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 37MODULE_AUTHOR("VMware, Inc."); 38MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver"); 39MODULE_ALIAS("dmi:*:svnVMware*:*"); 40MODULE_ALIAS("vmware_vmmemctl"); 41MODULE_LICENSE("GPL"); 42 43static bool __read_mostly vmwballoon_shrinker_enable; 44module_param(vmwballoon_shrinker_enable, bool, 0444); 45MODULE_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 64enum 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 92enum 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 100static const char * const vmballoon_page_size_names[] = { 101 [VMW_BALLOON_4K_PAGE] = "4k", 102 [VMW_BALLOON_2M_PAGE] = "2M" 103}; 104 105enum vmballoon_op { 106 VMW_BALLOON_INFLATE, 107 VMW_BALLOON_DEFLATE 108}; 109 110enum 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 */ 161enum 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 178enum 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 201static 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 214enum 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 225enum 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 236static DEFINE_STATIC_KEY_TRUE(vmw_balloon_batching); 237static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled); 238 239struct 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 */ 256struct vmballoon_batch_entry { 257 u64 status : 5; 258 u64 reserved : PAGE_SHIFT - 5; 259 u64 pfn : 52; 260} __packed; 261 262struct 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 386static struct vmballoon balloon; 387 388struct 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 400static inline bool is_vmballoon_stats_on(void) 401{ 402 return IS_ENABLED(CONFIG_DEBUG_FS) && 403 static_branch_unlikely(&balloon_stat_enabled); 404} 405 406static 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(&b->stats->ops[op][type]); 411} 412 413static 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(&b->stats->general_stat[stat]); 418} 419 420static 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(val, &b->stats->general_stat[stat]); 426} 427 428static 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(&b->stats->page_stat[stat][size]); 434} 435 436static 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(val, &b->stats->page_stat[stat][size]); 443} 444 445static 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, cmd, 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, cmd, 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 491static __always_inline unsigned long 492vmballoon_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, &dummy); 498} 499 500/* 501 * Send "start" command to the host, communicating supported version 502 * of the protocol. 503 */ 504static int vmballoon_send_start(struct vmballoon *b, unsigned long req_caps) 505{ 506 unsigned long status, capabilities; 507 508 status = __vmballoon_cmd(b, VMW_BALLOON_CMD_START, req_caps, 0, 509 &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 */ 548static int vmballoon_send_guest_id(struct vmballoon *b) 549{ 550 unsigned long status; 551 552 status = vmballoon_cmd(b, VMW_BALLOON_CMD_GUEST_ID, 553 VMW_BALLOON_GUEST_ID, 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 */ 564static inline 565unsigned 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 */ 576static inline unsigned int 577vmballoon_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 */ 587static void 588vmballoon_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 + 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 */ 602static void 603vmballoon_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 + 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 */ 621static 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, VMW_BALLOON_CMD_GET_TARGET, limit, 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 */ 650static 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(&ctl->prealloc_pages)) { 664 page = list_first_entry(&ctl->prealloc_pages, 665 struct page, lru); 666 list_del(&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, VMW_BALLOON_PAGE_STAT_ALLOC, 675 ctl->page_size); 676 } 677 678 if (page) { 679 /* Success. Add the page to the list and continue. */ 680 list_add(&page->lru, &ctl->pages); 681 continue; 682 } 683 684 /* Allocation failed. Update statistics and stop. */ 685 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC_FAIL, 686 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 */ 703static 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, VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC, 717 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 */ 735static 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 */ 771static 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, pfn, 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 */ 813static 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 */ 844static 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(&b->comm_lock); 856 857 i = 0; 858 list_for_each_entry(page, &ctl->pages, lru) 859 vmballoon_add_page(b, i++, page); 860 861 batch_status = vmballoon_lock_op(b, ctl->n_pages, ctl->page_size, 862 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, i, &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, 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(&page->lru, &ctl->refused_pages); 891 ctl->n_pages--; 892 ctl->n_refused_pages++; 893 } 894 895 spin_unlock(&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 */ 909static 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(&page->lru); 917 __free_pages(page, 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 */ 929static void vmballoon_release_refused_pages(struct vmballoon *b, 930 struct vmballoon_ctl *ctl) 931{ 932 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_FREE, 933 ctl->page_size); 934 935 vmballoon_release_page_list(&ctl->refused_pages, &ctl->n_refused_pages, 936 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 */ 947static int64_t vmballoon_change(struct vmballoon *b) 948{ 949 int64_t size, target; 950 951 size = atomic64_read(&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(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 */ 985static 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->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, VMW_BALLOON_2M_PAGE); 1004 } 1005 1006 list_splice_init(pages, &b->huge_pages); 1007 __count_vm_events(BALLOON_INFLATE, *n_pages * 1008 vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE)); 1009 spin_unlock_irqrestore(&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 */ 1028static 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->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, VMW_BALLOON_2M_PAGE); 1049 1050 list_move(&page->lru, pages); 1051 if (++i == n_req_pages) 1052 break; 1053 } 1054 1055 __count_vm_events(BALLOON_DEFLATE, 1056 i * vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE)); 1057 spin_unlock_irqrestore(&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 */ 1071static 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(ctl->page_size); 1077 1078 list_for_each_entry_safe(page, tmp, &ctl->refused_pages, lru) { 1079 list_del(&page->lru); 1080 split_page(page, order); 1081 for (i = 0; i < (1 << order); i++) 1082 list_add(&page[i].lru, &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 */ 1092static 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(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, 1118 to_inflate_pages); 1119 1120 /* Actually lock the pages by telling the hypervisor */ 1121 lock_error = vmballoon_lock(b, &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(ctl.n_pages * page_in_frames, &b->size); 1132 1133 vmballoon_enqueue_page_list(b, &ctl.pages, &ctl.n_pages, 1134 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); 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); 1163 1164 vmballoon_release_page_list(&ctl.prealloc_pages, NULL, 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 */ 1179static 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(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, &ctl.pages, &ctl.n_pages, 1227 ctl.page_size, 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); 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(n_unlocked_frames, &b->size); 1256 deflated_frames += n_unlocked_frames; 1257 1258 vmballoon_stats_page_add(b, VMW_BALLOON_PAGE_STAT_FREE, 1259 ctl.page_size, ctl.n_pages); 1260 1261 /* free the ballooned pages */ 1262 vmballoon_release_page_list(&ctl.pages, &ctl.n_pages, 1263 ctl.page_size); 1264 1265 /* Return the refused pages to the ballooned list. */ 1266 vmballoon_enqueue_page_list(b, &ctl.refused_pages, 1267 &ctl.n_refused_pages, 1268 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 */ 1291static 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 */ 1309static 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 */ 1328static void vmballoon_doorbell(void *client_data) 1329{ 1330 struct vmballoon *b = client_data; 1331 1332 vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_DOORBELL); 1333 1334 mod_delayed_work(system_freezable_wq, &b->dwork, 0); 1335} 1336 1337/* 1338 * Clean up vmci doorbell 1339 */ 1340static void vmballoon_vmci_cleanup(struct vmballoon *b) 1341{ 1342 vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET, 1343 VMCI_INVALID_ID, VMCI_INVALID_ID); 1344 1345 if (!vmci_handle_is_invalid(b->vmci_doorbell)) { 1346 vmci_doorbell_destroy(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 */ 1361static 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(&b->vmci_doorbell, VMCI_FLAG_DELAYED_CB, 1369 VMCI_PRIVILEGE_FLAG_RESTRICTED, 1370 vmballoon_doorbell, b); 1371 1372 if (error != VMCI_SUCCESS) 1373 goto fail; 1374 1375 error = __vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET, 1376 b->vmci_doorbell.context, 1377 b->vmci_doorbell.resource, NULL); 1378 1379 if (error != VMW_BALLOON_SUCCESS) 1380 goto fail; 1381 1382 return 0; 1383fail: 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 */ 1397static void vmballoon_pop(struct vmballoon *b) 1398{ 1399 unsigned long size; 1400 1401 while ((size = atomic64_read(&b->size))) 1402 vmballoon_deflate(b, size, 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 */ 1410static void vmballoon_reset(struct vmballoon *b) 1411{ 1412 int error; 1413 1414 down_write(&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, 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, 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 1449unlock: 1450 up_write(&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 */ 1461static 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(&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, 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, 0, true); 1490 } 1491 1492 up_read(&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(system_freezable_wq, 1499 dwork, 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 */ 1510static 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, 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(&b->conf_sem)) 1525 return 0; 1526 1527 deflated_frames = vmballoon_deflate(b, sc->nr_to_scan, true); 1528 1529 vmballoon_stats_gen_add(b, VMW_BALLOON_STAT_SHRINK_FREE, 1530 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(&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 */ 1552static unsigned long vmballoon_shrinker_count(struct shrinker *shrinker, 1553 struct shrink_control *sc) 1554{ 1555 struct vmballoon *b = &balloon; 1556 1557 return atomic64_read(&b->size); 1558} 1559 1560static void vmballoon_unregister_shrinker(struct vmballoon *b) 1561{ 1562 shrinker_free(b->shrinker); 1563 b->shrinker = NULL; 1564} 1565 1566static 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(0, "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(b->shrinker); 1581 1582 return 0; 1583} 1584 1585/* 1586 * DEBUGFS Interface 1587 */ 1588#ifdef CONFIG_DEBUG_FS 1589 1590static 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 1598static 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 1606static int vmballoon_enable_stats(struct vmballoon *b) 1607{ 1608 int r = 0; 1609 1610 down_write(&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(sizeof(*b->stats), GFP_KERNEL); 1617 1618 if (!b->stats) { 1619 /* allocation failed */ 1620 r = -ENOMEM; 1621 goto out; 1622 } 1623 static_key_enable(&balloon_stat_enabled.key); 1624out: 1625 up_write(&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 */ 1640static 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(f, "%-22s: %#16x\n", "balloon capabilities", 1655 VMW_BALLOON_CAPABILITIES); 1656 seq_printf(f, "%-22s: %#16lx\n", "used capabilities", b->capabilities); 1657 seq_printf(f, "%-22s: %16s\n", "is resetting", 1658 b->reset_required ? "y" : "n"); 1659 1660 /* format size info */ 1661 seq_printf(f, "%-22s: %16lu\n", "target", READ_ONCE(b->target)); 1662 seq_printf(f, "%-22s: %16llu\n", "current", atomic64_read(&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(f, "%-22s: %16llu (%llu failed)\n", 1669 vmballoon_cmd_names[i], 1670 atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_STAT]), 1671 atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_FAIL_STAT])); 1672 } 1673 1674 for (i = 0; i < VMW_BALLOON_STAT_NUM; i++) 1675 seq_printf(f, "%-22s: %16llu\n", 1676 vmballoon_stat_names[i], 1677 atomic64_read(&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(f, "%-18s(%s): %16llu\n", 1682 vmballoon_stat_page_names[i], 1683 vmballoon_page_size_names[j], 1684 atomic64_read(&b->stats->page_stat[i][j])); 1685 } 1686 1687 return 0; 1688} 1689 1690DEFINE_SHOW_ATTRIBUTE(vmballoon_debug); 1691 1692static void __init vmballoon_debugfs_init(struct vmballoon *b) 1693{ 1694 debugfs_create_file("vmmemctl", S_IRUGO, NULL, b, 1695 &vmballoon_debug_fops); 1696} 1697 1698static void __exit vmballoon_debugfs_exit(struct vmballoon *b) 1699{ 1700 static_key_disable(&balloon_stat_enabled.key); 1701 debugfs_lookup_and_remove("vmmemctl", NULL); 1702 kfree(b->stats); 1703 b->stats = NULL; 1704} 1705 1706#else 1707 1708static inline void vmballoon_debugfs_init(struct vmballoon *b) 1709{ 1710} 1711 1712static 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 */ 1734static 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(&b->conf_sem)) 1749 return -EAGAIN; 1750 1751 spin_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, 0, page); 1760 status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE, 1761 VMW_BALLOON_DEFLATE); 1762 1763 if (status == VMW_BALLOON_SUCCESS) 1764 status = vmballoon_status_page(b, 0, &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(&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, 0, newpage); 1787 status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE, 1788 VMW_BALLOON_INFLATE); 1789 1790 if (status == VMW_BALLOON_SUCCESS) 1791 status = vmballoon_status_page(b, 0, &newpage); 1792 1793 spin_unlock(&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(&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(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(&b->b_dev_info, newpage); 1823 __count_vm_event(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(&b->b_dev_info.pages_lock, flags); 1832 1833out_unlock: 1834 up_read(&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 */ 1849static __init void vmballoon_compaction_init(struct vmballoon *b) 1850{ 1851 b->b_dev_info.migratepage = vmballoon_migratepage; 1852} 1853 1854#else /* CONFIG_BALLOON_COMPACTION */ 1855static inline void vmballoon_compaction_init(struct vmballoon *b) 1856{ 1857} 1858#endif /* CONFIG_BALLOON_COMPACTION */ 1859 1860static 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(&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.b_dev_info); 1882 vmballoon_compaction_init(&balloon); 1883 1884 INIT_LIST_HEAD(&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(system_freezable_wq, &balloon.dwork, 0); 1893 1894 vmballoon_debugfs_init(&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 */ 1905late_initcall(vmballoon_init); 1906 1907static void __exit vmballoon_exit(void) 1908{ 1909 vmballoon_unregister_shrinker(&balloon); 1910 vmballoon_vmci_cleanup(&balloon); 1911 cancel_delayed_work_sync(&balloon.dwork); 1912 1913 vmballoon_debugfs_exit(&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(&balloon, 0); 1921 vmballoon_pop(&balloon); 1922} 1923module_exit(vmballoon_exit); 1924