Merge remote-tracking branch 'stable/linux-5.15.y' into rpi-5.15.y
[platform/kernel/linux-rpi.git] / drivers / misc / vmw_balloon.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * VMware Balloon driver.
4  *
5  * Copyright (C) 2000-2018, VMware, Inc. All Rights Reserved.
6  *
7  * This is VMware physical memory management driver for Linux. The driver
8  * acts like a "balloon" that can be inflated to reclaim physical pages by
9  * reserving them in the guest and invalidating them in the monitor,
10  * freeing up the underlying machine pages so they can be allocated to
11  * other guests.  The balloon can also be deflated to allow the guest to
12  * use more physical memory. Higher level policies can control the sizes
13  * of balloons in VMs in order to manage physical memory resources.
14  */
15
16 //#define DEBUG
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19 #include <linux/types.h>
20 #include <linux/io.h>
21 #include <linux/kernel.h>
22 #include <linux/mm.h>
23 #include <linux/vmalloc.h>
24 #include <linux/sched.h>
25 #include <linux/module.h>
26 #include <linux/workqueue.h>
27 #include <linux/debugfs.h>
28 #include <linux/seq_file.h>
29 #include <linux/rwsem.h>
30 #include <linux/slab.h>
31 #include <linux/spinlock.h>
32 #include <linux/mount.h>
33 #include <linux/pseudo_fs.h>
34 #include <linux/balloon_compaction.h>
35 #include <linux/vmw_vmci_defs.h>
36 #include <linux/vmw_vmci_api.h>
37 #include <asm/hypervisor.h>
38
39 MODULE_AUTHOR("VMware, Inc.");
40 MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
41 MODULE_ALIAS("dmi:*:svnVMware*:*");
42 MODULE_ALIAS("vmware_vmmemctl");
43 MODULE_LICENSE("GPL");
44
45 static bool __read_mostly vmwballoon_shrinker_enable;
46 module_param(vmwballoon_shrinker_enable, bool, 0444);
47 MODULE_PARM_DESC(vmwballoon_shrinker_enable,
48         "Enable non-cooperative out-of-memory protection. Disabled by default as it may degrade performance.");
49
50 /* Delay in seconds after shrink before inflation. */
51 #define VMBALLOON_SHRINK_DELAY          (5)
52
53 /* Maximum number of refused pages we accumulate during inflation cycle */
54 #define VMW_BALLOON_MAX_REFUSED         16
55
56 /* Magic number for the balloon mount-point */
57 #define BALLOON_VMW_MAGIC               0x0ba11007
58
59 /*
60  * Hypervisor communication port definitions.
61  */
62 #define VMW_BALLOON_HV_PORT             0x5670
63 #define VMW_BALLOON_HV_MAGIC            0x456c6d6f
64 #define VMW_BALLOON_GUEST_ID            1       /* Linux */
65
66 enum vmwballoon_capabilities {
67         /*
68          * Bit 0 is reserved and not associated to any capability.
69          */
70         VMW_BALLOON_BASIC_CMDS                  = (1 << 1),
71         VMW_BALLOON_BATCHED_CMDS                = (1 << 2),
72         VMW_BALLOON_BATCHED_2M_CMDS             = (1 << 3),
73         VMW_BALLOON_SIGNALLED_WAKEUP_CMD        = (1 << 4),
74         VMW_BALLOON_64_BIT_TARGET               = (1 << 5)
75 };
76
77 #define VMW_BALLOON_CAPABILITIES_COMMON (VMW_BALLOON_BASIC_CMDS \
78                                         | VMW_BALLOON_BATCHED_CMDS \
79                                         | VMW_BALLOON_BATCHED_2M_CMDS \
80                                         | VMW_BALLOON_SIGNALLED_WAKEUP_CMD)
81
82 #define VMW_BALLOON_2M_ORDER            (PMD_SHIFT - PAGE_SHIFT)
83
84 /*
85  * 64-bit targets are only supported in 64-bit
86  */
87 #ifdef CONFIG_64BIT
88 #define VMW_BALLOON_CAPABILITIES        (VMW_BALLOON_CAPABILITIES_COMMON \
89                                         | VMW_BALLOON_64_BIT_TARGET)
90 #else
91 #define VMW_BALLOON_CAPABILITIES        VMW_BALLOON_CAPABILITIES_COMMON
92 #endif
93
94 enum vmballoon_page_size_type {
95         VMW_BALLOON_4K_PAGE,
96         VMW_BALLOON_2M_PAGE,
97         VMW_BALLOON_LAST_SIZE = VMW_BALLOON_2M_PAGE
98 };
99
100 #define VMW_BALLOON_NUM_PAGE_SIZES      (VMW_BALLOON_LAST_SIZE + 1)
101
102 static const char * const vmballoon_page_size_names[] = {
103         [VMW_BALLOON_4K_PAGE]                   = "4k",
104         [VMW_BALLOON_2M_PAGE]                   = "2M"
105 };
106
107 enum vmballoon_op {
108         VMW_BALLOON_INFLATE,
109         VMW_BALLOON_DEFLATE
110 };
111
112 enum vmballoon_op_stat_type {
113         VMW_BALLOON_OP_STAT,
114         VMW_BALLOON_OP_FAIL_STAT
115 };
116
117 #define VMW_BALLOON_OP_STAT_TYPES       (VMW_BALLOON_OP_FAIL_STAT + 1)
118
119 /**
120  * enum vmballoon_cmd_type - backdoor commands.
121  *
122  * Availability of the commands is as followed:
123  *
124  * %VMW_BALLOON_CMD_START, %VMW_BALLOON_CMD_GET_TARGET and
125  * %VMW_BALLOON_CMD_GUEST_ID are always available.
126  *
127  * If the host reports %VMW_BALLOON_BASIC_CMDS are supported then
128  * %VMW_BALLOON_CMD_LOCK and %VMW_BALLOON_CMD_UNLOCK commands are available.
129  *
130  * If the host reports %VMW_BALLOON_BATCHED_CMDS are supported then
131  * %VMW_BALLOON_CMD_BATCHED_LOCK and VMW_BALLOON_CMD_BATCHED_UNLOCK commands
132  * are available.
133  *
134  * If the host reports %VMW_BALLOON_BATCHED_2M_CMDS are supported then
135  * %VMW_BALLOON_CMD_BATCHED_2M_LOCK and %VMW_BALLOON_CMD_BATCHED_2M_UNLOCK
136  * are supported.
137  *
138  * If the host reports  VMW_BALLOON_SIGNALLED_WAKEUP_CMD is supported then
139  * VMW_BALLOON_CMD_VMCI_DOORBELL_SET command is supported.
140  *
141  * @VMW_BALLOON_CMD_START: Communicating supported version with the hypervisor.
142  * @VMW_BALLOON_CMD_GET_TARGET: Gets the balloon target size.
143  * @VMW_BALLOON_CMD_LOCK: Informs the hypervisor about a ballooned page.
144  * @VMW_BALLOON_CMD_UNLOCK: Informs the hypervisor about a page that is about
145  *                          to be deflated from the balloon.
146  * @VMW_BALLOON_CMD_GUEST_ID: Informs the hypervisor about the type of OS that
147  *                            runs in the VM.
148  * @VMW_BALLOON_CMD_BATCHED_LOCK: Inform the hypervisor about a batch of
149  *                                ballooned pages (up to 512).
150  * @VMW_BALLOON_CMD_BATCHED_UNLOCK: Inform the hypervisor about a batch of
151  *                                pages that are about to be deflated from the
152  *                                balloon (up to 512).
153  * @VMW_BALLOON_CMD_BATCHED_2M_LOCK: Similar to @VMW_BALLOON_CMD_BATCHED_LOCK
154  *                                   for 2MB pages.
155  * @VMW_BALLOON_CMD_BATCHED_2M_UNLOCK: Similar to
156  *                                     @VMW_BALLOON_CMD_BATCHED_UNLOCK for 2MB
157  *                                     pages.
158  * @VMW_BALLOON_CMD_VMCI_DOORBELL_SET: A command to set doorbell notification
159  *                                     that would be invoked when the balloon
160  *                                     size changes.
161  * @VMW_BALLOON_CMD_LAST: Value of the last command.
162  */
163 enum vmballoon_cmd_type {
164         VMW_BALLOON_CMD_START,
165         VMW_BALLOON_CMD_GET_TARGET,
166         VMW_BALLOON_CMD_LOCK,
167         VMW_BALLOON_CMD_UNLOCK,
168         VMW_BALLOON_CMD_GUEST_ID,
169         /* No command 5 */
170         VMW_BALLOON_CMD_BATCHED_LOCK = 6,
171         VMW_BALLOON_CMD_BATCHED_UNLOCK,
172         VMW_BALLOON_CMD_BATCHED_2M_LOCK,
173         VMW_BALLOON_CMD_BATCHED_2M_UNLOCK,
174         VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
175         VMW_BALLOON_CMD_LAST = VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
176 };
177
178 #define VMW_BALLOON_CMD_NUM     (VMW_BALLOON_CMD_LAST + 1)
179
180 enum vmballoon_error_codes {
181         VMW_BALLOON_SUCCESS,
182         VMW_BALLOON_ERROR_CMD_INVALID,
183         VMW_BALLOON_ERROR_PPN_INVALID,
184         VMW_BALLOON_ERROR_PPN_LOCKED,
185         VMW_BALLOON_ERROR_PPN_UNLOCKED,
186         VMW_BALLOON_ERROR_PPN_PINNED,
187         VMW_BALLOON_ERROR_PPN_NOTNEEDED,
188         VMW_BALLOON_ERROR_RESET,
189         VMW_BALLOON_ERROR_BUSY
190 };
191
192 #define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES   (0x03000000)
193
194 #define VMW_BALLOON_CMD_WITH_TARGET_MASK                        \
195         ((1UL << VMW_BALLOON_CMD_GET_TARGET)            |       \
196          (1UL << VMW_BALLOON_CMD_LOCK)                  |       \
197          (1UL << VMW_BALLOON_CMD_UNLOCK)                |       \
198          (1UL << VMW_BALLOON_CMD_BATCHED_LOCK)          |       \
199          (1UL << VMW_BALLOON_CMD_BATCHED_UNLOCK)        |       \
200          (1UL << VMW_BALLOON_CMD_BATCHED_2M_LOCK)       |       \
201          (1UL << VMW_BALLOON_CMD_BATCHED_2M_UNLOCK))
202
203 static const char * const vmballoon_cmd_names[] = {
204         [VMW_BALLOON_CMD_START]                 = "start",
205         [VMW_BALLOON_CMD_GET_TARGET]            = "target",
206         [VMW_BALLOON_CMD_LOCK]                  = "lock",
207         [VMW_BALLOON_CMD_UNLOCK]                = "unlock",
208         [VMW_BALLOON_CMD_GUEST_ID]              = "guestType",
209         [VMW_BALLOON_CMD_BATCHED_LOCK]          = "batchLock",
210         [VMW_BALLOON_CMD_BATCHED_UNLOCK]        = "batchUnlock",
211         [VMW_BALLOON_CMD_BATCHED_2M_LOCK]       = "2m-lock",
212         [VMW_BALLOON_CMD_BATCHED_2M_UNLOCK]     = "2m-unlock",
213         [VMW_BALLOON_CMD_VMCI_DOORBELL_SET]     = "doorbellSet"
214 };
215
216 enum vmballoon_stat_page {
217         VMW_BALLOON_PAGE_STAT_ALLOC,
218         VMW_BALLOON_PAGE_STAT_ALLOC_FAIL,
219         VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC,
220         VMW_BALLOON_PAGE_STAT_REFUSED_FREE,
221         VMW_BALLOON_PAGE_STAT_FREE,
222         VMW_BALLOON_PAGE_STAT_LAST = VMW_BALLOON_PAGE_STAT_FREE
223 };
224
225 #define VMW_BALLOON_PAGE_STAT_NUM       (VMW_BALLOON_PAGE_STAT_LAST + 1)
226
227 enum vmballoon_stat_general {
228         VMW_BALLOON_STAT_TIMER,
229         VMW_BALLOON_STAT_DOORBELL,
230         VMW_BALLOON_STAT_RESET,
231         VMW_BALLOON_STAT_SHRINK,
232         VMW_BALLOON_STAT_SHRINK_FREE,
233         VMW_BALLOON_STAT_LAST = VMW_BALLOON_STAT_SHRINK_FREE
234 };
235
236 #define VMW_BALLOON_STAT_NUM            (VMW_BALLOON_STAT_LAST + 1)
237
238 static DEFINE_STATIC_KEY_TRUE(vmw_balloon_batching);
239 static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled);
240
241 struct vmballoon_ctl {
242         struct list_head pages;
243         struct list_head refused_pages;
244         struct list_head prealloc_pages;
245         unsigned int n_refused_pages;
246         unsigned int n_pages;
247         enum vmballoon_page_size_type page_size;
248         enum vmballoon_op op;
249 };
250
251 /**
252  * struct vmballoon_batch_entry - a batch entry for lock or unlock.
253  *
254  * @status: the status of the operation, which is written by the hypervisor.
255  * @reserved: reserved for future use. Must be set to zero.
256  * @pfn: the physical frame number of the page to be locked or unlocked.
257  */
258 struct vmballoon_batch_entry {
259         u64 status : 5;
260         u64 reserved : PAGE_SHIFT - 5;
261         u64 pfn : 52;
262 } __packed;
263
264 struct vmballoon {
265         /**
266          * @max_page_size: maximum supported page size for ballooning.
267          *
268          * Protected by @conf_sem
269          */
270         enum vmballoon_page_size_type max_page_size;
271
272         /**
273          * @size: balloon actual size in basic page size (frames).
274          *
275          * While we currently do not support size which is bigger than 32-bit,
276          * in preparation for future support, use 64-bits.
277          */
278         atomic64_t size;
279
280         /**
281          * @target: balloon target size in basic page size (frames).
282          *
283          * We do not protect the target under the assumption that setting the
284          * value is always done through a single write. If this assumption ever
285          * breaks, we would have to use X_ONCE for accesses, and suffer the less
286          * optimized code. Although we may read stale target value if multiple
287          * accesses happen at once, the performance impact should be minor.
288          */
289         unsigned long target;
290
291         /**
292          * @reset_required: reset flag
293          *
294          * Setting this flag may introduce races, but the code is expected to
295          * handle them gracefully. In the worst case, another operation will
296          * fail as reset did not take place. Clearing the flag is done while
297          * holding @conf_sem for write.
298          */
299         bool reset_required;
300
301         /**
302          * @capabilities: hypervisor balloon capabilities.
303          *
304          * Protected by @conf_sem.
305          */
306         unsigned long capabilities;
307
308         /**
309          * @batch_page: pointer to communication batch page.
310          *
311          * When batching is used, batch_page points to a page, which holds up to
312          * %VMW_BALLOON_BATCH_MAX_PAGES entries for locking or unlocking.
313          */
314         struct vmballoon_batch_entry *batch_page;
315
316         /**
317          * @batch_max_pages: maximum pages that can be locked/unlocked.
318          *
319          * Indicates the number of pages that the hypervisor can lock or unlock
320          * at once, according to whether batching is enabled. If batching is
321          * disabled, only a single page can be locked/unlock on each operation.
322          *
323          * Protected by @conf_sem.
324          */
325         unsigned int batch_max_pages;
326
327         /**
328          * @page: page to be locked/unlocked by the hypervisor
329          *
330          * @page is only used when batching is disabled and a single page is
331          * reclaimed on each iteration.
332          *
333          * Protected by @comm_lock.
334          */
335         struct page *page;
336
337         /**
338          * @shrink_timeout: timeout until the next inflation.
339          *
340          * After an shrink event, indicates the time in jiffies after which
341          * inflation is allowed again. Can be written concurrently with reads,
342          * so must use READ_ONCE/WRITE_ONCE when accessing.
343          */
344         unsigned long shrink_timeout;
345
346         /* statistics */
347         struct vmballoon_stats *stats;
348
349         /**
350          * @b_dev_info: balloon device information descriptor.
351          */
352         struct balloon_dev_info b_dev_info;
353
354         struct delayed_work dwork;
355
356         /**
357          * @huge_pages - list of the inflated 2MB pages.
358          *
359          * Protected by @b_dev_info.pages_lock .
360          */
361         struct list_head huge_pages;
362
363         /**
364          * @vmci_doorbell.
365          *
366          * Protected by @conf_sem.
367          */
368         struct vmci_handle vmci_doorbell;
369
370         /**
371          * @conf_sem: semaphore to protect the configuration and the statistics.
372          */
373         struct rw_semaphore conf_sem;
374
375         /**
376          * @comm_lock: lock to protect the communication with the host.
377          *
378          * Lock ordering: @conf_sem -> @comm_lock .
379          */
380         spinlock_t comm_lock;
381
382         /**
383          * @shrinker: shrinker interface that is used to avoid over-inflation.
384          */
385         struct shrinker shrinker;
386
387         /**
388          * @shrinker_registered: whether the shrinker was registered.
389          *
390          * The shrinker interface does not handle gracefully the removal of
391          * shrinker that was not registered before. This indication allows to
392          * simplify the unregistration process.
393          */
394         bool shrinker_registered;
395 };
396
397 static struct vmballoon balloon;
398
399 struct vmballoon_stats {
400         /* timer / doorbell operations */
401         atomic64_t general_stat[VMW_BALLOON_STAT_NUM];
402
403         /* allocation statistics for huge and small pages */
404         atomic64_t
405                page_stat[VMW_BALLOON_PAGE_STAT_NUM][VMW_BALLOON_NUM_PAGE_SIZES];
406
407         /* Monitor operations: total operations, and failures */
408         atomic64_t ops[VMW_BALLOON_CMD_NUM][VMW_BALLOON_OP_STAT_TYPES];
409 };
410
411 static inline bool is_vmballoon_stats_on(void)
412 {
413         return IS_ENABLED(CONFIG_DEBUG_FS) &&
414                 static_branch_unlikely(&balloon_stat_enabled);
415 }
416
417 static inline void vmballoon_stats_op_inc(struct vmballoon *b, unsigned int op,
418                                           enum vmballoon_op_stat_type type)
419 {
420         if (is_vmballoon_stats_on())
421                 atomic64_inc(&b->stats->ops[op][type]);
422 }
423
424 static inline void vmballoon_stats_gen_inc(struct vmballoon *b,
425                                            enum vmballoon_stat_general stat)
426 {
427         if (is_vmballoon_stats_on())
428                 atomic64_inc(&b->stats->general_stat[stat]);
429 }
430
431 static inline void vmballoon_stats_gen_add(struct vmballoon *b,
432                                            enum vmballoon_stat_general stat,
433                                            unsigned int val)
434 {
435         if (is_vmballoon_stats_on())
436                 atomic64_add(val, &b->stats->general_stat[stat]);
437 }
438
439 static inline void vmballoon_stats_page_inc(struct vmballoon *b,
440                                             enum vmballoon_stat_page stat,
441                                             enum vmballoon_page_size_type size)
442 {
443         if (is_vmballoon_stats_on())
444                 atomic64_inc(&b->stats->page_stat[stat][size]);
445 }
446
447 static inline void vmballoon_stats_page_add(struct vmballoon *b,
448                                             enum vmballoon_stat_page stat,
449                                             enum vmballoon_page_size_type size,
450                                             unsigned int val)
451 {
452         if (is_vmballoon_stats_on())
453                 atomic64_add(val, &b->stats->page_stat[stat][size]);
454 }
455
456 static inline unsigned long
457 __vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1,
458                 unsigned long arg2, unsigned long *result)
459 {
460         unsigned long status, dummy1, dummy2, dummy3, local_result;
461
462         vmballoon_stats_op_inc(b, cmd, VMW_BALLOON_OP_STAT);
463
464         asm volatile ("inl %%dx" :
465                 "=a"(status),
466                 "=c"(dummy1),
467                 "=d"(dummy2),
468                 "=b"(local_result),
469                 "=S"(dummy3) :
470                 "0"(VMW_BALLOON_HV_MAGIC),
471                 "1"(cmd),
472                 "2"(VMW_BALLOON_HV_PORT),
473                 "3"(arg1),
474                 "4"(arg2) :
475                 "memory");
476
477         /* update the result if needed */
478         if (result)
479                 *result = (cmd == VMW_BALLOON_CMD_START) ? dummy1 :
480                                                            local_result;
481
482         /* update target when applicable */
483         if (status == VMW_BALLOON_SUCCESS &&
484             ((1ul << cmd) & VMW_BALLOON_CMD_WITH_TARGET_MASK))
485                 WRITE_ONCE(b->target, local_result);
486
487         if (status != VMW_BALLOON_SUCCESS &&
488             status != VMW_BALLOON_SUCCESS_WITH_CAPABILITIES) {
489                 vmballoon_stats_op_inc(b, cmd, VMW_BALLOON_OP_FAIL_STAT);
490                 pr_debug("%s: %s [0x%lx,0x%lx) failed, returned %ld\n",
491                          __func__, vmballoon_cmd_names[cmd], arg1, arg2,
492                          status);
493         }
494
495         /* mark reset required accordingly */
496         if (status == VMW_BALLOON_ERROR_RESET)
497                 b->reset_required = true;
498
499         return status;
500 }
501
502 static __always_inline unsigned long
503 vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1,
504               unsigned long arg2)
505 {
506         unsigned long dummy;
507
508         return __vmballoon_cmd(b, cmd, arg1, arg2, &dummy);
509 }
510
511 /*
512  * Send "start" command to the host, communicating supported version
513  * of the protocol.
514  */
515 static int vmballoon_send_start(struct vmballoon *b, unsigned long req_caps)
516 {
517         unsigned long status, capabilities;
518
519         status = __vmballoon_cmd(b, VMW_BALLOON_CMD_START, req_caps, 0,
520                                  &capabilities);
521
522         switch (status) {
523         case VMW_BALLOON_SUCCESS_WITH_CAPABILITIES:
524                 b->capabilities = capabilities;
525                 break;
526         case VMW_BALLOON_SUCCESS:
527                 b->capabilities = VMW_BALLOON_BASIC_CMDS;
528                 break;
529         default:
530                 return -EIO;
531         }
532
533         /*
534          * 2MB pages are only supported with batching. If batching is for some
535          * reason disabled, do not use 2MB pages, since otherwise the legacy
536          * mechanism is used with 2MB pages, causing a failure.
537          */
538         b->max_page_size = VMW_BALLOON_4K_PAGE;
539         if ((b->capabilities & VMW_BALLOON_BATCHED_2M_CMDS) &&
540             (b->capabilities & VMW_BALLOON_BATCHED_CMDS))
541                 b->max_page_size = VMW_BALLOON_2M_PAGE;
542
543
544         return 0;
545 }
546
547 /**
548  * vmballoon_send_guest_id - communicate guest type to the host.
549  *
550  * @b: pointer to the balloon.
551  *
552  * Communicate guest type to the host so that it can adjust ballooning
553  * algorithm to the one most appropriate for the guest. This command
554  * is normally issued after sending "start" command and is part of
555  * standard reset sequence.
556  *
557  * Return: zero on success or appropriate error code.
558  */
559 static int vmballoon_send_guest_id(struct vmballoon *b)
560 {
561         unsigned long status;
562
563         status = vmballoon_cmd(b, VMW_BALLOON_CMD_GUEST_ID,
564                                VMW_BALLOON_GUEST_ID, 0);
565
566         return status == VMW_BALLOON_SUCCESS ? 0 : -EIO;
567 }
568
569 /**
570  * vmballoon_page_order() - return the order of the page
571  * @page_size: the size of the page.
572  *
573  * Return: the allocation order.
574  */
575 static inline
576 unsigned int vmballoon_page_order(enum vmballoon_page_size_type page_size)
577 {
578         return page_size == VMW_BALLOON_2M_PAGE ? VMW_BALLOON_2M_ORDER : 0;
579 }
580
581 /**
582  * vmballoon_page_in_frames() - returns the number of frames in a page.
583  * @page_size: the size of the page.
584  *
585  * Return: the number of 4k frames.
586  */
587 static inline unsigned int
588 vmballoon_page_in_frames(enum vmballoon_page_size_type page_size)
589 {
590         return 1 << vmballoon_page_order(page_size);
591 }
592
593 /**
594  * vmballoon_mark_page_offline() - mark a page as offline
595  * @page: pointer for the page.
596  * @page_size: the size of the page.
597  */
598 static void
599 vmballoon_mark_page_offline(struct page *page,
600                             enum vmballoon_page_size_type page_size)
601 {
602         int i;
603
604         for (i = 0; i < vmballoon_page_in_frames(page_size); i++)
605                 __SetPageOffline(page + i);
606 }
607
608 /**
609  * vmballoon_mark_page_online() - mark a page as online
610  * @page: pointer for the page.
611  * @page_size: the size of the page.
612  */
613 static void
614 vmballoon_mark_page_online(struct page *page,
615                            enum vmballoon_page_size_type page_size)
616 {
617         int i;
618
619         for (i = 0; i < vmballoon_page_in_frames(page_size); i++)
620                 __ClearPageOffline(page + i);
621 }
622
623 /**
624  * vmballoon_send_get_target() - Retrieve desired balloon size from the host.
625  *
626  * @b: pointer to the balloon.
627  *
628  * Return: zero on success, EINVAL if limit does not fit in 32-bit, as required
629  * by the host-guest protocol and EIO if an error occurred in communicating with
630  * the host.
631  */
632 static int vmballoon_send_get_target(struct vmballoon *b)
633 {
634         unsigned long status;
635         unsigned long limit;
636
637         limit = totalram_pages();
638
639         /* Ensure limit fits in 32-bits if 64-bit targets are not supported */
640         if (!(b->capabilities & VMW_BALLOON_64_BIT_TARGET) &&
641             limit != (u32)limit)
642                 return -EINVAL;
643
644         status = vmballoon_cmd(b, VMW_BALLOON_CMD_GET_TARGET, limit, 0);
645
646         return status == VMW_BALLOON_SUCCESS ? 0 : -EIO;
647 }
648
649 /**
650  * vmballoon_alloc_page_list - allocates a list of pages.
651  *
652  * @b: pointer to the balloon.
653  * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
654  * @req_n_pages: the number of requested pages.
655  *
656  * Tries to allocate @req_n_pages. Add them to the list of balloon pages in
657  * @ctl.pages and updates @ctl.n_pages to reflect the number of pages.
658  *
659  * Return: zero on success or error code otherwise.
660  */
661 static int vmballoon_alloc_page_list(struct vmballoon *b,
662                                      struct vmballoon_ctl *ctl,
663                                      unsigned int req_n_pages)
664 {
665         struct page *page;
666         unsigned int i;
667
668         for (i = 0; i < req_n_pages; i++) {
669                 /*
670                  * First check if we happen to have pages that were allocated
671                  * before. This happens when 2MB page rejected during inflation
672                  * by the hypervisor, and then split into 4KB pages.
673                  */
674                 if (!list_empty(&ctl->prealloc_pages)) {
675                         page = list_first_entry(&ctl->prealloc_pages,
676                                                 struct page, lru);
677                         list_del(&page->lru);
678                 } else {
679                         if (ctl->page_size == VMW_BALLOON_2M_PAGE)
680                                 page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN|
681                                         __GFP_NOMEMALLOC, VMW_BALLOON_2M_ORDER);
682                         else
683                                 page = balloon_page_alloc();
684
685                         vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC,
686                                                  ctl->page_size);
687                 }
688
689                 if (page) {
690                         /* Success. Add the page to the list and continue. */
691                         list_add(&page->lru, &ctl->pages);
692                         continue;
693                 }
694
695                 /* Allocation failed. Update statistics and stop. */
696                 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC_FAIL,
697                                          ctl->page_size);
698                 break;
699         }
700
701         ctl->n_pages = i;
702
703         return req_n_pages == ctl->n_pages ? 0 : -ENOMEM;
704 }
705
706 /**
707  * vmballoon_handle_one_result - Handle lock/unlock result for a single page.
708  *
709  * @b: pointer for %struct vmballoon.
710  * @page: pointer for the page whose result should be handled.
711  * @page_size: size of the page.
712  * @status: status of the operation as provided by the hypervisor.
713  */
714 static int vmballoon_handle_one_result(struct vmballoon *b, struct page *page,
715                                        enum vmballoon_page_size_type page_size,
716                                        unsigned long status)
717 {
718         /* On success do nothing. The page is already on the balloon list. */
719         if (likely(status == VMW_BALLOON_SUCCESS))
720                 return 0;
721
722         pr_debug("%s: failed comm pfn %lx status %lu page_size %s\n", __func__,
723                  page_to_pfn(page), status,
724                  vmballoon_page_size_names[page_size]);
725
726         /* Error occurred */
727         vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC,
728                                  page_size);
729
730         return -EIO;
731 }
732
733 /**
734  * vmballoon_status_page - returns the status of (un)lock operation
735  *
736  * @b: pointer to the balloon.
737  * @idx: index for the page for which the operation is performed.
738  * @p: pointer to where the page struct is returned.
739  *
740  * Following a lock or unlock operation, returns the status of the operation for
741  * an individual page. Provides the page that the operation was performed on on
742  * the @page argument.
743  *
744  * Returns: The status of a lock or unlock operation for an individual page.
745  */
746 static unsigned long vmballoon_status_page(struct vmballoon *b, int idx,
747                                            struct page **p)
748 {
749         if (static_branch_likely(&vmw_balloon_batching)) {
750                 /* batching mode */
751                 *p = pfn_to_page(b->batch_page[idx].pfn);
752                 return b->batch_page[idx].status;
753         }
754
755         /* non-batching mode */
756         *p = b->page;
757
758         /*
759          * If a failure occurs, the indication will be provided in the status
760          * of the entire operation, which is considered before the individual
761          * page status. So for non-batching mode, the indication is always of
762          * success.
763          */
764         return VMW_BALLOON_SUCCESS;
765 }
766
767 /**
768  * vmballoon_lock_op - notifies the host about inflated/deflated pages.
769  * @b: pointer to the balloon.
770  * @num_pages: number of inflated/deflated pages.
771  * @page_size: size of the page.
772  * @op: the type of operation (lock or unlock).
773  *
774  * Notify the host about page(s) that were ballooned (or removed from the
775  * balloon) so that host can use it without fear that guest will need it (or
776  * stop using them since the VM does). Host may reject some pages, we need to
777  * check the return value and maybe submit a different page. The pages that are
778  * inflated/deflated are pointed by @b->page.
779  *
780  * Return: result as provided by the hypervisor.
781  */
782 static unsigned long vmballoon_lock_op(struct vmballoon *b,
783                                        unsigned int num_pages,
784                                        enum vmballoon_page_size_type page_size,
785                                        enum vmballoon_op op)
786 {
787         unsigned long cmd, pfn;
788
789         lockdep_assert_held(&b->comm_lock);
790
791         if (static_branch_likely(&vmw_balloon_batching)) {
792                 if (op == VMW_BALLOON_INFLATE)
793                         cmd = page_size == VMW_BALLOON_2M_PAGE ?
794                                 VMW_BALLOON_CMD_BATCHED_2M_LOCK :
795                                 VMW_BALLOON_CMD_BATCHED_LOCK;
796                 else
797                         cmd = page_size == VMW_BALLOON_2M_PAGE ?
798                                 VMW_BALLOON_CMD_BATCHED_2M_UNLOCK :
799                                 VMW_BALLOON_CMD_BATCHED_UNLOCK;
800
801                 pfn = PHYS_PFN(virt_to_phys(b->batch_page));
802         } else {
803                 cmd = op == VMW_BALLOON_INFLATE ? VMW_BALLOON_CMD_LOCK :
804                                                   VMW_BALLOON_CMD_UNLOCK;
805                 pfn = page_to_pfn(b->page);
806
807                 /* In non-batching mode, PFNs must fit in 32-bit */
808                 if (unlikely(pfn != (u32)pfn))
809                         return VMW_BALLOON_ERROR_PPN_INVALID;
810         }
811
812         return vmballoon_cmd(b, cmd, pfn, num_pages);
813 }
814
815 /**
816  * vmballoon_add_page - adds a page towards lock/unlock operation.
817  *
818  * @b: pointer to the balloon.
819  * @idx: index of the page to be ballooned in this batch.
820  * @p: pointer to the page that is about to be ballooned.
821  *
822  * Adds the page to be ballooned. Must be called while holding @comm_lock.
823  */
824 static void vmballoon_add_page(struct vmballoon *b, unsigned int idx,
825                                struct page *p)
826 {
827         lockdep_assert_held(&b->comm_lock);
828
829         if (static_branch_likely(&vmw_balloon_batching))
830                 b->batch_page[idx] = (struct vmballoon_batch_entry)
831                                         { .pfn = page_to_pfn(p) };
832         else
833                 b->page = p;
834 }
835
836 /**
837  * vmballoon_lock - lock or unlock a batch of pages.
838  *
839  * @b: pointer to the balloon.
840  * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
841  *
842  * Notifies the host of about ballooned pages (after inflation or deflation,
843  * according to @ctl). If the host rejects the page put it on the
844  * @ctl refuse list. These refused page are then released when moving to the
845  * next size of pages.
846  *
847  * Note that we neither free any @page here nor put them back on the ballooned
848  * pages list. Instead we queue it for later processing. We do that for several
849  * reasons. First, we do not want to free the page under the lock. Second, it
850  * allows us to unify the handling of lock and unlock. In the inflate case, the
851  * caller will check if there are too many refused pages and release them.
852  * Although it is not identical to the past behavior, it should not affect
853  * performance.
854  */
855 static int vmballoon_lock(struct vmballoon *b, struct vmballoon_ctl *ctl)
856 {
857         unsigned long batch_status;
858         struct page *page;
859         unsigned int i, num_pages;
860
861         num_pages = ctl->n_pages;
862         if (num_pages == 0)
863                 return 0;
864
865         /* communication with the host is done under the communication lock */
866         spin_lock(&b->comm_lock);
867
868         i = 0;
869         list_for_each_entry(page, &ctl->pages, lru)
870                 vmballoon_add_page(b, i++, page);
871
872         batch_status = vmballoon_lock_op(b, ctl->n_pages, ctl->page_size,
873                                          ctl->op);
874
875         /*
876          * Iterate over the pages in the provided list. Since we are changing
877          * @ctl->n_pages we are saving the original value in @num_pages and
878          * use this value to bound the loop.
879          */
880         for (i = 0; i < num_pages; i++) {
881                 unsigned long status;
882
883                 status = vmballoon_status_page(b, i, &page);
884
885                 /*
886                  * Failure of the whole batch overrides a single operation
887                  * results.
888                  */
889                 if (batch_status != VMW_BALLOON_SUCCESS)
890                         status = batch_status;
891
892                 /* Continue if no error happened */
893                 if (!vmballoon_handle_one_result(b, page, ctl->page_size,
894                                                  status))
895                         continue;
896
897                 /*
898                  * Error happened. Move the pages to the refused list and update
899                  * the pages number.
900                  */
901                 list_move(&page->lru, &ctl->refused_pages);
902                 ctl->n_pages--;
903                 ctl->n_refused_pages++;
904         }
905
906         spin_unlock(&b->comm_lock);
907
908         return batch_status == VMW_BALLOON_SUCCESS ? 0 : -EIO;
909 }
910
911 /**
912  * vmballoon_release_page_list() - Releases a page list
913  *
914  * @page_list: list of pages to release.
915  * @n_pages: pointer to the number of pages.
916  * @page_size: whether the pages in the list are 2MB (or else 4KB).
917  *
918  * Releases the list of pages and zeros the number of pages.
919  */
920 static void vmballoon_release_page_list(struct list_head *page_list,
921                                        int *n_pages,
922                                        enum vmballoon_page_size_type page_size)
923 {
924         struct page *page, *tmp;
925
926         list_for_each_entry_safe(page, tmp, page_list, lru) {
927                 list_del(&page->lru);
928                 __free_pages(page, vmballoon_page_order(page_size));
929         }
930
931         if (n_pages)
932                 *n_pages = 0;
933 }
934
935
936 /*
937  * Release pages that were allocated while attempting to inflate the
938  * balloon but were refused by the host for one reason or another.
939  */
940 static void vmballoon_release_refused_pages(struct vmballoon *b,
941                                             struct vmballoon_ctl *ctl)
942 {
943         vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_FREE,
944                                  ctl->page_size);
945
946         vmballoon_release_page_list(&ctl->refused_pages, &ctl->n_refused_pages,
947                                     ctl->page_size);
948 }
949
950 /**
951  * vmballoon_change - retrieve the required balloon change
952  *
953  * @b: pointer for the balloon.
954  *
955  * Return: the required change for the balloon size. A positive number
956  * indicates inflation, a negative number indicates a deflation.
957  */
958 static int64_t vmballoon_change(struct vmballoon *b)
959 {
960         int64_t size, target;
961
962         size = atomic64_read(&b->size);
963         target = READ_ONCE(b->target);
964
965         /*
966          * We must cast first because of int sizes
967          * Otherwise we might get huge positives instead of negatives
968          */
969
970         if (b->reset_required)
971                 return 0;
972
973         /* consider a 2MB slack on deflate, unless the balloon is emptied */
974         if (target < size && target != 0 &&
975             size - target < vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE))
976                 return 0;
977
978         /* If an out-of-memory recently occurred, inflation is disallowed. */
979         if (target > size && time_before(jiffies, READ_ONCE(b->shrink_timeout)))
980                 return 0;
981
982         return target - size;
983 }
984
985 /**
986  * vmballoon_enqueue_page_list() - Enqueues list of pages after inflation.
987  *
988  * @b: pointer to balloon.
989  * @pages: list of pages to enqueue.
990  * @n_pages: pointer to number of pages in list. The value is zeroed.
991  * @page_size: whether the pages are 2MB or 4KB pages.
992  *
993  * Enqueues the provides list of pages in the ballooned page list, clears the
994  * list and zeroes the number of pages that was provided.
995  */
996 static void vmballoon_enqueue_page_list(struct vmballoon *b,
997                                         struct list_head *pages,
998                                         unsigned int *n_pages,
999                                         enum vmballoon_page_size_type page_size)
1000 {
1001         unsigned long flags;
1002         struct page *page;
1003
1004         if (page_size == VMW_BALLOON_4K_PAGE) {
1005                 balloon_page_list_enqueue(&b->b_dev_info, pages);
1006         } else {
1007                 /*
1008                  * Keep the huge pages in a local list which is not available
1009                  * for the balloon compaction mechanism.
1010                  */
1011                 spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
1012
1013                 list_for_each_entry(page, pages, lru) {
1014                         vmballoon_mark_page_offline(page, VMW_BALLOON_2M_PAGE);
1015                 }
1016
1017                 list_splice_init(pages, &b->huge_pages);
1018                 __count_vm_events(BALLOON_INFLATE, *n_pages *
1019                                   vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE));
1020                 spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
1021         }
1022
1023         *n_pages = 0;
1024 }
1025
1026 /**
1027  * vmballoon_dequeue_page_list() - Dequeues page lists for deflation.
1028  *
1029  * @b: pointer to balloon.
1030  * @pages: list of pages to enqueue.
1031  * @n_pages: pointer to number of pages in list. The value is zeroed.
1032  * @page_size: whether the pages are 2MB or 4KB pages.
1033  * @n_req_pages: the number of requested pages.
1034  *
1035  * Dequeues the number of requested pages from the balloon for deflation. The
1036  * number of dequeued pages may be lower, if not enough pages in the requested
1037  * size are available.
1038  */
1039 static void vmballoon_dequeue_page_list(struct vmballoon *b,
1040                                         struct list_head *pages,
1041                                         unsigned int *n_pages,
1042                                         enum vmballoon_page_size_type page_size,
1043                                         unsigned int n_req_pages)
1044 {
1045         struct page *page, *tmp;
1046         unsigned int i = 0;
1047         unsigned long flags;
1048
1049         /* In the case of 4k pages, use the compaction infrastructure */
1050         if (page_size == VMW_BALLOON_4K_PAGE) {
1051                 *n_pages = balloon_page_list_dequeue(&b->b_dev_info, pages,
1052                                                      n_req_pages);
1053                 return;
1054         }
1055
1056         /* 2MB pages */
1057         spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
1058         list_for_each_entry_safe(page, tmp, &b->huge_pages, lru) {
1059                 vmballoon_mark_page_online(page, VMW_BALLOON_2M_PAGE);
1060
1061                 list_move(&page->lru, pages);
1062                 if (++i == n_req_pages)
1063                         break;
1064         }
1065
1066         __count_vm_events(BALLOON_DEFLATE,
1067                           i * vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE));
1068         spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
1069         *n_pages = i;
1070 }
1071
1072 /**
1073  * vmballoon_split_refused_pages() - Split the 2MB refused pages to 4k.
1074  *
1075  * If inflation of 2MB pages was denied by the hypervisor, it is likely to be
1076  * due to one or few 4KB pages. These 2MB pages may keep being allocated and
1077  * then being refused. To prevent this case, this function splits the refused
1078  * pages into 4KB pages and adds them into @prealloc_pages list.
1079  *
1080  * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
1081  */
1082 static void vmballoon_split_refused_pages(struct vmballoon_ctl *ctl)
1083 {
1084         struct page *page, *tmp;
1085         unsigned int i, order;
1086
1087         order = vmballoon_page_order(ctl->page_size);
1088
1089         list_for_each_entry_safe(page, tmp, &ctl->refused_pages, lru) {
1090                 list_del(&page->lru);
1091                 split_page(page, order);
1092                 for (i = 0; i < (1 << order); i++)
1093                         list_add(&page[i].lru, &ctl->prealloc_pages);
1094         }
1095         ctl->n_refused_pages = 0;
1096 }
1097
1098 /**
1099  * vmballoon_inflate() - Inflate the balloon towards its target size.
1100  *
1101  * @b: pointer to the balloon.
1102  */
1103 static void vmballoon_inflate(struct vmballoon *b)
1104 {
1105         int64_t to_inflate_frames;
1106         struct vmballoon_ctl ctl = {
1107                 .pages = LIST_HEAD_INIT(ctl.pages),
1108                 .refused_pages = LIST_HEAD_INIT(ctl.refused_pages),
1109                 .prealloc_pages = LIST_HEAD_INIT(ctl.prealloc_pages),
1110                 .page_size = b->max_page_size,
1111                 .op = VMW_BALLOON_INFLATE
1112         };
1113
1114         while ((to_inflate_frames = vmballoon_change(b)) > 0) {
1115                 unsigned int to_inflate_pages, page_in_frames;
1116                 int alloc_error, lock_error = 0;
1117
1118                 VM_BUG_ON(!list_empty(&ctl.pages));
1119                 VM_BUG_ON(ctl.n_pages != 0);
1120
1121                 page_in_frames = vmballoon_page_in_frames(ctl.page_size);
1122
1123                 to_inflate_pages = min_t(unsigned long, b->batch_max_pages,
1124                                          DIV_ROUND_UP_ULL(to_inflate_frames,
1125                                                           page_in_frames));
1126
1127                 /* Start by allocating */
1128                 alloc_error = vmballoon_alloc_page_list(b, &ctl,
1129                                                         to_inflate_pages);
1130
1131                 /* Actually lock the pages by telling the hypervisor */
1132                 lock_error = vmballoon_lock(b, &ctl);
1133
1134                 /*
1135                  * If an error indicates that something serious went wrong,
1136                  * stop the inflation.
1137                  */
1138                 if (lock_error)
1139                         break;
1140
1141                 /* Update the balloon size */
1142                 atomic64_add(ctl.n_pages * page_in_frames, &b->size);
1143
1144                 vmballoon_enqueue_page_list(b, &ctl.pages, &ctl.n_pages,
1145                                             ctl.page_size);
1146
1147                 /*
1148                  * If allocation failed or the number of refused pages exceeds
1149                  * the maximum allowed, move to the next page size.
1150                  */
1151                 if (alloc_error ||
1152                     ctl.n_refused_pages >= VMW_BALLOON_MAX_REFUSED) {
1153                         if (ctl.page_size == VMW_BALLOON_4K_PAGE)
1154                                 break;
1155
1156                         /*
1157                          * Split the refused pages to 4k. This will also empty
1158                          * the refused pages list.
1159                          */
1160                         vmballoon_split_refused_pages(&ctl);
1161                         ctl.page_size--;
1162                 }
1163
1164                 cond_resched();
1165         }
1166
1167         /*
1168          * Release pages that were allocated while attempting to inflate the
1169          * balloon but were refused by the host for one reason or another,
1170          * and update the statistics.
1171          */
1172         if (ctl.n_refused_pages != 0)
1173                 vmballoon_release_refused_pages(b, &ctl);
1174
1175         vmballoon_release_page_list(&ctl.prealloc_pages, NULL, ctl.page_size);
1176 }
1177
1178 /**
1179  * vmballoon_deflate() - Decrease the size of the balloon.
1180  *
1181  * @b: pointer to the balloon
1182  * @n_frames: the number of frames to deflate. If zero, automatically
1183  * calculated according to the target size.
1184  * @coordinated: whether to coordinate with the host
1185  *
1186  * Decrease the size of the balloon allowing guest to use more memory.
1187  *
1188  * Return: The number of deflated frames (i.e., basic page size units)
1189  */
1190 static unsigned long vmballoon_deflate(struct vmballoon *b, uint64_t n_frames,
1191                                        bool coordinated)
1192 {
1193         unsigned long deflated_frames = 0;
1194         unsigned long tried_frames = 0;
1195         struct vmballoon_ctl ctl = {
1196                 .pages = LIST_HEAD_INIT(ctl.pages),
1197                 .refused_pages = LIST_HEAD_INIT(ctl.refused_pages),
1198                 .page_size = VMW_BALLOON_4K_PAGE,
1199                 .op = VMW_BALLOON_DEFLATE
1200         };
1201
1202         /* free pages to reach target */
1203         while (true) {
1204                 unsigned int to_deflate_pages, n_unlocked_frames;
1205                 unsigned int page_in_frames;
1206                 int64_t to_deflate_frames;
1207                 bool deflated_all;
1208
1209                 page_in_frames = vmballoon_page_in_frames(ctl.page_size);
1210
1211                 VM_BUG_ON(!list_empty(&ctl.pages));
1212                 VM_BUG_ON(ctl.n_pages);
1213                 VM_BUG_ON(!list_empty(&ctl.refused_pages));
1214                 VM_BUG_ON(ctl.n_refused_pages);
1215
1216                 /*
1217                  * If we were requested a specific number of frames, we try to
1218                  * deflate this number of frames. Otherwise, deflation is
1219                  * performed according to the target and balloon size.
1220                  */
1221                 to_deflate_frames = n_frames ? n_frames - tried_frames :
1222                                                -vmballoon_change(b);
1223
1224                 /* break if no work to do */
1225                 if (to_deflate_frames <= 0)
1226                         break;
1227
1228                 /*
1229                  * Calculate the number of frames based on current page size,
1230                  * but limit the deflated frames to a single chunk
1231                  */
1232                 to_deflate_pages = min_t(unsigned long, b->batch_max_pages,
1233                                          DIV_ROUND_UP_ULL(to_deflate_frames,
1234                                                           page_in_frames));
1235
1236                 /* First take the pages from the balloon pages. */
1237                 vmballoon_dequeue_page_list(b, &ctl.pages, &ctl.n_pages,
1238                                             ctl.page_size, to_deflate_pages);
1239
1240                 /*
1241                  * Before pages are moving to the refused list, count their
1242                  * frames as frames that we tried to deflate.
1243                  */
1244                 tried_frames += ctl.n_pages * page_in_frames;
1245
1246                 /*
1247                  * Unlock the pages by communicating with the hypervisor if the
1248                  * communication is coordinated (i.e., not pop). We ignore the
1249                  * return code. Instead we check if all the pages we manage to
1250                  * unlock all the pages. If we failed, we will move to the next
1251                  * page size, and would eventually try again later.
1252                  */
1253                 if (coordinated)
1254                         vmballoon_lock(b, &ctl);
1255
1256                 /*
1257                  * Check if we deflated enough. We will move to the next page
1258                  * size if we did not manage to do so. This calculation takes
1259                  * place now, as once the pages are released, the number of
1260                  * pages is zeroed.
1261                  */
1262                 deflated_all = (ctl.n_pages == to_deflate_pages);
1263
1264                 /* Update local and global counters */
1265                 n_unlocked_frames = ctl.n_pages * page_in_frames;
1266                 atomic64_sub(n_unlocked_frames, &b->size);
1267                 deflated_frames += n_unlocked_frames;
1268
1269                 vmballoon_stats_page_add(b, VMW_BALLOON_PAGE_STAT_FREE,
1270                                          ctl.page_size, ctl.n_pages);
1271
1272                 /* free the ballooned pages */
1273                 vmballoon_release_page_list(&ctl.pages, &ctl.n_pages,
1274                                             ctl.page_size);
1275
1276                 /* Return the refused pages to the ballooned list. */
1277                 vmballoon_enqueue_page_list(b, &ctl.refused_pages,
1278                                             &ctl.n_refused_pages,
1279                                             ctl.page_size);
1280
1281                 /* If we failed to unlock all the pages, move to next size. */
1282                 if (!deflated_all) {
1283                         if (ctl.page_size == b->max_page_size)
1284                                 break;
1285                         ctl.page_size++;
1286                 }
1287
1288                 cond_resched();
1289         }
1290
1291         return deflated_frames;
1292 }
1293
1294 /**
1295  * vmballoon_deinit_batching - disables batching mode.
1296  *
1297  * @b: pointer to &struct vmballoon.
1298  *
1299  * Disables batching, by deallocating the page for communication with the
1300  * hypervisor and disabling the static key to indicate that batching is off.
1301  */
1302 static void vmballoon_deinit_batching(struct vmballoon *b)
1303 {
1304         free_page((unsigned long)b->batch_page);
1305         b->batch_page = NULL;
1306         static_branch_disable(&vmw_balloon_batching);
1307         b->batch_max_pages = 1;
1308 }
1309
1310 /**
1311  * vmballoon_init_batching - enable batching mode.
1312  *
1313  * @b: pointer to &struct vmballoon.
1314  *
1315  * Enables batching, by allocating a page for communication with the hypervisor
1316  * and enabling the static_key to use batching.
1317  *
1318  * Return: zero on success or an appropriate error-code.
1319  */
1320 static int vmballoon_init_batching(struct vmballoon *b)
1321 {
1322         struct page *page;
1323
1324         page = alloc_page(GFP_KERNEL | __GFP_ZERO);
1325         if (!page)
1326                 return -ENOMEM;
1327
1328         b->batch_page = page_address(page);
1329         b->batch_max_pages = PAGE_SIZE / sizeof(struct vmballoon_batch_entry);
1330
1331         static_branch_enable(&vmw_balloon_batching);
1332
1333         return 0;
1334 }
1335
1336 /*
1337  * Receive notification and resize balloon
1338  */
1339 static void vmballoon_doorbell(void *client_data)
1340 {
1341         struct vmballoon *b = client_data;
1342
1343         vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_DOORBELL);
1344
1345         mod_delayed_work(system_freezable_wq, &b->dwork, 0);
1346 }
1347
1348 /*
1349  * Clean up vmci doorbell
1350  */
1351 static void vmballoon_vmci_cleanup(struct vmballoon *b)
1352 {
1353         vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
1354                       VMCI_INVALID_ID, VMCI_INVALID_ID);
1355
1356         if (!vmci_handle_is_invalid(b->vmci_doorbell)) {
1357                 vmci_doorbell_destroy(b->vmci_doorbell);
1358                 b->vmci_doorbell = VMCI_INVALID_HANDLE;
1359         }
1360 }
1361
1362 /**
1363  * vmballoon_vmci_init - Initialize vmci doorbell.
1364  *
1365  * @b: pointer to the balloon.
1366  *
1367  * Return: zero on success or when wakeup command not supported. Error-code
1368  * otherwise.
1369  *
1370  * Initialize vmci doorbell, to get notified as soon as balloon changes.
1371  */
1372 static int vmballoon_vmci_init(struct vmballoon *b)
1373 {
1374         unsigned long error;
1375
1376         if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) == 0)
1377                 return 0;
1378
1379         error = vmci_doorbell_create(&b->vmci_doorbell, VMCI_FLAG_DELAYED_CB,
1380                                      VMCI_PRIVILEGE_FLAG_RESTRICTED,
1381                                      vmballoon_doorbell, b);
1382
1383         if (error != VMCI_SUCCESS)
1384                 goto fail;
1385
1386         error = __vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
1387                                 b->vmci_doorbell.context,
1388                                 b->vmci_doorbell.resource, NULL);
1389
1390         if (error != VMW_BALLOON_SUCCESS)
1391                 goto fail;
1392
1393         return 0;
1394 fail:
1395         vmballoon_vmci_cleanup(b);
1396         return -EIO;
1397 }
1398
1399 /**
1400  * vmballoon_pop - Quickly release all pages allocate for the balloon.
1401  *
1402  * @b: pointer to the balloon.
1403  *
1404  * This function is called when host decides to "reset" balloon for one reason
1405  * or another. Unlike normal "deflate" we do not (shall not) notify host of the
1406  * pages being released.
1407  */
1408 static void vmballoon_pop(struct vmballoon *b)
1409 {
1410         unsigned long size;
1411
1412         while ((size = atomic64_read(&b->size)))
1413                 vmballoon_deflate(b, size, false);
1414 }
1415
1416 /*
1417  * Perform standard reset sequence by popping the balloon (in case it
1418  * is not  empty) and then restarting protocol. This operation normally
1419  * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
1420  */
1421 static void vmballoon_reset(struct vmballoon *b)
1422 {
1423         int error;
1424
1425         down_write(&b->conf_sem);
1426
1427         vmballoon_vmci_cleanup(b);
1428
1429         /* free all pages, skipping monitor unlock */
1430         vmballoon_pop(b);
1431
1432         if (vmballoon_send_start(b, VMW_BALLOON_CAPABILITIES))
1433                 goto unlock;
1434
1435         if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) {
1436                 if (vmballoon_init_batching(b)) {
1437                         /*
1438                          * We failed to initialize batching, inform the monitor
1439                          * about it by sending a null capability.
1440                          *
1441                          * The guest will retry in one second.
1442                          */
1443                         vmballoon_send_start(b, 0);
1444                         goto unlock;
1445                 }
1446         } else if ((b->capabilities & VMW_BALLOON_BASIC_CMDS) != 0) {
1447                 vmballoon_deinit_batching(b);
1448         }
1449
1450         vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_RESET);
1451         b->reset_required = false;
1452
1453         error = vmballoon_vmci_init(b);
1454         if (error)
1455                 pr_err("failed to initialize vmci doorbell\n");
1456
1457         if (vmballoon_send_guest_id(b))
1458                 pr_err("failed to send guest ID to the host\n");
1459
1460 unlock:
1461         up_write(&b->conf_sem);
1462 }
1463
1464 /**
1465  * vmballoon_work - periodic balloon worker for reset, inflation and deflation.
1466  *
1467  * @work: pointer to the &work_struct which is provided by the workqueue.
1468  *
1469  * Resets the protocol if needed, gets the new size and adjusts balloon as
1470  * needed. Repeat in 1 sec.
1471  */
1472 static void vmballoon_work(struct work_struct *work)
1473 {
1474         struct delayed_work *dwork = to_delayed_work(work);
1475         struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
1476         int64_t change = 0;
1477
1478         if (b->reset_required)
1479                 vmballoon_reset(b);
1480
1481         down_read(&b->conf_sem);
1482
1483         /*
1484          * Update the stats while holding the semaphore to ensure that
1485          * @stats_enabled is consistent with whether the stats are actually
1486          * enabled
1487          */
1488         vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_TIMER);
1489
1490         if (!vmballoon_send_get_target(b))
1491                 change = vmballoon_change(b);
1492
1493         if (change != 0) {
1494                 pr_debug("%s - size: %llu, target %lu\n", __func__,
1495                          atomic64_read(&b->size), READ_ONCE(b->target));
1496
1497                 if (change > 0)
1498                         vmballoon_inflate(b);
1499                 else  /* (change < 0) */
1500                         vmballoon_deflate(b, 0, true);
1501         }
1502
1503         up_read(&b->conf_sem);
1504
1505         /*
1506          * We are using a freezable workqueue so that balloon operations are
1507          * stopped while the system transitions to/from sleep/hibernation.
1508          */
1509         queue_delayed_work(system_freezable_wq,
1510                            dwork, round_jiffies_relative(HZ));
1511
1512 }
1513
1514 /**
1515  * vmballoon_shrinker_scan() - deflate the balloon due to memory pressure.
1516  * @shrinker: pointer to the balloon shrinker.
1517  * @sc: page reclaim information.
1518  *
1519  * Returns: number of pages that were freed during deflation.
1520  */
1521 static unsigned long vmballoon_shrinker_scan(struct shrinker *shrinker,
1522                                              struct shrink_control *sc)
1523 {
1524         struct vmballoon *b = &balloon;
1525         unsigned long deflated_frames;
1526
1527         pr_debug("%s - size: %llu", __func__, atomic64_read(&b->size));
1528
1529         vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_SHRINK);
1530
1531         /*
1532          * If the lock is also contended for read, we cannot easily reclaim and
1533          * we bail out.
1534          */
1535         if (!down_read_trylock(&b->conf_sem))
1536                 return 0;
1537
1538         deflated_frames = vmballoon_deflate(b, sc->nr_to_scan, true);
1539
1540         vmballoon_stats_gen_add(b, VMW_BALLOON_STAT_SHRINK_FREE,
1541                                 deflated_frames);
1542
1543         /*
1544          * Delay future inflation for some time to mitigate the situations in
1545          * which balloon continuously grows and shrinks. Use WRITE_ONCE() since
1546          * the access is asynchronous.
1547          */
1548         WRITE_ONCE(b->shrink_timeout, jiffies + HZ * VMBALLOON_SHRINK_DELAY);
1549
1550         up_read(&b->conf_sem);
1551
1552         return deflated_frames;
1553 }
1554
1555 /**
1556  * vmballoon_shrinker_count() - return the number of ballooned pages.
1557  * @shrinker: pointer to the balloon shrinker.
1558  * @sc: page reclaim information.
1559  *
1560  * Returns: number of 4k pages that are allocated for the balloon and can
1561  *          therefore be reclaimed under pressure.
1562  */
1563 static unsigned long vmballoon_shrinker_count(struct shrinker *shrinker,
1564                                               struct shrink_control *sc)
1565 {
1566         struct vmballoon *b = &balloon;
1567
1568         return atomic64_read(&b->size);
1569 }
1570
1571 static void vmballoon_unregister_shrinker(struct vmballoon *b)
1572 {
1573         if (b->shrinker_registered)
1574                 unregister_shrinker(&b->shrinker);
1575         b->shrinker_registered = false;
1576 }
1577
1578 static int vmballoon_register_shrinker(struct vmballoon *b)
1579 {
1580         int r;
1581
1582         /* Do nothing if the shrinker is not enabled */
1583         if (!vmwballoon_shrinker_enable)
1584                 return 0;
1585
1586         b->shrinker.scan_objects = vmballoon_shrinker_scan;
1587         b->shrinker.count_objects = vmballoon_shrinker_count;
1588         b->shrinker.seeks = DEFAULT_SEEKS;
1589
1590         r = register_shrinker(&b->shrinker);
1591
1592         if (r == 0)
1593                 b->shrinker_registered = true;
1594
1595         return r;
1596 }
1597
1598 /*
1599  * DEBUGFS Interface
1600  */
1601 #ifdef CONFIG_DEBUG_FS
1602
1603 static const char * const vmballoon_stat_page_names[] = {
1604         [VMW_BALLOON_PAGE_STAT_ALLOC]           = "alloc",
1605         [VMW_BALLOON_PAGE_STAT_ALLOC_FAIL]      = "allocFail",
1606         [VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC]   = "errAlloc",
1607         [VMW_BALLOON_PAGE_STAT_REFUSED_FREE]    = "errFree",
1608         [VMW_BALLOON_PAGE_STAT_FREE]            = "free"
1609 };
1610
1611 static const char * const vmballoon_stat_names[] = {
1612         [VMW_BALLOON_STAT_TIMER]                = "timer",
1613         [VMW_BALLOON_STAT_DOORBELL]             = "doorbell",
1614         [VMW_BALLOON_STAT_RESET]                = "reset",
1615         [VMW_BALLOON_STAT_SHRINK]               = "shrink",
1616         [VMW_BALLOON_STAT_SHRINK_FREE]          = "shrinkFree"
1617 };
1618
1619 static int vmballoon_enable_stats(struct vmballoon *b)
1620 {
1621         int r = 0;
1622
1623         down_write(&b->conf_sem);
1624
1625         /* did we somehow race with another reader which enabled stats? */
1626         if (b->stats)
1627                 goto out;
1628
1629         b->stats = kzalloc(sizeof(*b->stats), GFP_KERNEL);
1630
1631         if (!b->stats) {
1632                 /* allocation failed */
1633                 r = -ENOMEM;
1634                 goto out;
1635         }
1636         static_key_enable(&balloon_stat_enabled.key);
1637 out:
1638         up_write(&b->conf_sem);
1639         return r;
1640 }
1641
1642 /**
1643  * vmballoon_debug_show - shows statistics of balloon operations.
1644  * @f: pointer to the &struct seq_file.
1645  * @offset: ignored.
1646  *
1647  * Provides the statistics that can be accessed in vmmemctl in the debugfs.
1648  * To avoid the overhead - mainly that of memory - of collecting the statistics,
1649  * we only collect statistics after the first time the counters are read.
1650  *
1651  * Return: zero on success or an error code.
1652  */
1653 static int vmballoon_debug_show(struct seq_file *f, void *offset)
1654 {
1655         struct vmballoon *b = f->private;
1656         int i, j;
1657
1658         /* enables stats if they are disabled */
1659         if (!b->stats) {
1660                 int r = vmballoon_enable_stats(b);
1661
1662                 if (r)
1663                         return r;
1664         }
1665
1666         /* format capabilities info */
1667         seq_printf(f, "%-22s: %#16x\n", "balloon capabilities",
1668                    VMW_BALLOON_CAPABILITIES);
1669         seq_printf(f, "%-22s: %#16lx\n", "used capabilities", b->capabilities);
1670         seq_printf(f, "%-22s: %16s\n", "is resetting",
1671                    b->reset_required ? "y" : "n");
1672
1673         /* format size info */
1674         seq_printf(f, "%-22s: %16lu\n", "target", READ_ONCE(b->target));
1675         seq_printf(f, "%-22s: %16llu\n", "current", atomic64_read(&b->size));
1676
1677         for (i = 0; i < VMW_BALLOON_CMD_NUM; i++) {
1678                 if (vmballoon_cmd_names[i] == NULL)
1679                         continue;
1680
1681                 seq_printf(f, "%-22s: %16llu (%llu failed)\n",
1682                            vmballoon_cmd_names[i],
1683                            atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_STAT]),
1684                            atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_FAIL_STAT]));
1685         }
1686
1687         for (i = 0; i < VMW_BALLOON_STAT_NUM; i++)
1688                 seq_printf(f, "%-22s: %16llu\n",
1689                            vmballoon_stat_names[i],
1690                            atomic64_read(&b->stats->general_stat[i]));
1691
1692         for (i = 0; i < VMW_BALLOON_PAGE_STAT_NUM; i++) {
1693                 for (j = 0; j < VMW_BALLOON_NUM_PAGE_SIZES; j++)
1694                         seq_printf(f, "%-18s(%s): %16llu\n",
1695                                    vmballoon_stat_page_names[i],
1696                                    vmballoon_page_size_names[j],
1697                                    atomic64_read(&b->stats->page_stat[i][j]));
1698         }
1699
1700         return 0;
1701 }
1702
1703 DEFINE_SHOW_ATTRIBUTE(vmballoon_debug);
1704
1705 static void __init vmballoon_debugfs_init(struct vmballoon *b)
1706 {
1707         debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
1708                             &vmballoon_debug_fops);
1709 }
1710
1711 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
1712 {
1713         static_key_disable(&balloon_stat_enabled.key);
1714         debugfs_remove(debugfs_lookup("vmmemctl", NULL));
1715         kfree(b->stats);
1716         b->stats = NULL;
1717 }
1718
1719 #else
1720
1721 static inline void vmballoon_debugfs_init(struct vmballoon *b)
1722 {
1723 }
1724
1725 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
1726 {
1727 }
1728
1729 #endif  /* CONFIG_DEBUG_FS */
1730
1731
1732 #ifdef CONFIG_BALLOON_COMPACTION
1733
1734 static int vmballoon_init_fs_context(struct fs_context *fc)
1735 {
1736         return init_pseudo(fc, BALLOON_VMW_MAGIC) ? 0 : -ENOMEM;
1737 }
1738
1739 static struct file_system_type vmballoon_fs = {
1740         .name                   = "balloon-vmware",
1741         .init_fs_context        = vmballoon_init_fs_context,
1742         .kill_sb                = kill_anon_super,
1743 };
1744
1745 static struct vfsmount *vmballoon_mnt;
1746
1747 /**
1748  * vmballoon_migratepage() - migrates a balloon page.
1749  * @b_dev_info: balloon device information descriptor.
1750  * @newpage: the page to which @page should be migrated.
1751  * @page: a ballooned page that should be migrated.
1752  * @mode: migration mode, ignored.
1753  *
1754  * This function is really open-coded, but that is according to the interface
1755  * that balloon_compaction provides.
1756  *
1757  * Return: zero on success, -EAGAIN when migration cannot be performed
1758  *         momentarily, and -EBUSY if migration failed and should be retried
1759  *         with that specific page.
1760  */
1761 static int vmballoon_migratepage(struct balloon_dev_info *b_dev_info,
1762                                  struct page *newpage, struct page *page,
1763                                  enum migrate_mode mode)
1764 {
1765         unsigned long status, flags;
1766         struct vmballoon *b;
1767         int ret;
1768
1769         b = container_of(b_dev_info, struct vmballoon, b_dev_info);
1770
1771         /*
1772          * If the semaphore is taken, there is ongoing configuration change
1773          * (i.e., balloon reset), so try again.
1774          */
1775         if (!down_read_trylock(&b->conf_sem))
1776                 return -EAGAIN;
1777
1778         spin_lock(&b->comm_lock);
1779         /*
1780          * We must start by deflating and not inflating, as otherwise the
1781          * hypervisor may tell us that it has enough memory and the new page is
1782          * not needed. Since the old page is isolated, we cannot use the list
1783          * interface to unlock it, as the LRU field is used for isolation.
1784          * Instead, we use the native interface directly.
1785          */
1786         vmballoon_add_page(b, 0, page);
1787         status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE,
1788                                    VMW_BALLOON_DEFLATE);
1789
1790         if (status == VMW_BALLOON_SUCCESS)
1791                 status = vmballoon_status_page(b, 0, &page);
1792
1793         /*
1794          * If a failure happened, let the migration mechanism know that it
1795          * should not retry.
1796          */
1797         if (status != VMW_BALLOON_SUCCESS) {
1798                 spin_unlock(&b->comm_lock);
1799                 ret = -EBUSY;
1800                 goto out_unlock;
1801         }
1802
1803         /*
1804          * The page is isolated, so it is safe to delete it without holding
1805          * @pages_lock . We keep holding @comm_lock since we will need it in a
1806          * second.
1807          */
1808         balloon_page_delete(page);
1809
1810         put_page(page);
1811
1812         /* Inflate */
1813         vmballoon_add_page(b, 0, newpage);
1814         status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE,
1815                                    VMW_BALLOON_INFLATE);
1816
1817         if (status == VMW_BALLOON_SUCCESS)
1818                 status = vmballoon_status_page(b, 0, &newpage);
1819
1820         spin_unlock(&b->comm_lock);
1821
1822         if (status != VMW_BALLOON_SUCCESS) {
1823                 /*
1824                  * A failure happened. While we can deflate the page we just
1825                  * inflated, this deflation can also encounter an error. Instead
1826                  * we will decrease the size of the balloon to reflect the
1827                  * change and report failure.
1828                  */
1829                 atomic64_dec(&b->size);
1830                 ret = -EBUSY;
1831         } else {
1832                 /*
1833                  * Success. Take a reference for the page, and we will add it to
1834                  * the list after acquiring the lock.
1835                  */
1836                 get_page(newpage);
1837                 ret = MIGRATEPAGE_SUCCESS;
1838         }
1839
1840         /* Update the balloon list under the @pages_lock */
1841         spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
1842
1843         /*
1844          * On inflation success, we already took a reference for the @newpage.
1845          * If we succeed just insert it to the list and update the statistics
1846          * under the lock.
1847          */
1848         if (ret == MIGRATEPAGE_SUCCESS) {
1849                 balloon_page_insert(&b->b_dev_info, newpage);
1850                 __count_vm_event(BALLOON_MIGRATE);
1851         }
1852
1853         /*
1854          * We deflated successfully, so regardless to the inflation success, we
1855          * need to reduce the number of isolated_pages.
1856          */
1857         b->b_dev_info.isolated_pages--;
1858         spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
1859
1860 out_unlock:
1861         up_read(&b->conf_sem);
1862         return ret;
1863 }
1864
1865 /**
1866  * vmballoon_compaction_deinit() - removes compaction related data.
1867  *
1868  * @b: pointer to the balloon.
1869  */
1870 static void vmballoon_compaction_deinit(struct vmballoon *b)
1871 {
1872         if (!IS_ERR(b->b_dev_info.inode))
1873                 iput(b->b_dev_info.inode);
1874
1875         b->b_dev_info.inode = NULL;
1876         kern_unmount(vmballoon_mnt);
1877         vmballoon_mnt = NULL;
1878 }
1879
1880 /**
1881  * vmballoon_compaction_init() - initialized compaction for the balloon.
1882  *
1883  * @b: pointer to the balloon.
1884  *
1885  * If during the initialization a failure occurred, this function does not
1886  * perform cleanup. The caller must call vmballoon_compaction_deinit() in this
1887  * case.
1888  *
1889  * Return: zero on success or error code on failure.
1890  */
1891 static __init int vmballoon_compaction_init(struct vmballoon *b)
1892 {
1893         vmballoon_mnt = kern_mount(&vmballoon_fs);
1894         if (IS_ERR(vmballoon_mnt))
1895                 return PTR_ERR(vmballoon_mnt);
1896
1897         b->b_dev_info.migratepage = vmballoon_migratepage;
1898         b->b_dev_info.inode = alloc_anon_inode(vmballoon_mnt->mnt_sb);
1899
1900         if (IS_ERR(b->b_dev_info.inode))
1901                 return PTR_ERR(b->b_dev_info.inode);
1902
1903         b->b_dev_info.inode->i_mapping->a_ops = &balloon_aops;
1904         return 0;
1905 }
1906
1907 #else /* CONFIG_BALLOON_COMPACTION */
1908
1909 static void vmballoon_compaction_deinit(struct vmballoon *b)
1910 {
1911 }
1912
1913 static int vmballoon_compaction_init(struct vmballoon *b)
1914 {
1915         return 0;
1916 }
1917
1918 #endif /* CONFIG_BALLOON_COMPACTION */
1919
1920 static int __init vmballoon_init(void)
1921 {
1922         int error;
1923
1924         /*
1925          * Check if we are running on VMware's hypervisor and bail out
1926          * if we are not.
1927          */
1928         if (x86_hyper_type != X86_HYPER_VMWARE)
1929                 return -ENODEV;
1930
1931         INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
1932
1933         error = vmballoon_register_shrinker(&balloon);
1934         if (error)
1935                 goto fail;
1936
1937         /*
1938          * Initialization of compaction must be done after the call to
1939          * balloon_devinfo_init() .
1940          */
1941         balloon_devinfo_init(&balloon.b_dev_info);
1942         error = vmballoon_compaction_init(&balloon);
1943         if (error)
1944                 goto fail;
1945
1946         INIT_LIST_HEAD(&balloon.huge_pages);
1947         spin_lock_init(&balloon.comm_lock);
1948         init_rwsem(&balloon.conf_sem);
1949         balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
1950         balloon.batch_page = NULL;
1951         balloon.page = NULL;
1952         balloon.reset_required = true;
1953
1954         queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
1955
1956         vmballoon_debugfs_init(&balloon);
1957
1958         return 0;
1959 fail:
1960         vmballoon_unregister_shrinker(&balloon);
1961         vmballoon_compaction_deinit(&balloon);
1962         return error;
1963 }
1964
1965 /*
1966  * Using late_initcall() instead of module_init() allows the balloon to use the
1967  * VMCI doorbell even when the balloon is built into the kernel. Otherwise the
1968  * VMCI is probed only after the balloon is initialized. If the balloon is used
1969  * as a module, late_initcall() is equivalent to module_init().
1970  */
1971 late_initcall(vmballoon_init);
1972
1973 static void __exit vmballoon_exit(void)
1974 {
1975         vmballoon_unregister_shrinker(&balloon);
1976         vmballoon_vmci_cleanup(&balloon);
1977         cancel_delayed_work_sync(&balloon.dwork);
1978
1979         vmballoon_debugfs_exit(&balloon);
1980
1981         /*
1982          * Deallocate all reserved memory, and reset connection with monitor.
1983          * Reset connection before deallocating memory to avoid potential for
1984          * additional spurious resets from guest touching deallocated pages.
1985          */
1986         vmballoon_send_start(&balloon, 0);
1987         vmballoon_pop(&balloon);
1988
1989         /* Only once we popped the balloon, compaction can be deinit */
1990         vmballoon_compaction_deinit(&balloon);
1991 }
1992 module_exit(vmballoon_exit);