drivers/misc/vmw_balloon.c

   1 /*
   2  * VMware Balloon driver.
   3  *
   4  * Copyright (C) 2000-2010, 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/sched.h>
  41 #include <linux/module.h>
  42 #include <linux/workqueue.h>
  43 #include <linux/debugfs.h>
  44 #include <linux/seq_file.h>
  45 #include <asm/hypervisor.h>
  46
  47 MODULE_AUTHOR("VMware, Inc.");
  48 MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
  49 MODULE_VERSION("1.3.0.0-k");
  50 MODULE_ALIAS("dmi:*:svnVMware*:*");
  51 MODULE_ALIAS("vmware_vmmemctl");
  52 MODULE_LICENSE("GPL");
  53
  54 /*
  55  * Various constants controlling rate of inflaint/deflating balloon,
  56  * measured in pages.
  57  */
  58
  59 /*
  60  * Rate of allocating memory when there is no memory pressure
  61  * (driver performs non-sleeping allocations).
  62  */
  63 #define VMW_BALLOON_NOSLEEP_ALLOC_MAX   16384U
  64
  65 /*
  66  * Rates of memory allocaton when guest experiences memory pressure
  67  * (driver performs sleeping allocations).
  68  */
  69 #define VMW_BALLOON_RATE_ALLOC_MIN      512U
  70 #define VMW_BALLOON_RATE_ALLOC_MAX      2048U
  71 #define VMW_BALLOON_RATE_ALLOC_INC      16U
  72
  73 /*
  74  * Rates for releasing pages while deflating balloon.
  75  */
  76 #define VMW_BALLOON_RATE_FREE_MIN       512U
  77 #define VMW_BALLOON_RATE_FREE_MAX       16384U
  78 #define VMW_BALLOON_RATE_FREE_INC       16U
  79
  80 /*
  81  * When guest is under memory pressure, use a reduced page allocation
  82  * rate for next several cycles.
  83  */
  84 #define VMW_BALLOON_SLOW_CYCLES         4
  85
  86 /*
  87  * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't
  88  * allow wait (__GFP_WAIT) for NOSLEEP page allocations. Use
  89  * __GFP_NOWARN, to suppress page allocation failure warnings.
  90  */
  91 #define VMW_PAGE_ALLOC_NOSLEEP          (__GFP_HIGHMEM|__GFP_NOWARN)
  92
  93 /*
  94  * Use GFP_HIGHUSER when executing in a separate kernel thread
  95  * context and allocation can sleep.  This is less stressful to
  96  * the guest memory system, since it allows the thread to block
  97  * while memory is reclaimed, and won't take pages from emergency
  98  * low-memory pools.
  99  */
 100 #define VMW_PAGE_ALLOC_CANSLEEP         (GFP_HIGHUSER)
 101
 102 /* Maximum number of page allocations without yielding processor */
 103 #define VMW_BALLOON_YIELD_THRESHOLD     1024
 104
 105 /* Maximum number of refused pages we accumulate during inflation cycle */
 106 #define VMW_BALLOON_MAX_REFUSED         16
 107
 108 /*
 109  * Hypervisor communication port definitions.
 110  */
 111 #define VMW_BALLOON_HV_PORT             0x5670
 112 #define VMW_BALLOON_HV_MAGIC            0x456c6d6f
 113 #define VMW_BALLOON_GUEST_ID            1       /* Linux */
 114
 115 enum vmwballoon_capabilities {
 116         /*
 117          * Bit 0 is reserved and not associated to any capability.
 118          */
 119         VMW_BALLOON_BASIC_CMDS          = (1 << 1),
 120         VMW_BALLOON_BATCHED_CMDS        = (1 << 2)
 121 };
 122
 123 #define VMW_BALLOON_CAPABILITIES        (VMW_BALLOON_BASIC_CMDS)
 124
 125 #define VMW_BALLOON_CMD_START           0
 126 #define VMW_BALLOON_CMD_GET_TARGET      1
 127 #define VMW_BALLOON_CMD_LOCK            2
 128 #define VMW_BALLOON_CMD_UNLOCK          3
 129 #define VMW_BALLOON_CMD_GUEST_ID        4
 130
 131 /* error codes */
 132 #define VMW_BALLOON_SUCCESS                     0
 133 #define VMW_BALLOON_FAILURE                     -1
 134 #define VMW_BALLOON_ERROR_CMD_INVALID           1
 135 #define VMW_BALLOON_ERROR_PPN_INVALID           2
 136 #define VMW_BALLOON_ERROR_PPN_LOCKED            3
 137 #define VMW_BALLOON_ERROR_PPN_UNLOCKED          4
 138 #define VMW_BALLOON_ERROR_PPN_PINNED            5
 139 #define VMW_BALLOON_ERROR_PPN_NOTNEEDED         6
 140 #define VMW_BALLOON_ERROR_RESET                 7
 141 #define VMW_BALLOON_ERROR_BUSY                  8
 142
 143 #define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES   (0x03000000)
 144
 145 #define VMWARE_BALLOON_CMD(cmd, data, result)                   \
 146 ({                                                              \
 147         unsigned long __status, __dummy1, __dummy2;             \
 148         __asm__ __volatile__ ("inl %%dx" :                      \
 149                 "=a"(__status),                                 \
 150                 "=c"(__dummy1),                                 \
 151                 "=d"(__dummy2),                                 \
 152                 "=b"(result) :                                  \
 153                 "0"(VMW_BALLOON_HV_MAGIC),                      \
 154                 "1"(VMW_BALLOON_CMD_##cmd),                     \
 155                 "2"(VMW_BALLOON_HV_PORT),                       \
 156                 "3"(data) :                                     \
 157                 "memory");                                      \
 158         if (VMW_BALLOON_CMD_##cmd == VMW_BALLOON_CMD_START)     \
 159                 result = __dummy1;                              \
 160         result &= -1UL;                                         \
 161         __status & -1UL;                                        \
 162 })
 163
 164 #ifdef CONFIG_DEBUG_FS
 165 struct vmballoon_stats {
 166         unsigned int timer;
 167
 168         /* allocation statistics */
 169         unsigned int alloc;
 170         unsigned int alloc_fail;
 171         unsigned int sleep_alloc;
 172         unsigned int sleep_alloc_fail;
 173         unsigned int refused_alloc;
 174         unsigned int refused_free;
 175         unsigned int free;
 176
 177         /* monitor operations */
 178         unsigned int lock;
 179         unsigned int lock_fail;
 180         unsigned int unlock;
 181         unsigned int unlock_fail;
 182         unsigned int target;
 183         unsigned int target_fail;
 184         unsigned int start;
 185         unsigned int start_fail;
 186         unsigned int guest_type;
 187         unsigned int guest_type_fail;
 188 };
 189
 190 #define STATS_INC(stat) (stat)++
 191 #else
 192 #define STATS_INC(stat)
 193 #endif
 194
 195 struct vmballoon {
 196
 197         /* list of reserved physical pages */
 198         struct list_head pages;
 199
 200         /* transient list of non-balloonable pages */
 201         struct list_head refused_pages;
 202         unsigned int n_refused_pages;
 203
 204         /* balloon size in pages */
 205         unsigned int size;
 206         unsigned int target;
 207
 208         /* reset flag */
 209         bool reset_required;
 210
 211         /* adjustment rates (pages per second) */
 212         unsigned int rate_alloc;
 213         unsigned int rate_free;
 214
 215         /* slowdown page allocations for next few cycles */
 216         unsigned int slow_allocation_cycles;
 217
 218 #ifdef CONFIG_DEBUG_FS
 219         /* statistics */
 220         struct vmballoon_stats stats;
 221
 222         /* debugfs file exporting statistics */
 223         struct dentry *dbg_entry;
 224 #endif
 225
 226         struct sysinfo sysinfo;
 227
 228         struct delayed_work dwork;
 229 };
 230
 231 static struct vmballoon balloon;
 232
 233 /*
 234  * Send "start" command to the host, communicating supported version
 235  * of the protocol.
 236  */
 237 static bool vmballoon_send_start(struct vmballoon *b)
 238 {
 239         unsigned long status, capabilities;
 240
 241         STATS_INC(b->stats.start);
 242
 243         status = VMWARE_BALLOON_CMD(START, VMW_BALLOON_CAPABILITIES,
 244                                 capabilities);
 245         if (status == VMW_BALLOON_SUCCESS)
 246                 return true;
 247
 248         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 249         STATS_INC(b->stats.start_fail);
 250         return false;
 251 }
 252
 253 static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
 254 {
 255         switch (status) {
 256         case VMW_BALLOON_SUCCESS:
 257                 return true;
 258
 259         case VMW_BALLOON_ERROR_RESET:
 260                 b->reset_required = true;
 261                 /* fall through */
 262
 263         default:
 264                 return false;
 265         }
 266 }
 267
 268 /*
 269  * Communicate guest type to the host so that it can adjust ballooning
 270  * algorithm to the one most appropriate for the guest. This command
 271  * is normally issued after sending "start" command and is part of
 272  * standard reset sequence.
 273  */
 274 static bool vmballoon_send_guest_id(struct vmballoon *b)
 275 {
 276         unsigned long status, dummy;
 277
 278         status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy);
 279
 280         STATS_INC(b->stats.guest_type);
 281
 282         if (vmballoon_check_status(b, status))
 283                 return true;
 284
 285         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 286         STATS_INC(b->stats.guest_type_fail);
 287         return false;
 288 }
 289
 290 /*
 291  * Retrieve desired balloon size from the host.
 292  */
 293 static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
 294 {
 295         unsigned long status;
 296         unsigned long target;
 297         unsigned long limit;
 298         u32 limit32;
 299
 300         /*
 301          * si_meminfo() is cheap. Moreover, we want to provide dynamic
 302          * max balloon size later. So let us call si_meminfo() every
 303          * iteration.
 304          */
 305         si_meminfo(&b->sysinfo);
 306         limit = b->sysinfo.totalram;
 307
 308         /* Ensure limit fits in 32-bits */
 309         limit32 = (u32)limit;
 310         if (limit != limit32)
 311                 return false;
 312
 313         /* update stats */
 314         STATS_INC(b->stats.target);
 315
 316         status = VMWARE_BALLOON_CMD(GET_TARGET, limit, target);
 317         if (vmballoon_check_status(b, status)) {
 318                 *new_target = target;
 319                 return true;
 320         }
 321
 322         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 323         STATS_INC(b->stats.target_fail);
 324         return false;
 325 }
 326
 327 /*
 328  * Notify the host about allocated page so that host can use it without
 329  * fear that guest will need it. Host may reject some pages, we need to
 330  * check the return value and maybe submit a different page.
 331  */
 332 static int vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
 333                                      unsigned int *hv_status)
 334 {
 335         unsigned long status, dummy;
 336         u32 pfn32;
 337
 338         pfn32 = (u32)pfn;
 339         if (pfn32 != pfn)
 340                 return -1;
 341
 342         STATS_INC(b->stats.lock);
 343
 344         *hv_status = status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy);
 345         if (vmballoon_check_status(b, status))
 346                 return 0;
 347
 348         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 349         STATS_INC(b->stats.lock_fail);
 350         return 1;
 351 }
 352
 353 /*
 354  * Notify the host that guest intends to release given page back into
 355  * the pool of available (to the guest) pages.
 356  */
 357 static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn)
 358 {
 359         unsigned long status, dummy;
 360         u32 pfn32;
 361
 362         pfn32 = (u32)pfn;
 363         if (pfn32 != pfn)
 364                 return false;
 365
 366         STATS_INC(b->stats.unlock);
 367
 368         status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy);
 369         if (vmballoon_check_status(b, status))
 370                 return true;
 371
 372         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 373         STATS_INC(b->stats.unlock_fail);
 374         return false;
 375 }
 376
 377 /*
 378  * Quickly release all pages allocated for the balloon. This function is
 379  * called when host decides to "reset" balloon for one reason or another.
 380  * Unlike normal "deflate" we do not (shall not) notify host of the pages
 381  * being released.
 382  */
 383 static void vmballoon_pop(struct vmballoon *b)
 384 {
 385         struct page *page, *next;
 386         unsigned int count = 0;
 387
 388         list_for_each_entry_safe(page, next, &b->pages, lru) {
 389                 list_del(&page->lru);
 390                 __free_page(page);
 391                 STATS_INC(b->stats.free);
 392                 b->size--;
 393
 394                 if (++count >= b->rate_free) {
 395                         count = 0;
 396                         cond_resched();
 397                 }
 398         }
 399 }
 400
 401 /*
 402  * Perform standard reset sequence by popping the balloon (in case it
 403  * is not  empty) and then restarting protocol. This operation normally
 404  * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
 405  */
 406 static void vmballoon_reset(struct vmballoon *b)
 407 {
 408         /* free all pages, skipping monitor unlock */
 409         vmballoon_pop(b);
 410
 411         if (vmballoon_send_start(b)) {
 412                 b->reset_required = false;
 413                 if (!vmballoon_send_guest_id(b))
 414                         pr_err("failed to send guest ID to the host\n");
 415         }
 416 }
 417
 418 /*
 419  * Notify the host of a ballooned page. If host rejects the page put it on the
 420  * refuse list, those refused page are then released at the end of the
 421  * inflation cycle.
 422  */
 423 static int vmballoon_lock_page(struct vmballoon *b, struct page *page)
 424 {
 425         int locked, hv_status;
 426
 427         locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status);
 428         if (locked > 0) {
 429                 STATS_INC(b->stats.refused_alloc);
 430
 431                 if (hv_status == VMW_BALLOON_ERROR_RESET ||
 432                                 hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED) {
 433                         __free_page(page);
 434                         return -EIO;
 435                 }
 436
 437                 /*
 438                  * Place page on the list of non-balloonable pages
 439                  * and retry allocation, unless we already accumulated
 440                  * too many of them, in which case take a breather.
 441                  */
 442                 if (b->n_refused_pages < VMW_BALLOON_MAX_REFUSED) {
 443                         b->n_refused_pages++;
 444                         list_add(&page->lru, &b->refused_pages);
 445                 } else {
 446                         __free_page(page);
 447                 }
 448                 return -EIO;
 449         }
 450
 451         /* track allocated page */
 452         list_add(&page->lru, &b->pages);
 453
 454         /* update balloon size */
 455         b->size++;
 456
 457         return 0;
 458 }
 459
 460 /*
 461  * Release the page allocated for the balloon. Note that we first notify
 462  * the host so it can make sure the page will be available for the guest
 463  * to use, if needed.
 464  */
 465 static int vmballoon_release_page(struct vmballoon *b, struct page *page)
 466 {
 467         if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
 468                 return -EIO;
 469
 470         list_del(&page->lru);
 471
 472         /* deallocate page */
 473         __free_page(page);
 474         STATS_INC(b->stats.free);
 475
 476         /* update balloon size */
 477         b->size--;
 478
 479         return 0;
 480 }
 481
 482 /*
 483  * Release pages that were allocated while attempting to inflate the
 484  * balloon but were refused by the host for one reason or another.
 485  */
 486 static void vmballoon_release_refused_pages(struct vmballoon *b)
 487 {
 488         struct page *page, *next;
 489
 490         list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
 491                 list_del(&page->lru);
 492                 __free_page(page);
 493                 STATS_INC(b->stats.refused_free);
 494         }
 495
 496         b->n_refused_pages = 0;
 497 }
 498
 499 /*
 500  * Inflate the balloon towards its target size. Note that we try to limit
 501  * the rate of allocation to make sure we are not choking the rest of the
 502  * system.
 503  */
 504 static void vmballoon_inflate(struct vmballoon *b)
 505 {
 506         unsigned int goal;
 507         unsigned int rate;
 508         unsigned int i;
 509         unsigned int allocations = 0;
 510         int error = 0;
 511         gfp_t flags = VMW_PAGE_ALLOC_NOSLEEP;
 512
 513         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 514
 515         /*
 516          * First try NOSLEEP page allocations to inflate balloon.
 517          *
 518          * If we do not throttle nosleep allocations, we can drain all
 519          * free pages in the guest quickly (if the balloon target is high).
 520          * As a side-effect, draining free pages helps to inform (force)
 521          * the guest to start swapping if balloon target is not met yet,
 522          * which is a desired behavior. However, balloon driver can consume
 523          * all available CPU cycles if too many pages are allocated in a
 524          * second. Therefore, we throttle nosleep allocations even when
 525          * the guest is not under memory pressure. OTOH, if we have already
 526          * predicted that the guest is under memory pressure, then we
 527          * slowdown page allocations considerably.
 528          */
 529
 530         goal = b->target - b->size;
 531         /*
 532          * Start with no sleep allocation rate which may be higher
 533          * than sleeping allocation rate.
 534          */
 535         rate = b->slow_allocation_cycles ?
 536                         b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
 537
 538         pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
 539                  __func__, goal, rate, b->rate_alloc);
 540
 541         for (i = 0; i < goal; i++) {
 542                 struct page *page;
 543
 544                 if (flags == VMW_PAGE_ALLOC_NOSLEEP)
 545                         STATS_INC(b->stats.alloc);
 546                 else
 547                         STATS_INC(b->stats.sleep_alloc);
 548
 549                 page = alloc_page(flags);
 550                 if (!page) {
 551                         if (flags == VMW_PAGE_ALLOC_CANSLEEP) {
 552                                 /*
 553                                  * CANSLEEP page allocation failed, so guest
 554                                  * is under severe memory pressure. Quickly
 555                                  * decrease allocation rate.
 556                                  */
 557                                 b->rate_alloc = max(b->rate_alloc / 2,
 558                                                     VMW_BALLOON_RATE_ALLOC_MIN);
 559                                 STATS_INC(b->stats.sleep_alloc_fail);
 560                                 break;
 561                         }
 562                         STATS_INC(b->stats.alloc_fail);
 563
 564                         /*
 565                          * NOSLEEP page allocation failed, so the guest is
 566                          * under memory pressure. Let us slow down page
 567                          * allocations for next few cycles so that the guest
 568                          * gets out of memory pressure. Also, if we already
 569                          * allocated b->rate_alloc pages, let's pause,
 570                          * otherwise switch to sleeping allocations.
 571                          */
 572                         b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
 573
 574                         if (i >= b->rate_alloc)
 575                                 break;
 576
 577                         flags = VMW_PAGE_ALLOC_CANSLEEP;
 578                         /* Lower rate for sleeping allocations. */
 579                         rate = b->rate_alloc;
 580                         continue;
 581                 }
 582
 583                 error = vmballoon_lock_page(b, page);
 584                 if (error)
 585                         break;
 586
 587                 if (++allocations > VMW_BALLOON_YIELD_THRESHOLD) {
 588                         cond_resched();
 589                         allocations = 0;
 590                 }
 591
 592                 if (i >= rate) {
 593                         /* We allocated enough pages, let's take a break. */
 594                         break;
 595                 }
 596         }
 597
 598         /*
 599          * We reached our goal without failures so try increasing
 600          * allocation rate.
 601          */
 602         if (error == 0 && i >= b->rate_alloc) {
 603                 unsigned int mult = i / b->rate_alloc;
 604
 605                 b->rate_alloc =
 606                         min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
 607                             VMW_BALLOON_RATE_ALLOC_MAX);
 608         }
 609
 610         vmballoon_release_refused_pages(b);
 611 }
 612
 613 /*
 614  * Decrease the size of the balloon allowing guest to use more memory.
 615  */
 616 static void vmballoon_deflate(struct vmballoon *b)
 617 {
 618         struct page *page, *next;
 619         unsigned int i = 0;
 620         unsigned int goal;
 621         int error;
 622
 623         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 624
 625         /* limit deallocation rate */
 626         goal = min(b->size - b->target, b->rate_free);
 627
 628         pr_debug("%s - goal: %d, rate: %d\n", __func__, goal, b->rate_free);
 629
 630         /* free pages to reach target */
 631         list_for_each_entry_safe(page, next, &b->pages, lru) {
 632                 error = vmballoon_release_page(b, page);
 633                 if (error) {
 634                         /* quickly decrease rate in case of error */
 635                         b->rate_free = max(b->rate_free / 2,
 636                                            VMW_BALLOON_RATE_FREE_MIN);
 637                         return;
 638                 }
 639
 640                 if (++i >= goal)
 641                         break;
 642         }
 643
 644         /* slowly increase rate if there were no errors */
 645         b->rate_free = min(b->rate_free + VMW_BALLOON_RATE_FREE_INC,
 646                            VMW_BALLOON_RATE_FREE_MAX);
 647 }
 648
 649 /*
 650  * Balloon work function: reset protocol, if needed, get the new size and
 651  * adjust balloon as needed. Repeat in 1 sec.
 652  */
 653 static void vmballoon_work(struct work_struct *work)
 654 {
 655         struct delayed_work *dwork = to_delayed_work(work);
 656         struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
 657         unsigned int target;
 658
 659         STATS_INC(b->stats.timer);
 660
 661         if (b->reset_required)
 662                 vmballoon_reset(b);
 663
 664         if (b->slow_allocation_cycles > 0)
 665                 b->slow_allocation_cycles--;
 666
 667         if (vmballoon_send_get_target(b, &target)) {
 668                 /* update target, adjust size */
 669                 b->target = target;
 670
 671                 if (b->size < target)
 672                         vmballoon_inflate(b);
 673                 else if (b->size > target)
 674                         vmballoon_deflate(b);
 675         }
 676
 677         /*
 678          * We are using a freezable workqueue so that balloon operations are
 679          * stopped while the system transitions to/from sleep/hibernation.
 680          */
 681         queue_delayed_work(system_freezable_wq,
 682                            dwork, round_jiffies_relative(HZ));
 683 }
 684
 685 /*
 686  * DEBUGFS Interface
 687  */
 688 #ifdef CONFIG_DEBUG_FS
 689
 690 static int vmballoon_debug_show(struct seq_file *f, void *offset)
 691 {
 692         struct vmballoon *b = f->private;
 693         struct vmballoon_stats *stats = &b->stats;
 694
 695         /* format size info */
 696         seq_printf(f,
 697                    "target:             %8d pages\n"
 698                    "current:            %8d pages\n",
 699                    b->target, b->size);
 700
 701         /* format rate info */
 702         seq_printf(f,
 703                    "rateNoSleepAlloc:   %8d pages/sec\n"
 704                    "rateSleepAlloc:     %8d pages/sec\n"
 705                    "rateFree:           %8d pages/sec\n",
 706                    VMW_BALLOON_NOSLEEP_ALLOC_MAX,
 707                    b->rate_alloc, b->rate_free);
 708
 709         seq_printf(f,
 710                    "\n"
 711                    "timer:              %8u\n"
 712                    "start:              %8u (%4u failed)\n"
 713                    "guestType:          %8u (%4u failed)\n"
 714                    "lock:               %8u (%4u failed)\n"
 715                    "unlock:             %8u (%4u failed)\n"
 716                    "target:             %8u (%4u failed)\n"
 717                    "primNoSleepAlloc:   %8u (%4u failed)\n"
 718                    "primCanSleepAlloc:  %8u (%4u failed)\n"
 719                    "primFree:           %8u\n"
 720                    "errAlloc:           %8u\n"
 721                    "errFree:            %8u\n",
 722                    stats->timer,
 723                    stats->start, stats->start_fail,
 724                    stats->guest_type, stats->guest_type_fail,
 725                    stats->lock,  stats->lock_fail,
 726                    stats->unlock, stats->unlock_fail,
 727                    stats->target, stats->target_fail,
 728                    stats->alloc, stats->alloc_fail,
 729                    stats->sleep_alloc, stats->sleep_alloc_fail,
 730                    stats->free,
 731                    stats->refused_alloc, stats->refused_free);
 732
 733         return 0;
 734 }
 735
 736 static int vmballoon_debug_open(struct inode *inode, struct file *file)
 737 {
 738         return single_open(file, vmballoon_debug_show, inode->i_private);
 739 }
 740
 741 static const struct file_operations vmballoon_debug_fops = {
 742         .owner          = THIS_MODULE,
 743         .open           = vmballoon_debug_open,
 744         .read           = seq_read,
 745         .llseek         = seq_lseek,
 746         .release        = single_release,
 747 };
 748
 749 static int __init vmballoon_debugfs_init(struct vmballoon *b)
 750 {
 751         int error;
 752
 753         b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
 754                                            &vmballoon_debug_fops);
 755         if (IS_ERR(b->dbg_entry)) {
 756                 error = PTR_ERR(b->dbg_entry);
 757                 pr_err("failed to create debugfs entry, error: %d\n", error);
 758                 return error;
 759         }
 760
 761         return 0;
 762 }
 763
 764 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
 765 {
 766         debugfs_remove(b->dbg_entry);
 767 }
 768
 769 #else
 770
 771 static inline int vmballoon_debugfs_init(struct vmballoon *b)
 772 {
 773         return 0;
 774 }
 775
 776 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
 777 {
 778 }
 779
 780 #endif  /* CONFIG_DEBUG_FS */
 781
 782 static int __init vmballoon_init(void)
 783 {
 784         int error;
 785
 786         /*
 787          * Check if we are running on VMware's hypervisor and bail out
 788          * if we are not.
 789          */
 790         if (x86_hyper != &x86_hyper_vmware)
 791                 return -ENODEV;
 792
 793         INIT_LIST_HEAD(&balloon.pages);
 794         INIT_LIST_HEAD(&balloon.refused_pages);
 795
 796         /* initialize rates */
 797         balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
 798         balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
 799
 800         INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
 801
 802         /*
 803          * Start balloon.
 804          */
 805         if (!vmballoon_send_start(&balloon)) {
 806                 pr_err("failed to send start command to the host\n");
 807                 return -EIO;
 808         }
 809
 810         if (!vmballoon_send_guest_id(&balloon)) {
 811                 pr_err("failed to send guest ID to the host\n");
 812                 return -EIO;
 813         }
 814
 815         error = vmballoon_debugfs_init(&balloon);
 816         if (error)
 817                 return error;
 818
 819         queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
 820
 821         return 0;
 822 }
 823 module_init(vmballoon_init);
 824
 825 static void __exit vmballoon_exit(void)
 826 {
 827         cancel_delayed_work_sync(&balloon.dwork);
 828
 829         vmballoon_debugfs_exit(&balloon);
 830
 831         /*
 832          * Deallocate all reserved memory, and reset connection with monitor.
 833          * Reset connection before deallocating memory to avoid potential for
 834          * additional spurious resets from guest touching deallocated pages.
 835          */
 836         vmballoon_send_start(&balloon);
 837         vmballoon_pop(&balloon);
 838 }
 839 module_exit(vmballoon_exit);