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-rw-r--r--drivers/misc/vmware_balloon.c832
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diff --git a/drivers/misc/vmware_balloon.c b/drivers/misc/vmware_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: 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/vmware.h>
45
46MODULE_AUTHOR("VMware, Inc.");
47MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
48MODULE_VERSION("1.2.1.0-K");
49MODULE_ALIAS("dmi:*:svnVMware*:*");
50MODULE_ALIAS("vmware_vmmemctl");
51MODULE_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
105/*
106 * Hypervisor communication port definitions.
107 */
108#define VMW_BALLOON_HV_PORT 0x5670
109#define VMW_BALLOON_HV_MAGIC 0x456c6d6f
110#define VMW_BALLOON_PROTOCOL_VERSION 2
111#define VMW_BALLOON_GUEST_ID 1 /* Linux */
112
113#define VMW_BALLOON_CMD_START 0
114#define VMW_BALLOON_CMD_GET_TARGET 1
115#define VMW_BALLOON_CMD_LOCK 2
116#define VMW_BALLOON_CMD_UNLOCK 3
117#define VMW_BALLOON_CMD_GUEST_ID 4
118
119/* error codes */
120#define VMW_BALLOON_SUCCESS 0
121#define VMW_BALLOON_FAILURE -1
122#define VMW_BALLOON_ERROR_CMD_INVALID 1
123#define VMW_BALLOON_ERROR_PPN_INVALID 2
124#define VMW_BALLOON_ERROR_PPN_LOCKED 3
125#define VMW_BALLOON_ERROR_PPN_UNLOCKED 4
126#define VMW_BALLOON_ERROR_PPN_PINNED 5
127#define VMW_BALLOON_ERROR_PPN_NOTNEEDED 6
128#define VMW_BALLOON_ERROR_RESET 7
129#define VMW_BALLOON_ERROR_BUSY 8
130
131#define VMWARE_BALLOON_CMD(cmd, data, result) \
132({ \
133 unsigned long __stat, __dummy1, __dummy2; \
134 __asm__ __volatile__ ("inl (%%dx)" : \
135 "=a"(__stat), \
136 "=c"(__dummy1), \
137 "=d"(__dummy2), \
138 "=b"(result) : \
139 "0"(VMW_BALLOON_HV_MAGIC), \
140 "1"(VMW_BALLOON_CMD_##cmd), \
141 "2"(VMW_BALLOON_HV_PORT), \
142 "3"(data) : \
143 "memory"); \
144 result &= -1UL; \
145 __stat & -1UL; \
146})
147
148#ifdef CONFIG_DEBUG_FS
149struct vmballoon_stats {
150 unsigned int timer;
151
152 /* allocation statustics */
153 unsigned int alloc;
154 unsigned int alloc_fail;
155 unsigned int sleep_alloc;
156 unsigned int sleep_alloc_fail;
157 unsigned int refused_alloc;
158 unsigned int refused_free;
159 unsigned int free;
160
161 /* monitor operations */
162 unsigned int lock;
163 unsigned int lock_fail;
164 unsigned int unlock;
165 unsigned int unlock_fail;
166 unsigned int target;
167 unsigned int target_fail;
168 unsigned int start;
169 unsigned int start_fail;
170 unsigned int guest_type;
171 unsigned int guest_type_fail;
172};
173
174#define STATS_INC(stat) (stat)++
175#else
176#define STATS_INC(stat)
177#endif
178
179struct vmballoon {
180
181 /* list of reserved physical pages */
182 struct list_head pages;
183
184 /* transient list of non-balloonable pages */
185 struct list_head refused_pages;
186
187 /* balloon size in pages */
188 unsigned int size;
189 unsigned int target;
190
191 /* reset flag */
192 bool reset_required;
193
194 /* adjustment rates (pages per second) */
195 unsigned int rate_alloc;
196 unsigned int rate_free;
197
198 /* slowdown page allocations for next few cycles */
199 unsigned int slow_allocation_cycles;
200
201#ifdef CONFIG_DEBUG_FS
202 /* statistics */
203 struct vmballoon_stats stats;
204
205 /* debugfs file exporting statistics */
206 struct dentry *dbg_entry;
207#endif
208
209 struct sysinfo sysinfo;
210
211 struct delayed_work dwork;
212};
213
214static struct vmballoon balloon;
215static struct workqueue_struct *vmballoon_wq;
216
217/*
218 * Send "start" command to the host, communicating supported version
219 * of the protocol.
220 */
221static bool vmballoon_send_start(struct vmballoon *b)
222{
223 unsigned long status, dummy;
224
225 STATS_INC(b->stats.start);
226
227 status = VMWARE_BALLOON_CMD(START, VMW_BALLOON_PROTOCOL_VERSION, dummy);
228 if (status == VMW_BALLOON_SUCCESS)
229 return true;
230
231 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
232 STATS_INC(b->stats.start_fail);
233 return false;
234}
235
236static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
237{
238 switch (status) {
239 case VMW_BALLOON_SUCCESS:
240 return true;
241
242 case VMW_BALLOON_ERROR_RESET:
243 b->reset_required = true;
244 /* fall through */
245
246 default:
247 return false;
248 }
249}
250
251/*
252 * Communicate guest type to the host so that it can adjust ballooning
253 * algorithm to the one most appropriate for the guest. This command
254 * is normally issued after sending "start" command and is part of
255 * standard reset sequence.
256 */
257static bool vmballoon_send_guest_id(struct vmballoon *b)
258{
259 unsigned long status, dummy;
260
261 status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy);
262
263 STATS_INC(b->stats.guest_type);
264
265 if (vmballoon_check_status(b, status))
266 return true;
267
268 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
269 STATS_INC(b->stats.guest_type_fail);
270 return false;
271}
272
273/*
274 * Retrieve desired balloon size from the host.
275 */
276static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
277{
278 unsigned long status;
279 unsigned long target;
280 unsigned long limit;
281 u32 limit32;
282
283 /*
284 * si_meminfo() is cheap. Moreover, we want to provide dynamic
285 * max balloon size later. So let us call si_meminfo() every
286 * iteration.
287 */
288 si_meminfo(&b->sysinfo);
289 limit = b->sysinfo.totalram;
290
291 /* Ensure limit fits in 32-bits */
292 limit32 = (u32)limit;
293 if (limit != limit32)
294 return false;
295
296 /* update stats */
297 STATS_INC(b->stats.target);
298
299 status = VMWARE_BALLOON_CMD(GET_TARGET, limit, target);
300 if (vmballoon_check_status(b, status)) {
301 *new_target = target;
302 return true;
303 }
304
305 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
306 STATS_INC(b->stats.target_fail);
307 return false;
308}
309
310/*
311 * Notify the host about allocated page so that host can use it without
312 * fear that guest will need it. Host may reject some pages, we need to
313 * check the return value and maybe submit a different page.
314 */
315static bool vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn)
316{
317 unsigned long status, dummy;
318 u32 pfn32;
319
320 pfn32 = (u32)pfn;
321 if (pfn32 != pfn)
322 return false;
323
324 STATS_INC(b->stats.lock);
325
326 status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy);
327 if (vmballoon_check_status(b, status))
328 return true;
329
330 pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
331 STATS_INC(b->stats.lock_fail);
332 return false;
333}
334
335/*
336 * Notify the host that guest intends to release given page back into
337 * the pool of available (to the guest) pages.
338 */
339static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn)
340{
341 unsigned long status, dummy;
342 u32 pfn32;
343
344 pfn32 = (u32)pfn;
345 if (pfn32 != pfn)
346 return false;
347
348 STATS_INC(b->stats.unlock);
349
350 status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy);
351 if (vmballoon_check_status(b, status))
352 return true;
353
354 pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
355 STATS_INC(b->stats.unlock_fail);
356 return false;
357}
358
359/*
360 * Quickly release all pages allocated for the balloon. This function is
361 * called when host decides to "reset" balloon for one reason or another.
362 * Unlike normal "deflate" we do not (shall not) notify host of the pages
363 * being released.
364 */
365static void vmballoon_pop(struct vmballoon *b)
366{
367 struct page *page, *next;
368 unsigned int count = 0;
369
370 list_for_each_entry_safe(page, next, &b->pages, lru) {
371 list_del(&page->lru);
372 __free_page(page);
373 STATS_INC(b->stats.free);
374 b->size--;
375
376 if (++count >= b->rate_free) {
377 count = 0;
378 cond_resched();
379 }
380 }
381}
382
383/*
384 * Perform standard reset sequence by popping the balloon (in case it
385 * is not empty) and then restarting protocol. This operation normally
386 * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
387 */
388static void vmballoon_reset(struct vmballoon *b)
389{
390 /* free all pages, skipping monitor unlock */
391 vmballoon_pop(b);
392
393 if (vmballoon_send_start(b)) {
394 b->reset_required = false;
395 if (!vmballoon_send_guest_id(b))
396 pr_err("failed to send guest ID to the host\n");
397 }
398}
399
400/*
401 * Allocate (or reserve) a page for the balloon and notify the host. If host
402 * refuses the page put it on "refuse" list and allocate another one until host
403 * is satisfied. "Refused" pages are released at the end of inflation cycle
404 * (when we allocate b->rate_alloc pages).
405 */
406static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
407{
408 struct page *page;
409 gfp_t flags;
410 bool locked = false;
411
412 do {
413 if (!can_sleep)
414 STATS_INC(b->stats.alloc);
415 else
416 STATS_INC(b->stats.sleep_alloc);
417
418 flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
419 page = alloc_page(flags);
420 if (!page) {
421 if (!can_sleep)
422 STATS_INC(b->stats.alloc_fail);
423 else
424 STATS_INC(b->stats.sleep_alloc_fail);
425 return -ENOMEM;
426 }
427
428 /* inform monitor */
429 locked = vmballoon_send_lock_page(b, page_to_pfn(page));
430 if (!locked) {
431 if (b->reset_required) {
432 __free_page(page);
433 return -EIO;
434 }
435
436 /* place on list of non-balloonable pages, retry allocation */
437 list_add(&page->lru, &b->refused_pages);
438 STATS_INC(b->stats.refused_alloc);
439 }
440 } while (!locked);
441
442 /* track allocated page */
443 list_add(&page->lru, &b->pages);
444
445 /* update balloon size */
446 b->size++;
447
448 return 0;
449}
450
451/*
452 * Release the page allocated for the balloon. Note that we first notify
453 * the host so it can make sure the page will be available for the guest
454 * to use, if needed.
455 */
456static int vmballoon_release_page(struct vmballoon *b, struct page *page)
457{
458 if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
459 return -EIO;
460
461 list_del(&page->lru);
462
463 /* deallocate page */
464 __free_page(page);
465 STATS_INC(b->stats.free);
466
467 /* update balloon size */
468 b->size--;
469
470 return 0;
471}
472
473/*
474 * Release pages that were allocated while attempting to inflate the
475 * balloon but were refused by the host for one reason or another.
476 */
477static void vmballoon_release_refused_pages(struct vmballoon *b)
478{
479 struct page *page, *next;
480
481 list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
482 list_del(&page->lru);
483 __free_page(page);
484 STATS_INC(b->stats.refused_free);
485 }
486}
487
488/*
489 * Inflate the balloon towards its target size. Note that we try to limit
490 * the rate of allocation to make sure we are not choking the rest of the
491 * system.
492 */
493static void vmballoon_inflate(struct vmballoon *b)
494{
495 unsigned int goal;
496 unsigned int rate;
497 unsigned int i;
498 unsigned int allocations = 0;
499 int error = 0;
500 bool alloc_can_sleep = false;
501
502 pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
503
504 /*
505 * First try NOSLEEP page allocations to inflate balloon.
506 *
507 * If we do not throttle nosleep allocations, we can drain all
508 * free pages in the guest quickly (if the balloon target is high).
509 * As a side-effect, draining free pages helps to inform (force)
510 * the guest to start swapping if balloon target is not met yet,
511 * which is a desired behavior. However, balloon driver can consume
512 * all available CPU cycles if too many pages are allocated in a
513 * second. Therefore, we throttle nosleep allocations even when
514 * the guest is not under memory pressure. OTOH, if we have already
515 * predicted that the guest is under memory pressure, then we
516 * slowdown page allocations considerably.
517 */
518
519 goal = b->target - b->size;
520 /*
521 * Start with no sleep allocation rate which may be higher
522 * than sleeping allocation rate.
523 */
524 rate = b->slow_allocation_cycles ?
525 b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
526
527 pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
528 __func__, goal, rate, b->rate_alloc);
529
530 for (i = 0; i < goal; i++) {
531
532 error = vmballoon_reserve_page(b, alloc_can_sleep);
533 if (error) {
534 if (error != -ENOMEM) {
535 /*
536 * Not a page allocation failure, stop this
537 * cycle. Maybe we'll get new target from
538 * the host soon.
539 */
540 break;
541 }
542
543 if (alloc_can_sleep) {
544 /*
545 * CANSLEEP page allocation failed, so guest
546 * is under severe memory pressure. Quickly
547 * decrease allocation rate.
548 */
549 b->rate_alloc = max(b->rate_alloc / 2,
550 VMW_BALLOON_RATE_ALLOC_MIN);
551 break;
552 }
553
554 /*
555 * NOSLEEP page allocation failed, so the guest is
556 * under memory pressure. Let us slow down page
557 * allocations for next few cycles so that the guest
558 * gets out of memory pressure. Also, if we already
559 * allocated b->rate_alloc pages, let's pause,
560 * otherwise switch to sleeping allocations.
561 */
562 b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
563
564 if (i >= b->rate_alloc)
565 break;
566
567 alloc_can_sleep = true;
568 /* Lower rate for sleeping allocations. */
569 rate = b->rate_alloc;
570 }
571
572 if (++allocations > VMW_BALLOON_YIELD_THRESHOLD) {
573 cond_resched();
574 allocations = 0;
575 }
576
577 if (i >= rate) {
578 /* We allocated enough pages, let's take a break. */
579 break;
580 }
581 }
582
583 /*
584 * We reached our goal without failures so try increasing
585 * allocation rate.
586 */
587 if (error == 0 && i >= b->rate_alloc) {
588 unsigned int mult = i / b->rate_alloc;
589
590 b->rate_alloc =
591 min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
592 VMW_BALLOON_RATE_ALLOC_MAX);
593 }
594
595 vmballoon_release_refused_pages(b);
596}
597
598/*
599 * Decrease the size of the balloon allowing guest to use more memory.
600 */
601static void vmballoon_deflate(struct vmballoon *b)
602{
603 struct page *page, *next;
604 unsigned int i = 0;
605 unsigned int goal;
606 int error;
607
608 pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
609
610 /* limit deallocation rate */
611 goal = min(b->size - b->target, b->rate_free);
612
613 pr_debug("%s - goal: %d, rate: %d\n", __func__, goal, b->rate_free);
614
615 /* free pages to reach target */
616 list_for_each_entry_safe(page, next, &b->pages, lru) {
617 error = vmballoon_release_page(b, page);
618 if (error) {
619 /* quickly decrease rate in case of error */
620 b->rate_free = max(b->rate_free / 2,
621 VMW_BALLOON_RATE_FREE_MIN);
622 return;
623 }
624
625 if (++i >= goal)
626 break;
627 }
628
629 /* slowly increase rate if there were no errors */
630 b->rate_free = min(b->rate_free + VMW_BALLOON_RATE_FREE_INC,
631 VMW_BALLOON_RATE_FREE_MAX);
632}
633
634/*
635 * Balloon work function: reset protocol, if needed, get the new size and
636 * adjust balloon as needed. Repeat in 1 sec.
637 */
638static void vmballoon_work(struct work_struct *work)
639{
640 struct delayed_work *dwork = to_delayed_work(work);
641 struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
642 unsigned int target;
643
644 STATS_INC(b->stats.timer);
645
646 if (b->reset_required)
647 vmballoon_reset(b);
648
649 if (b->slow_allocation_cycles > 0)
650 b->slow_allocation_cycles--;
651
652 if (vmballoon_send_get_target(b, &target)) {
653 /* update target, adjust size */
654 b->target = target;
655
656 if (b->size < target)
657 vmballoon_inflate(b);
658 else if (b->size > target)
659 vmballoon_deflate(b);
660 }
661
662 queue_delayed_work(vmballoon_wq, dwork, round_jiffies_relative(HZ));
663}
664
665/*
666 * DEBUGFS Interface
667 */
668#ifdef CONFIG_DEBUG_FS
669
670static int vmballoon_debug_show(struct seq_file *f, void *offset)
671{
672 struct vmballoon *b = f->private;
673 struct vmballoon_stats *stats = &b->stats;
674
675 /* format size info */
676 seq_printf(f,
677 "target: %8d pages\n"
678 "current: %8d pages\n",
679 b->target, b->size);
680
681 /* format rate info */
682 seq_printf(f,
683 "rateNoSleepAlloc: %8d pages/sec\n"
684 "rateSleepAlloc: %8d pages/sec\n"
685 "rateFree: %8d pages/sec\n",
686 VMW_BALLOON_NOSLEEP_ALLOC_MAX,
687 b->rate_alloc, b->rate_free);
688
689 seq_printf(f,
690 "\n"
691 "timer: %8u\n"
692 "start: %8u (%4u failed)\n"
693 "guestType: %8u (%4u failed)\n"
694 "lock: %8u (%4u failed)\n"
695 "unlock: %8u (%4u failed)\n"
696 "target: %8u (%4u failed)\n"
697 "primNoSleepAlloc: %8u (%4u failed)\n"
698 "primCanSleepAlloc: %8u (%4u failed)\n"
699 "primFree: %8u\n"
700 "errAlloc: %8u\n"
701 "errFree: %8u\n",
702 stats->timer,
703 stats->start, stats->start_fail,
704 stats->guest_type, stats->guest_type_fail,
705 stats->lock, stats->lock_fail,
706 stats->unlock, stats->unlock_fail,
707 stats->target, stats->target_fail,
708 stats->alloc, stats->alloc_fail,
709 stats->sleep_alloc, stats->sleep_alloc_fail,
710 stats->free,
711 stats->refused_alloc, stats->refused_free);
712
713 return 0;
714}
715
716static int vmballoon_debug_open(struct inode *inode, struct file *file)
717{
718 return single_open(file, vmballoon_debug_show, inode->i_private);
719}
720
721static const struct file_operations vmballoon_debug_fops = {
722 .owner = THIS_MODULE,
723 .open = vmballoon_debug_open,
724 .read = seq_read,
725 .llseek = seq_lseek,
726 .release = single_release,
727};
728
729static int __init vmballoon_debugfs_init(struct vmballoon *b)
730{
731 int error;
732
733 b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
734 &vmballoon_debug_fops);
735 if (IS_ERR(b->dbg_entry)) {
736 error = PTR_ERR(b->dbg_entry);
737 pr_err("failed to create debugfs entry, error: %d\n", error);
738 return error;
739 }
740
741 return 0;
742}
743
744static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
745{
746 debugfs_remove(b->dbg_entry);
747}
748
749#else
750
751static inline int vmballoon_debugfs_init(struct vmballoon *b)
752{
753 return 0;
754}
755
756static inline void vmballoon_debugfs_exit(struct vmballoon *b)
757{
758}
759
760#endif /* CONFIG_DEBUG_FS */
761
762static int __init vmballoon_init(void)
763{
764 int error;
765
766 /*
767 * Check if we are running on VMware's hypervisor and bail out
768 * if we are not.
769 */
770 if (!vmware_platform())
771 return -ENODEV;
772
773 vmballoon_wq = create_freezeable_workqueue("vmmemctl");
774 if (!vmballoon_wq) {
775 pr_err("failed to create workqueue\n");
776 return -ENOMEM;
777 }
778
779 INIT_LIST_HEAD(&balloon.pages);
780 INIT_LIST_HEAD(&balloon.refused_pages);
781
782 /* initialize rates */
783 balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
784 balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
785
786 INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
787
788 /*
789 * Start balloon.
790 */
791 if (!vmballoon_send_start(&balloon)) {
792 pr_err("failed to send start command to the host\n");
793 error = -EIO;
794 goto fail;
795 }
796
797 if (!vmballoon_send_guest_id(&balloon)) {
798 pr_err("failed to send guest ID to the host\n");
799 error = -EIO;
800 goto fail;
801 }
802
803 error = vmballoon_debugfs_init(&balloon);
804 if (error)
805 goto fail;
806
807 queue_delayed_work(vmballoon_wq, &balloon.dwork, 0);
808
809 return 0;
810
811fail:
812 destroy_workqueue(vmballoon_wq);
813 return error;
814}
815module_init(vmballoon_init);
816
817static void __exit vmballoon_exit(void)
818{
819 cancel_delayed_work_sync(&balloon.dwork);
820 destroy_workqueue(vmballoon_wq);
821
822 vmballoon_debugfs_exit(&balloon);
823
824 /*
825 * Deallocate all reserved memory, and reset connection with monitor.
826 * Reset connection before deallocating memory to avoid potential for
827 * additional spurious resets from guest touching deallocated pages.
828 */
829 vmballoon_send_start(&balloon);
830 vmballoon_pop(&balloon);
831}
832module_exit(vmballoon_exit);