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("1.2.1.2-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                                      unsigned int *hv_status)
 320 {
 321         unsigned long status, dummy;
 322         u32 pfn32;
 323
 324         pfn32 = (u32)pfn;
 325         if (pfn32 != pfn)
 326                 return false;
 327
 328         STATS_INC(b->stats.lock);
 329
 330         *hv_status = status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy);
 331         if (vmballoon_check_status(b, status))
 332                 return true;
 333
 334         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 335         STATS_INC(b->stats.lock_fail);
 336         return false;
 337 }
 338
 339 /*
 340  * Notify the host that guest intends to release given page back into
 341  * the pool of available (to the guest) pages.
 342  */
 343 static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn)
 344 {
 345         unsigned long status, dummy;
 346         u32 pfn32;
 347
 348         pfn32 = (u32)pfn;
 349         if (pfn32 != pfn)
 350                 return false;
 351
 352         STATS_INC(b->stats.unlock);
 353
 354         status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy);
 355         if (vmballoon_check_status(b, status))
 356                 return true;
 357
 358         pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 359         STATS_INC(b->stats.unlock_fail);
 360         return false;
 361 }
 362
 363 /*
 364  * Quickly release all pages allocated for the balloon. This function is
 365  * called when host decides to "reset" balloon for one reason or another.
 366  * Unlike normal "deflate" we do not (shall not) notify host of the pages
 367  * being released.
 368  */
 369 static void vmballoon_pop(struct vmballoon *b)
 370 {
 371         struct page *page, *next;
 372         unsigned int count = 0;
 373
 374         list_for_each_entry_safe(page, next, &b->pages, lru) {
 375                 list_del(&page->lru);
 376                 __free_page(page);
 377                 STATS_INC(b->stats.free);
 378                 b->size--;
 379
 380                 if (++count >= b->rate_free) {
 381                         count = 0;
 382                         cond_resched();
 383                 }
 384         }
 385 }
 386
 387 /*
 388  * Perform standard reset sequence by popping the balloon (in case it
 389  * is not  empty) and then restarting protocol. This operation normally
 390  * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
 391  */
 392 static void vmballoon_reset(struct vmballoon *b)
 393 {
 394         /* free all pages, skipping monitor unlock */
 395         vmballoon_pop(b);
 396
 397         if (vmballoon_send_start(b)) {
 398                 b->reset_required = false;
 399                 if (!vmballoon_send_guest_id(b))
 400                         pr_err("failed to send guest ID to the host\n");
 401         }
 402 }
 403
 404 /*
 405  * Allocate (or reserve) a page for the balloon and notify the host.  If host
 406  * refuses the page put it on "refuse" list and allocate another one until host
 407  * is satisfied. "Refused" pages are released at the end of inflation cycle
 408  * (when we allocate b->rate_alloc pages).
 409  */
 410 static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
 411 {
 412         struct page *page;
 413         gfp_t flags;
 414         unsigned int hv_status;
 415         bool locked = false;
 416
 417         do {
 418                 if (!can_sleep)
 419                         STATS_INC(b->stats.alloc);
 420                 else
 421                         STATS_INC(b->stats.sleep_alloc);
 422
 423                 flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
 424                 page = alloc_page(flags);
 425                 if (!page) {
 426                         if (!can_sleep)
 427                                 STATS_INC(b->stats.alloc_fail);
 428                         else
 429                                 STATS_INC(b->stats.sleep_alloc_fail);
 430                         return -ENOMEM;
 431                 }
 432
 433                 /* inform monitor */
 434                 locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status);
 435                 if (!locked) {
 436                         STATS_INC(b->stats.refused_alloc);
 437
 438                         if (hv_status == VMW_BALLOON_ERROR_RESET ||
 439                             hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED) {
 440                                 __free_page(page);
 441                                 return -EIO;
 442                         }
 443
 444                         /*
 445                          * Place page on the list of non-balloonable pages
 446                          * and retry allocation, unless we already accumulated
 447                          * too many of them, in which case take a breather.
 448                          */
 449                         list_add(&page->lru, &b->refused_pages);
 450                         if (++b->n_refused_pages >= VMW_BALLOON_MAX_REFUSED)
 451                                 return -EIO;
 452                 }
 453         } while (!locked);
 454
 455         /* track allocated page */
 456         list_add(&page->lru, &b->pages);
 457
 458         /* update balloon size */
 459         b->size++;
 460
 461         return 0;
 462 }
 463
 464 /*
 465  * Release the page allocated for the balloon. Note that we first notify
 466  * the host so it can make sure the page will be available for the guest
 467  * to use, if needed.
 468  */
 469 static int vmballoon_release_page(struct vmballoon *b, struct page *page)
 470 {
 471         if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
 472                 return -EIO;
 473
 474         list_del(&page->lru);
 475
 476         /* deallocate page */
 477         __free_page(page);
 478         STATS_INC(b->stats.free);
 479
 480         /* update balloon size */
 481         b->size--;
 482
 483         return 0;
 484 }
 485
 486 /*
 487  * Release pages that were allocated while attempting to inflate the
 488  * balloon but were refused by the host for one reason or another.
 489  */
 490 static void vmballoon_release_refused_pages(struct vmballoon *b)
 491 {
 492         struct page *page, *next;
 493
 494         list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
 495                 list_del(&page->lru);
 496                 __free_page(page);
 497                 STATS_INC(b->stats.refused_free);
 498         }
 499
 500         b->n_refused_pages = 0;
 501 }
 502
 503 /*
 504  * Inflate the balloon towards its target size. Note that we try to limit
 505  * the rate of allocation to make sure we are not choking the rest of the
 506  * system.
 507  */
 508 static void vmballoon_inflate(struct vmballoon *b)
 509 {
 510         unsigned int goal;
 511         unsigned int rate;
 512         unsigned int i;
 513         unsigned int allocations = 0;
 514         int error = 0;
 515         bool alloc_can_sleep = false;
 516
 517         pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
 518
 519         /*
 520          * First try NOSLEEP page allocations to inflate balloon.
 521          *
 522          * If we do not throttle nosleep allocations, we can drain all
 523          * free pages in the guest quickly (if the balloon target is high).
 524          * As a side-effect, draining free pages helps to inform (force)
 525          * the guest to start swapping if balloon target is not met yet,
 526          * which is a desired behavior. However, balloon driver can consume
 527          * all available CPU cycles if too many pages are allocated in a
 528          * second. Therefore, we throttle nosleep allocations even when
 529          * the guest is not under memory pressure. OTOH, if we have already
 530          * predicted that the guest is under memory pressure, then we
 531          * slowdown page allocations considerably.
 532          */
 533
 534         goal = b->target - b->size;
 535         /*
 536          * Start with no sleep allocation rate which may be higher
 537          * than sleeping allocation rate.
 538          */
 539         rate = b->slow_allocation_cycles ?
 540                         b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
 541
 542         pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
 543                  __func__, goal, rate, b->rate_alloc);
 544
 545         for (i = 0; i < goal; i++) {
 546
 547                 error = vmballoon_reserve_page(b, alloc_can_sleep);
 548                 if (error) {
 549                         if (error != -ENOMEM) {
 550                                 /*
 551                                  * Not a page allocation failure, stop this
 552                                  * cycle. Maybe we'll get new target from
 553                                  * the host soon.
 554                                  */
 555                                 break;
 556                         }
 557
 558                         if (alloc_can_sleep) {
 559                                 /*
 560                                  * CANSLEEP page allocation failed, so guest
 561                                  * is under severe memory pressure. Quickly
 562                                  * decrease allocation rate.
 563                                  */
 564                                 b->rate_alloc = max(b->rate_alloc / 2,
 565                                                     VMW_BALLOON_RATE_ALLOC_MIN);
 566                                 break;
 567                         }
 568
 569                         /*
 570                          * NOSLEEP page allocation failed, so the guest is
 571                          * under memory pressure. Let us slow down page
 572                          * allocations for next few cycles so that the guest
 573                          * gets out of memory pressure. Also, if we already
 574                          * allocated b->rate_alloc pages, let's pause,
 575                          * otherwise switch to sleeping allocations.
 576                          */
 577                         b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
 578
 579                         if (i >= b->rate_alloc)
 580                                 break;
 581
 582                         alloc_can_sleep = true;
 583                         /* Lower rate for sleeping allocations. */
 584                         rate = b->rate_alloc;
 585                 }
 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         queue_delayed_work(vmballoon_wq, dwork, round_jiffies_relative(HZ));
 678 }
 679
 680 /*
 681  * DEBUGFS Interface
 682  */
 683 #ifdef CONFIG_DEBUG_FS
 684
 685 static int vmballoon_debug_show(struct seq_file *f, void *offset)
 686 {
 687         struct vmballoon *b = f->private;
 688         struct vmballoon_stats *stats = &b->stats;
 689
 690         /* format size info */
 691         seq_printf(f,
 692                    "target:             %8d pages\n"
 693                    "current:            %8d pages\n",
 694                    b->target, b->size);
 695
 696         /* format rate info */
 697         seq_printf(f,
 698                    "rateNoSleepAlloc:   %8d pages/sec\n"
 699                    "rateSleepAlloc:     %8d pages/sec\n"
 700                    "rateFree:           %8d pages/sec\n",
 701                    VMW_BALLOON_NOSLEEP_ALLOC_MAX,
 702                    b->rate_alloc, b->rate_free);
 703
 704         seq_printf(f,
 705                    "\n"
 706                    "timer:              %8u\n"
 707                    "start:              %8u (%4u failed)\n"
 708                    "guestType:          %8u (%4u failed)\n"
 709                    "lock:               %8u (%4u failed)\n"
 710                    "unlock:             %8u (%4u failed)\n"
 711                    "target:             %8u (%4u failed)\n"
 712                    "primNoSleepAlloc:   %8u (%4u failed)\n"
 713                    "primCanSleepAlloc:  %8u (%4u failed)\n"
 714                    "primFree:           %8u\n"
 715                    "errAlloc:           %8u\n"
 716                    "errFree:            %8u\n",
 717                    stats->timer,
 718                    stats->start, stats->start_fail,
 719                    stats->guest_type, stats->guest_type_fail,
 720                    stats->lock,  stats->lock_fail,
 721                    stats->unlock, stats->unlock_fail,
 722                    stats->target, stats->target_fail,
 723                    stats->alloc, stats->alloc_fail,
 724                    stats->sleep_alloc, stats->sleep_alloc_fail,
 725                    stats->free,
 726                    stats->refused_alloc, stats->refused_free);
 727
 728         return 0;
 729 }
 730
 731 static int vmballoon_debug_open(struct inode *inode, struct file *file)
 732 {
 733         return single_open(file, vmballoon_debug_show, inode->i_private);
 734 }
 735
 736 static const struct file_operations vmballoon_debug_fops = {
 737         .owner          = THIS_MODULE,
 738         .open           = vmballoon_debug_open,
 739         .read           = seq_read,
 740         .llseek         = seq_lseek,
 741         .release        = single_release,
 742 };
 743
 744 static int __init vmballoon_debugfs_init(struct vmballoon *b)
 745 {
 746         int error;
 747
 748         b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
 749                                            &vmballoon_debug_fops);
 750         if (IS_ERR(b->dbg_entry)) {
 751                 error = PTR_ERR(b->dbg_entry);
 752                 pr_err("failed to create debugfs entry, error: %d\n", error);
 753                 return error;
 754         }
 755
 756         return 0;
 757 }
 758
 759 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
 760 {
 761         debugfs_remove(b->dbg_entry);
 762 }
 763
 764 #else
 765
 766 static inline int vmballoon_debugfs_init(struct vmballoon *b)
 767 {
 768         return 0;
 769 }
 770
 771 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
 772 {
 773 }
 774
 775 #endif  /* CONFIG_DEBUG_FS */
 776
 777 static int __init vmballoon_init(void)
 778 {
 779         int error;
 780
 781         /*
 782          * Check if we are running on VMware's hypervisor and bail out
 783          * if we are not.
 784          */
 785         if (x86_hyper != &x86_hyper_vmware)
 786                 return -ENODEV;
 787
 788         vmballoon_wq = create_freezable_workqueue("vmmemctl");
 789         if (!vmballoon_wq) {
 790                 pr_err("failed to create workqueue\n");
 791                 return -ENOMEM;
 792         }
 793
 794         INIT_LIST_HEAD(&balloon.pages);
 795         INIT_LIST_HEAD(&balloon.refused_pages);
 796
 797         /* initialize rates */
 798         balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
 799         balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
 800
 801         INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
 802
 803         /*
 804          * Start balloon.
 805          */
 806         if (!vmballoon_send_start(&balloon)) {
 807                 pr_err("failed to send start command to the host\n");
 808                 error = -EIO;
 809                 goto fail;
 810         }
 811
 812         if (!vmballoon_send_guest_id(&balloon)) {
 813                 pr_err("failed to send guest ID to the host\n");
 814                 error = -EIO;
 815                 goto fail;
 816         }
 817
 818         error = vmballoon_debugfs_init(&balloon);
 819         if (error)
 820                 goto fail;
 821
 822         queue_delayed_work(vmballoon_wq, &balloon.dwork, 0);
 823
 824         return 0;
 825
 826 fail:
 827         destroy_workqueue(vmballoon_wq);
 828         return error;
 829 }
 830 module_init(vmballoon_init);
 831
 832 static void __exit vmballoon_exit(void)
 833 {
 834         cancel_delayed_work_sync(&balloon.dwork);
 835         destroy_workqueue(vmballoon_wq);
 836
 837         vmballoon_debugfs_exit(&balloon);
 838
 839         /*
 840          * Deallocate all reserved memory, and reset connection with monitor.
 841          * Reset connection before deallocating memory to avoid potential for
 842          * additional spurious resets from guest touching deallocated pages.
 843          */
 844         vmballoon_send_start(&balloon);
 845         vmballoon_pop(&balloon);
 846 }
 847 module_exit(vmballoon_exit);