end_pfn += new_inc;
 685                }
 686
 687                /*
 688                 * If the current start pfn is not where the covered_end
 689                 * is, update it.
 690                 */
 691
 692                if (has->covered_end_pfn != start_pfn) {
 693                        has->covered_end_pfn = start_pfn;
 694                        has->covered_start_pfn = start_pfn;
 695                }
 696                return true;
 697
 698        }
 699
 700        return false;
 701}
 702
 703static unsigned long handle_pg_range(unsigned long pg_start,
 704                                        unsigned long pg_count)
 705{
 706        unsigned long start_pfn = pg_start;
 707        unsigned long pfn_cnt = pg_count;
 708        unsigned long size;
 709        struct list_head *cur;
 710        struct hv_hotadd_state *has;
 711        unsigned long pgs_ol = 0;
 712        unsigned long old_covered_state;
 713
 714        if (list_empty(&dm_device.ha_region_list))
 715                return 0;
 716
 717        list_for_each(cur, &dm_device.ha_region_list) {
 718                has = list_entry(cur, struct hv_hotadd_state, list);
 719
 720                /*
 721                 * If the pfn range we are dealing with is not in the current
 722                 * "hot add block", move on.
 723                 */
 724                if ((start_pfn >= has->end_pfn))
 725                        continue;
 726
 727                old_covered_state = has->covered_end_pfn;
 728
 729                if (start_pfn < has->ha_end_pfn) {
 730                        /*
 731                         * This is the case where we are backing pages
 732                         * in an already hot added region. Bring
 733                         * these pages online first.
 734                         */
 735                        pgs_ol = has->ha_end_pfn - start_pfn;
 736                        if (pgs_ol > pfn_cnt)
 737                                pgs_ol = pfn_cnt;
 738                        hv_bring_pgs_online(start_pfn, pgs_ol);
 739                        has->covered_end_pfn +=  pgs_ol;
 740                        has->covered_start_pfn +=  pgs_ol;
 741                        pfn_cnt -= pgs_ol;
 742                }
 743
 744                if ((has->ha_end_pfn < has->end_pfn) && (pfn_cnt > 0)) {
 745                        /*
 746                         * We have some residual hot add range
 747                         * that needs to be hot added; hot add
 748                         * it now. Hot add a multiple of
 749                         * of HA_CHUNK that fully covers the pages
 750                         * we have.
 751                         */
 752                        size = (has->end_pfn - has->ha_end_pfn);
 753                        if (pfn_cnt <= size) {
 754                                size = ((pfn_cnt / HA_CHUNK) * HA_CHUNK);
 755                                if (pfn_cnt % HA_CHUNK)
 756                                        size += HA_CHUNK;
 757                        } else {
 758                                pfn_cnt = size;
 759                        }
 760                        hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has);
 761                }
 762                /*
 763                 * If we managed to online any pages that were given to us,
 764                 * we declare success.
 765                 */
 766                return has->covered_end_pfn - old_covered_state;
 767
 768        }
 769
 770        return 0;
 771}
 772
 773static unsigned long process_hot_add(unsigned long pg_start,
 774                                        unsigned long pfn_cnt,
 775                                        unsigned long rg_start,
 776                                        unsigned long rg_size)
 777{
 778        struct hv_hotadd_state *ha_region = NULL;
 779
 780        if (pfn_cnt == 0)
 781                return 0;
 782
 783        if (!dm_device.host_specified_ha_region)
 784                if (pfn_covered(pg_start, pfn_cnt))
 785                        goto do_pg_range;
 786
 787        /*
 788         * If the host has specified a hot-add range; deal with it first.
 789         */
 790
 791        if (rg_size != 0) {
 792                ha_region = kzalloc(sizeof(struct hv_hotadd_state), GFP_KERNEL);
 793                if (!ha_region)
 794                        return 0;
 795
 796                INIT_LIST_HEAD(&ha_region->list);
 797
 798                list_add_tail(&ha_region->list, &dm_device.ha_region_list);
 799                ha_region->start_pfn = rg_start;
 800                ha_region->ha_end_pfn = rg_start;
 801                ha_region->covered_start_pfn = pg_start;
 802                ha_region->covered_end_pfn = pg_start;
 803                ha_region->end_pfn = rg_start + rg_size;
 804        }
 805
 806do_pg_range:
 807        /*
 808         * Process the page range specified; bringing them
 809         * online if possible.
 810         */
 811        return handle_pg_range(pg_start, pfn_cnt);
 812}
 813
 814#endif
 815
 816static void hot_add_req(struct work_struct *dummy)
 817{
 818        struct dm_hot_add_response resp;
 819#ifdef CONFIG_MEMORY_HOTPLUG
 820        unsigned long pg_start, pfn_cnt;
 821        unsigned long rg_start, rg_sz;
 822#endif
 823        struct hv_dynmem_device *dm = &dm_device;
 824
 825        memset(&resp, 0, sizeof(struct dm_hot_add_response));
 826        resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
 827        resp.hdr.size = sizeof(struct dm_hot_add_response);
 828        resp.hdr.trans_id = atomic_inc_return(&trans_id);
 829
 830#ifdef CONFIG_MEMORY_HOTPLUG
 831        pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
 832        pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
 833
 834        rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
 835        rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;
 836
 837        if ((rg_start == 0) && (!dm->host_specified_ha_region)) {
 838                unsigned long region_size;
 839                unsigned long region_start;
 840
 841                /*
 842                 * The host has not specified the hot-add region.
 843                 * Based on the hot-add page range being specified,
 844                 * compute a hot-add region that can cover the pages
 845                 * that need to be hot-added while ensuring the alignment
 846                 * and size requirements of Linux as it relates to hot-add.
 847                 */
 848                region_start = pg_start;
 849                region_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
 850                if (pfn_cnt % HA_CHUNK)
 851                        region_size += HA_CHUNK;
 852
 853                region_start = (pg_start / HA_CHUNK) * HA_CHUNK;
 854
 855                rg_start = region_start;
 856                rg_sz = region_size;
 857        }
 858
 859        if (do_hot_add)
 860                resp.page_count = process_hot_add(pg_start, pfn_cnt,
 861                                                rg_start, rg_sz);
 862#endif
 863        /*
 864         * The result field of the response structure has the
 865         * following semantics:
 866         *
 867         * 1. If all or some pages hot-added: Guest should return success.
 868         *
 869         * 2. If no pages could be hot-added:
 870         *
 871         * If the guest returns success, then the host
 872         * will not attempt any further hot-add operations. This
 873         * signifies a permanent failure.
 874         *
 875         * If the guest returns failure, then this failure will be
 876         * treated as a transient failure and the host may retry the
 877         * hot-add operation after some delay.
 878         */
 879        if (resp.page_count > 0)
 880                resp.result = 1;
 881        else if (!do_hot_add)
 882                resp.result = 1;
 883        else
 884                resp.result = 0;
 885
 886        if (!do_hot_add || (resp.page_count == 0))
 887                pr_info("Memory hot add failed\n");
 888
 889        dm->state = DM_INITIALIZED;
 890        vmbus_sendpacket(dm->dev->channel, &resp,
 891                        sizeof(struct dm_hot_add_response),
 892                        (unsigned long)NULL,
 893                        VM_PKT_DATA_INBAND, 0);
 894}
 895
 896static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
 897{
 898        struct dm_info_header *info_hdr;
 899
 900        info_hdr = (struct dm_info_header *)msg->info;
 901
 902        switch (info_hdr->type) {
 903        case INFO_TYPE_MAX_PAGE_CNT:
 904                pr_info("Received INFO_TYPE_MAX_PAGE_CNT\n");
 905                pr_info("Data Size is %d\n", info_hdr->data_size);
 906                break;
 907        default:
 908                pr_info("Received Unknown type: %d\n", info_hdr->type);
 909        }
 910}
 911
 912static unsigned long compute_balloon_floor(void)
 913{
 914        unsigned long min_pages;
 915#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
 916        /* Simple continuous piecewiese linear function:
 917         *  max MiB -> min MiB  gradient
 918         *       0         0
 919         *      16        16
 920         *      32        24
 921         *     128        72    (1/2)
 922         *     512       168    (1/4)
 923         *    2048       360    (1/8)
 924         *    8192       552    (1/32)
 925         *   32768      1320
 926         *  131072      4392
 927         */
 928        if (totalram_pages < MB2PAGES(128))
 929                min_pages = MB2PAGES(8) + (totalram_pages >> 1);
 930        else if (totalram_pages < MB2PAGES(512))
 931                min_pages = MB2PAGES(40) + (totalram_pages >> 2);
 932        else if (totalram_pages < MB2PAGES(2048))
 933                min_pages = MB2PAGES(104) + (totalram_pages >> 3);
 934        else
 935                min_pages = MB2PAGES(296) + (totalram_pages >> 5);
 936#undef MB2PAGES
 937        return min_pages;
 938}
 939
 940/*
 941 * Post our status as it relates memory pressure to the
 942 * host. Host expects the guests to post this status
 943 * periodically at 1 second intervals.
 944 *
 945 * The metrics specified in this protocol are very Windows
 946 * specific and so we cook up numbers here to convey our memory
 947 * pressure.
 948 */
 949
 950static void post_status(struct hv_dynmem_device *dm)
 951{
 952        struct dm_status status;
 953        struct sysinfo val;
 954
 955        if (pressure_report_delay > 0) {
 956                --pressure_report_delay;
 957                return;
 958        }
 959        si_meminfo(&val);
 960        memset(&status, 0, sizeof(struct dm_status));
 961        status.hdr.type = DM_STATUS_REPORT;
 962        status.hdr.size = sizeof(struct dm_status);
 963        status.hdr.trans_id = atomic_inc_return(&trans_id);
 964
 965        /*
 966         * The host expects the guest to report free memory.
 967         * Further, the host expects the pressure information to
 968         * include the ballooned out pages.
 969         * For a given amount of memory that we are managing, we
 970         * need to compute a floor below which we should not balloon.
 971         * Compute this and add it to the pressure report.
 972         */
 973        status.num_avail = val.freeram;
 974        status.num_committed = vm_memory_committed() +
 975                                dm->num_pages_ballooned +
 976                                compute_balloon_floor();
 977
 978        /*
 979         * If our transaction ID is no longer current, just don't
 980         * send the status. This can happen if we were interrupted
 981         * after we picked our transaction ID.
 982         */
 983        if (status.hdr.trans_id != atomic_read(&trans_id))
 984                return;
 985
 986        vmbus_sendpacket(dm->dev->channel, &status,
 987                                sizeof(struct dm_status),
 988                                (unsigned long)NULL,
 989                                VM_PKT_DATA_INBAND, 0);
 990
 991}
 992
 993static void free_balloon_pages(struct hv_dynmem_device *dm,
 994                         union dm_mem_page_range *range_array)
 995{
 996        int num_pages = range_array->finfo.page_cnt;
 997        __u64 start_frame = range_array->finfo.start_page;
 998        struct page *pg;
 999        int i;
1000
1001        for (i = 0; i < num_pages; i++) {
1002                pg = pfn_to_page(i + start_frame);
1003                __free_page(pg);
1004                dm->num_pages_ballooned--;
1005        }
1006}
1007
1008
1009
1010static int  alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,
1011                         struct dm_balloon_response *bl_resp, int alloc_unit,
1012                         bool *alloc_error)
1013{
1014        int i = 0;
1015        struct page *pg;
1016
1017        if (num_pages < alloc_unit)
1018                return 0;
1019
1020        for (i = 0; (i * alloc_unit) < num_pages; i++) {
1021                if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
1022                        PAGE_SIZE)
1023                        return i * alloc_unit;
1024
1025                /*
1026                 * We execute this code in a thread context. Furthermore,
1027                 * we don't want the kernel to try too hard.
1028                 */
1029                pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
1030                                __GFP_NOMEMALLOC | __GFP_NOWARN,
1031                                get_order(alloc_unit << PAGE_SHIFT));
1032
1033                if (!pg) {
1034                        *alloc_error = true;
1035                        return i * alloc_unit;
1036                }
1037
1038
1039                dm->num_pages_ballooned += alloc_unit;
1040
1041                /*
1042                 * If we allocatted 2M pages; split them so we
1043                 * can free them in any order we get.
1044                 */
1045
1046                if (alloc_unit != 1)
1047                        split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
1048
1049                bl_resp->range_count++;
1050                bl_resp->range_array[i].finfo.start_page =
1051                        page_to_pfn(pg);
1052                bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
1053                bl_resp->hdr.size += sizeof(union dm_mem_page_range);
1054
1055        }
1056
1057        return num_pages;
1058}
1059
1060
1061
1062static void balloon_up(struct work_struct *dummy)
1063{
1064        int num_pages = dm_device.balloon_wrk.num_pages;
1065        int num_ballooned = 0;
1066        struct dm_balloon_response *bl_resp;
1067        int alloc_unit;
1068        int ret;
1069        bool alloc_error = false;
1070        bool done = false;
1071        int i;
1072
1073
1074        /*
1075         * We will attempt 2M allocations. However, if we fail to
1076         * allocate 2M chunks, we will go back to 4k allocations.
1077         */
1078        alloc_unit = 512;
1079
1080        while (!done) {
1081                bl_resp = (struct dm_balloon_response *)send_buffer;
1082                memset(send_buffer, 0, PAGE_SIZE);
1083                bl_resp->hdr.type = DM_BALLOON_RESPONSE;
1084                bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
1085                bl_resp->hdr.size = sizeof(struct dm_balloon_response);
1086                bl_resp->more_pages = 1;
1087
1088
1089                num_pages -= num_ballooned;
1090                num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
1091                                                bl_resp, alloc_unit,
1092                                                 &alloc_error);
1093
1094                if ((alloc_error) && (alloc_unit != 1)) {
1095                        alloc_unit = 1;
1096                        continue;
1097                }
1098
1099                if ((alloc_error) || (num_ballooned == num_pages)) {
1100                        bl_resp->more_pages = 0;
1101                        done = true;
1102                        dm_device.state = DM_INITIALIZED;
1103                }
1104
1105                /*
1106                 * We are pushing a lot of data through the channel;
1107                 * deal with transient failures caused because of the
1108                 * lack of space in the ring buffer.
1109                 */
1110
1111                do {
1112                        ret = vmbus_sendpacket(dm_device.dev->channel,
1113                                                bl_resp,
1114                                                bl_resp->hdr.size,
1115                                                (unsigned long)NULL,
1116                                                VM_PKT_DATA_INBAND, 0);
1117
1118                        if (ret == -EAGAIN)
1119                                msleep(20);
1120
1121                } while (ret == -EAGAIN);
1122
1123                if (ret) {
1124                        /*
1125                         * Free up the memory we allocatted.
1126                         */
1127                        pr_info("Balloon response failed\n");
1128
1129                        for (i = 0; i < bl_resp->range_count; i++)
1130                                free_balloon_pages(&dm_device,
1131                                                 &bl_resp->range_array[i]);
1132
1133                        done = true;
1134                }
1135        }
1136
1137}
1138
1139static void balloon_down(struct hv_dynmem_device *dm,
1140                        struct dm_unballoon_request *req)
1141{
1142        union dm_mem_page_range *range_array = req->range_array;
1143        int range_count = req->range_count;
1144        struct dm_unballoon_response resp;
1145        int i;
1146
1147        for (i = 0; i < range_count; i++)
1148                free_balloon_pages(dm, &range_array[i]);
1149
1150        if (req->more_pages == 1)
1151                return;
1152
1153        memset(&resp, 0, sizeof(struct dm_unballoon_response));
1154        resp.hdr.type = DM_UNBALLOON_RESPONSE;
1155        resp.hdr.trans_id = atomic_inc_return(&trans_id);
1156        resp.hdr.size = sizeof(struct dm_unballoon_response);
1157
1158        vmbus_sendpacket(dm_device.dev->channel, &resp,
1159                                sizeof(struct dm_unballoon_response),
1160                                (unsigned long)NULL,
1161                                VM_PKT_DATA_INBAND, 0);
1162
1163        dm->state = DM_INITIALIZED;
1164}
1165
1166static void balloon_onchannelcallback(void *context);
1167
1168static int dm_thread_func(void *dm_dev)
1169{
1170        struct hv_dynmem_device *dm = dm_dev;
1171        int t;
1172
1173        while (!kthread_should_stop()) {
1174                t = wait_for_completion_timeout(&dm_device.config_event, 1*HZ);
1175                /*
1176                 * The host expects us to post information on the memory
1177                 * pressure every second.
1178                 */
1179
1180                if (t == 0)
1181                        post_status(dm);
1182
1183        }
1184
1185        return 0;
1186}
1187
1188
1189static void version_resp(struct hv_dynmem_device *dm,
1190                        struct dm_version_response *vresp)
1191{
1192        struct dm_version_request version_req;
1193        int ret;
1194
1195        if (vresp->is_accepted) {
1196                /*
1197                 * We are done; wakeup the
1198                 * context waiting for version
1199                 * negotiation.
1200                 */
1201                complete(&dm->host_event);
1202                return;
1203        }
1204        /*
1205         * If there are more versions to try, continue
1206         * with negotiations; if not
1207         * shutdown the service since we are not able
1208         * to negotiate a suitable version number
1209         * with the host.
1210         */
1211        if (dm->next_version == 0)
1212                goto version_error;
1213
1214        dm->next_version = 0;
1215        memset(&version_req, 0, sizeof(struct dm_version_request));
1216        version_req.hdr.type = DM_VERSION_REQUEST;
1217        version_req.hdr.size = sizeof(struct dm_version_request);
1218        version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1219        version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN7;
1220        version_req.is_last_attempt = 1;
1221
1222        ret = vmbus_sendpacket(dm->dev->channel, &version_req,
1223                                sizeof(struct dm_version_request),
1224                                (unsigned long)NULL,
1225                                VM_PKT_DATA_INBAND, 0);
1226
1227        if (ret)
1228                goto version_error;
1229
1230        return;
1231
1232version_error:
1233        dm->state = DM_INIT_ERROR;
1234        complete(&dm->host_event);
1235}
1236
1237static void cap_resp(struct hv_dynmem_device *dm,
1238                        struct dm_capabilities_resp_msg *cap_resp)
1239{
1240        if (!cap_resp->is_accepted) {
1241                pr_info("Capabilities not accepted by host\n");
1242                dm->state = DM_INIT_ERROR;
1243        }
1244        complete(&dm->host_event);
1245}
1246
1247static void balloon_onchannelcallback(void *context)
1248{
1249        struct hv_device *dev = context;
1250        u32 recvlen;
1251        u64 requestid;
1252        struct dm_message *dm_msg;
1253        struct dm_header *dm_hdr;
1254        struct hv_dynmem_device *dm = hv_get_drvdata(dev);
1255        struct dm_balloon *bal_msg;
1256        struct dm_hot_add *ha_msg;
1257        union dm_mem_page_range *ha_pg_range;
1258        union dm_mem_page_range *ha_region;
1259
1260        memset(recv_buffer, 0, sizeof(recv_buffer));
1261        vmbus_recvpacket(dev->channel, recv_buffer,
1262                         PAGE_SIZE, &recvlen, &requestid);
1263
1264        if (recvlen > 0) {
1265                dm_msg = (struct dm_message *)recv_buffer;
1266                dm_hdr = &dm_msg->hdr;
1267
1268                switch (dm_hdr->type) {
1269                case DM_VERSION_RESPONSE:
1270                        version_resp(dm,
1271                                 (struct dm_version_response *)dm_msg);
1272                        break;
1273
1274                case DM_CAPABILITIES_RESPONSE:
1275                        cap_resp(dm,
1276                                 (struct dm_capabilities_resp_msg *)dm_msg);
1277                        break;
1278
1279                case DM_BALLOON_REQUEST:
1280                        if (dm->state == DM_BALLOON_UP)
1281                                pr_warn("Currently ballooning\n");
1282                        bal_msg = (struct dm_balloon *)recv_buffer;
1283                        dm->state = DM_BALLOON_UP;
1284                        dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
1285                        schedule_work(&dm_device.balloon_wrk.wrk);
1286                        break;
1287
1288                case DM_UNBALLOON_REQUEST:
1289                        dm->state = DM_BALLOON_DOWN;
1290                        balloon_down(dm,
1291                                 (struct dm_unballoon_request *)recv_buffer);
1292                        break;
1293
1294                case DM_MEM_HOT_ADD_REQUEST:
1295                        if (dm->state == DM_HOT_ADD)
1296                                pr_warn("Currently hot-adding\n");
1297                        dm->state = DM_HOT_ADD;
1298                        ha_msg = (struct dm_hot_add *)recv_buffer;
1299                        if (ha_msg->hdr.size == sizeof(struct dm_hot_add)) {
1300                                /*
1301                                 * This is a normal hot-add request specifying
1302                                 * hot-add memory.
1303                                 */
1304                                ha_pg_range = &ha_msg->range;
1305                                dm->ha_wrk.ha_page_range = *ha_pg_range;
1306                                dm->ha_wrk.ha_region_range.page_range = 0;
1307                        } else {
1308                                /*
1309                                 * Host is specifying that we first hot-add
1310                                 * a region and then partially populate this
1311                                 * region.
1312                                 */
1313                                dm->host_specified_ha_region = true;
1314                                ha_pg_range = &ha_msg->range;
1315                                ha_region = &ha_pg_range[1];
1316                                dm->ha_wrk.ha_page_range = *ha_pg_range;
1317                                dm->ha_wrk.ha_region_range = *ha_region;
1318                        }
1319                        schedule_work(&dm_device.ha_wrk.wrk);
1320                        break;
1321
1322                case DM_INFO_MESSAGE:
1323                        process_info(dm, (struct dm_info_msg *)dm_msg);
1324                        break;
1325
1326                default:
1327                        pr_err("Unhandled message: type: %d\n", dm_hdr->type);
1328
1329                }
1330        }
1331
1332}
1333
1334static int balloon_probe(struct hv_device *dev,
1335                        const struct hv_vmbus_device_id *dev_id)
1336{
1337        int ret, t;
1338        struct dm_version_request version_req;
1339        struct dm_capabilities cap_msg;
1340
1341        do_hot_add = hot_add;
1342
1343        /*
1344         * First allocate a send buffer.
1345         */
1346
1347        send_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
1348        if (!send_buffer)
1349                return -ENOMEM;
1350
1351        ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
1352                        balloon_onchannelcallback, dev);
1353
1354        if (ret)
1355                goto probe_error0;
1356
1357        dm_device.dev = dev;
1358        dm_device.state = DM_INITIALIZING;
1359        dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
1360        init_completion(&dm_device.host_event);
1361        init_completion(&dm_device.config_event);
1362        INIT_LIST_HEAD(&dm_device.ha_region_list);
1363        INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
1364        INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
1365        dm_device.host_specified_ha_region = false;
1366
1367        dm_device.thread =
1368                 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
1369        if (IS_ERR(dm_device.thread)) {
1370                ret = PTR_ERR(dm_device.thread);
1371                goto probe_error1;
1372        }
1373
1374#ifdef CONFIG_MEMORY_HOTPLUG
1375        set_online_page_callback(&hv_online_page);
1376#endif
1377
1378        hv_set_drvdata(dev, &dm_device);
1379        /*
1380         * Initiate the hand shake with the host and negotiate
1381         * a version that the host can support. We start with the
1382         * highest version number and go down if the host cannot
1383         * support it.
1384         */
1385        memset(&version_req, 0, sizeof(struct dm_version_request));
1386        version_req.hdr.type = DM_VERSION_REQUEST;
1387        version_req.hdr.size = sizeof(struct dm_version_request);
1388        version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1389        version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN8;
1390        version_req.is_last_attempt = 0;
1391
1392        ret = vmbus_sendpacket(dev->channel, &version_req,
1393                                sizeof(struct dm_version_request),
1394                                (unsigned long)NULL,
1395                                VM_PKT_DATA_INBAND, 0);
1396        if (ret)
1397                goto probe_error2;
1398
1399        t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
1400        if (t == 0) {
1401                ret = -ETIMEDOUT;
1402                goto probe_error2;
1403        }
1404
1405        /*
1406         * If we could not negotiate a compatible version with the host
1407         * fail the probe function.
1408         */
1409        if (dm_device.state == DM_INIT_ERROR) {
1410                ret = -ETIMEDOUT;
1411                goto probe_error2;
1412        }
1413        /*
1414         * Now submit our capabilities to the host.
1415         */
1416        memset(&cap_msg, 0, sizeof(struct dm_capabilities));
1417        cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
1418        cap_msg.hdr.size = sizeof(struct dm_capabilities);
1419        cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);
1420
1421        cap_msg.caps.cap_bits.balloon = 1;
1422        cap_msg.caps.cap_bits.hot_add = 1;
1423
1424        /*
1425         * Specify our alignment requirements as it relates
1426         * memory hot-add. Specify 128MB alignment.
1427         */
1428        cap_msg.caps.cap_bits.hot_add_alignment = 7;
1429
1430        /*
1431         * Currently the host does not use these
1432         * values and we set them to what is done in the
1433         * Windows driver.
1434         */
1435        cap_msg.min_page_cnt = 0;
1436        cap_msg.max_page_number = -1;
1437
1438        ret = vmbus_sendpacket(dev->channel, &cap_msg,
1439                                sizeof(struct dm_capabilities),
1440                                (unsigned long)NULL,
1441                                VM_PKT_DATA_INBAND, 0);
1442        if (ret)
1443                goto probe_error2;
1444
1445        t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
1446        if (t == 0) {
1447                ret = -ETIMEDOUT;
1448                goto probe_error2;
1449        }
1450
1451        /*
1452         * If the host does not like our capabilities,
1453         * fail the probe function.
1454         */
1455        if (dm_device.state == DM_INIT_ERROR) {
1456                ret = -ETIMEDOUT;
1457                goto probe_error2;
1458        }
1459
1460        dm_device.state = DM_INITIALIZED;
1461
1462        return 0;
1463
1464probe_error2:
1465#ifdef CONFIG_MEMORY_HOTPLUG
1466        restore_online_page_callback(&hv_online_page);
1467#endif
1468        kthread_stop(dm_device.thread);
1469
1470probe_error1:
1471        vmbus_close(dev->channel);
1472probe_error0:
1473        kfree(send_buffer);
1474        return ret;
1475}
1476
1477static int balloon_remove(struct hv_device *dev)
1478{
1479        struct hv_dynmem_device *dm = hv_get_drvdata(dev);
1480        struct list_head *cur, *tmp;
1481        struct hv_hotadd_state *has;
1482
1483        if (dm->num_pages_ballooned != 0)
1484                pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
1485
1486        cancel_work_sync(&dm->balloon_wrk.wrk);
1487        cancel_work_sync(&dm->ha_wrk.wrk);
1488
1489        vmbus_close(dev->channel);
1490        kthread_stop(dm->thread);
1491        kfree(send_buffer);
1492#ifdef CONFIG_MEMORY_HOTPLUG
1493        restore_online_page_callback(&hv_online_page);
1494#endif
1495        list_for_each_safe(cur, tmp, &dm->ha_region_list) {
1496                has = list_entry(cur, struct hv_hotadd_state, list);
1497                list_del(&has->list);
1498                kfree(has);
1499        }
1500
1501        return 0;
1502}
1503
1504static const struct hv_vmbus_device_id id_table[] = {
1505        /* Dynamic Memory Class ID */
1506        /* 525074DC-8985-46e2-8057-A307DC18A502 */
1507        { HV_DM_GUID, },
1508        { },
1509};
1510
1511MODULE_DEVICE_TABLE(vmbus, id_table);
1512
1513static  struct hv_driver balloon_drv = {
1514        .name = "hv_balloon",
1515        .id_table = id_table,
1516        .probe =  balloon_probe,
1517        .remove =  balloon_remove,
1518};
1519
1520static int __init init_balloon_drv(void)
1521{
1522
1523        return vmbus_driver_register(&balloon_drv);
1524}
1525
1526module_init(init_balloon_drv);
1527
1528MODULE_DESCRIPTION("Hyper-V Balloon");
1529MODULE_VERSION(HV_DRV_VERSION);
1530MODULE_LICENSE("GPL");
1531
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