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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
47 MODULE_AUTHOR("VMware, Inc.");
48 MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
49 MODULE_VERSION("1.2.1.3-k");
50 MODULE_ALIAS("dmi:*:svnVMware*:*");
51 MODULE_ALIAS("vmware_vmmemctl");
52 MODULE_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
152 struct 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
182 struct 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
218 static struct vmballoon balloon;
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 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 */
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 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 */
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 /*
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
690 static 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
736 static int vmballoon_debug_open(struct inode *inode, struct file *file)
737 {
738 return single_open(file, vmballoon_debug_show, inode->i_private);
739 }
740
741 static 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
749 static 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
764 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
765 {
766 debugfs_remove(b->dbg_entry);
767 }
768
769 #else
770
771 static inline int vmballoon_debugfs_init(struct vmballoon *b)
772 {
773 return 0;
774 }
775
776 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
777 {
778 }
779
780 #endif /* CONFIG_DEBUG_FS */
781
782 static 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 }
823 module_init(vmballoon_init);
824
825 static 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 }
839 module_exit(vmballoon_exit);