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("1.2.1.1-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 static struct workqueue_struct *vmballoon_wq;
 219
 220 /*
 221  * Send "start" command to the host, communicating supported version
 222  * of the protocol.
 223  */
 224 static bool vmballoon_send_start(struct vmballoon *b)
 225 {
 226         unsigned long status, dummy;
 227
 228         STATS_INC(b->stats.start);
 229
 230         status = VMWARE_BALLOON_CMD(START, VMW_BALLOON_PROTOCOL_VERSION, dummy);
 231         if (status == VMW_BALLOON_SUCCESS)
 232                 return true;
 233
 234         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 235         STATS_INC(b->stats.start_fail);
 236         return false;
 237 }
 238
 239 static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
 240 {
 241         switch (status) {
 242         case VMW_BALLOON_SUCCESS:
 243                 return true;
 244
 245         case VMW_BALLOON_ERROR_RESET:
 246                 b->reset_required = true;
 247                 /* fall through */
 248
 249         default:
 250                 return false;
 251         }
 252 }
 253
 254 /*
 255  * Communicate guest type to the host so that it can adjust ballooning
 256  * algorithm to the one most appropriate for the guest. This command
 257  * is normally issued after sending "start" command and is part of
 258  * standard reset sequence.
 259  */
 260 static bool vmballoon_send_guest_id(struct vmballoon *b)
 261 {
 262         unsigned long status, dummy;
 263
 264         status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy);
 265
 266         STATS_INC(b->stats.guest_type);
 267
 268         if (vmballoon_check_status(b, status))
 269                 return true;
 270
 271         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 272         STATS_INC(b->stats.guest_type_fail);
 273         return false;
 274 }
 275
 276 /*
 277  * Retrieve desired balloon size from the host.
 278  */
 279 static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
 280 {
 281         unsigned long status;
 282         unsigned long target;
 283         unsigned long limit;
 284         u32 limit32;
 285
 286         /*
 287          * si_meminfo() is cheap. Moreover, we want to provide dynamic
 288          * max balloon size later. So let us call si_meminfo() every
 289          * iteration.
 290          */
 291         si_meminfo(&b->sysinfo);
 292         limit = b->sysinfo.totalram;
 293
 294         /* Ensure limit fits in 32-bits */
 295         limit32 = (u32)limit;
 296         if (limit != limit32)
 297                 return false;
 298
 299         /* update stats */
 300         STATS_INC(b->stats.target);
 301
 302         status = VMWARE_BALLOON_CMD(GET_TARGET, limit, target);
 303         if (vmballoon_check_status(b, status)) {
 304                 *new_target = target;
 305                 return true;
 306         }
 307
 308         pr_debug("%s - failed, hv returns %ld\n", __func__, status);
 309         STATS_INC(b->stats.target_fail);
 310         return false;
 311 }
 312
 313 /*
 314  * Notify the host about allocated page so that host can use it without
 315  * fear that guest will need it. Host may reject some pages, we need to
 316  * check the return value and maybe submit a different page.
 317  */
 318 static bool vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn)
 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         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         bool locked = false;
 414
 415         do {
 416                 if (!can_sleep)
 417                         STATS_INC(b->stats.alloc);
 418                 else
 419                         STATS_INC(b->stats.sleep_alloc);
 420
 421                 flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
 422                 page = alloc_page(flags);
 423                 if (!page) {
 424                         if (!can_sleep)
 425                                 STATS_INC(b->stats.alloc_fail);
 426                         else
 427                                 STATS_INC(b->stats.sleep_alloc_fail);
 428                         return -ENOMEM;
 429                 }
 430
 431                 /* inform monitor */
 432                 locked = vmballoon_send_lock_page(b, page_to_pfn(page));
 433                 if (!locked) {
 434                         STATS_INC(b->stats.refused_alloc);
 435
 436                         if (b->reset_required) {
 437                                 __free_page(page);
 438                                 return -EIO;
 439                         }
 440
 441                         /*
 442                          * Place page on the list of non-balloonable pages
 443                          * and retry allocation, unless we already accumulated
 444                          * too many of them, in which case take a breather.
 445                          */
 446                         list_add(&page->lru, &b->refused_pages);
 447                         if (++b->n_refused_pages >= VMW_BALLOON_MAX_REFUSED)
 448                                 return -EIO;
 449                 }
 450         } while (!locked);
 451
 452         /* track allocated page */
 453         list_add(&page->lru, &b->pages);
 454
 455         /* update balloon size */
 456         b->size++;
 457
 458         return 0;
 459 }
 460
 461 /*
 462  * Release the page allocated for the balloon. Note that we first notify
 463  * the host so it can make sure the page will be available for the guest
 464  * to use, if needed.
 465  */
 466 static int vmballoon_release_page(struct vmballoon *b, struct page *page)
 467 {
 468         if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
 469                 return -EIO;
 470
 471         list_del(&page->lru);
 472
 473         /* deallocate page */
 474         __free_page(page);
 475         STATS_INC(b->stats.free);
 476
 477         /* update balloon size */
 478         b->size--;
 479
 480         return 0;
 481 }
 482
 483 /*
 484  * Release pages that were allocated while attempting to inflate the
 485  * balloon but were refused by the host for one reason or another.
 486  */
 487 static void vmballoon_release_refused_pages(struct vmballoon *b)
 488 {
 489         struct page *page, *next;
 490
 491         list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
 492                 list_del(&page->lru);
 493                 __free_page(page);
 494                 STATS_INC(b->stats.refused_free);
 495         }
 496
 497         b->n_refused_pages = 0;
 498 }
 499
 500 /*
 501  * Inflate the balloon towards its target size. Note that we try to limit
 502  * the rate of allocation to make sure we are not choking the rest of the
 503  * system.
 504  */
 505 static void vmballoon_inflate(struct vmballoon *b)
 506 {
 507         unsigned int goal;
 508         unsigned int rate;
 509         unsigned int i;
 510         unsigned int allocations = 0;
 511         int error = 0;
 512         bool alloc_can_sleep = false;
 513
 514         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 515
 516         /*
 517          * First try NOSLEEP page allocations to inflate balloon.
 518          *
 519          * If we do not throttle nosleep allocations, we can drain all
 520          * free pages in the guest quickly (if the balloon target is high).
 521          * As a side-effect, draining free pages helps to inform (force)
 522          * the guest to start swapping if balloon target is not met yet,
 523          * which is a desired behavior. However, balloon driver can consume
 524          * all available CPU cycles if too many pages are allocated in a
 525          * second. Therefore, we throttle nosleep allocations even when
 526          * the guest is not under memory pressure. OTOH, if we have already
 527          * predicted that the guest is under memory pressure, then we
 528          * slowdown page allocations considerably.
 529          */
 530
 531         goal = b->target - b->size;
 532         /*
 533          * Start with no sleep allocation rate which may be higher
 534          * than sleeping allocation rate.
 535          */
 536         rate = b->slow_allocation_cycles ?
 537                         b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
 538
 539         pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
 540                  __func__, goal, rate, b->rate_alloc);
 541
 542         for (i = 0; i < goal; i++) {
 543
 544                 error = vmballoon_reserve_page(b, alloc_can_sleep);
 545                 if (error) {
 546                         if (error != -ENOMEM) {
 547                                 /*
 548                                  * Not a page allocation failure, stop this
 549                                  * cycle. Maybe we'll get new target from
 550                                  * the host soon.
 551                                  */
 552                                 break;
 553                         }
 554
 555                         if (alloc_can_sleep) {
 556                                 /*
 557                                  * CANSLEEP page allocation failed, so guest
 558                                  * is under severe memory pressure. Quickly
 559                                  * decrease allocation rate.
 560                                  */
 561                                 b->rate_alloc = max(b->rate_alloc / 2,
 562                                                     VMW_BALLOON_RATE_ALLOC_MIN);
 563                                 break;
 564                         }
 565
 566                         /*
 567                          * NOSLEEP page allocation failed, so the guest is
 568                          * under memory pressure. Let us slow down page
 569                          * allocations for next few cycles so that the guest
 570                          * gets out of memory pressure. Also, if we already
 571                          * allocated b->rate_alloc pages, let's pause,
 572                          * otherwise switch to sleeping allocations.
 573                          */
 574                         b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
 575
 576                         if (i >= b->rate_alloc)
 577                                 break;
 578
 579                         alloc_can_sleep = true;
 580                         /* Lower rate for sleeping allocations. */
 581                         rate = b->rate_alloc;
 582                 }
 583
 584                 if (++allocations > VMW_BALLOON_YIELD_THRESHOLD) {
 585                         cond_resched();
 586                         allocations = 0;
 587                 }
 588
 589                 if (i >= rate) {
 590                         /* We allocated enough pages, let's take a break. */
 591                         break;
 592                 }
 593         }
 594
 595         /*
 596          * We reached our goal without failures so try increasing
 597          * allocation rate.
 598          */
 599         if (error == 0 && i >= b->rate_alloc) {
 600                 unsigned int mult = i / b->rate_alloc;
 601
 602                 b->rate_alloc =
 603                         min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
 604                             VMW_BALLOON_RATE_ALLOC_MAX);
 605         }
 606
 607         vmballoon_release_refused_pages(b);
 608 }
 609
 610 /*
 611  * Decrease the size of the balloon allowing guest to use more memory.
 612  */
 613 static void vmballoon_deflate(struct vmballoon *b)
 614 {
 615         struct page *page, *next;
 616         unsigned int i = 0;
 617         unsigned int goal;
 618         int error;
 619
 620         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 621
 622         /* limit deallocation rate */
 623         goal = min(b->size - b->target, b->rate_free);
 624
 625         pr_debug("%s - goal: %d, rate: %d\n", __func__, goal, b->rate_free);
 626
 627         /* free pages to reach target */
 628         list_for_each_entry_safe(page, next, &b->pages, lru) {
 629                 error = vmballoon_release_page(b, page);
 630                 if (error) {
 631                         /* quickly decrease rate in case of error */
 632                         b->rate_free = max(b->rate_free / 2,
 633                                            VMW_BALLOON_RATE_FREE_MIN);
 634                         return;
 635                 }
 636
 637                 if (++i >= goal)
 638                         break;
 639         }
 640
 641         /* slowly increase rate if there were no errors */
 642         b->rate_free = min(b->rate_free + VMW_BALLOON_RATE_FREE_INC,
 643                            VMW_BALLOON_RATE_FREE_MAX);
 644 }
 645
 646 /*
 647  * Balloon work function: reset protocol, if needed, get the new size and
 648  * adjust balloon as needed. Repeat in 1 sec.
 649  */
 650 static void vmballoon_work(struct work_struct *work)
 651 {
 652         struct delayed_work *dwork = to_delayed_work(work);
 653         struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
 654         unsigned int target;
 655
 656         STATS_INC(b->stats.timer);
 657
 658         if (b->reset_required)
 659                 vmballoon_reset(b);
 660
 661         if (b->slow_allocation_cycles > 0)
 662                 b->slow_allocation_cycles--;
 663
 664         if (vmballoon_send_get_target(b, &target)) {
 665                 /* update target, adjust size */
 666                 b->target = target;
 667
 668                 if (b->size < target)
 669                         vmballoon_inflate(b);
 670                 else if (b->size > target)
 671                         vmballoon_deflate(b);
 672         }
 673
 674         queue_delayed_work(vmballoon_wq, dwork, round_jiffies_relative(HZ));
 675 }
 676
 677 /*
 678  * DEBUGFS Interface
 679  */
 680 #ifdef CONFIG_DEBUG_FS
 681
 682 static int vmballoon_debug_show(struct seq_file *f, void *offset)
 683 {
 684         struct vmballoon *b = f->private;
 685         struct vmballoon_stats *stats = &b->stats;
 686
 687         /* format size info */
 688         seq_printf(f,
 689                    "target:             %8d pages\n"
 690                    "current:            %8d pages\n",
 691                    b->target, b->size);
 692
 693         /* format rate info */
 694         seq_printf(f,
 695                    "rateNoSleepAlloc:   %8d pages/sec\n"
 696                    "rateSleepAlloc:     %8d pages/sec\n"
 697                    "rateFree:           %8d pages/sec\n",
 698                    VMW_BALLOON_NOSLEEP_ALLOC_MAX,
 699                    b->rate_alloc, b->rate_free);
 700
 701         seq_printf(f,
 702                    "\n"
 703                    "timer:              %8u\n"
 704                    "start:              %8u (%4u failed)\n"
 705                    "guestType:          %8u (%4u failed)\n"
 706                    "lock:               %8u (%4u failed)\n"
 707                    "unlock:             %8u (%4u failed)\n"
 708                    "target:             %8u (%4u failed)\n"
 709                    "primNoSleepAlloc:   %8u (%4u failed)\n"
 710                    "primCanSleepAlloc:  %8u (%4u failed)\n"
 711                    "primFree:           %8u\n"
 712                    "errAlloc:           %8u\n"
 713                    "errFree:            %8u\n",
 714                    stats->timer,
 715                    stats->start, stats->start_fail,
 716                    stats->guest_type, stats->guest_type_fail,
 717                    stats->lock,  stats->lock_fail,
 718                    stats->unlock, stats->unlock_fail,
 719                    stats->target, stats->target_fail,
 720                    stats->alloc, stats->alloc_fail,
 721                    stats->sleep_alloc, stats->sleep_alloc_fail,
 722                    stats->free,
 723                    stats->refused_alloc, stats->refused_free);
 724
 725         return 0;
 726 }
 727
 728 static int vmballoon_debug_open(struct inode *inode, struct file *file)
 729 {
 730         return single_open(file, vmballoon_debug_show, inode->i_private);
 731 }
 732
 733 static const struct file_operations vmballoon_debug_fops = {
 734         .owner          = THIS_MODULE,
 735         .open           = vmballoon_debug_open,
 736         .read           = seq_read,
 737         .llseek         = seq_lseek,
 738         .release        = single_release,
 739 };
 740
 741 static int __init vmballoon_debugfs_init(struct vmballoon *b)
 742 {
 743         int error;
 744
 745         b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
 746                                            &vmballoon_debug_fops);
 747         if (IS_ERR(b->dbg_entry)) {
 748                 error = PTR_ERR(b->dbg_entry);
 749                 pr_err("failed to create debugfs entry, error: %d\n", error);
 750                 return error;
 751         }
 752
 753         return 0;
 754 }
 755
 756 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
 757 {
 758         debugfs_remove(b->dbg_entry);
 759 }
 760
 761 #else
 762
 763 static inline int vmballoon_debugfs_init(struct vmballoon *b)
 764 {
 765         return 0;
 766 }
 767
 768 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
 769 {
 770 }
 771
 772 #endif  /* CONFIG_DEBUG_FS */
 773
 774 static int __init vmballoon_init(void)
 775 {
 776         int error;
 777
 778         /*
 779          * Check if we are running on VMware's hypervisor and bail out
 780          * if we are not.
 781          */
 782         if (x86_hyper != &x86_hyper_vmware)
 783                 return -ENODEV;
 784
 785         vmballoon_wq = create_freezeable_workqueue("vmmemctl");
 786         if (!vmballoon_wq) {
 787                 pr_err("failed to create workqueue\n");
 788                 return -ENOMEM;
 789         }
 790
 791         INIT_LIST_HEAD(&balloon.pages);
 792         INIT_LIST_HEAD(&balloon.refused_pages);
 793
 794         /* initialize rates */
 795         balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
 796         balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
 797
 798         INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
 799
 800         /*
 801          * Start balloon.
 802          */
 803         if (!vmballoon_send_start(&balloon)) {
 804                 pr_err("failed to send start command to the host\n");
 805                 error = -EIO;
 806                 goto fail;
 807         }
 808
 809         if (!vmballoon_send_guest_id(&balloon)) {
 810                 pr_err("failed to send guest ID to the host\n");
 811                 error = -EIO;
 812                 goto fail;
 813         }
 814
 815         error = vmballoon_debugfs_init(&balloon);
 816         if (error)
 817                 goto fail;
 818
 819         queue_delayed_work(vmballoon_wq, &balloon.dwork, 0);
 820
 821         return 0;
 822
 823 fail:
 824         destroy_workqueue(vmballoon_wq);
 825         return error;
 826 }
 827 module_init(vmballoon_init);
 828
 829 static void __exit vmballoon_exit(void)
 830 {
 831         cancel_delayed_work_sync(&balloon.dwork);
 832         destroy_workqueue(vmballoon_wq);
 833
 834         vmballoon_debugfs_exit(&balloon);
 835
 836         /*
 837          * Deallocate all reserved memory, and reset connection with monitor.
 838          * Reset connection before deallocating memory to avoid potential for
 839          * additional spurious resets from guest touching deallocated pages.
 840          */
 841         vmballoon_send_start(&balloon);
 842         vmballoon_pop(&balloon);
 843 }
 844 module_exit(vmballoon_exit);