linux/drivers/misc/vmw_balloon.c
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   1/*
   2 * VMware Balloon driver.
   3 *
   4 * Copyright (C) 2000-2010, VMware, Inc. All Rights Reserved.
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms of the GNU General Public License as published by the
   8 * Free Software Foundation; version 2 of the License and no later version.
   9 *
  10 * This program is distributed in the hope that it will be useful, but
  11 * WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  13 * NON INFRINGEMENT.  See the GNU General Public License for more
  14 * details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19 *
  20 * Maintained by:       Xavier Deguillard <xdeguillard@vmware.com>
  21 *                      Philip Moltmann <moltmann@vmware.com>
  22 */
  23
  24/*
  25 * This is VMware physical memory management driver for Linux. The driver
  26 * acts like a "balloon" that can be inflated to reclaim physical pages by
  27 * reserving them in the guest and invalidating them in the monitor,
  28 * freeing up the underlying machine pages so they can be allocated to
  29 * other guests.  The balloon can also be deflated to allow the guest to
  30 * use more physical memory. Higher level policies can control the sizes
  31 * of balloons in VMs in order to manage physical memory resources.
  32 */
  33
  34//#define DEBUG
  35#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37#include <linux/types.h>
  38#include <linux/kernel.h>
  39#include <linux/mm.h>
  40#include <linux/sched.h>
  41#include <linux/module.h>
  42#include <linux/workqueue.h>
  43#include <linux/debugfs.h>
  44#include <linux/seq_file.h>
  45#include <asm/hypervisor.h>
  46
  47MODULE_AUTHOR("VMware, Inc.");
  48MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
  49MODULE_VERSION("1.2.1.3-k");
  50MODULE_ALIAS("dmi:*:svnVMware*:*");
  51MODULE_ALIAS("vmware_vmmemctl");
  52MODULE_LICENSE("GPL");
  53
  54/*
  55 * Various constants controlling rate of inflaint/deflating balloon,
  56 * measured in pages.
  57 */
  58
  59/*
  60 * Rate of allocating memory when there is no memory pressure
  61 * (driver performs non-sleeping allocations).
  62 */
  63#define VMW_BALLOON_NOSLEEP_ALLOC_MAX   16384U
  64
  65/*
  66 * Rates of memory allocaton when guest experiences memory pressure
  67 * (driver performs sleeping allocations).
  68 */
  69#define VMW_BALLOON_RATE_ALLOC_MIN      512U
  70#define VMW_BALLOON_RATE_ALLOC_MAX      2048U
  71#define VMW_BALLOON_RATE_ALLOC_INC      16U
  72
  73/*
  74 * Rates for releasing pages while deflating balloon.
  75 */
  76#define VMW_BALLOON_RATE_FREE_MIN       512U
  77#define VMW_BALLOON_RATE_FREE_MAX       16384U
  78#define VMW_BALLOON_RATE_FREE_INC       16U
  79
  80/*
  81 * When guest is under memory pressure, use a reduced page allocation
  82 * rate for next several cycles.
  83 */
  84#define VMW_BALLOON_SLOW_CYCLES         4
  85
  86/*
  87 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't
  88 * allow wait (__GFP_WAIT) for NOSLEEP page allocations. Use
  89 * __GFP_NOWARN, to suppress page allocation failure warnings.
  90 */
  91#define VMW_PAGE_ALLOC_NOSLEEP          (__GFP_HIGHMEM|__GFP_NOWARN)
  92
  93/*
  94 * Use GFP_HIGHUSER when executing in a separate kernel thread
  95 * context and allocation can sleep.  This is less stressful to
  96 * the guest memory system, since it allows the thread to block
  97 * while memory is reclaimed, and won't take pages from emergency
  98 * low-memory pools.
  99 */
 100#define VMW_PAGE_ALLOC_CANSLEEP         (GFP_HIGHUSER)
 101
 102/* Maximum number of page allocations without yielding processor */
 103#define VMW_BALLOON_YIELD_THRESHOLD     1024
 104
 105/* Maximum number of refused pages we accumulate during inflation cycle */
 106#define VMW_BALLOON_MAX_REFUSED         16
 107
 108/*
 109 * Hypervisor communication port definitions.
 110 */
 111#define VMW_BALLOON_HV_PORT             0x5670
 112#define VMW_BALLOON_HV_MAGIC            0x456c6d6f
 113#define VMW_BALLOON_PROTOCOL_VERSION    2
 114#define VMW_BALLOON_GUEST_ID            1       /* Linux */
 115
 116#define VMW_BALLOON_CMD_START           0
 117#define VMW_BALLOON_CMD_GET_TARGET      1
 118#define VMW_BALLOON_CMD_LOCK            2
 119#define VMW_BALLOON_CMD_UNLOCK          3
 120#define VMW_BALLOON_CMD_GUEST_ID        4
 121
 122/* error codes */
 123#define VMW_BALLOON_SUCCESS             0
 124#define VMW_BALLOON_FAILURE             -1
 125#define VMW_BALLOON_ERROR_CMD_INVALID   1
 126#define VMW_BALLOON_ERROR_PPN_INVALID   2
 127#define VMW_BALLOON_ERROR_PPN_LOCKED    3
 128#define VMW_BALLOON_ERROR_PPN_UNLOCKED  4
 129#define VMW_BALLOON_ERROR_PPN_PINNED    5
 130#define VMW_BALLOON_ERROR_PPN_NOTNEEDED 6
 131#define VMW_BALLOON_ERROR_RESET         7
 132#define VMW_BALLOON_ERROR_BUSY          8
 133
 134#define VMWARE_BALLOON_CMD(cmd, data, result)           \
 135({                                                      \
 136        unsigned long __stat, __dummy1, __dummy2;       \
 137        __asm__ __volatile__ ("inl %%dx" :              \
 138                "=a"(__stat),                           \
 139                "=c"(__dummy1),                         \
 140                "=d"(__dummy2),                         \
 141                "=b"(result) :                          \
 142                "0"(VMW_BALLOON_HV_MAGIC),              \
 143                "1"(VMW_BALLOON_CMD_##cmd),             \
 144                "2"(VMW_BALLOON_HV_PORT),               \
 145                "3"(data) :                             \
 146                "memory");                              \
 147        result &= -1UL;                                 \
 148        __stat & -1UL;                                  \
 149})
 150
 151#ifdef CONFIG_DEBUG_FS
 152struct vmballoon_stats {
 153        unsigned int timer;
 154
 155        /* allocation statistics */
 156        unsigned int alloc;
 157        unsigned int alloc_fail;
 158        unsigned int sleep_alloc;
 159        unsigned int sleep_alloc_fail;
 160        unsigned int refused_alloc;
 161        unsigned int refused_free;
 162        unsigned int free;
 163
 164        /* monitor operations */
 165        unsigned int lock;
 166        unsigned int lock_fail;
 167        unsigned int unlock;
 168        unsigned int unlock_fail;
 169        unsigned int target;
 170        unsigned int target_fail;
 171        unsigned int start;
 172        unsigned int start_fail;
 173        unsigned int guest_type;
 174        unsigned int guest_type_fail;
 175};
 176
 177#define STATS_INC(stat) (stat)++
 178#else
 179#define STATS_INC(stat)
 180#endif
 181
 182struct vmballoon {
 183
 184        /* list of reserved physical pages */
 185        struct list_head pages;
 186
 187        /* transient list of non-balloonable pages */
 188        struct list_head refused_pages;
 189        unsigned int n_refused_pages;
 190
 191        /* balloon size in pages */
 192        unsigned int size;
 193        unsigned int target;
 194
 195        /* reset flag */
 196        bool reset_required;
 197
 198        /* adjustment rates (pages per second) */
 199        unsigned int rate_alloc;
 200        unsigned int rate_free;
 201
 202        /* slowdown page allocations for next few cycles */
 203        unsigned int slow_allocation_cycles;
 204
 205#ifdef CONFIG_DEBUG_FS
 206        /* statistics */
 207        struct vmballoon_stats stats;
 208
 209        /* debugfs file exporting statistics */
 210        struct dentry *dbg_entry;
 211#endif
 212
 213        struct sysinfo sysinfo;
 214
 215        struct delayed_work dwork;
 216};
 217
 218static struct vmballoon balloon;
 219
 220/*
 221 * Send "start" command to the host, communicating supported version
 222 * of the protocol.
 223 */
 224static 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
 239static 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 */
 260static 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 */
 279static 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 */
 318static int 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 -1;
 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 0;
 333
 334        pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 335        STATS_INC(b->stats.lock_fail);
 336        return 1;
 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 */
 343static 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 */
 369static 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 */
 392static 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 */
 410static 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        int locked;
 416        flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
 417
 418        do {
 419                if (!can_sleep)
 420                        STATS_INC(b->stats.alloc);
 421                else
 422                        STATS_INC(b->stats.sleep_alloc);
 423
 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 > 0) {
 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 != 0);
 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 */
 469static 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 */
 490static 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 */
 508static 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 */
 616static 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 */
 653static void vmballoon_work(struct work_struct *work)
 654{
 655        struct delayed_work *dwork = to_delayed_work(work);
 656        struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
 657        unsigned int target;
 658
 659        STATS_INC(b->stats.timer);
 660
 661        if (b->reset_required)
 662                vmballoon_reset(b);
 663
 664        if (b->slow_allocation_cycles > 0)
 665                b->slow_allocation_cycles--;
 666
 667        if (vmballoon_send_get_target(b, &target)) {
 668                /* update target, adjust size */
 669                b->target = target;
 670
 671                if (b->size < target)
 672                        vmballoon_inflate(b);
 673                else if (b->size > target)
 674                        vmballoon_deflate(b);
 675        }
 676
 677        /*
 678         * We are using a freezable workqueue so that balloon operations are
 679         * stopped while the system transitions to/from sleep/hibernation.
 680         */
 681        queue_delayed_work(system_freezable_wq,
 682                           dwork, round_jiffies_relative(HZ));
 683}
 684
 685/*
 686 * DEBUGFS Interface
 687 */
 688#ifdef CONFIG_DEBUG_FS
 689
 690static int vmballoon_debug_show(struct seq_file *f, void *offset)
 691{
 692        struct vmballoon *b = f->private;
 693        struct vmballoon_stats *stats = &b->stats;
 694
 695        /* format size info */
 696        seq_printf(f,
 697                   "target:             %8d pages\n"
 698                   "current:            %8d pages\n",
 699                   b->target, b->size);
 700
 701        /* format rate info */
 702        seq_printf(f,
 703                   "rateNoSleepAlloc:   %8d pages/sec\n"
 704                   "rateSleepAlloc:     %8d pages/sec\n"
 705                   "rateFree:           %8d pages/sec\n",
 706                   VMW_BALLOON_NOSLEEP_ALLOC_MAX,
 707                   b->rate_alloc, b->rate_free);
 708
 709        seq_printf(f,
 710                   "\n"
 711                   "timer:              %8u\n"
 712                   "start:              %8u (%4u failed)\n"
 713                   "guestType:          %8u (%4u failed)\n"
 714                   "lock:               %8u (%4u failed)\n"
 715                   "unlock:             %8u (%4u failed)\n"
 716                   "target:             %8u (%4u failed)\n"
 717                   "primNoSleepAlloc:   %8u (%4u failed)\n"
 718                   "primCanSleepAlloc:  %8u (%4u failed)\n"
 719                   "primFree:           %8u\n"
 720                   "errAlloc:           %8u\n"
 721                   "errFree:            %8u\n",
 722                   stats->timer,
 723                   stats->start, stats->start_fail,
 724                   stats->guest_type, stats->guest_type_fail,
 725                   stats->lock,  stats->lock_fail,
 726                   stats->unlock, stats->unlock_fail,
 727                   stats->target, stats->target_fail,
 728                   stats->alloc, stats->alloc_fail,
 729                   stats->sleep_alloc, stats->sleep_alloc_fail,
 730                   stats->free,
 731                   stats->refused_alloc, stats->refused_free);
 732
 733        return 0;
 734}
 735
 736static int vmballoon_debug_open(struct inode *inode, struct file *file)
 737{
 738        return single_open(file, vmballoon_debug_show, inode->i_private);
 739}
 740
 741static const struct file_operations vmballoon_debug_fops = {
 742        .owner          = THIS_MODULE,
 743        .open           = vmballoon_debug_open,
 744        .read           = seq_read,
 745        .llseek         = seq_lseek,
 746        .release        = single_release,
 747};
 748
 749static int __init vmballoon_debugfs_init(struct vmballoon *b)
 750{
 751        int error;
 752
 753        b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
 754                                           &vmballoon_debug_fops);
 755        if (IS_ERR(b->dbg_entry)) {
 756                error = PTR_ERR(b->dbg_entry);
 757                pr_err("failed to create debugfs entry, error: %d\n", error);
 758                return error;
 759        }
 760
 761        return 0;
 762}
 763
 764static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
 765{
 766        debugfs_remove(b->dbg_entry);
 767}
 768
 769#else
 770
 771static inline int vmballoon_debugfs_init(struct vmballoon *b)
 772{
 773        return 0;
 774}
 775
 776static inline void vmballoon_debugfs_exit(struct vmballoon *b)
 777{
 778}
 779
 780#endif  /* CONFIG_DEBUG_FS */
 781
 782static int __init vmballoon_init(void)
 783{
 784        int error;
 785
 786        /*
 787         * Check if we are running on VMware's hypervisor and bail out
 788         * if we are not.
 789         */
 790        if (x86_hyper != &x86_hyper_vmware)
 791                return -ENODEV;
 792
 793        INIT_LIST_HEAD(&balloon.pages);
 794        INIT_LIST_HEAD(&balloon.refused_pages);
 795
 796        /* initialize rates */
 797        balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
 798        balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
 799
 800        INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
 801
 802        /*
 803         * Start balloon.
 804         */
 805        if (!vmballoon_send_start(&balloon)) {
 806                pr_err("failed to send start command to the host\n");
 807                return -EIO;
 808        }
 809
 810        if (!vmballoon_send_guest_id(&balloon)) {
 811                pr_err("failed to send guest ID to the host\n");
 812                return -EIO;
 813        }
 814
 815        error = vmballoon_debugfs_init(&balloon);
 816        if (error)
 817                return error;
 818
 819        queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
 820
 821        return 0;
 822}
 823module_init(vmballoon_init);
 824
 825static void __exit vmballoon_exit(void)
 826{
 827        cancel_delayed_work_sync(&balloon.dwork);
 828
 829        vmballoon_debugfs_exit(&balloon);
 830
 831        /*
 832         * Deallocate all reserved memory, and reset connection with monitor.
 833         * Reset connection before deallocating memory to avoid potential for
 834         * additional spurious resets from guest touching deallocated pages.
 835         */
 836        vmballoon_send_start(&balloon);
 837        vmballoon_pop(&balloon);
 838}
 839module_exit(vmballoon_exit);
 840