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