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