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: Dmitry Torokhov <dtor@vmware.com>
  21  */
  22
  23 /*
  24  * This is VMware physical memory management driver for Linux. The driver
  25  * acts like a "balloon" that can be inflated to reclaim physical pages by
  26  * reserving them in the guest and invalidating them in the monitor,
  27  * freeing up the underlying machine pages so they can be allocated to
  28  * other guests.  The balloon can also be deflated to allow the guest to
  29  * use more physical memory. Higher level policies can control the sizes
  30  * of balloons in VMs in order to manage physical memory resources.
  31  */
  32
  33 //#define DEBUG
  34 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/types.h>
  37 #include <linux/kernel.h>
  38 #include <linux/mm.h>
  39 #include <linux/sched.h>
  40 #include <linux/module.h>
  41 #include <linux/workqueue.h>
  42 #include <linux/debugfs.h>
  43 #include <linux/seq_file.h>
  44 #include <asm/hypervisor.h>
  45
  46 MODULE_AUTHOR("VMware, Inc.");
  47 MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
  48 MODULE_VERSION("1.2.1.3-k");
  49 MODULE_ALIAS("dmi:*:svnVMware*:*");
  50 MODULE_ALIAS("vmware_vmmemctl");
  51 MODULE_LICENSE("GPL");
  52
  53 /*
  54  * Various constants controlling rate of inflaint/deflating balloon,
  55  * measured in pages.
  56  */
  57
  58 /*
  59  * Rate of allocating memory when there is no memory pressure
  60  * (driver performs non-sleeping allocations).
  61  */
  62 #define VMW_BALLOON_NOSLEEP_ALLOC_MAX   16384U
  63
  64 /*
  65  * Rates of memory allocaton when guest experiences memory pressure
  66  * (driver performs sleeping allocations).
  67  */
  68 #define VMW_BALLOON_RATE_ALLOC_MIN      512U
  69 #define VMW_BALLOON_RATE_ALLOC_MAX      2048U
  70 #define VMW_BALLOON_RATE_ALLOC_INC      16U
  71
  72 /*
  73  * Rates for releasing pages while deflating balloon.
  74  */
  75 #define VMW_BALLOON_RATE_FREE_MIN       512U
  76 #define VMW_BALLOON_RATE_FREE_MAX       16384U
  77 #define VMW_BALLOON_RATE_FREE_INC       16U
  78
  79 /*
  80  * When guest is under memory pressure, use a reduced page allocation
  81  * rate for next several cycles.
  82  */
  83 #define VMW_BALLOON_SLOW_CYCLES         4
  84
  85 /*
  86  * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't
  87  * allow wait (__GFP_WAIT) for NOSLEEP page allocations. Use
  88  * __GFP_NOWARN, to suppress page allocation failure warnings.
  89  */
  90 #define VMW_PAGE_ALLOC_NOSLEEP          (__GFP_HIGHMEM|__GFP_NOWARN)
  91
  92 /*
  93  * Use GFP_HIGHUSER when executing in a separate kernel thread
  94  * context and allocation can sleep.  This is less stressful to
  95  * the guest memory system, since it allows the thread to block
  96  * while memory is reclaimed, and won't take pages from emergency
  97  * low-memory pools.
  98  */
  99 #define VMW_PAGE_ALLOC_CANSLEEP         (GFP_HIGHUSER)
 100
 101 /* Maximum number of page allocations without yielding processor */
 102 #define VMW_BALLOON_YIELD_THRESHOLD     1024
 103
 104 /* Maximum number of refused pages we accumulate during inflation cycle */
 105 #define VMW_BALLOON_MAX_REFUSED         16
 106
 107 /*
 108  * Hypervisor communication port definitions.
 109  */
 110 #define VMW_BALLOON_HV_PORT             0x5670
 111 #define VMW_BALLOON_HV_MAGIC            0x456c6d6f
 112 #define VMW_BALLOON_PROTOCOL_VERSION    2
 113 #define VMW_BALLOON_GUEST_ID            1       /* Linux */
 114
 115 #define VMW_BALLOON_CMD_START           0
 116 #define VMW_BALLOON_CMD_GET_TARGET      1
 117 #define VMW_BALLOON_CMD_LOCK            2
 118 #define VMW_BALLOON_CMD_UNLOCK          3
 119 #define VMW_BALLOON_CMD_GUEST_ID        4
 120
 121 /* error codes */
 122 #define VMW_BALLOON_SUCCESS             0
 123 #define VMW_BALLOON_FAILURE             -1
 124 #define VMW_BALLOON_ERROR_CMD_INVALID   1
 125 #define VMW_BALLOON_ERROR_PPN_INVALID   2
 126 #define VMW_BALLOON_ERROR_PPN_LOCKED    3
 127 #define VMW_BALLOON_ERROR_PPN_UNLOCKED  4
 128 #define VMW_BALLOON_ERROR_PPN_PINNED    5
 129 #define VMW_BALLOON_ERROR_PPN_NOTNEEDED 6
 130 #define VMW_BALLOON_ERROR_RESET         7
 131 #define VMW_BALLOON_ERROR_BUSY          8
 132
 133 #define VMWARE_BALLOON_CMD(cmd, data, result)           \
 134 ({                                                      \
 135         unsigned long __stat, __dummy1, __dummy2;       \
 136         __asm__ __volatile__ ("inl (%%dx)" :            \
 137                 "=a"(__stat),                           \
 138                 "=c"(__dummy1),                         \
 139                 "=d"(__dummy2),                         \
 140                 "=b"(result) :                          \
 141                 "0"(VMW_BALLOON_HV_MAGIC),              \
 142                 "1"(VMW_BALLOON_CMD_##cmd),             \
 143                 "2"(VMW_BALLOON_HV_PORT),               \
 144                 "3"(data) :                             \
 145                 "memory");                              \
 146         result &= -1UL;                                 \
 147         __stat & -1UL;                                  \
 148 })
 149
 150 #ifdef CONFIG_DEBUG_FS
 151 struct vmballoon_stats {
 152         unsigned int timer;
 153
 154         /* allocation statustics */
 155         unsigned int alloc;
 156         unsigned int alloc_fail;
 157         unsigned int sleep_alloc;
 158         unsigned int sleep_alloc_fail;
 159         unsigned int refused_alloc;
 160         unsigned int refused_free;
 161         unsigned int free;
 162
 163         /* monitor operations */
 164         unsigned int lock;
 165         unsigned int lock_fail;
 166         unsigned int unlock;
 167         unsigned int unlock_fail;
 168         unsigned int target;
 169         unsigned int target_fail;
 170         unsigned int start;
 171         unsigned int start_fail;
 172         unsigned int guest_type;
 173         unsigned int guest_type_fail;
 174 };
 175
 176 #define STATS_INC(stat) (stat)++
 177 #else
 178 #define STATS_INC(stat)
 179 #endif
 180
 181 struct vmballoon {
 182
 183         /* list of reserved physical pages */
 184         struct list_head pages;
 185
 186         /* transient list of non-balloonable pages */
 187         struct list_head refused_pages;
 188         unsigned int n_refused_pages;
 189
 190         /* balloon size in pages */
 191         unsigned int size;
 192         unsigned int target;
 193
 194         /* reset flag */
 195         bool reset_required;
 196
 197         /* adjustment rates (pages per second) */
 198         unsigned int rate_alloc;
 199         unsigned int rate_free;
 200
 201         /* slowdown page allocations for next few cycles */
 202         unsigned int slow_allocation_cycles;
 203
 204 #ifdef CONFIG_DEBUG_FS
 205         /* statistics */
 206         struct vmballoon_stats stats;
 207
 208         /* debugfs file exporting statistics */
 209         struct dentry *dbg_entry;
 210 #endif
 211
 212         struct sysinfo sysinfo;
 213
 214         struct delayed_work dwork;
 215 };
 216
 217 static struct vmballoon balloon;
 218
 219 /*
 220  * Send "start" command to the host, communicating supported version
 221  * of the protocol.
 222  */
 223 static bool vmballoon_send_start(struct vmballoon *b)
 224 {
 225         unsigned long status, dummy;
 226
 227         STATS_INC(b->stats.start);
 228
 229         status = VMWARE_BALLOON_CMD(START, VMW_BALLOON_PROTOCOL_VERSION, dummy);
 230         if (status == VMW_BALLOON_SUCCESS)
 231                 return true;
 232
 233         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 234         STATS_INC(b->stats.start_fail);
 235         return false;
 236 }
 237
 238 static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
 239 {
 240         switch (status) {
 241         case VMW_BALLOON_SUCCESS:
 242                 return true;
 243
 244         case VMW_BALLOON_ERROR_RESET:
 245                 b->reset_required = true;
 246                 /* fall through */
 247
 248         default:
 249                 return false;
 250         }
 251 }
 252
 253 /*
 254  * Communicate guest type to the host so that it can adjust ballooning
 255  * algorithm to the one most appropriate for the guest. This command
 256  * is normally issued after sending "start" command and is part of
 257  * standard reset sequence.
 258  */
 259 static bool vmballoon_send_guest_id(struct vmballoon *b)
 260 {
 261         unsigned long status, dummy;
 262
 263         status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy);
 264
 265         STATS_INC(b->stats.guest_type);
 266
 267         if (vmballoon_check_status(b, status))
 268                 return true;
 269
 270         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 271         STATS_INC(b->stats.guest_type_fail);
 272         return false;
 273 }
 274
 275 /*
 276  * Retrieve desired balloon size from the host.
 277  */
 278 static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
 279 {
 280         unsigned long status;
 281         unsigned long target;
 282         unsigned long limit;
 283         u32 limit32;
 284
 285         /*
 286          * si_meminfo() is cheap. Moreover, we want to provide dynamic
 287          * max balloon size later. So let us call si_meminfo() every
 288          * iteration.
 289          */
 290         si_meminfo(&b->sysinfo);
 291         limit = b->sysinfo.totalram;
 292
 293         /* Ensure limit fits in 32-bits */
 294         limit32 = (u32)limit;
 295         if (limit != limit32)
 296                 return false;
 297
 298         /* update stats */
 299         STATS_INC(b->stats.target);
 300
 301         status = VMWARE_BALLOON_CMD(GET_TARGET, limit, target);
 302         if (vmballoon_check_status(b, status)) {
 303                 *new_target = target;
 304                 return true;
 305         }
 306
 307         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 308         STATS_INC(b->stats.target_fail);
 309         return false;
 310 }
 311
 312 /*
 313  * Notify the host about allocated page so that host can use it without
 314  * fear that guest will need it. Host may reject some pages, we need to
 315  * check the return value and maybe submit a different page.
 316  */
 317 static bool vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
 318                                      unsigned int *hv_status)
 319 {
 320         unsigned long status, dummy;
 321         u32 pfn32;
 322
 323         pfn32 = (u32)pfn;
 324         if (pfn32 != pfn)
 325                 return false;
 326
 327         STATS_INC(b->stats.lock);
 328
 329         *hv_status = status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy);
 330         if (vmballoon_check_status(b, status))
 331                 return true;
 332
 333         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 334         STATS_INC(b->stats.lock_fail);
 335         return false;
 336 }
 337
 338 /*
 339  * Notify the host that guest intends to release given page back into
 340  * the pool of available (to the guest) pages.
 341  */
 342 static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn)
 343 {
 344         unsigned long status, dummy;
 345         u32 pfn32;
 346
 347         pfn32 = (u32)pfn;
 348         if (pfn32 != pfn)
 349                 return false;
 350
 351         STATS_INC(b->stats.unlock);
 352
 353         status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy);
 354         if (vmballoon_check_status(b, status))
 355                 return true;
 356
 357         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 358         STATS_INC(b->stats.unlock_fail);
 359         return false;
 360 }
 361
 362 /*
 363  * Quickly release all pages allocated for the balloon. This function is
 364  * called when host decides to "reset" balloon for one reason or another.
 365  * Unlike normal "deflate" we do not (shall not) notify host of the pages
 366  * being released.
 367  */
 368 static void vmballoon_pop(struct vmballoon *b)
 369 {
 370         struct page *page, *next;
 371         unsigned int count = 0;
 372
 373         list_for_each_entry_safe(page, next, &b->pages, lru) {
 374                 list_del(&page->lru);
 375                 __free_page(page);
 376                 STATS_INC(b->stats.free);
 377                 b->size--;
 378
 379                 if (++count >= b->rate_free) {
 380                         count = 0;
 381                         cond_resched();
 382                 }
 383         }
 384 }
 385
 386 /*
 387  * Perform standard reset sequence by popping the balloon (in case it
 388  * is not  empty) and then restarting protocol. This operation normally
 389  * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
 390  */
 391 static void vmballoon_reset(struct vmballoon *b)
 392 {
 393         /* free all pages, skipping monitor unlock */
 394         vmballoon_pop(b);
 395
 396         if (vmballoon_send_start(b)) {
 397                 b->reset_required = false;
 398                 if (!vmballoon_send_guest_id(b))
 399                         pr_err("failed to send guest ID to the host\n");
 400         }
 401 }
 402
 403 /*
 404  * Allocate (or reserve) a page for the balloon and notify the host.  If host
 405  * refuses the page put it on "refuse" list and allocate another one until host
 406  * is satisfied. "Refused" pages are released at the end of inflation cycle
 407  * (when we allocate b->rate_alloc pages).
 408  */
 409 static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
 410 {
 411         struct page *page;
 412         gfp_t flags;
 413         unsigned int hv_status;
 414         bool locked = false;
 415
 416         do {
 417                 if (!can_sleep)
 418                         STATS_INC(b->stats.alloc);
 419                 else
 420                         STATS_INC(b->stats.sleep_alloc);
 421
 422                 flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
 423                 page = alloc_page(flags);
 424                 if (!page) {
 425                         if (!can_sleep)
 426                                 STATS_INC(b->stats.alloc_fail);
 427                         else
 428                                 STATS_INC(b->stats.sleep_alloc_fail);
 429                         return -ENOMEM;
 430                 }
 431
 432                 /* inform monitor */
 433                 locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status);
 434                 if (!locked) {
 435                         STATS_INC(b->stats.refused_alloc);
 436
 437                         if (hv_status == VMW_BALLOON_ERROR_RESET ||
 438                             hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED) {
 439                                 __free_page(page);
 440                                 return -EIO;
 441                         }
 442
 443                         /*
 444                          * Place page on the list of non-balloonable pages
 445                          * and retry allocation, unless we already accumulated
 446                          * too many of them, in which case take a breather.
 447                          */
 448                         list_add(&page->lru, &b->refused_pages);
 449                         if (++b->n_refused_pages >= VMW_BALLOON_MAX_REFUSED)
 450                                 return -EIO;
 451                 }
 452         } while (!locked);
 453
 454         /* track allocated page */
 455         list_add(&page->lru, &b->pages);
 456
 457         /* update balloon size */
 458         b->size++;
 459
 460         return 0;
 461 }
 462
 463 /*
 464  * Release the page allocated for the balloon. Note that we first notify
 465  * the host so it can make sure the page will be available for the guest
 466  * to use, if needed.
 467  */
 468 static int vmballoon_release_page(struct vmballoon *b, struct page *page)
 469 {
 470         if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
 471                 return -EIO;
 472
 473         list_del(&page->lru);
 474
 475         /* deallocate page */
 476         __free_page(page);
 477         STATS_INC(b->stats.free);
 478
 479         /* update balloon size */
 480         b->size--;
 481
 482         return 0;
 483 }
 484
 485 /*
 486  * Release pages that were allocated while attempting to inflate the
 487  * balloon but were refused by the host for one reason or another.
 488  */
 489 static void vmballoon_release_refused_pages(struct vmballoon *b)
 490 {
 491         struct page *page, *next;
 492
 493         list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
 494                 list_del(&page->lru);
 495                 __free_page(page);
 496                 STATS_INC(b->stats.refused_free);
 497         }
 498
 499         b->n_refused_pages = 0;
 500 }
 501
 502 /*
 503  * Inflate the balloon towards its target size. Note that we try to limit
 504  * the rate of allocation to make sure we are not choking the rest of the
 505  * system.
 506  */
 507 static void vmballoon_inflate(struct vmballoon *b)
 508 {
 509         unsigned int goal;
 510         unsigned int rate;
 511         unsigned int i;
 512         unsigned int allocations = 0;
 513         int error = 0;
 514         bool alloc_can_sleep = false;
 515
 516         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 517
 518         /*
 519          * First try NOSLEEP page allocations to inflate balloon.
 520          *
 521          * If we do not throttle nosleep allocations, we can drain all
 522          * free pages in the guest quickly (if the balloon target is high).
 523          * As a side-effect, draining free pages helps to inform (force)
 524          * the guest to start swapping if balloon target is not met yet,
 525          * which is a desired behavior. However, balloon driver can consume
 526          * all available CPU cycles if too many pages are allocated in a
 527          * second. Therefore, we throttle nosleep allocations even when
 528          * the guest is not under memory pressure. OTOH, if we have already
 529          * predicted that the guest is under memory pressure, then we
 530          * slowdown page allocations considerably.
 531          */
 532
 533         goal = b->target - b->size;
 534         /*
 535          * Start with no sleep allocation rate which may be higher
 536          * than sleeping allocation rate.
 537          */
 538         rate = b->slow_allocation_cycles ?
 539                         b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
 540
 541         pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
 542                  __func__, goal, rate, b->rate_alloc);
 543
 544         for (i = 0; i < goal; i++) {
 545
 546                 error = vmballoon_reserve_page(b, alloc_can_sleep);
 547                 if (error) {
 548                         if (error != -ENOMEM) {
 549                                 /*
 550                                  * Not a page allocation failure, stop this
 551                                  * cycle. Maybe we'll get new target from
 552                                  * the host soon.
 553                                  */
 554                                 break;
 555                         }
 556
 557                         if (alloc_can_sleep) {
 558                                 /*
 559                                  * CANSLEEP page allocation failed, so guest
 560                                  * is under severe memory pressure. Quickly
 561                                  * decrease allocation rate.
 562                                  */
 563                                 b->rate_alloc = max(b->rate_alloc / 2,
 564                                                     VMW_BALLOON_RATE_ALLOC_MIN);
 565                                 break;
 566                         }
 567
 568                         /*
 569                          * NOSLEEP page allocation failed, so the guest is
 570                          * under memory pressure. Let us slow down page
 571                          * allocations for next few cycles so that the guest
 572                          * gets out of memory pressure. Also, if we already
 573                          * allocated b->rate_alloc pages, let's pause,
 574                          * otherwise switch to sleeping allocations.
 575                          */
 576                         b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
 577
 578                         if (i >= b->rate_alloc)
 579                                 break;
 580
 581                         alloc_can_sleep = true;
 582                         /* Lower rate for sleeping allocations. */
 583                         rate = b->rate_alloc;
 584                 }
 585
 586                 if (++allocations > VMW_BALLOON_YIELD_THRESHOLD) {
 587                         cond_resched();
 588                         allocations = 0;
 589                 }
 590
 591                 if (i >= rate) {
 592                         /* We allocated enough pages, let's take a break. */
 593                         break;
 594                 }
 595         }
 596
 597         /*
 598          * We reached our goal without failures so try increasing
 599          * allocation rate.
 600          */
 601         if (error == 0 && i >= b->rate_alloc) {
 602                 unsigned int mult = i / b->rate_alloc;
 603
 604                 b->rate_alloc =
 605                         min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
 606                             VMW_BALLOON_RATE_ALLOC_MAX);
 607         }
 608
 609         vmballoon_release_refused_pages(b);
 610 }
 611
 612 /*
 613  * Decrease the size of the balloon allowing guest to use more memory.
 614  */
 615 static void vmballoon_deflate(struct vmballoon *b)
 616 {
 617         struct page *page, *next;
 618         unsigned int i = 0;
 619         unsigned int goal;
 620         int error;
 621
 622         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 623
 624         /* limit deallocation rate */
 625         goal = min(b->size - b->target, b->rate_free);
 626
 627         pr_debug("%s - goal: %d, rate: %d\n", __func__, goal, b->rate_free);
 628
 629         /* free pages to reach target */
 630         list_for_each_entry_safe(page, next, &b->pages, lru) {
 631                 error = vmballoon_release_page(b, page);
 632                 if (error) {
 633                         /* quickly decrease rate in case of error */
 634                         b->rate_free = max(b->rate_free / 2,
 635                                            VMW_BALLOON_RATE_FREE_MIN);
 636                         return;
 637                 }
 638
 639                 if (++i >= goal)
 640                         break;
 641         }
 642
 643         /* slowly increase rate if there were no errors */
 644         b->rate_free = min(b->rate_free + VMW_BALLOON_RATE_FREE_INC,
 645                            VMW_BALLOON_RATE_FREE_MAX);
 646 }
 647
 648 /*
 649  * Balloon work function: reset protocol, if needed, get the new size and
 650  * adjust balloon as needed. Repeat in 1 sec.
 651  */
 652 static void vmballoon_work(struct work_struct *work)
 653 {
 654         struct delayed_work *dwork = to_delayed_work(work);
 655         struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
 656         unsigned int target;
 657
 658         STATS_INC(b->stats.timer);
 659
 660         if (b->reset_required)
 661                 vmballoon_reset(b);
 662
 663         if (b->slow_allocation_cycles > 0)
 664                 b->slow_allocation_cycles--;
 665
 666         if (vmballoon_send_get_target(b, &target)) {
 667                 /* update target, adjust size */
 668                 b->target = target;
 669
 670                 if (b->size < target)
 671                         vmballoon_inflate(b);
 672                 else if (b->size > target)
 673                         vmballoon_deflate(b);
 674         }
 675
 676         /*
 677          * We are using a freezable workqueue so that balloon operations are
 678          * stopped while the system transitions to/from sleep/hibernation.
 679          */
 680         queue_delayed_work(system_freezable_wq,
 681                            dwork, round_jiffies_relative(HZ));
 682 }
 683
 684 /*
 685  * DEBUGFS Interface
 686  */
 687 #ifdef CONFIG_DEBUG_FS
 688
 689 static int vmballoon_debug_show(struct seq_file *f, void *offset)
 690 {
 691         struct vmballoon *b = f->private;
 692         struct vmballoon_stats *stats = &b->stats;
 693
 694         /* format size info */
 695         seq_printf(f,
 696                    "target:             %8d pages\n"
 697                    "current:            %8d pages\n",
 698                    b->target, b->size);
 699
 700         /* format rate info */
 701         seq_printf(f,
 702                    "rateNoSleepAlloc:   %8d pages/sec\n"
 703                    "rateSleepAlloc:     %8d pages/sec\n"
 704                    "rateFree:           %8d pages/sec\n",
 705                    VMW_BALLOON_NOSLEEP_ALLOC_MAX,
 706                    b->rate_alloc, b->rate_free);
 707
 708         seq_printf(f,
 709                    "\n"
 710                    "timer:              %8u\n"
 711                    "start:              %8u (%4u failed)\n"
 712                    "guestType:          %8u (%4u failed)\n"
 713                    "lock:               %8u (%4u failed)\n"
 714                    "unlock:             %8u (%4u failed)\n"
 715                    "target:             %8u (%4u failed)\n"
 716                    "primNoSleepAlloc:   %8u (%4u failed)\n"
 717                    "primCanSleepAlloc:  %8u (%4u failed)\n"
 718                    "primFree:           %8u\n"
 719                    "errAlloc:           %8u\n"
 720                    "errFree:            %8u\n",
 721                    stats->timer,
 722                    stats->start, stats->start_fail,
 723                    stats->guest_type, stats->guest_type_fail,
 724                    stats->lock,  stats->lock_fail,
 725                    stats->unlock, stats->unlock_fail,
 726                    stats->target, stats->target_fail,
 727                    stats->alloc, stats->alloc_fail,
 728                    stats->sleep_alloc, stats->sleep_alloc_fail,
 729                    stats->free,
 730                    stats->refused_alloc, stats->refused_free);
 731
 732         return 0;
 733 }
 734
 735 static int vmballoon_debug_open(struct inode *inode, struct file *file)
 736 {
 737         return single_open(file, vmballoon_debug_show, inode->i_private);
 738 }
 739
 740 static const struct file_operations vmballoon_debug_fops = {
 741         .owner          = THIS_MODULE,
 742         .open           = vmballoon_debug_open,
 743         .read           = seq_read,
 744         .llseek         = seq_lseek,
 745         .release        = single_release,
 746 };
 747
 748 static int __init vmballoon_debugfs_init(struct vmballoon *b)
 749 {
 750         int error;
 751
 752         b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
 753                                            &vmballoon_debug_fops);
 754         if (IS_ERR(b->dbg_entry)) {
 755                 error = PTR_ERR(b->dbg_entry);
 756                 pr_err("failed to create debugfs entry, error: %d\n", error);
 757                 return error;
 758         }
 759
 760         return 0;
 761 }
 762
 763 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
 764 {
 765         debugfs_remove(b->dbg_entry);
 766 }
 767
 768 #else
 769
 770 static inline int vmballoon_debugfs_init(struct vmballoon *b)
 771 {
 772         return 0;
 773 }
 774
 775 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
 776 {
 777 }
 778
 779 #endif  /* CONFIG_DEBUG_FS */
 780
 781 static int __init vmballoon_init(void)
 782 {
 783         int error;
 784
 785         /*
 786          * Check if we are running on VMware's hypervisor and bail out
 787          * if we are not.
 788          */
 789         if (x86_hyper != &x86_hyper_vmware)
 790                 return -ENODEV;
 791
 792         INIT_LIST_HEAD(&balloon.pages);
 793         INIT_LIST_HEAD(&balloon.refused_pages);
 794
 795         /* initialize rates */
 796         balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
 797         balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
 798
 799         INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
 800
 801         /*
 802          * Start balloon.
 803          */
 804         if (!vmballoon_send_start(&balloon)) {
 805                 pr_err("failed to send start command to the host\n");
 806                 return -EIO;
 807         }
 808
 809         if (!vmballoon_send_guest_id(&balloon)) {
 810                 pr_err("failed to send guest ID to the host\n");
 811                 return -EIO;
 812         }
 813
 814         error = vmballoon_debugfs_init(&balloon);
 815         if (error)
 816                 return error;
 817
 818         queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
 819
 820         return 0;
 821 }
 822 module_init(vmballoon_init);
 823
 824 static void __exit vmballoon_exit(void)
 825 {
 826         cancel_delayed_work_sync(&balloon.dwork);
 827
 828         vmballoon_debugfs_exit(&balloon);
 829
 830         /*
 831          * Deallocate all reserved memory, and reset connection with monitor.
 832          * Reset connection before deallocating memory to avoid potential for
 833          * additional spurious resets from guest touching deallocated pages.
 834          */
 835         vmballoon_send_start(&balloon);
 836         vmballoon_pop(&balloon);
 837 }
 838 module_exit(vmballoon_exit);