drivers/misc/vmw_balloon.c

   1 /*
   2  * VMware Balloon driver.
   3  *
   4  * Copyright (C) 2000-2014, VMware, Inc. All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; version 2 of the License and no later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  13  * NON INFRINGEMENT.  See the GNU General Public License for more
  14  * details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Maintained by:       Xavier Deguillard <xdeguillard@vmware.com>
  21  *                      Philip Moltmann <moltmann@vmware.com>
  22  */
  23
  24 /*
  25  * This is VMware physical memory management driver for Linux. The driver
  26  * acts like a "balloon" that can be inflated to reclaim physical pages by
  27  * reserving them in the guest and invalidating them in the monitor,
  28  * freeing up the underlying machine pages so they can be allocated to
  29  * other guests.  The balloon can also be deflated to allow the guest to
  30  * use more physical memory. Higher level policies can control the sizes
  31  * of balloons in VMs in order to manage physical memory resources.
  32  */
  33
  34 //#define DEBUG
  35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37 #include <linux/types.h>
  38 #include <linux/kernel.h>
  39 #include <linux/mm.h>
  40 #include <linux/vmalloc.h>
  41 #include <linux/sched.h>
  42 #include <linux/module.h>
  43 #include <linux/workqueue.h>
  44 #include <linux/debugfs.h>
  45 #include <linux/seq_file.h>
  46 #include <linux/vmw_vmci_defs.h>
  47 #include <linux/vmw_vmci_api.h>
  48 #include <linux/io.h>
  49 #include <asm/hypervisor.h>
  50
  51 MODULE_AUTHOR("VMware, Inc.");
  52 MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
  53 MODULE_VERSION("1.5.0.0-k");
  54 MODULE_ALIAS("dmi:*:svnVMware*:*");
  55 MODULE_ALIAS("vmware_vmmemctl");
  56 MODULE_LICENSE("GPL");
  57
  58 /*
  59  * Various constants controlling rate of inflaint/deflating balloon,
  60  * measured in pages.
  61  */
  62
  63 /*
  64  * Rates of memory allocaton when guest experiences memory pressure
  65  * (driver performs sleeping allocations).
  66  */
  67 #define VMW_BALLOON_RATE_ALLOC_MIN      512U
  68 #define VMW_BALLOON_RATE_ALLOC_MAX      2048U
  69 #define VMW_BALLOON_RATE_ALLOC_INC      16U
  70
  71 /*
  72  * When guest is under memory pressure, use a reduced page allocation
  73  * rate for next several cycles.
  74  */
  75 #define VMW_BALLOON_SLOW_CYCLES         4
  76
  77 /*
  78  * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't
  79  * allow wait (__GFP_RECLAIM) for NOSLEEP page allocations. Use
  80  * __GFP_NOWARN, to suppress page allocation failure warnings.
  81  */
  82 #define VMW_PAGE_ALLOC_NOSLEEP          (__GFP_HIGHMEM|__GFP_NOWARN)
  83
  84 /*
  85  * Use GFP_HIGHUSER when executing in a separate kernel thread
  86  * context and allocation can sleep.  This is less stressful to
  87  * the guest memory system, since it allows the thread to block
  88  * while memory is reclaimed, and won't take pages from emergency
  89  * low-memory pools.
  90  */
  91 #define VMW_PAGE_ALLOC_CANSLEEP         (GFP_HIGHUSER)
  92
  93 /* Maximum number of refused pages we accumulate during inflation cycle */
  94 #define VMW_BALLOON_MAX_REFUSED         16
  95
  96 /*
  97  * Hypervisor communication port definitions.
  98  */
  99 #define VMW_BALLOON_HV_PORT             0x5670
 100 #define VMW_BALLOON_HV_MAGIC            0x456c6d6f
 101 #define VMW_BALLOON_GUEST_ID            1       /* Linux */
 102
 103 enum vmwballoon_capabilities {
 104         /*
 105          * Bit 0 is reserved and not associated to any capability.
 106          */
 107         VMW_BALLOON_BASIC_CMDS                  = (1 << 1),
 108         VMW_BALLOON_BATCHED_CMDS                = (1 << 2),
 109         VMW_BALLOON_BATCHED_2M_CMDS             = (1 << 3),
 110         VMW_BALLOON_SIGNALLED_WAKEUP_CMD        = (1 << 4),
 111 };
 112
 113 #define VMW_BALLOON_CAPABILITIES        (VMW_BALLOON_BASIC_CMDS \
 114                                         | VMW_BALLOON_BATCHED_CMDS \
 115                                         | VMW_BALLOON_BATCHED_2M_CMDS \
 116                                         | VMW_BALLOON_SIGNALLED_WAKEUP_CMD)
 117
 118 #define VMW_BALLOON_2M_SHIFT            (9)
 119 #define VMW_BALLOON_NUM_PAGE_SIZES      (2)
 120
 121 /*
 122  * Backdoor commands availability:
 123  *
 124  * START, GET_TARGET and GUEST_ID are always available,
 125  *
 126  * VMW_BALLOON_BASIC_CMDS:
 127  *      LOCK and UNLOCK commands,
 128  * VMW_BALLOON_BATCHED_CMDS:
 129  *      BATCHED_LOCK and BATCHED_UNLOCK commands.
 130  * VMW BALLOON_BATCHED_2M_CMDS:
 131  *      BATCHED_2M_LOCK and BATCHED_2M_UNLOCK commands,
 132  * VMW VMW_BALLOON_SIGNALLED_WAKEUP_CMD:
 133  *      VMW_BALLOON_CMD_VMCI_DOORBELL_SET command.
 134  */
 135 #define VMW_BALLOON_CMD_START                   0
 136 #define VMW_BALLOON_CMD_GET_TARGET              1
 137 #define VMW_BALLOON_CMD_LOCK                    2
 138 #define VMW_BALLOON_CMD_UNLOCK                  3
 139 #define VMW_BALLOON_CMD_GUEST_ID                4
 140 #define VMW_BALLOON_CMD_BATCHED_LOCK            6
 141 #define VMW_BALLOON_CMD_BATCHED_UNLOCK          7
 142 #define VMW_BALLOON_CMD_BATCHED_2M_LOCK         8
 143 #define VMW_BALLOON_CMD_BATCHED_2M_UNLOCK       9
 144 #define VMW_BALLOON_CMD_VMCI_DOORBELL_SET       10
 145
 146
 147 /* error codes */
 148 #define VMW_BALLOON_SUCCESS                     0
 149 #define VMW_BALLOON_FAILURE                     -1
 150 #define VMW_BALLOON_ERROR_CMD_INVALID           1
 151 #define VMW_BALLOON_ERROR_PPN_INVALID           2
 152 #define VMW_BALLOON_ERROR_PPN_LOCKED            3
 153 #define VMW_BALLOON_ERROR_PPN_UNLOCKED          4
 154 #define VMW_BALLOON_ERROR_PPN_PINNED            5
 155 #define VMW_BALLOON_ERROR_PPN_NOTNEEDED         6
 156 #define VMW_BALLOON_ERROR_RESET                 7
 157 #define VMW_BALLOON_ERROR_BUSY                  8
 158
 159 #define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES   (0x03000000)
 160
 161 /* Batch page description */
 162
 163 /*
 164  * Layout of a page in the batch page:
 165  *
 166  * +-------------+----------+--------+
 167  * |             |          |        |
 168  * | Page number | Reserved | Status |
 169  * |             |          |        |
 170  * +-------------+----------+--------+
 171  * 64  PAGE_SHIFT          6         0
 172  *
 173  * The reserved field should be set to 0.
 174  */
 175 #define VMW_BALLOON_BATCH_MAX_PAGES     (PAGE_SIZE / sizeof(u64))
 176 #define VMW_BALLOON_BATCH_STATUS_MASK   ((1UL << 5) - 1)
 177 #define VMW_BALLOON_BATCH_PAGE_MASK     (~((1UL << PAGE_SHIFT) - 1))
 178
 179 struct vmballoon_batch_page {
 180         u64 pages[VMW_BALLOON_BATCH_MAX_PAGES];
 181 };
 182
 183 static u64 vmballoon_batch_get_pa(struct vmballoon_batch_page *batch, int idx)
 184 {
 185         return batch->pages[idx] & VMW_BALLOON_BATCH_PAGE_MASK;
 186 }
 187
 188 static int vmballoon_batch_get_status(struct vmballoon_batch_page *batch,
 189                                 int idx)
 190 {
 191         return (int)(batch->pages[idx] & VMW_BALLOON_BATCH_STATUS_MASK);
 192 }
 193
 194 static void vmballoon_batch_set_pa(struct vmballoon_batch_page *batch, int idx,
 195                                 u64 pa)
 196 {
 197         batch->pages[idx] = pa;
 198 }
 199
 200
 201 #define VMWARE_BALLOON_CMD(cmd, arg1, arg2, result)             \
 202 ({                                                              \
 203         unsigned long __status, __dummy1, __dummy2, __dummy3;   \
 204         __asm__ __volatile__ ("inl %%dx" :                      \
 205                 "=a"(__status),                                 \
 206                 "=c"(__dummy1),                                 \
 207                 "=d"(__dummy2),                                 \
 208                 "=b"(result),                                   \
 209                 "=S" (__dummy3) :                               \
 210                 "0"(VMW_BALLOON_HV_MAGIC),                      \
 211                 "1"(VMW_BALLOON_CMD_##cmd),                     \
 212                 "2"(VMW_BALLOON_HV_PORT),                       \
 213                 "3"(arg1),                                      \
 214                 "4" (arg2) :                                    \
 215                 "memory");                                      \
 216         if (VMW_BALLOON_CMD_##cmd == VMW_BALLOON_CMD_START)     \
 217                 result = __dummy1;                              \
 218         result &= -1UL;                                         \
 219         __status & -1UL;                                        \
 220 })
 221
 222 #ifdef CONFIG_DEBUG_FS
 223 struct vmballoon_stats {
 224         unsigned int timer;
 225         unsigned int doorbell;
 226
 227         /* allocation statistics */
 228         unsigned int alloc[VMW_BALLOON_NUM_PAGE_SIZES];
 229         unsigned int alloc_fail[VMW_BALLOON_NUM_PAGE_SIZES];
 230         unsigned int sleep_alloc;
 231         unsigned int sleep_alloc_fail;
 232         unsigned int refused_alloc[VMW_BALLOON_NUM_PAGE_SIZES];
 233         unsigned int refused_free[VMW_BALLOON_NUM_PAGE_SIZES];
 234         unsigned int free[VMW_BALLOON_NUM_PAGE_SIZES];
 235
 236         /* monitor operations */
 237         unsigned int lock[VMW_BALLOON_NUM_PAGE_SIZES];
 238         unsigned int lock_fail[VMW_BALLOON_NUM_PAGE_SIZES];
 239         unsigned int unlock[VMW_BALLOON_NUM_PAGE_SIZES];
 240         unsigned int unlock_fail[VMW_BALLOON_NUM_PAGE_SIZES];
 241         unsigned int target;
 242         unsigned int target_fail;
 243         unsigned int start;
 244         unsigned int start_fail;
 245         unsigned int guest_type;
 246         unsigned int guest_type_fail;
 247         unsigned int doorbell_set;
 248         unsigned int doorbell_unset;
 249 };
 250
 251 #define STATS_INC(stat) (stat)++
 252 #else
 253 #define STATS_INC(stat)
 254 #endif
 255
 256 struct vmballoon;
 257
 258 struct vmballoon_ops {
 259         void (*add_page)(struct vmballoon *b, int idx, struct page *p);
 260         int (*lock)(struct vmballoon *b, unsigned int num_pages,
 261                         bool is_2m_pages, unsigned int *target);
 262         int (*unlock)(struct vmballoon *b, unsigned int num_pages,
 263                         bool is_2m_pages, unsigned int *target);
 264 };
 265
 266 struct vmballoon_page_size {
 267         /* list of reserved physical pages */
 268         struct list_head pages;
 269
 270         /* transient list of non-balloonable pages */
 271         struct list_head refused_pages;
 272         unsigned int n_refused_pages;
 273 };
 274
 275 struct vmballoon {
 276         struct vmballoon_page_size page_sizes[VMW_BALLOON_NUM_PAGE_SIZES];
 277
 278         /* supported page sizes. 1 == 4k pages only, 2 == 4k and 2m pages */
 279         unsigned supported_page_sizes;
 280
 281         /* balloon size in pages */
 282         unsigned int size;
 283         unsigned int target;
 284
 285         /* reset flag */
 286         bool reset_required;
 287
 288         /* adjustment rates (pages per second) */
 289         unsigned int rate_alloc;
 290
 291         /* slowdown page allocations for next few cycles */
 292         unsigned int slow_allocation_cycles;
 293
 294         unsigned long capabilities;
 295
 296         struct vmballoon_batch_page *batch_page;
 297         unsigned int batch_max_pages;
 298         struct page *page;
 299
 300         const struct vmballoon_ops *ops;
 301
 302 #ifdef CONFIG_DEBUG_FS
 303         /* statistics */
 304         struct vmballoon_stats stats;
 305
 306         /* debugfs file exporting statistics */
 307         struct dentry *dbg_entry;
 308 #endif
 309
 310         struct sysinfo sysinfo;
 311
 312         struct delayed_work dwork;
 313
 314         struct vmci_handle vmci_doorbell;
 315 };
 316
 317 static struct vmballoon balloon;
 318
 319 /*
 320  * Send "start" command to the host, communicating supported version
 321  * of the protocol.
 322  */
 323 static bool vmballoon_send_start(struct vmballoon *b, unsigned long req_caps)
 324 {
 325         unsigned long status, capabilities, dummy = 0;
 326         bool success;
 327
 328         STATS_INC(b->stats.start);
 329
 330         status = VMWARE_BALLOON_CMD(START, req_caps, dummy, capabilities);
 331
 332         switch (status) {
 333         case VMW_BALLOON_SUCCESS_WITH_CAPABILITIES:
 334                 b->capabilities = capabilities;
 335                 success = true;
 336                 break;
 337         case VMW_BALLOON_SUCCESS:
 338                 b->capabilities = VMW_BALLOON_BASIC_CMDS;
 339                 success = true;
 340                 break;
 341         default:
 342                 success = false;
 343         }
 344
 345         /*
 346          * 2MB pages are only supported with batching. If batching is for some
 347          * reason disabled, do not use 2MB pages, since otherwise the legacy
 348          * mechanism is used with 2MB pages, causing a failure.
 349          */
 350         if ((b->capabilities & VMW_BALLOON_BATCHED_2M_CMDS) &&
 351             (b->capabilities & VMW_BALLOON_BATCHED_CMDS))
 352                 b->supported_page_sizes = 2;
 353         else
 354                 b->supported_page_sizes = 1;
 355
 356         if (!success) {
 357                 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 358                 STATS_INC(b->stats.start_fail);
 359         }
 360         return success;
 361 }
 362
 363 static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
 364 {
 365         switch (status) {
 366         case VMW_BALLOON_SUCCESS:
 367                 return true;
 368
 369         case VMW_BALLOON_ERROR_RESET:
 370                 b->reset_required = true;
 371                 /* fall through */
 372
 373         default:
 374                 return false;
 375         }
 376 }
 377
 378 /*
 379  * Communicate guest type to the host so that it can adjust ballooning
 380  * algorithm to the one most appropriate for the guest. This command
 381  * is normally issued after sending "start" command and is part of
 382  * standard reset sequence.
 383  */
 384 static bool vmballoon_send_guest_id(struct vmballoon *b)
 385 {
 386         unsigned long status, dummy = 0;
 387
 388         status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy,
 389                                 dummy);
 390
 391         STATS_INC(b->stats.guest_type);
 392
 393         if (vmballoon_check_status(b, status))
 394                 return true;
 395
 396         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 397         STATS_INC(b->stats.guest_type_fail);
 398         return false;
 399 }
 400
 401 static u16 vmballoon_page_size(bool is_2m_page)
 402 {
 403         if (is_2m_page)
 404                 return 1 << VMW_BALLOON_2M_SHIFT;
 405
 406         return 1;
 407 }
 408
 409 /*
 410  * Retrieve desired balloon size from the host.
 411  */
 412 static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
 413 {
 414         unsigned long status;
 415         unsigned long target;
 416         unsigned long limit;
 417         unsigned long dummy = 0;
 418         u32 limit32;
 419
 420         /*
 421          * si_meminfo() is cheap. Moreover, we want to provide dynamic
 422          * max balloon size later. So let us call si_meminfo() every
 423          * iteration.
 424          */
 425         si_meminfo(&b->sysinfo);
 426         limit = b->sysinfo.totalram;
 427
 428         /* Ensure limit fits in 32-bits */
 429         limit32 = (u32)limit;
 430         if (limit != limit32)
 431                 return false;
 432
 433         /* update stats */
 434         STATS_INC(b->stats.target);
 435
 436         status = VMWARE_BALLOON_CMD(GET_TARGET, limit, dummy, target);
 437         if (vmballoon_check_status(b, status)) {
 438                 *new_target = target;
 439                 return true;
 440         }
 441
 442         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 443         STATS_INC(b->stats.target_fail);
 444         return false;
 445 }
 446
 447 /*
 448  * Notify the host about allocated page so that host can use it without
 449  * fear that guest will need it. Host may reject some pages, we need to
 450  * check the return value and maybe submit a different page.
 451  */
 452 static int vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
 453                                 unsigned int *hv_status, unsigned int *target)
 454 {
 455         unsigned long status, dummy = 0;
 456         u32 pfn32;
 457
 458         pfn32 = (u32)pfn;
 459         if (pfn32 != pfn)
 460                 return -EINVAL;
 461
 462         STATS_INC(b->stats.lock[false]);
 463
 464         *hv_status = status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy, *target);
 465         if (vmballoon_check_status(b, status))
 466                 return 0;
 467
 468         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 469         STATS_INC(b->stats.lock_fail[false]);
 470         return -EIO;
 471 }
 472
 473 static int vmballoon_send_batched_lock(struct vmballoon *b,
 474                 unsigned int num_pages, bool is_2m_pages, unsigned int *target)
 475 {
 476         unsigned long status;
 477         unsigned long pfn = PHYS_PFN(virt_to_phys(b->batch_page));
 478
 479         STATS_INC(b->stats.lock[is_2m_pages]);
 480
 481         if (is_2m_pages)
 482                 status = VMWARE_BALLOON_CMD(BATCHED_2M_LOCK, pfn, num_pages,
 483                                 *target);
 484         else
 485                 status = VMWARE_BALLOON_CMD(BATCHED_LOCK, pfn, num_pages,
 486                                 *target);
 487
 488         if (vmballoon_check_status(b, status))
 489                 return 0;
 490
 491         pr_debug("%s - batch ppn %lx, hv returns %ld\n", __func__, pfn, status);
 492         STATS_INC(b->stats.lock_fail[is_2m_pages]);
 493         return 1;
 494 }
 495
 496 /*
 497  * Notify the host that guest intends to release given page back into
 498  * the pool of available (to the guest) pages.
 499  */
 500 static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn,
 501                                                         unsigned int *target)
 502 {
 503         unsigned long status, dummy = 0;
 504         u32 pfn32;
 505
 506         pfn32 = (u32)pfn;
 507         if (pfn32 != pfn)
 508                 return false;
 509
 510         STATS_INC(b->stats.unlock[false]);
 511
 512         status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy, *target);
 513         if (vmballoon_check_status(b, status))
 514                 return true;
 515
 516         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 517         STATS_INC(b->stats.unlock_fail[false]);
 518         return false;
 519 }
 520
 521 static bool vmballoon_send_batched_unlock(struct vmballoon *b,
 522                 unsigned int num_pages, bool is_2m_pages, unsigned int *target)
 523 {
 524         unsigned long status;
 525         unsigned long pfn = PHYS_PFN(virt_to_phys(b->batch_page));
 526
 527         STATS_INC(b->stats.unlock[is_2m_pages]);
 528
 529         if (is_2m_pages)
 530                 status = VMWARE_BALLOON_CMD(BATCHED_2M_UNLOCK, pfn, num_pages,
 531                                 *target);
 532         else
 533                 status = VMWARE_BALLOON_CMD(BATCHED_UNLOCK, pfn, num_pages,
 534                                 *target);
 535
 536         if (vmballoon_check_status(b, status))
 537                 return true;
 538
 539         pr_debug("%s - batch ppn %lx, hv returns %ld\n", __func__, pfn, status);
 540         STATS_INC(b->stats.unlock_fail[is_2m_pages]);
 541         return false;
 542 }
 543
 544 static struct page *vmballoon_alloc_page(gfp_t flags, bool is_2m_page)
 545 {
 546         if (is_2m_page)
 547                 return alloc_pages(flags, VMW_BALLOON_2M_SHIFT);
 548
 549         return alloc_page(flags);
 550 }
 551
 552 static void vmballoon_free_page(struct page *page, bool is_2m_page)
 553 {
 554         if (is_2m_page)
 555                 __free_pages(page, VMW_BALLOON_2M_SHIFT);
 556         else
 557                 __free_page(page);
 558 }
 559
 560 /*
 561  * Quickly release all pages allocated for the balloon. This function is
 562  * called when host decides to "reset" balloon for one reason or another.
 563  * Unlike normal "deflate" we do not (shall not) notify host of the pages
 564  * being released.
 565  */
 566 static void vmballoon_pop(struct vmballoon *b)
 567 {
 568         struct page *page, *next;
 569         unsigned is_2m_pages;
 570
 571         for (is_2m_pages = 0; is_2m_pages < VMW_BALLOON_NUM_PAGE_SIZES;
 572                         is_2m_pages++) {
 573                 struct vmballoon_page_size *page_size =
 574                                 &b->page_sizes[is_2m_pages];
 575                 u16 size_per_page = vmballoon_page_size(is_2m_pages);
 576
 577                 list_for_each_entry_safe(page, next, &page_size->pages, lru) {
 578                         list_del(&page->lru);
 579                         vmballoon_free_page(page, is_2m_pages);
 580                         STATS_INC(b->stats.free[is_2m_pages]);
 581                         b->size -= size_per_page;
 582                         cond_resched();
 583                 }
 584         }
 585
 586         /* Clearing the batch_page unconditionally has no adverse effect */
 587         free_page((unsigned long)b->batch_page);
 588         b->batch_page = NULL;
 589 }
 590
 591 /*
 592  * Notify the host of a ballooned page. If host rejects the page put it on the
 593  * refuse list, those refused page are then released at the end of the
 594  * inflation cycle.
 595  */
 596 static int vmballoon_lock_page(struct vmballoon *b, unsigned int num_pages,
 597                                 bool is_2m_pages, unsigned int *target)
 598 {
 599         int locked, hv_status;
 600         struct page *page = b->page;
 601         struct vmballoon_page_size *page_size = &b->page_sizes[false];
 602
 603         /* is_2m_pages can never happen as 2m pages support implies batching */
 604
 605         locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status,
 606                                                                 target);
 607         if (locked) {
 608                 STATS_INC(b->stats.refused_alloc[false]);
 609
 610                 if (locked == -EIO &&
 611                     (hv_status == VMW_BALLOON_ERROR_RESET ||
 612                      hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED)) {
 613                         vmballoon_free_page(page, false);
 614                         return -EIO;
 615                 }
 616
 617                 /*
 618                  * Place page on the list of non-balloonable pages
 619                  * and retry allocation, unless we already accumulated
 620                  * too many of them, in which case take a breather.
 621                  */
 622                 if (page_size->n_refused_pages < VMW_BALLOON_MAX_REFUSED) {
 623                         page_size->n_refused_pages++;
 624                         list_add(&page->lru, &page_size->refused_pages);
 625                 } else {
 626                         vmballoon_free_page(page, false);
 627                 }
 628                 return locked;
 629         }
 630
 631         /* track allocated page */
 632         list_add(&page->lru, &page_size->pages);
 633
 634         /* update balloon size */
 635         b->size++;
 636
 637         return 0;
 638 }
 639
 640 static int vmballoon_lock_batched_page(struct vmballoon *b,
 641                 unsigned int num_pages, bool is_2m_pages, unsigned int *target)
 642 {
 643         int locked, i;
 644         u16 size_per_page = vmballoon_page_size(is_2m_pages);
 645
 646         locked = vmballoon_send_batched_lock(b, num_pages, is_2m_pages,
 647                         target);
 648         if (locked > 0) {
 649                 for (i = 0; i < num_pages; i++) {
 650                         u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
 651                         struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
 652
 653                         vmballoon_free_page(p, is_2m_pages);
 654                 }
 655
 656                 return -EIO;
 657         }
 658
 659         for (i = 0; i < num_pages; i++) {
 660                 u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
 661                 struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
 662                 struct vmballoon_page_size *page_size =
 663                                 &b->page_sizes[is_2m_pages];
 664
 665                 locked = vmballoon_batch_get_status(b->batch_page, i);
 666
 667                 switch (locked) {
 668                 case VMW_BALLOON_SUCCESS:
 669                         list_add(&p->lru, &page_size->pages);
 670                         b->size += size_per_page;
 671                         break;
 672                 case VMW_BALLOON_ERROR_PPN_PINNED:
 673                 case VMW_BALLOON_ERROR_PPN_INVALID:
 674                         if (page_size->n_refused_pages
 675                                         < VMW_BALLOON_MAX_REFUSED) {
 676                                 list_add(&p->lru, &page_size->refused_pages);
 677                                 page_size->n_refused_pages++;
 678                                 break;
 679                         }
 680                         /* Fallthrough */
 681                 case VMW_BALLOON_ERROR_RESET:
 682                 case VMW_BALLOON_ERROR_PPN_NOTNEEDED:
 683                         vmballoon_free_page(p, is_2m_pages);
 684                         break;
 685                 default:
 686                         /* This should never happen */
 687                         WARN_ON_ONCE(true);
 688                 }
 689         }
 690
 691         return 0;
 692 }
 693
 694 /*
 695  * Release the page allocated for the balloon. Note that we first notify
 696  * the host so it can make sure the page will be available for the guest
 697  * to use, if needed.
 698  */
 699 static int vmballoon_unlock_page(struct vmballoon *b, unsigned int num_pages,
 700                 bool is_2m_pages, unsigned int *target)
 701 {
 702         struct page *page = b->page;
 703         struct vmballoon_page_size *page_size = &b->page_sizes[false];
 704
 705         /* is_2m_pages can never happen as 2m pages support implies batching */
 706
 707         if (!vmballoon_send_unlock_page(b, page_to_pfn(page), target)) {
 708                 list_add(&page->lru, &page_size->pages);
 709                 return -EIO;
 710         }
 711
 712         /* deallocate page */
 713         vmballoon_free_page(page, false);
 714         STATS_INC(b->stats.free[false]);
 715
 716         /* update balloon size */
 717         b->size--;
 718
 719         return 0;
 720 }
 721
 722 static int vmballoon_unlock_batched_page(struct vmballoon *b,
 723                                 unsigned int num_pages, bool is_2m_pages,
 724                                 unsigned int *target)
 725 {
 726         int locked, i, ret = 0;
 727         bool hv_success;
 728         u16 size_per_page = vmballoon_page_size(is_2m_pages);
 729
 730         hv_success = vmballoon_send_batched_unlock(b, num_pages, is_2m_pages,
 731                         target);
 732         if (!hv_success)
 733                 ret = -EIO;
 734
 735         for (i = 0; i < num_pages; i++) {
 736                 u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
 737                 struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
 738                 struct vmballoon_page_size *page_size =
 739                                 &b->page_sizes[is_2m_pages];
 740
 741                 locked = vmballoon_batch_get_status(b->batch_page, i);
 742                 if (!hv_success || locked != VMW_BALLOON_SUCCESS) {
 743                         /*
 744                          * That page wasn't successfully unlocked by the
 745                          * hypervisor, re-add it to the list of pages owned by
 746                          * the balloon driver.
 747                          */
 748                         list_add(&p->lru, &page_size->pages);
 749                 } else {
 750                         /* deallocate page */
 751                         vmballoon_free_page(p, is_2m_pages);
 752                         STATS_INC(b->stats.free[is_2m_pages]);
 753
 754                         /* update balloon size */
 755                         b->size -= size_per_page;
 756                 }
 757         }
 758
 759         return ret;
 760 }
 761
 762 /*
 763  * Release pages that were allocated while attempting to inflate the
 764  * balloon but were refused by the host for one reason or another.
 765  */
 766 static void vmballoon_release_refused_pages(struct vmballoon *b,
 767                 bool is_2m_pages)
 768 {
 769         struct page *page, *next;
 770         struct vmballoon_page_size *page_size =
 771                         &b->page_sizes[is_2m_pages];
 772
 773         list_for_each_entry_safe(page, next, &page_size->refused_pages, lru) {
 774                 list_del(&page->lru);
 775                 vmballoon_free_page(page, is_2m_pages);
 776                 STATS_INC(b->stats.refused_free[is_2m_pages]);
 777         }
 778
 779         page_size->n_refused_pages = 0;
 780 }
 781
 782 static void vmballoon_add_page(struct vmballoon *b, int idx, struct page *p)
 783 {
 784         b->page = p;
 785 }
 786
 787 static void vmballoon_add_batched_page(struct vmballoon *b, int idx,
 788                                 struct page *p)
 789 {
 790         vmballoon_batch_set_pa(b->batch_page, idx,
 791                         (u64)page_to_pfn(p) << PAGE_SHIFT);
 792 }
 793
 794 /*
 795  * Inflate the balloon towards its target size. Note that we try to limit
 796  * the rate of allocation to make sure we are not choking the rest of the
 797  * system.
 798  */
 799 static void vmballoon_inflate(struct vmballoon *b)
 800 {
 801         unsigned rate;
 802         unsigned int allocations = 0;
 803         unsigned int num_pages = 0;
 804         int error = 0;
 805         gfp_t flags = VMW_PAGE_ALLOC_NOSLEEP;
 806         bool is_2m_pages;
 807
 808         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 809
 810         /*
 811          * First try NOSLEEP page allocations to inflate balloon.
 812          *
 813          * If we do not throttle nosleep allocations, we can drain all
 814          * free pages in the guest quickly (if the balloon target is high).
 815          * As a side-effect, draining free pages helps to inform (force)
 816          * the guest to start swapping if balloon target is not met yet,
 817          * which is a desired behavior. However, balloon driver can consume
 818          * all available CPU cycles if too many pages are allocated in a
 819          * second. Therefore, we throttle nosleep allocations even when
 820          * the guest is not under memory pressure. OTOH, if we have already
 821          * predicted that the guest is under memory pressure, then we
 822          * slowdown page allocations considerably.
 823          */
 824
 825         /*
 826          * Start with no sleep allocation rate which may be higher
 827          * than sleeping allocation rate.
 828          */
 829         if (b->slow_allocation_cycles) {
 830                 rate = b->rate_alloc;
 831                 is_2m_pages = false;
 832         } else {
 833                 rate = UINT_MAX;
 834                 is_2m_pages =
 835                         b->supported_page_sizes == VMW_BALLOON_NUM_PAGE_SIZES;
 836         }
 837
 838         pr_debug("%s - goal: %d, no-sleep rate: %u, sleep rate: %d\n",
 839                  __func__, b->target - b->size, rate, b->rate_alloc);
 840
 841         while (!b->reset_required &&
 842                 b->size + num_pages * vmballoon_page_size(is_2m_pages)
 843                 < b->target) {
 844                 struct page *page;
 845
 846                 if (flags == VMW_PAGE_ALLOC_NOSLEEP)
 847                         STATS_INC(b->stats.alloc[is_2m_pages]);
 848                 else
 849                         STATS_INC(b->stats.sleep_alloc);
 850
 851                 page = vmballoon_alloc_page(flags, is_2m_pages);
 852                 if (!page) {
 853                         STATS_INC(b->stats.alloc_fail[is_2m_pages]);
 854
 855                         if (is_2m_pages) {
 856                                 b->ops->lock(b, num_pages, true, &b->target);
 857
 858                                 /*
 859                                  * ignore errors from locking as we now switch
 860                                  * to 4k pages and we might get different
 861                                  * errors.
 862                                  */
 863
 864                                 num_pages = 0;
 865                                 is_2m_pages = false;
 866                                 continue;
 867                         }
 868
 869                         if (flags == VMW_PAGE_ALLOC_CANSLEEP) {
 870                                 /*
 871                                  * CANSLEEP page allocation failed, so guest
 872                                  * is under severe memory pressure. Quickly
 873                                  * decrease allocation rate.
 874                                  */
 875                                 b->rate_alloc = max(b->rate_alloc / 2,
 876                                                     VMW_BALLOON_RATE_ALLOC_MIN);
 877                                 STATS_INC(b->stats.sleep_alloc_fail);
 878                                 break;
 879                         }
 880
 881                         /*
 882                          * NOSLEEP page allocation failed, so the guest is
 883                          * under memory pressure. Let us slow down page
 884                          * allocations for next few cycles so that the guest
 885                          * gets out of memory pressure. Also, if we already
 886                          * allocated b->rate_alloc pages, let's pause,
 887                          * otherwise switch to sleeping allocations.
 888                          */
 889                         b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
 890
 891                         if (allocations >= b->rate_alloc)
 892                                 break;
 893
 894                         flags = VMW_PAGE_ALLOC_CANSLEEP;
 895                         /* Lower rate for sleeping allocations. */
 896                         rate = b->rate_alloc;
 897                         continue;
 898                 }
 899
 900                 b->ops->add_page(b, num_pages++, page);
 901                 if (num_pages == b->batch_max_pages) {
 902                         error = b->ops->lock(b, num_pages, is_2m_pages,
 903                                         &b->target);
 904                         num_pages = 0;
 905                         if (error)
 906                                 break;
 907                 }
 908
 909                 cond_resched();
 910
 911                 if (allocations >= rate) {
 912                         /* We allocated enough pages, let's take a break. */
 913                         break;
 914                 }
 915         }
 916
 917         if (num_pages > 0)
 918                 b->ops->lock(b, num_pages, is_2m_pages, &b->target);
 919
 920         /*
 921          * We reached our goal without failures so try increasing
 922          * allocation rate.
 923          */
 924         if (error == 0 && allocations >= b->rate_alloc) {
 925                 unsigned int mult = allocations / b->rate_alloc;
 926
 927                 b->rate_alloc =
 928                         min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
 929                             VMW_BALLOON_RATE_ALLOC_MAX);
 930         }
 931
 932         vmballoon_release_refused_pages(b, true);
 933         vmballoon_release_refused_pages(b, false);
 934 }
 935
 936 /*
 937  * Decrease the size of the balloon allowing guest to use more memory.
 938  */
 939 static void vmballoon_deflate(struct vmballoon *b)
 940 {
 941         unsigned is_2m_pages;
 942
 943         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 944
 945         /* free pages to reach target */
 946         for (is_2m_pages = 0; is_2m_pages < b->supported_page_sizes;
 947                         is_2m_pages++) {
 948                 struct page *page, *next;
 949                 unsigned int num_pages = 0;
 950                 struct vmballoon_page_size *page_size =
 951                                 &b->page_sizes[is_2m_pages];
 952
 953                 list_for_each_entry_safe(page, next, &page_size->pages, lru) {
 954                         if (b->reset_required ||
 955                                 (b->target > 0 &&
 956                                         b->size - num_pages
 957                                         * vmballoon_page_size(is_2m_pages)
 958                                 < b->target + vmballoon_page_size(true)))
 959                                 break;
 960
 961                         list_del(&page->lru);
 962                         b->ops->add_page(b, num_pages++, page);
 963
 964                         if (num_pages == b->batch_max_pages) {
 965                                 int error;
 966
 967                                 error = b->ops->unlock(b, num_pages,
 968                                                 is_2m_pages, &b->target);
 969                                 num_pages = 0;
 970                                 if (error)
 971                                         return;
 972                         }
 973
 974                         cond_resched();
 975                 }
 976
 977                 if (num_pages > 0)
 978                         b->ops->unlock(b, num_pages, is_2m_pages, &b->target);
 979         }
 980 }
 981
 982 static const struct vmballoon_ops vmballoon_basic_ops = {
 983         .add_page = vmballoon_add_page,
 984         .lock = vmballoon_lock_page,
 985         .unlock = vmballoon_unlock_page
 986 };
 987
 988 static const struct vmballoon_ops vmballoon_batched_ops = {
 989         .add_page = vmballoon_add_batched_page,
 990         .lock = vmballoon_lock_batched_page,
 991         .unlock = vmballoon_unlock_batched_page
 992 };
 993
 994 static bool vmballoon_init_batching(struct vmballoon *b)
 995 {
 996         struct page *page;
 997
 998         page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 999         if (!page)
1000                 return false;
1001
1002         b->batch_page = page_address(page);
1003         return true;
1004 }
1005
1006 /*
1007  * Receive notification and resize balloon
1008  */
1009 static void vmballoon_doorbell(void *client_data)
1010 {
1011         struct vmballoon *b = client_data;
1012
1013         STATS_INC(b->stats.doorbell);
1014
1015         mod_delayed_work(system_freezable_wq, &b->dwork, 0);
1016 }
1017
1018 /*
1019  * Clean up vmci doorbell
1020  */
1021 static void vmballoon_vmci_cleanup(struct vmballoon *b)
1022 {
1023         int error;
1024
1025         VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET, VMCI_INVALID_ID,
1026                         VMCI_INVALID_ID, error);
1027         STATS_INC(b->stats.doorbell_unset);
1028
1029         if (!vmci_handle_is_invalid(b->vmci_doorbell)) {
1030                 vmci_doorbell_destroy(b->vmci_doorbell);
1031                 b->vmci_doorbell = VMCI_INVALID_HANDLE;
1032         }
1033 }
1034
1035 /*
1036  * Initialize vmci doorbell, to get notified as soon as balloon changes
1037  */
1038 static int vmballoon_vmci_init(struct vmballoon *b)
1039 {
1040         unsigned long error, dummy;
1041
1042         if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) == 0)
1043                 return 0;
1044
1045         error = vmci_doorbell_create(&b->vmci_doorbell, VMCI_FLAG_DELAYED_CB,
1046                                      VMCI_PRIVILEGE_FLAG_RESTRICTED,
1047                                      vmballoon_doorbell, b);
1048
1049         if (error != VMCI_SUCCESS)
1050                 goto fail;
1051
1052         error = VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET, b->vmci_doorbell.context,
1053                                    b->vmci_doorbell.resource, dummy);
1054
1055         STATS_INC(b->stats.doorbell_set);
1056
1057         if (error != VMW_BALLOON_SUCCESS)
1058                 goto fail;
1059
1060         return 0;
1061 fail:
1062         vmballoon_vmci_cleanup(b);
1063         return -EIO;
1064 }
1065
1066 /*
1067  * Perform standard reset sequence by popping the balloon (in case it
1068  * is not  empty) and then restarting protocol. This operation normally
1069  * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
1070  */
1071 static void vmballoon_reset(struct vmballoon *b)
1072 {
1073         int error;
1074
1075         vmballoon_vmci_cleanup(b);
1076
1077         /* free all pages, skipping monitor unlock */
1078         vmballoon_pop(b);
1079
1080         if (!vmballoon_send_start(b, VMW_BALLOON_CAPABILITIES))
1081                 return;
1082
1083         if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) {
1084                 b->ops = &vmballoon_batched_ops;
1085                 b->batch_max_pages = VMW_BALLOON_BATCH_MAX_PAGES;
1086                 if (!vmballoon_init_batching(b)) {
1087                         /*
1088                          * We failed to initialize batching, inform the monitor
1089                          * about it by sending a null capability.
1090                          *
1091                          * The guest will retry in one second.
1092                          */
1093                         vmballoon_send_start(b, 0);
1094                         return;
1095                 }
1096         } else if ((b->capabilities & VMW_BALLOON_BASIC_CMDS) != 0) {
1097                 b->ops = &vmballoon_basic_ops;
1098                 b->batch_max_pages = 1;
1099         }
1100
1101         b->reset_required = false;
1102
1103         error = vmballoon_vmci_init(b);
1104         if (error)
1105                 pr_err("failed to initialize vmci doorbell\n");
1106
1107         if (!vmballoon_send_guest_id(b))
1108                 pr_err("failed to send guest ID to the host\n");
1109 }
1110
1111 /*
1112  * Balloon work function: reset protocol, if needed, get the new size and
1113  * adjust balloon as needed. Repeat in 1 sec.
1114  */
1115 static void vmballoon_work(struct work_struct *work)
1116 {
1117         struct delayed_work *dwork = to_delayed_work(work);
1118         struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
1119         unsigned int target;
1120
1121         STATS_INC(b->stats.timer);
1122
1123         if (b->reset_required)
1124                 vmballoon_reset(b);
1125
1126         if (b->slow_allocation_cycles > 0)
1127                 b->slow_allocation_cycles--;
1128
1129         if (!b->reset_required && vmballoon_send_get_target(b, &target)) {
1130                 /* update target, adjust size */
1131                 b->target = target;
1132
1133                 if (b->size < target)
1134                         vmballoon_inflate(b);
1135                 else if (target == 0 ||
1136                                 b->size > target + vmballoon_page_size(true))
1137                         vmballoon_deflate(b);
1138         }
1139
1140         /*
1141          * We are using a freezable workqueue so that balloon operations are
1142          * stopped while the system transitions to/from sleep/hibernation.
1143          */
1144         queue_delayed_work(system_freezable_wq,
1145                            dwork, round_jiffies_relative(HZ));
1146 }
1147
1148 /*
1149  * DEBUGFS Interface
1150  */
1151 #ifdef CONFIG_DEBUG_FS
1152
1153 static int vmballoon_debug_show(struct seq_file *f, void *offset)
1154 {
1155         struct vmballoon *b = f->private;
1156         struct vmballoon_stats *stats = &b->stats;
1157
1158         /* format capabilities info */
1159         seq_printf(f,
1160                    "balloon capabilities:   %#4x\n"
1161                    "used capabilities:      %#4lx\n"
1162                    "is resetting:           %c\n",
1163                    VMW_BALLOON_CAPABILITIES, b->capabilities,
1164                    b->reset_required ? 'y' : 'n');
1165
1166         /* format size info */
1167         seq_printf(f,
1168                    "target:             %8d pages\n"
1169                    "current:            %8d pages\n",
1170                    b->target, b->size);
1171
1172         /* format rate info */
1173         seq_printf(f,
1174                    "rateSleepAlloc:     %8d pages/sec\n",
1175                    b->rate_alloc);
1176
1177         seq_printf(f,
1178                    "\n"
1179                    "timer:              %8u\n"
1180                    "doorbell:           %8u\n"
1181                    "start:              %8u (%4u failed)\n"
1182                    "guestType:          %8u (%4u failed)\n"
1183                    "2m-lock:            %8u (%4u failed)\n"
1184                    "lock:               %8u (%4u failed)\n"
1185                    "2m-unlock:          %8u (%4u failed)\n"
1186                    "unlock:             %8u (%4u failed)\n"
1187                    "target:             %8u (%4u failed)\n"
1188                    "prim2mAlloc:        %8u (%4u failed)\n"
1189                    "primNoSleepAlloc:   %8u (%4u failed)\n"
1190                    "primCanSleepAlloc:  %8u (%4u failed)\n"
1191                    "prim2mFree:         %8u\n"
1192                    "primFree:           %8u\n"
1193                    "err2mAlloc:         %8u\n"
1194                    "errAlloc:           %8u\n"
1195                    "err2mFree:          %8u\n"
1196                    "errFree:            %8u\n"
1197                    "doorbellSet:        %8u\n"
1198                    "doorbellUnset:      %8u\n",
1199                    stats->timer,
1200                    stats->doorbell,
1201                    stats->start, stats->start_fail,
1202                    stats->guest_type, stats->guest_type_fail,
1203                    stats->lock[true],  stats->lock_fail[true],
1204                    stats->lock[false],  stats->lock_fail[false],
1205                    stats->unlock[true], stats->unlock_fail[true],
1206                    stats->unlock[false], stats->unlock_fail[false],
1207                    stats->target, stats->target_fail,
1208                    stats->alloc[true], stats->alloc_fail[true],
1209                    stats->alloc[false], stats->alloc_fail[false],
1210                    stats->sleep_alloc, stats->sleep_alloc_fail,
1211                    stats->free[true],
1212                    stats->free[false],
1213                    stats->refused_alloc[true], stats->refused_alloc[false],
1214                    stats->refused_free[true], stats->refused_free[false],
1215                    stats->doorbell_set, stats->doorbell_unset);
1216
1217         return 0;
1218 }
1219
1220 static int vmballoon_debug_open(struct inode *inode, struct file *file)
1221 {
1222         return single_open(file, vmballoon_debug_show, inode->i_private);
1223 }
1224
1225 static const struct file_operations vmballoon_debug_fops = {
1226         .owner          = THIS_MODULE,
1227         .open           = vmballoon_debug_open,
1228         .read           = seq_read,
1229         .llseek         = seq_lseek,
1230         .release        = single_release,
1231 };
1232
1233 static int __init vmballoon_debugfs_init(struct vmballoon *b)
1234 {
1235         int error;
1236
1237         b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
1238                                            &vmballoon_debug_fops);
1239         if (IS_ERR(b->dbg_entry)) {
1240                 error = PTR_ERR(b->dbg_entry);
1241                 pr_err("failed to create debugfs entry, error: %d\n", error);
1242                 return error;
1243         }
1244
1245         return 0;
1246 }
1247
1248 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
1249 {
1250         debugfs_remove(b->dbg_entry);
1251 }
1252
1253 #else
1254
1255 static inline int vmballoon_debugfs_init(struct vmballoon *b)
1256 {
1257         return 0;
1258 }
1259
1260 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
1261 {
1262 }
1263
1264 #endif  /* CONFIG_DEBUG_FS */
1265
1266 static int __init vmballoon_init(void)
1267 {
1268         int error;
1269         unsigned is_2m_pages;
1270         /*
1271          * Check if we are running on VMware's hypervisor and bail out
1272          * if we are not.
1273          */
1274         if (x86_hyper_type != X86_HYPER_VMWARE)
1275                 return -ENODEV;
1276
1277         for (is_2m_pages = 0; is_2m_pages < VMW_BALLOON_NUM_PAGE_SIZES;
1278                         is_2m_pages++) {
1279                 INIT_LIST_HEAD(&balloon.page_sizes[is_2m_pages].pages);
1280                 INIT_LIST_HEAD(&balloon.page_sizes[is_2m_pages].refused_pages);
1281         }
1282
1283         /* initialize rates */
1284         balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
1285
1286         INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
1287
1288         error = vmballoon_debugfs_init(&balloon);
1289         if (error)
1290                 return error;
1291
1292         balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
1293         balloon.batch_page = NULL;
1294         balloon.page = NULL;
1295         balloon.reset_required = true;
1296
1297         queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
1298
1299         return 0;
1300 }
1301
1302 /*
1303  * Using late_initcall() instead of module_init() allows the balloon to use the
1304  * VMCI doorbell even when the balloon is built into the kernel. Otherwise the
1305  * VMCI is probed only after the balloon is initialized. If the balloon is used
1306  * as a module, late_initcall() is equivalent to module_init().
1307  */
1308 late_initcall(vmballoon_init);
1309
1310 static void __exit vmballoon_exit(void)
1311 {
1312         vmballoon_vmci_cleanup(&balloon);
1313         cancel_delayed_work_sync(&balloon.dwork);
1314
1315         vmballoon_debugfs_exit(&balloon);
1316
1317         /*
1318          * Deallocate all reserved memory, and reset connection with monitor.
1319          * Reset connection before deallocating memory to avoid potential for
1320          * additional spurious resets from guest touching deallocated pages.
1321          */
1322         vmballoon_send_start(&balloon, 0);
1323         vmballoon_pop(&balloon);
1324 }
1325 module_exit(vmballoon_exit);