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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/hypervisor.h>
45
46MODULE_AUTHOR("VMware, Inc.");
47MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
48MODULE_VERSION("1.2.1.3-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/* 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
151struct 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
181struct 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
217static struct vmballoon balloon;
218
219/*
220 * Send "start" command to the host, communicating supported version
221 * of the protocol.
222 */
223static bool vmballoon_send_start(struct vmballoon *b)
224{
225 unsigned long status, dummy;
226
227 STATS_INC(b->stats.start);
228
229 status = VMWARE_BALLOON_CMD(START, VMW_BALLOON_PROTOCOL_VERSION, dummy);
230 if (status == VMW_BALLOON_SUCCESS)
231 return true;
232
233 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
234 STATS_INC(b->stats.start_fail);
235 return false;
236}
237
238static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
239{
240 switch (status) {
241 case VMW_BALLOON_SUCCESS:
242 return true;
243
244 case VMW_BALLOON_ERROR_RESET:
245 b->reset_required = true;
246 /* fall through */
247
248 default:
249 return false;
250 }
251}
252
253/*
254 * Communicate guest type to the host so that it can adjust ballooning
255 * algorithm to the one most appropriate for the guest. This command
256 * is normally issued after sending "start" command and is part of
257 * standard reset sequence.
258 */
259static bool vmballoon_send_guest_id(struct vmballoon *b)
260{
261 unsigned long status, dummy;
262
263 status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy);
264
265 STATS_INC(b->stats.guest_type);
266
267 if (vmballoon_check_status(b, status))
268 return true;
269
270 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
271 STATS_INC(b->stats.guest_type_fail);
272 return false;
273}
274
275/*
276 * Retrieve desired balloon size from the host.
277 */
278static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
279{
280 unsigned long status;
281 unsigned long target;
282 unsigned long limit;
283 u32 limit32;
284
285 /*
286 * si_meminfo() is cheap. Moreover, we want to provide dynamic
287 * max balloon size later. So let us call si_meminfo() every
288 * iteration.
289 */
290 si_meminfo(&b->sysinfo);
291 limit = b->sysinfo.totalram;
292
293 /* Ensure limit fits in 32-bits */
294 limit32 = (u32)limit;
295 if (limit != limit32)
296 return false;
297
298 /* update stats */
299 STATS_INC(b->stats.target);
300
301 status = VMWARE_BALLOON_CMD(GET_TARGET, limit, target);
302 if (vmballoon_check_status(b, status)) {
303 *new_target = target;
304 return true;
305 }
306
307 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
308 STATS_INC(b->stats.target_fail);
309 return false;
310}
311
312/*
313 * Notify the host about allocated page so that host can use it without
314 * fear that guest will need it. Host may reject some pages, we need to
315 * check the return value and maybe submit a different page.
316 */
317static bool vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
318 unsigned int *hv_status)
319{
320 unsigned long status, dummy;
321 u32 pfn32;
322
323 pfn32 = (u32)pfn;
324 if (pfn32 != pfn)
325 return false;
326
327 STATS_INC(b->stats.lock);
328
329 *hv_status = status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy);
330 if (vmballoon_check_status(b, status))
331 return true;
332
333 pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
334 STATS_INC(b->stats.lock_fail);
335 return false;
336}
337
338/*
339 * Notify the host that guest intends to release given page back into
340 * the pool of available (to the guest) pages.
341 */
342static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn)
343{
344 unsigned long status, dummy;
345 u32 pfn32;
346
347 pfn32 = (u32)pfn;
348 if (pfn32 != pfn)
349 return false;
350
351 STATS_INC(b->stats.unlock);
352
353 status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy);
354 if (vmballoon_check_status(b, status))
355 return true;
356
357 pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
358 STATS_INC(b->stats.unlock_fail);
359 return false;
360}
361
362/*
363 * Quickly release all pages allocated for the balloon. This function is
364 * called when host decides to "reset" balloon for one reason or another.
365 * Unlike normal "deflate" we do not (shall not) notify host of the pages
366 * being released.
367 */
368static void vmballoon_pop(struct vmballoon *b)
369{
370 struct page *page, *next;
371 unsigned int count = 0;
372
373 list_for_each_entry_safe(page, next, &b->pages, lru) {
374 list_del(&page->lru);
375 __free_page(page);
376 STATS_INC(b->stats.free);
377 b->size--;
378
379 if (++count >= b->rate_free) {
380 count = 0;
381 cond_resched();
382 }
383 }
384}
385
386/*
387 * Perform standard reset sequence by popping the balloon (in case it
388 * is not empty) and then restarting protocol. This operation normally
389 * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
390 */
391static void vmballoon_reset(struct vmballoon *b)
392{
393 /* free all pages, skipping monitor unlock */
394 vmballoon_pop(b);
395
396 if (vmballoon_send_start(b)) {
397 b->reset_required = false;
398 if (!vmballoon_send_guest_id(b))
399 pr_err("failed to send guest ID to the host\n");
400 }
401}
402
403/*
404 * Allocate (or reserve) a page for the balloon and notify the host. If host
405 * refuses the page put it on "refuse" list and allocate another one until host
406 * is satisfied. "Refused" pages are released at the end of inflation cycle
407 * (when we allocate b->rate_alloc pages).
408 */
409static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
410{
411 struct page *page;
412 gfp_t flags;
413 unsigned int hv_status;
414 bool locked = false;
415
416 do {
417 if (!can_sleep)
418 STATS_INC(b->stats.alloc);
419 else
420 STATS_INC(b->stats.sleep_alloc);
421
422 flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
423 page = alloc_page(flags);
424 if (!page) {
425 if (!can_sleep)
426 STATS_INC(b->stats.alloc_fail);
427 else
428 STATS_INC(b->stats.sleep_alloc_fail);
429 return -ENOMEM;
430 }
431
432 /* inform monitor */
433 locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status);
434 if (!locked) {
435 STATS_INC(b->stats.refused_alloc);
436
437 if (hv_status == VMW_BALLOON_ERROR_RESET ||
438 hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED) {
439 __free_page(page);
440 return -EIO;
441 }
442
443 /*
444 * Place page on the list of non-balloonable pages
445 * and retry allocation, unless we already accumulated
446 * too many of them, in which case take a breather.
447 */
448 list_add(&page->lru, &b->refused_pages);
449 if (++b->n_refused_pages >= VMW_BALLOON_MAX_REFUSED)
450 return -EIO;
451 }
452 } while (!locked);
453
454 /* track allocated page */
455 list_add(&page->lru, &b->pages);
456
457 /* update balloon size */
458 b->size++;
459
460 return 0;
461}
462
463/*
464 * Release the page allocated for the balloon. Note that we first notify
465 * the host so it can make sure the page will be available for the guest
466 * to use, if needed.
467 */
468static int vmballoon_release_page(struct vmballoon *b, struct page *page)
469{
470 if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
471 return -EIO;
472
473 list_del(&page->lru);
474
475 /* deallocate page */
476 __free_page(page);
477 STATS_INC(b->stats.free);
478
479 /* update balloon size */
480 b->size--;
481
482 return 0;
483}
484
485/*
486 * Release pages that were allocated while attempting to inflate the
487 * balloon but were refused by the host for one reason or another.
488 */
489static void vmballoon_release_refused_pages(struct vmballoon *b)
490{
491 struct page *page, *next;
492
493 list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
494 list_del(&page->lru);
495 __free_page(page);
496 STATS_INC(b->stats.refused_free);
497 }
498
499 b->n_refused_pages = 0;
500}
501
502/*
503 * Inflate the balloon towards its target size. Note that we try to limit
504 * the rate of allocation to make sure we are not choking the rest of the
505 * system.
506 */
507static void vmballoon_inflate(struct vmballoon *b)
508{
509 unsigned int goal;
510 unsigned int rate;
511 unsigned int i;
512 unsigned int allocations = 0;
513 int error = 0;
514 bool alloc_can_sleep = false;
515
516 pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
517
518 /*
519 * First try NOSLEEP page allocations to inflate balloon.
520 *
521 * If we do not throttle nosleep allocations, we can drain all
522 * free pages in the guest quickly (if the balloon target is high).
523 * As a side-effect, draining free pages helps to inform (force)
524 * the guest to start swapping if balloon target is not met yet,
525 * which is a desired behavior. However, balloon driver can consume
526 * all available CPU cycles if too many pages are allocated in a
527 * second. Therefore, we throttle nosleep allocations even when
528 * the guest is not under memory pressure. OTOH, if we have already
529 * predicted that the guest is under memory pressure, then we
530 * slowdown page allocations considerably.
531 */
532
533 goal = b->target - b->size;
534 /*
535 * Start with no sleep allocation rate which may be higher
536 * than sleeping allocation rate.
537 */
538 rate = b->slow_allocation_cycles ?
539 b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
540
541 pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
542 __func__, goal, rate, b->rate_alloc);
543
544 for (i = 0; i < goal; i++) {
545
546 error = vmballoon_reserve_page(b, alloc_can_sleep);
547 if (error) {
548 if (error != -ENOMEM) {
549 /*
550 * Not a page allocation failure, stop this
551 * cycle. Maybe we'll get new target from
552 * the host soon.
553 */
554 break;
555 }
556
557 if (alloc_can_sleep) {
558 /*
559 * CANSLEEP page allocation failed, so guest
560 * is under severe memory pressure. Quickly
561 * decrease allocation rate.
562 */
563 b->rate_alloc = max(b->rate_alloc / 2,
564 VMW_BALLOON_RATE_ALLOC_MIN);
565 break;
566 }
567
568 /*
569 * NOSLEEP page allocation failed, so the guest is
570 * under memory pressure. Let us slow down page
571 * allocations for next few cycles so that the guest
572 * gets out of memory pressure. Also, if we already
573 * allocated b->rate_alloc pages, let's pause,
574 * otherwise switch to sleeping allocations.
575 */
576 b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
577
578 if (i >= b->rate_alloc)
579 break;
580
581 alloc_can_sleep = true;
582 /* Lower rate for sleeping allocations. */
583 rate = b->rate_alloc;
584 }
585
586 if (++allocations > VMW_BALLOON_YIELD_THRESHOLD) {
587 cond_resched();
588 allocations = 0;
589 }
590
591 if (i >= rate) {
592 /* We allocated enough pages, let's take a break. */
593 break;
594 }
595 }
596
597 /*
598 * We reached our goal without failures so try increasing
599 * allocation rate.
600 */
601 if (error == 0 && i >= b->rate_alloc) {
602 unsigned int mult = i / b->rate_alloc;
603
604 b->rate_alloc =
605 min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
606 VMW_BALLOON_RATE_ALLOC_MAX);
607 }
608
609 vmballoon_release_refused_pages(b);
610}
611
612/*
613 * Decrease the size of the balloon allowing guest to use more memory.
614 */
615static void vmballoon_deflate(struct vmballoon *b)
616{
617 struct page *page, *next;
618 unsigned int i = 0;
619 unsigned int goal;
620 int error;
621
622 pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
623
624 /* limit deallocation rate */
625 goal = min(b->size - b->target, b->rate_free);
626
627 pr_debug("%s - goal: %d, rate: %d\n", __func__, goal, b->rate_free);
628
629 /* free pages to reach target */
630 list_for_each_entry_safe(page, next, &b->pages, lru) {
631 error = vmballoon_release_page(b, page);
632 if (error) {
633 /* quickly decrease rate in case of error */
634 b->rate_free = max(b->rate_free / 2,
635 VMW_BALLOON_RATE_FREE_MIN);
636 return;
637 }
638
639 if (++i >= goal)
640 break;
641 }
642
643 /* slowly increase rate if there were no errors */
644 b->rate_free = min(b->rate_free + VMW_BALLOON_RATE_FREE_INC,
645 VMW_BALLOON_RATE_FREE_MAX);
646}
647
648/*
649 * Balloon work function: reset protocol, if needed, get the new size and
650 * adjust balloon as needed. Repeat in 1 sec.
651 */
652static void vmballoon_work(struct work_struct *work)
653{
654 struct delayed_work *dwork = to_delayed_work(work);
655 struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
656 unsigned int target;
657
658 STATS_INC(b->stats.timer);
659
660 if (b->reset_required)
661 vmballoon_reset(b);
662
663 if (b->slow_allocation_cycles > 0)
664 b->slow_allocation_cycles--;
665
666 if (vmballoon_send_get_target(b, &target)) {
667 /* update target, adjust size */
668 b->target = target;
669
670 if (b->size < target)
671 vmballoon_inflate(b);
672 else if (b->size > target)
673 vmballoon_deflate(b);
674 }
675
676 /*
677 * We are using a freezable workqueue so that balloon operations are
678 * stopped while the system transitions to/from sleep/hibernation.
679 */
680 queue_delayed_work(system_freezable_wq,
681 dwork, round_jiffies_relative(HZ));
682}
683
684/*
685 * DEBUGFS Interface
686 */
687#ifdef CONFIG_DEBUG_FS
688
689static int vmballoon_debug_show(struct seq_file *f, void *offset)
690{
691 struct vmballoon *b = f->private;
692 struct vmballoon_stats *stats = &b->stats;
693
694 /* format size info */
695 seq_printf(f,
696 "target: %8d pages\n"
697 "current: %8d pages\n",
698 b->target, b->size);
699
700 /* format rate info */
701 seq_printf(f,
702 "rateNoSleepAlloc: %8d pages/sec\n"
703 "rateSleepAlloc: %8d pages/sec\n"
704 "rateFree: %8d pages/sec\n",
705 VMW_BALLOON_NOSLEEP_ALLOC_MAX,
706 b->rate_alloc, b->rate_free);
707
708 seq_printf(f,
709 "\n"
710 "timer: %8u\n"
711 "start: %8u (%4u failed)\n"
712 "guestType: %8u (%4u failed)\n"
713 "lock: %8u (%4u failed)\n"
714 "unlock: %8u (%4u failed)\n"
715 "target: %8u (%4u failed)\n"
716 "primNoSleepAlloc: %8u (%4u failed)\n"
717 "primCanSleepAlloc: %8u (%4u failed)\n"
718 "primFree: %8u\n"
719 "errAlloc: %8u\n"
720 "errFree: %8u\n",
721 stats->timer,
722 stats->start, stats->start_fail,
723 stats->guest_type, stats->guest_type_fail,
724 stats->lock, stats->lock_fail,
725 stats->unlock, stats->unlock_fail,
726 stats->target, stats->target_fail,
727 stats->alloc, stats->alloc_fail,
728 stats->sleep_alloc, stats->sleep_alloc_fail,
729 stats->free,
730 stats->refused_alloc, stats->refused_free);
731
732 return 0;
733}
734
735static int vmballoon_debug_open(struct inode *inode, struct file *file)
736{
737 return single_open(file, vmballoon_debug_show, inode->i_private);
738}
739
740static const struct file_operations vmballoon_debug_fops = {
741 .owner = THIS_MODULE,
742 .open = vmballoon_debug_open,
743 .read = seq_read,
744 .llseek = seq_lseek,
745 .release = single_release,
746};
747
748static int __init vmballoon_debugfs_init(struct vmballoon *b)
749{
750 int error;
751
752 b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
753 &vmballoon_debug_fops);
754 if (IS_ERR(b->dbg_entry)) {
755 error = PTR_ERR(b->dbg_entry);
756 pr_err("failed to create debugfs entry, error: %d\n", error);
757 return error;
758 }
759
760 return 0;
761}
762
763static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
764{
765 debugfs_remove(b->dbg_entry);
766}
767
768#else
769
770static inline int vmballoon_debugfs_init(struct vmballoon *b)
771{
772 return 0;
773}
774
775static inline void vmballoon_debugfs_exit(struct vmballoon *b)
776{
777}
778
779#endif /* CONFIG_DEBUG_FS */
780
781static int __init vmballoon_init(void)
782{
783 int error;
784
785 /*
786 * Check if we are running on VMware's hypervisor and bail out
787 * if we are not.
788 */
789 if (x86_hyper != &x86_hyper_vmware)
790 return -ENODEV;
791
792 INIT_LIST_HEAD(&balloon.pages);
793 INIT_LIST_HEAD(&balloon.refused_pages);
794
795 /* initialize rates */
796 balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
797 balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
798
799 INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
800
801 /*
802 * Start balloon.
803 */
804 if (!vmballoon_send_start(&balloon)) {
805 pr_err("failed to send start command to the host\n");
806 return -EIO;
807 }
808
809 if (!vmballoon_send_guest_id(&balloon)) {
810 pr_err("failed to send guest ID to the host\n");
811 return -EIO;
812 }
813
814 error = vmballoon_debugfs_init(&balloon);
815 if (error)
816 return error;
817
818 queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
819
820 return 0;
821}
822module_init(vmballoon_init);
823
824static void __exit vmballoon_exit(void)
825{
826 cancel_delayed_work_sync(&balloon.dwork);
827
828 vmballoon_debugfs_exit(&balloon);
829
830 /*
831 * Deallocate all reserved memory, and reset connection with monitor.
832 * Reset connection before deallocating memory to avoid potential for
833 * additional spurious resets from guest touching deallocated pages.
834 */
835 vmballoon_send_start(&balloon);
836 vmballoon_pop(&balloon);
837}
838module_exit(vmballoon_exit);
1/*
2 * VMware Balloon driver.
3 *
4 * Copyright (C) 2000-2014, 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/vmalloc.h>
41#include <linux/sched.h>
42#include <linux/module.h>
43#include <linux/workqueue.h>
44#include <linux/debugfs.h>
45#include <linux/seq_file.h>
46#include <linux/vmw_vmci_defs.h>
47#include <linux/vmw_vmci_api.h>
48#include <asm/hypervisor.h>
49
50MODULE_AUTHOR("VMware, Inc.");
51MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
52MODULE_VERSION("1.5.0.0-k");
53MODULE_ALIAS("dmi:*:svnVMware*:*");
54MODULE_ALIAS("vmware_vmmemctl");
55MODULE_LICENSE("GPL");
56
57/*
58 * Various constants controlling rate of inflaint/deflating balloon,
59 * measured in pages.
60 */
61
62/*
63 * Rates of memory allocaton when guest experiences memory pressure
64 * (driver performs sleeping allocations).
65 */
66#define VMW_BALLOON_RATE_ALLOC_MIN 512U
67#define VMW_BALLOON_RATE_ALLOC_MAX 2048U
68#define VMW_BALLOON_RATE_ALLOC_INC 16U
69
70/*
71 * When guest is under memory pressure, use a reduced page allocation
72 * rate for next several cycles.
73 */
74#define VMW_BALLOON_SLOW_CYCLES 4
75
76/*
77 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't
78 * allow wait (__GFP_RECLAIM) for NOSLEEP page allocations. Use
79 * __GFP_NOWARN, to suppress page allocation failure warnings.
80 */
81#define VMW_PAGE_ALLOC_NOSLEEP (__GFP_HIGHMEM|__GFP_NOWARN)
82
83/*
84 * Use GFP_HIGHUSER when executing in a separate kernel thread
85 * context and allocation can sleep. This is less stressful to
86 * the guest memory system, since it allows the thread to block
87 * while memory is reclaimed, and won't take pages from emergency
88 * low-memory pools.
89 */
90#define VMW_PAGE_ALLOC_CANSLEEP (GFP_HIGHUSER)
91
92/* Maximum number of refused pages we accumulate during inflation cycle */
93#define VMW_BALLOON_MAX_REFUSED 16
94
95/*
96 * Hypervisor communication port definitions.
97 */
98#define VMW_BALLOON_HV_PORT 0x5670
99#define VMW_BALLOON_HV_MAGIC 0x456c6d6f
100#define VMW_BALLOON_GUEST_ID 1 /* Linux */
101
102enum vmwballoon_capabilities {
103 /*
104 * Bit 0 is reserved and not associated to any capability.
105 */
106 VMW_BALLOON_BASIC_CMDS = (1 << 1),
107 VMW_BALLOON_BATCHED_CMDS = (1 << 2),
108 VMW_BALLOON_BATCHED_2M_CMDS = (1 << 3),
109 VMW_BALLOON_SIGNALLED_WAKEUP_CMD = (1 << 4),
110};
111
112#define VMW_BALLOON_CAPABILITIES (VMW_BALLOON_BASIC_CMDS \
113 | VMW_BALLOON_BATCHED_CMDS \
114 | VMW_BALLOON_BATCHED_2M_CMDS \
115 | VMW_BALLOON_SIGNALLED_WAKEUP_CMD)
116
117#define VMW_BALLOON_2M_SHIFT (9)
118#define VMW_BALLOON_NUM_PAGE_SIZES (2)
119
120/*
121 * Backdoor commands availability:
122 *
123 * START, GET_TARGET and GUEST_ID are always available,
124 *
125 * VMW_BALLOON_BASIC_CMDS:
126 * LOCK and UNLOCK commands,
127 * VMW_BALLOON_BATCHED_CMDS:
128 * BATCHED_LOCK and BATCHED_UNLOCK commands.
129 * VMW BALLOON_BATCHED_2M_CMDS:
130 * BATCHED_2M_LOCK and BATCHED_2M_UNLOCK commands,
131 * VMW VMW_BALLOON_SIGNALLED_WAKEUP_CMD:
132 * VMW_BALLOON_CMD_VMCI_DOORBELL_SET command.
133 */
134#define VMW_BALLOON_CMD_START 0
135#define VMW_BALLOON_CMD_GET_TARGET 1
136#define VMW_BALLOON_CMD_LOCK 2
137#define VMW_BALLOON_CMD_UNLOCK 3
138#define VMW_BALLOON_CMD_GUEST_ID 4
139#define VMW_BALLOON_CMD_BATCHED_LOCK 6
140#define VMW_BALLOON_CMD_BATCHED_UNLOCK 7
141#define VMW_BALLOON_CMD_BATCHED_2M_LOCK 8
142#define VMW_BALLOON_CMD_BATCHED_2M_UNLOCK 9
143#define VMW_BALLOON_CMD_VMCI_DOORBELL_SET 10
144
145
146/* error codes */
147#define VMW_BALLOON_SUCCESS 0
148#define VMW_BALLOON_FAILURE -1
149#define VMW_BALLOON_ERROR_CMD_INVALID 1
150#define VMW_BALLOON_ERROR_PPN_INVALID 2
151#define VMW_BALLOON_ERROR_PPN_LOCKED 3
152#define VMW_BALLOON_ERROR_PPN_UNLOCKED 4
153#define VMW_BALLOON_ERROR_PPN_PINNED 5
154#define VMW_BALLOON_ERROR_PPN_NOTNEEDED 6
155#define VMW_BALLOON_ERROR_RESET 7
156#define VMW_BALLOON_ERROR_BUSY 8
157
158#define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES (0x03000000)
159
160/* Batch page description */
161
162/*
163 * Layout of a page in the batch page:
164 *
165 * +-------------+----------+--------+
166 * | | | |
167 * | Page number | Reserved | Status |
168 * | | | |
169 * +-------------+----------+--------+
170 * 64 PAGE_SHIFT 6 0
171 *
172 * The reserved field should be set to 0.
173 */
174#define VMW_BALLOON_BATCH_MAX_PAGES (PAGE_SIZE / sizeof(u64))
175#define VMW_BALLOON_BATCH_STATUS_MASK ((1UL << 5) - 1)
176#define VMW_BALLOON_BATCH_PAGE_MASK (~((1UL << PAGE_SHIFT) - 1))
177
178struct vmballoon_batch_page {
179 u64 pages[VMW_BALLOON_BATCH_MAX_PAGES];
180};
181
182static u64 vmballoon_batch_get_pa(struct vmballoon_batch_page *batch, int idx)
183{
184 return batch->pages[idx] & VMW_BALLOON_BATCH_PAGE_MASK;
185}
186
187static int vmballoon_batch_get_status(struct vmballoon_batch_page *batch,
188 int idx)
189{
190 return (int)(batch->pages[idx] & VMW_BALLOON_BATCH_STATUS_MASK);
191}
192
193static void vmballoon_batch_set_pa(struct vmballoon_batch_page *batch, int idx,
194 u64 pa)
195{
196 batch->pages[idx] = pa;
197}
198
199
200#define VMWARE_BALLOON_CMD(cmd, arg1, arg2, result) \
201({ \
202 unsigned long __status, __dummy1, __dummy2, __dummy3; \
203 __asm__ __volatile__ ("inl %%dx" : \
204 "=a"(__status), \
205 "=c"(__dummy1), \
206 "=d"(__dummy2), \
207 "=b"(result), \
208 "=S" (__dummy3) : \
209 "0"(VMW_BALLOON_HV_MAGIC), \
210 "1"(VMW_BALLOON_CMD_##cmd), \
211 "2"(VMW_BALLOON_HV_PORT), \
212 "3"(arg1), \
213 "4" (arg2) : \
214 "memory"); \
215 if (VMW_BALLOON_CMD_##cmd == VMW_BALLOON_CMD_START) \
216 result = __dummy1; \
217 result &= -1UL; \
218 __status & -1UL; \
219})
220
221#ifdef CONFIG_DEBUG_FS
222struct vmballoon_stats {
223 unsigned int timer;
224 unsigned int doorbell;
225
226 /* allocation statistics */
227 unsigned int alloc[VMW_BALLOON_NUM_PAGE_SIZES];
228 unsigned int alloc_fail[VMW_BALLOON_NUM_PAGE_SIZES];
229 unsigned int sleep_alloc;
230 unsigned int sleep_alloc_fail;
231 unsigned int refused_alloc[VMW_BALLOON_NUM_PAGE_SIZES];
232 unsigned int refused_free[VMW_BALLOON_NUM_PAGE_SIZES];
233 unsigned int free[VMW_BALLOON_NUM_PAGE_SIZES];
234
235 /* monitor operations */
236 unsigned int lock[VMW_BALLOON_NUM_PAGE_SIZES];
237 unsigned int lock_fail[VMW_BALLOON_NUM_PAGE_SIZES];
238 unsigned int unlock[VMW_BALLOON_NUM_PAGE_SIZES];
239 unsigned int unlock_fail[VMW_BALLOON_NUM_PAGE_SIZES];
240 unsigned int target;
241 unsigned int target_fail;
242 unsigned int start;
243 unsigned int start_fail;
244 unsigned int guest_type;
245 unsigned int guest_type_fail;
246 unsigned int doorbell_set;
247 unsigned int doorbell_unset;
248};
249
250#define STATS_INC(stat) (stat)++
251#else
252#define STATS_INC(stat)
253#endif
254
255struct vmballoon;
256
257struct vmballoon_ops {
258 void (*add_page)(struct vmballoon *b, int idx, struct page *p);
259 int (*lock)(struct vmballoon *b, unsigned int num_pages,
260 bool is_2m_pages, unsigned int *target);
261 int (*unlock)(struct vmballoon *b, unsigned int num_pages,
262 bool is_2m_pages, unsigned int *target);
263};
264
265struct vmballoon_page_size {
266 /* list of reserved physical pages */
267 struct list_head pages;
268
269 /* transient list of non-balloonable pages */
270 struct list_head refused_pages;
271 unsigned int n_refused_pages;
272};
273
274struct vmballoon {
275 struct vmballoon_page_size page_sizes[VMW_BALLOON_NUM_PAGE_SIZES];
276
277 /* supported page sizes. 1 == 4k pages only, 2 == 4k and 2m pages */
278 unsigned supported_page_sizes;
279
280 /* balloon size in pages */
281 unsigned int size;
282 unsigned int target;
283
284 /* reset flag */
285 bool reset_required;
286
287 /* adjustment rates (pages per second) */
288 unsigned int rate_alloc;
289
290 /* slowdown page allocations for next few cycles */
291 unsigned int slow_allocation_cycles;
292
293 unsigned long capabilities;
294
295 struct vmballoon_batch_page *batch_page;
296 unsigned int batch_max_pages;
297 struct page *page;
298
299 const struct vmballoon_ops *ops;
300
301#ifdef CONFIG_DEBUG_FS
302 /* statistics */
303 struct vmballoon_stats stats;
304
305 /* debugfs file exporting statistics */
306 struct dentry *dbg_entry;
307#endif
308
309 struct sysinfo sysinfo;
310
311 struct delayed_work dwork;
312
313 struct vmci_handle vmci_doorbell;
314};
315
316static struct vmballoon balloon;
317
318/*
319 * Send "start" command to the host, communicating supported version
320 * of the protocol.
321 */
322static bool vmballoon_send_start(struct vmballoon *b, unsigned long req_caps)
323{
324 unsigned long status, capabilities, dummy = 0;
325 bool success;
326
327 STATS_INC(b->stats.start);
328
329 status = VMWARE_BALLOON_CMD(START, req_caps, dummy, capabilities);
330
331 switch (status) {
332 case VMW_BALLOON_SUCCESS_WITH_CAPABILITIES:
333 b->capabilities = capabilities;
334 success = true;
335 break;
336 case VMW_BALLOON_SUCCESS:
337 b->capabilities = VMW_BALLOON_BASIC_CMDS;
338 success = true;
339 break;
340 default:
341 success = false;
342 }
343
344 if (b->capabilities & VMW_BALLOON_BATCHED_2M_CMDS)
345 b->supported_page_sizes = 2;
346 else
347 b->supported_page_sizes = 1;
348
349 if (!success) {
350 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
351 STATS_INC(b->stats.start_fail);
352 }
353 return success;
354}
355
356static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
357{
358 switch (status) {
359 case VMW_BALLOON_SUCCESS:
360 return true;
361
362 case VMW_BALLOON_ERROR_RESET:
363 b->reset_required = true;
364 /* fall through */
365
366 default:
367 return false;
368 }
369}
370
371/*
372 * Communicate guest type to the host so that it can adjust ballooning
373 * algorithm to the one most appropriate for the guest. This command
374 * is normally issued after sending "start" command and is part of
375 * standard reset sequence.
376 */
377static bool vmballoon_send_guest_id(struct vmballoon *b)
378{
379 unsigned long status, dummy = 0;
380
381 status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy,
382 dummy);
383
384 STATS_INC(b->stats.guest_type);
385
386 if (vmballoon_check_status(b, status))
387 return true;
388
389 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
390 STATS_INC(b->stats.guest_type_fail);
391 return false;
392}
393
394static u16 vmballoon_page_size(bool is_2m_page)
395{
396 if (is_2m_page)
397 return 1 << VMW_BALLOON_2M_SHIFT;
398
399 return 1;
400}
401
402/*
403 * Retrieve desired balloon size from the host.
404 */
405static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
406{
407 unsigned long status;
408 unsigned long target;
409 unsigned long limit;
410 unsigned long dummy = 0;
411 u32 limit32;
412
413 /*
414 * si_meminfo() is cheap. Moreover, we want to provide dynamic
415 * max balloon size later. So let us call si_meminfo() every
416 * iteration.
417 */
418 si_meminfo(&b->sysinfo);
419 limit = b->sysinfo.totalram;
420
421 /* Ensure limit fits in 32-bits */
422 limit32 = (u32)limit;
423 if (limit != limit32)
424 return false;
425
426 /* update stats */
427 STATS_INC(b->stats.target);
428
429 status = VMWARE_BALLOON_CMD(GET_TARGET, limit, dummy, target);
430 if (vmballoon_check_status(b, status)) {
431 *new_target = target;
432 return true;
433 }
434
435 pr_debug("%s - failed, hv returns %ld\n", __func__, status);
436 STATS_INC(b->stats.target_fail);
437 return false;
438}
439
440/*
441 * Notify the host about allocated page so that host can use it without
442 * fear that guest will need it. Host may reject some pages, we need to
443 * check the return value and maybe submit a different page.
444 */
445static int vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
446 unsigned int *hv_status, unsigned int *target)
447{
448 unsigned long status, dummy = 0;
449 u32 pfn32;
450
451 pfn32 = (u32)pfn;
452 if (pfn32 != pfn)
453 return -1;
454
455 STATS_INC(b->stats.lock[false]);
456
457 *hv_status = status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy, *target);
458 if (vmballoon_check_status(b, status))
459 return 0;
460
461 pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
462 STATS_INC(b->stats.lock_fail[false]);
463 return 1;
464}
465
466static int vmballoon_send_batched_lock(struct vmballoon *b,
467 unsigned int num_pages, bool is_2m_pages, unsigned int *target)
468{
469 unsigned long status;
470 unsigned long pfn = page_to_pfn(b->page);
471
472 STATS_INC(b->stats.lock[is_2m_pages]);
473
474 if (is_2m_pages)
475 status = VMWARE_BALLOON_CMD(BATCHED_2M_LOCK, pfn, num_pages,
476 *target);
477 else
478 status = VMWARE_BALLOON_CMD(BATCHED_LOCK, pfn, num_pages,
479 *target);
480
481 if (vmballoon_check_status(b, status))
482 return 0;
483
484 pr_debug("%s - batch ppn %lx, hv returns %ld\n", __func__, pfn, status);
485 STATS_INC(b->stats.lock_fail[is_2m_pages]);
486 return 1;
487}
488
489/*
490 * Notify the host that guest intends to release given page back into
491 * the pool of available (to the guest) pages.
492 */
493static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn,
494 unsigned int *target)
495{
496 unsigned long status, dummy = 0;
497 u32 pfn32;
498
499 pfn32 = (u32)pfn;
500 if (pfn32 != pfn)
501 return false;
502
503 STATS_INC(b->stats.unlock[false]);
504
505 status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy, *target);
506 if (vmballoon_check_status(b, status))
507 return true;
508
509 pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
510 STATS_INC(b->stats.unlock_fail[false]);
511 return false;
512}
513
514static bool vmballoon_send_batched_unlock(struct vmballoon *b,
515 unsigned int num_pages, bool is_2m_pages, unsigned int *target)
516{
517 unsigned long status;
518 unsigned long pfn = page_to_pfn(b->page);
519
520 STATS_INC(b->stats.unlock[is_2m_pages]);
521
522 if (is_2m_pages)
523 status = VMWARE_BALLOON_CMD(BATCHED_2M_UNLOCK, pfn, num_pages,
524 *target);
525 else
526 status = VMWARE_BALLOON_CMD(BATCHED_UNLOCK, pfn, num_pages,
527 *target);
528
529 if (vmballoon_check_status(b, status))
530 return true;
531
532 pr_debug("%s - batch ppn %lx, hv returns %ld\n", __func__, pfn, status);
533 STATS_INC(b->stats.unlock_fail[is_2m_pages]);
534 return false;
535}
536
537static struct page *vmballoon_alloc_page(gfp_t flags, bool is_2m_page)
538{
539 if (is_2m_page)
540 return alloc_pages(flags, VMW_BALLOON_2M_SHIFT);
541
542 return alloc_page(flags);
543}
544
545static void vmballoon_free_page(struct page *page, bool is_2m_page)
546{
547 if (is_2m_page)
548 __free_pages(page, VMW_BALLOON_2M_SHIFT);
549 else
550 __free_page(page);
551}
552
553/*
554 * Quickly release all pages allocated for the balloon. This function is
555 * called when host decides to "reset" balloon for one reason or another.
556 * Unlike normal "deflate" we do not (shall not) notify host of the pages
557 * being released.
558 */
559static void vmballoon_pop(struct vmballoon *b)
560{
561 struct page *page, *next;
562 unsigned is_2m_pages;
563
564 for (is_2m_pages = 0; is_2m_pages < VMW_BALLOON_NUM_PAGE_SIZES;
565 is_2m_pages++) {
566 struct vmballoon_page_size *page_size =
567 &b->page_sizes[is_2m_pages];
568 u16 size_per_page = vmballoon_page_size(is_2m_pages);
569
570 list_for_each_entry_safe(page, next, &page_size->pages, lru) {
571 list_del(&page->lru);
572 vmballoon_free_page(page, is_2m_pages);
573 STATS_INC(b->stats.free[is_2m_pages]);
574 b->size -= size_per_page;
575 cond_resched();
576 }
577 }
578
579 if (b->batch_page) {
580 vunmap(b->batch_page);
581 b->batch_page = NULL;
582 }
583
584 if (b->page) {
585 __free_page(b->page);
586 b->page = NULL;
587 }
588}
589
590/*
591 * Notify the host of a ballooned page. If host rejects the page put it on the
592 * refuse list, those refused page are then released at the end of the
593 * inflation cycle.
594 */
595static int vmballoon_lock_page(struct vmballoon *b, unsigned int num_pages,
596 bool is_2m_pages, unsigned int *target)
597{
598 int locked, hv_status;
599 struct page *page = b->page;
600 struct vmballoon_page_size *page_size = &b->page_sizes[false];
601
602 /* is_2m_pages can never happen as 2m pages support implies batching */
603
604 locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status,
605 target);
606 if (locked > 0) {
607 STATS_INC(b->stats.refused_alloc[false]);
608
609 if (hv_status == VMW_BALLOON_ERROR_RESET ||
610 hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED) {
611 vmballoon_free_page(page, false);
612 return -EIO;
613 }
614
615 /*
616 * Place page on the list of non-balloonable pages
617 * and retry allocation, unless we already accumulated
618 * too many of them, in which case take a breather.
619 */
620 if (page_size->n_refused_pages < VMW_BALLOON_MAX_REFUSED) {
621 page_size->n_refused_pages++;
622 list_add(&page->lru, &page_size->refused_pages);
623 } else {
624 vmballoon_free_page(page, false);
625 }
626 return -EIO;
627 }
628
629 /* track allocated page */
630 list_add(&page->lru, &page_size->pages);
631
632 /* update balloon size */
633 b->size++;
634
635 return 0;
636}
637
638static int vmballoon_lock_batched_page(struct vmballoon *b,
639 unsigned int num_pages, bool is_2m_pages, unsigned int *target)
640{
641 int locked, i;
642 u16 size_per_page = vmballoon_page_size(is_2m_pages);
643
644 locked = vmballoon_send_batched_lock(b, num_pages, is_2m_pages,
645 target);
646 if (locked > 0) {
647 for (i = 0; i < num_pages; i++) {
648 u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
649 struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
650
651 vmballoon_free_page(p, is_2m_pages);
652 }
653
654 return -EIO;
655 }
656
657 for (i = 0; i < num_pages; i++) {
658 u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
659 struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
660 struct vmballoon_page_size *page_size =
661 &b->page_sizes[is_2m_pages];
662
663 locked = vmballoon_batch_get_status(b->batch_page, i);
664
665 switch (locked) {
666 case VMW_BALLOON_SUCCESS:
667 list_add(&p->lru, &page_size->pages);
668 b->size += size_per_page;
669 break;
670 case VMW_BALLOON_ERROR_PPN_PINNED:
671 case VMW_BALLOON_ERROR_PPN_INVALID:
672 if (page_size->n_refused_pages
673 < VMW_BALLOON_MAX_REFUSED) {
674 list_add(&p->lru, &page_size->refused_pages);
675 page_size->n_refused_pages++;
676 break;
677 }
678 /* Fallthrough */
679 case VMW_BALLOON_ERROR_RESET:
680 case VMW_BALLOON_ERROR_PPN_NOTNEEDED:
681 vmballoon_free_page(p, is_2m_pages);
682 break;
683 default:
684 /* This should never happen */
685 WARN_ON_ONCE(true);
686 }
687 }
688
689 return 0;
690}
691
692/*
693 * Release the page allocated for the balloon. Note that we first notify
694 * the host so it can make sure the page will be available for the guest
695 * to use, if needed.
696 */
697static int vmballoon_unlock_page(struct vmballoon *b, unsigned int num_pages,
698 bool is_2m_pages, unsigned int *target)
699{
700 struct page *page = b->page;
701 struct vmballoon_page_size *page_size = &b->page_sizes[false];
702
703 /* is_2m_pages can never happen as 2m pages support implies batching */
704
705 if (!vmballoon_send_unlock_page(b, page_to_pfn(page), target)) {
706 list_add(&page->lru, &page_size->pages);
707 return -EIO;
708 }
709
710 /* deallocate page */
711 vmballoon_free_page(page, false);
712 STATS_INC(b->stats.free[false]);
713
714 /* update balloon size */
715 b->size--;
716
717 return 0;
718}
719
720static int vmballoon_unlock_batched_page(struct vmballoon *b,
721 unsigned int num_pages, bool is_2m_pages,
722 unsigned int *target)
723{
724 int locked, i, ret = 0;
725 bool hv_success;
726 u16 size_per_page = vmballoon_page_size(is_2m_pages);
727
728 hv_success = vmballoon_send_batched_unlock(b, num_pages, is_2m_pages,
729 target);
730 if (!hv_success)
731 ret = -EIO;
732
733 for (i = 0; i < num_pages; i++) {
734 u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
735 struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
736 struct vmballoon_page_size *page_size =
737 &b->page_sizes[is_2m_pages];
738
739 locked = vmballoon_batch_get_status(b->batch_page, i);
740 if (!hv_success || locked != VMW_BALLOON_SUCCESS) {
741 /*
742 * That page wasn't successfully unlocked by the
743 * hypervisor, re-add it to the list of pages owned by
744 * the balloon driver.
745 */
746 list_add(&p->lru, &page_size->pages);
747 } else {
748 /* deallocate page */
749 vmballoon_free_page(p, is_2m_pages);
750 STATS_INC(b->stats.free[is_2m_pages]);
751
752 /* update balloon size */
753 b->size -= size_per_page;
754 }
755 }
756
757 return ret;
758}
759
760/*
761 * Release pages that were allocated while attempting to inflate the
762 * balloon but were refused by the host for one reason or another.
763 */
764static void vmballoon_release_refused_pages(struct vmballoon *b,
765 bool is_2m_pages)
766{
767 struct page *page, *next;
768 struct vmballoon_page_size *page_size =
769 &b->page_sizes[is_2m_pages];
770
771 list_for_each_entry_safe(page, next, &page_size->refused_pages, lru) {
772 list_del(&page->lru);
773 vmballoon_free_page(page, is_2m_pages);
774 STATS_INC(b->stats.refused_free[is_2m_pages]);
775 }
776
777 page_size->n_refused_pages = 0;
778}
779
780static void vmballoon_add_page(struct vmballoon *b, int idx, struct page *p)
781{
782 b->page = p;
783}
784
785static void vmballoon_add_batched_page(struct vmballoon *b, int idx,
786 struct page *p)
787{
788 vmballoon_batch_set_pa(b->batch_page, idx,
789 (u64)page_to_pfn(p) << PAGE_SHIFT);
790}
791
792/*
793 * Inflate the balloon towards its target size. Note that we try to limit
794 * the rate of allocation to make sure we are not choking the rest of the
795 * system.
796 */
797static void vmballoon_inflate(struct vmballoon *b)
798{
799 unsigned rate;
800 unsigned int allocations = 0;
801 unsigned int num_pages = 0;
802 int error = 0;
803 gfp_t flags = VMW_PAGE_ALLOC_NOSLEEP;
804 bool is_2m_pages;
805
806 pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
807
808 /*
809 * First try NOSLEEP page allocations to inflate balloon.
810 *
811 * If we do not throttle nosleep allocations, we can drain all
812 * free pages in the guest quickly (if the balloon target is high).
813 * As a side-effect, draining free pages helps to inform (force)
814 * the guest to start swapping if balloon target is not met yet,
815 * which is a desired behavior. However, balloon driver can consume
816 * all available CPU cycles if too many pages are allocated in a
817 * second. Therefore, we throttle nosleep allocations even when
818 * the guest is not under memory pressure. OTOH, if we have already
819 * predicted that the guest is under memory pressure, then we
820 * slowdown page allocations considerably.
821 */
822
823 /*
824 * Start with no sleep allocation rate which may be higher
825 * than sleeping allocation rate.
826 */
827 if (b->slow_allocation_cycles) {
828 rate = b->rate_alloc;
829 is_2m_pages = false;
830 } else {
831 rate = UINT_MAX;
832 is_2m_pages =
833 b->supported_page_sizes == VMW_BALLOON_NUM_PAGE_SIZES;
834 }
835
836 pr_debug("%s - goal: %d, no-sleep rate: %u, sleep rate: %d\n",
837 __func__, b->target - b->size, rate, b->rate_alloc);
838
839 while (!b->reset_required &&
840 b->size + num_pages * vmballoon_page_size(is_2m_pages)
841 < b->target) {
842 struct page *page;
843
844 if (flags == VMW_PAGE_ALLOC_NOSLEEP)
845 STATS_INC(b->stats.alloc[is_2m_pages]);
846 else
847 STATS_INC(b->stats.sleep_alloc);
848
849 page = vmballoon_alloc_page(flags, is_2m_pages);
850 if (!page) {
851 STATS_INC(b->stats.alloc_fail[is_2m_pages]);
852
853 if (is_2m_pages) {
854 b->ops->lock(b, num_pages, true, &b->target);
855
856 /*
857 * ignore errors from locking as we now switch
858 * to 4k pages and we might get different
859 * errors.
860 */
861
862 num_pages = 0;
863 is_2m_pages = false;
864 continue;
865 }
866
867 if (flags == VMW_PAGE_ALLOC_CANSLEEP) {
868 /*
869 * CANSLEEP page allocation failed, so guest
870 * is under severe memory pressure. Quickly
871 * decrease allocation rate.
872 */
873 b->rate_alloc = max(b->rate_alloc / 2,
874 VMW_BALLOON_RATE_ALLOC_MIN);
875 STATS_INC(b->stats.sleep_alloc_fail);
876 break;
877 }
878
879 /*
880 * NOSLEEP page allocation failed, so the guest is
881 * under memory pressure. Let us slow down page
882 * allocations for next few cycles so that the guest
883 * gets out of memory pressure. Also, if we already
884 * allocated b->rate_alloc pages, let's pause,
885 * otherwise switch to sleeping allocations.
886 */
887 b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
888
889 if (allocations >= b->rate_alloc)
890 break;
891
892 flags = VMW_PAGE_ALLOC_CANSLEEP;
893 /* Lower rate for sleeping allocations. */
894 rate = b->rate_alloc;
895 continue;
896 }
897
898 b->ops->add_page(b, num_pages++, page);
899 if (num_pages == b->batch_max_pages) {
900 error = b->ops->lock(b, num_pages, is_2m_pages,
901 &b->target);
902 num_pages = 0;
903 if (error)
904 break;
905 }
906
907 cond_resched();
908
909 if (allocations >= rate) {
910 /* We allocated enough pages, let's take a break. */
911 break;
912 }
913 }
914
915 if (num_pages > 0)
916 b->ops->lock(b, num_pages, is_2m_pages, &b->target);
917
918 /*
919 * We reached our goal without failures so try increasing
920 * allocation rate.
921 */
922 if (error == 0 && allocations >= b->rate_alloc) {
923 unsigned int mult = allocations / b->rate_alloc;
924
925 b->rate_alloc =
926 min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
927 VMW_BALLOON_RATE_ALLOC_MAX);
928 }
929
930 vmballoon_release_refused_pages(b, true);
931 vmballoon_release_refused_pages(b, false);
932}
933
934/*
935 * Decrease the size of the balloon allowing guest to use more memory.
936 */
937static void vmballoon_deflate(struct vmballoon *b)
938{
939 unsigned is_2m_pages;
940
941 pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
942
943 /* free pages to reach target */
944 for (is_2m_pages = 0; is_2m_pages < b->supported_page_sizes;
945 is_2m_pages++) {
946 struct page *page, *next;
947 unsigned int num_pages = 0;
948 struct vmballoon_page_size *page_size =
949 &b->page_sizes[is_2m_pages];
950
951 list_for_each_entry_safe(page, next, &page_size->pages, lru) {
952 if (b->reset_required ||
953 (b->target > 0 &&
954 b->size - num_pages
955 * vmballoon_page_size(is_2m_pages)
956 < b->target + vmballoon_page_size(true)))
957 break;
958
959 list_del(&page->lru);
960 b->ops->add_page(b, num_pages++, page);
961
962 if (num_pages == b->batch_max_pages) {
963 int error;
964
965 error = b->ops->unlock(b, num_pages,
966 is_2m_pages, &b->target);
967 num_pages = 0;
968 if (error)
969 return;
970 }
971
972 cond_resched();
973 }
974
975 if (num_pages > 0)
976 b->ops->unlock(b, num_pages, is_2m_pages, &b->target);
977 }
978}
979
980static const struct vmballoon_ops vmballoon_basic_ops = {
981 .add_page = vmballoon_add_page,
982 .lock = vmballoon_lock_page,
983 .unlock = vmballoon_unlock_page
984};
985
986static const struct vmballoon_ops vmballoon_batched_ops = {
987 .add_page = vmballoon_add_batched_page,
988 .lock = vmballoon_lock_batched_page,
989 .unlock = vmballoon_unlock_batched_page
990};
991
992static bool vmballoon_init_batching(struct vmballoon *b)
993{
994 b->page = alloc_page(VMW_PAGE_ALLOC_NOSLEEP);
995 if (!b->page)
996 return false;
997
998 b->batch_page = vmap(&b->page, 1, VM_MAP, PAGE_KERNEL);
999 if (!b->batch_page) {
1000 __free_page(b->page);
1001 return false;
1002 }
1003
1004 return true;
1005}
1006
1007/*
1008 * Receive notification and resize balloon
1009 */
1010static void vmballoon_doorbell(void *client_data)
1011{
1012 struct vmballoon *b = client_data;
1013
1014 STATS_INC(b->stats.doorbell);
1015
1016 mod_delayed_work(system_freezable_wq, &b->dwork, 0);
1017}
1018
1019/*
1020 * Clean up vmci doorbell
1021 */
1022static void vmballoon_vmci_cleanup(struct vmballoon *b)
1023{
1024 int error;
1025
1026 VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET, VMCI_INVALID_ID,
1027 VMCI_INVALID_ID, error);
1028 STATS_INC(b->stats.doorbell_unset);
1029
1030 if (!vmci_handle_is_invalid(b->vmci_doorbell)) {
1031 vmci_doorbell_destroy(b->vmci_doorbell);
1032 b->vmci_doorbell = VMCI_INVALID_HANDLE;
1033 }
1034}
1035
1036/*
1037 * Initialize vmci doorbell, to get notified as soon as balloon changes
1038 */
1039static int vmballoon_vmci_init(struct vmballoon *b)
1040{
1041 int error = 0;
1042
1043 if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) != 0) {
1044 error = vmci_doorbell_create(&b->vmci_doorbell,
1045 VMCI_FLAG_DELAYED_CB,
1046 VMCI_PRIVILEGE_FLAG_RESTRICTED,
1047 vmballoon_doorbell, b);
1048
1049 if (error == VMCI_SUCCESS) {
1050 VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET,
1051 b->vmci_doorbell.context,
1052 b->vmci_doorbell.resource, error);
1053 STATS_INC(b->stats.doorbell_set);
1054 }
1055 }
1056
1057 if (error != 0) {
1058 vmballoon_vmci_cleanup(b);
1059
1060 return -EIO;
1061 }
1062
1063 return 0;
1064}
1065
1066/*
1067 * Perform standard reset sequence by popping the balloon (in case it
1068 * is not empty) and then restarting protocol. This operation normally
1069 * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
1070 */
1071static void vmballoon_reset(struct vmballoon *b)
1072{
1073 int error;
1074
1075 vmballoon_vmci_cleanup(b);
1076
1077 /* free all pages, skipping monitor unlock */
1078 vmballoon_pop(b);
1079
1080 if (!vmballoon_send_start(b, VMW_BALLOON_CAPABILITIES))
1081 return;
1082
1083 if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) {
1084 b->ops = &vmballoon_batched_ops;
1085 b->batch_max_pages = VMW_BALLOON_BATCH_MAX_PAGES;
1086 if (!vmballoon_init_batching(b)) {
1087 /*
1088 * We failed to initialize batching, inform the monitor
1089 * about it by sending a null capability.
1090 *
1091 * The guest will retry in one second.
1092 */
1093 vmballoon_send_start(b, 0);
1094 return;
1095 }
1096 } else if ((b->capabilities & VMW_BALLOON_BASIC_CMDS) != 0) {
1097 b->ops = &vmballoon_basic_ops;
1098 b->batch_max_pages = 1;
1099 }
1100
1101 b->reset_required = false;
1102
1103 error = vmballoon_vmci_init(b);
1104 if (error)
1105 pr_err("failed to initialize vmci doorbell\n");
1106
1107 if (!vmballoon_send_guest_id(b))
1108 pr_err("failed to send guest ID to the host\n");
1109}
1110
1111/*
1112 * Balloon work function: reset protocol, if needed, get the new size and
1113 * adjust balloon as needed. Repeat in 1 sec.
1114 */
1115static void vmballoon_work(struct work_struct *work)
1116{
1117 struct delayed_work *dwork = to_delayed_work(work);
1118 struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
1119 unsigned int target;
1120
1121 STATS_INC(b->stats.timer);
1122
1123 if (b->reset_required)
1124 vmballoon_reset(b);
1125
1126 if (b->slow_allocation_cycles > 0)
1127 b->slow_allocation_cycles--;
1128
1129 if (!b->reset_required && vmballoon_send_get_target(b, &target)) {
1130 /* update target, adjust size */
1131 b->target = target;
1132
1133 if (b->size < target)
1134 vmballoon_inflate(b);
1135 else if (target == 0 ||
1136 b->size > target + vmballoon_page_size(true))
1137 vmballoon_deflate(b);
1138 }
1139
1140 /*
1141 * We are using a freezable workqueue so that balloon operations are
1142 * stopped while the system transitions to/from sleep/hibernation.
1143 */
1144 queue_delayed_work(system_freezable_wq,
1145 dwork, round_jiffies_relative(HZ));
1146}
1147
1148/*
1149 * DEBUGFS Interface
1150 */
1151#ifdef CONFIG_DEBUG_FS
1152
1153static int vmballoon_debug_show(struct seq_file *f, void *offset)
1154{
1155 struct vmballoon *b = f->private;
1156 struct vmballoon_stats *stats = &b->stats;
1157
1158 /* format capabilities info */
1159 seq_printf(f,
1160 "balloon capabilities: %#4x\n"
1161 "used capabilities: %#4lx\n"
1162 "is resetting: %c\n",
1163 VMW_BALLOON_CAPABILITIES, b->capabilities,
1164 b->reset_required ? 'y' : 'n');
1165
1166 /* format size info */
1167 seq_printf(f,
1168 "target: %8d pages\n"
1169 "current: %8d pages\n",
1170 b->target, b->size);
1171
1172 /* format rate info */
1173 seq_printf(f,
1174 "rateSleepAlloc: %8d pages/sec\n",
1175 b->rate_alloc);
1176
1177 seq_printf(f,
1178 "\n"
1179 "timer: %8u\n"
1180 "doorbell: %8u\n"
1181 "start: %8u (%4u failed)\n"
1182 "guestType: %8u (%4u failed)\n"
1183 "2m-lock: %8u (%4u failed)\n"
1184 "lock: %8u (%4u failed)\n"
1185 "2m-unlock: %8u (%4u failed)\n"
1186 "unlock: %8u (%4u failed)\n"
1187 "target: %8u (%4u failed)\n"
1188 "prim2mAlloc: %8u (%4u failed)\n"
1189 "primNoSleepAlloc: %8u (%4u failed)\n"
1190 "primCanSleepAlloc: %8u (%4u failed)\n"
1191 "prim2mFree: %8u\n"
1192 "primFree: %8u\n"
1193 "err2mAlloc: %8u\n"
1194 "errAlloc: %8u\n"
1195 "err2mFree: %8u\n"
1196 "errFree: %8u\n"
1197 "doorbellSet: %8u\n"
1198 "doorbellUnset: %8u\n",
1199 stats->timer,
1200 stats->doorbell,
1201 stats->start, stats->start_fail,
1202 stats->guest_type, stats->guest_type_fail,
1203 stats->lock[true], stats->lock_fail[true],
1204 stats->lock[false], stats->lock_fail[false],
1205 stats->unlock[true], stats->unlock_fail[true],
1206 stats->unlock[false], stats->unlock_fail[false],
1207 stats->target, stats->target_fail,
1208 stats->alloc[true], stats->alloc_fail[true],
1209 stats->alloc[false], stats->alloc_fail[false],
1210 stats->sleep_alloc, stats->sleep_alloc_fail,
1211 stats->free[true],
1212 stats->free[false],
1213 stats->refused_alloc[true], stats->refused_alloc[false],
1214 stats->refused_free[true], stats->refused_free[false],
1215 stats->doorbell_set, stats->doorbell_unset);
1216
1217 return 0;
1218}
1219
1220static int vmballoon_debug_open(struct inode *inode, struct file *file)
1221{
1222 return single_open(file, vmballoon_debug_show, inode->i_private);
1223}
1224
1225static const struct file_operations vmballoon_debug_fops = {
1226 .owner = THIS_MODULE,
1227 .open = vmballoon_debug_open,
1228 .read = seq_read,
1229 .llseek = seq_lseek,
1230 .release = single_release,
1231};
1232
1233static int __init vmballoon_debugfs_init(struct vmballoon *b)
1234{
1235 int error;
1236
1237 b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
1238 &vmballoon_debug_fops);
1239 if (IS_ERR(b->dbg_entry)) {
1240 error = PTR_ERR(b->dbg_entry);
1241 pr_err("failed to create debugfs entry, error: %d\n", error);
1242 return error;
1243 }
1244
1245 return 0;
1246}
1247
1248static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
1249{
1250 debugfs_remove(b->dbg_entry);
1251}
1252
1253#else
1254
1255static inline int vmballoon_debugfs_init(struct vmballoon *b)
1256{
1257 return 0;
1258}
1259
1260static inline void vmballoon_debugfs_exit(struct vmballoon *b)
1261{
1262}
1263
1264#endif /* CONFIG_DEBUG_FS */
1265
1266static int __init vmballoon_init(void)
1267{
1268 int error;
1269 unsigned is_2m_pages;
1270 /*
1271 * Check if we are running on VMware's hypervisor and bail out
1272 * if we are not.
1273 */
1274 if (x86_hyper_type != X86_HYPER_VMWARE)
1275 return -ENODEV;
1276
1277 for (is_2m_pages = 0; is_2m_pages < VMW_BALLOON_NUM_PAGE_SIZES;
1278 is_2m_pages++) {
1279 INIT_LIST_HEAD(&balloon.page_sizes[is_2m_pages].pages);
1280 INIT_LIST_HEAD(&balloon.page_sizes[is_2m_pages].refused_pages);
1281 }
1282
1283 /* initialize rates */
1284 balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
1285
1286 INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
1287
1288 error = vmballoon_debugfs_init(&balloon);
1289 if (error)
1290 return error;
1291
1292 balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
1293 balloon.batch_page = NULL;
1294 balloon.page = NULL;
1295 balloon.reset_required = true;
1296
1297 queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
1298
1299 return 0;
1300}
1301module_init(vmballoon_init);
1302
1303static void __exit vmballoon_exit(void)
1304{
1305 vmballoon_vmci_cleanup(&balloon);
1306 cancel_delayed_work_sync(&balloon.dwork);
1307
1308 vmballoon_debugfs_exit(&balloon);
1309
1310 /*
1311 * Deallocate all reserved memory, and reset connection with monitor.
1312 * Reset connection before deallocating memory to avoid potential for
1313 * additional spurious resets from guest touching deallocated pages.
1314 */
1315 vmballoon_send_start(&balloon, 0);
1316 vmballoon_pop(&balloon);
1317}
1318module_exit(vmballoon_exit);