1 // SPDX-License-Identifier: GPL-2.0
3 * VMware Balloon driver.
5 * Copyright (C) 2000-2018, VMware, Inc. All Rights Reserved.
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.
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/types.h>
20 #include <linux/kernel.h>
22 #include <linux/vmalloc.h>
23 #include <linux/sched.h>
24 #include <linux/module.h>
25 #include <linux/workqueue.h>
26 #include <linux/debugfs.h>
27 #include <linux/seq_file.h>
28 #include <linux/rwsem.h>
29 #include <linux/slab.h>
30 #include <linux/spinlock.h>
31 #include <linux/vmw_vmci_defs.h>
32 #include <linux/vmw_vmci_api.h>
33 #include <asm/hypervisor.h>
35 MODULE_AUTHOR("VMware, Inc.");
36 MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
37 MODULE_ALIAS("dmi:*:svnVMware*:*");
38 MODULE_ALIAS("vmware_vmmemctl");
39 MODULE_LICENSE("GPL");
42 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't allow wait
43 * (__GFP_RECLAIM) for huge page allocations. Use __GFP_NOWARN, to suppress page
44 * allocation failure warnings. Disallow access to emergency low-memory pools.
46 #define VMW_HUGE_PAGE_ALLOC_FLAGS (__GFP_HIGHMEM|__GFP_NOWARN| \
50 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We allow lightweight
51 * reclamation (__GFP_NORETRY). Use __GFP_NOWARN, to suppress page allocation
52 * failure warnings. Disallow access to emergency low-memory pools.
54 #define VMW_PAGE_ALLOC_FLAGS (__GFP_HIGHMEM|__GFP_NOWARN| \
55 __GFP_NOMEMALLOC|__GFP_NORETRY)
57 /* Maximum number of refused pages we accumulate during inflation cycle */
58 #define VMW_BALLOON_MAX_REFUSED 16
61 * Hypervisor communication port definitions.
63 #define VMW_BALLOON_HV_PORT 0x5670
64 #define VMW_BALLOON_HV_MAGIC 0x456c6d6f
65 #define VMW_BALLOON_GUEST_ID 1 /* Linux */
67 enum vmwballoon_capabilities {
69 * Bit 0 is reserved and not associated to any capability.
71 VMW_BALLOON_BASIC_CMDS = (1 << 1),
72 VMW_BALLOON_BATCHED_CMDS = (1 << 2),
73 VMW_BALLOON_BATCHED_2M_CMDS = (1 << 3),
74 VMW_BALLOON_SIGNALLED_WAKEUP_CMD = (1 << 4),
75 VMW_BALLOON_64_BIT_TARGET = (1 << 5)
78 #define VMW_BALLOON_CAPABILITIES_COMMON (VMW_BALLOON_BASIC_CMDS \
79 | VMW_BALLOON_BATCHED_CMDS \
80 | VMW_BALLOON_BATCHED_2M_CMDS \
81 | VMW_BALLOON_SIGNALLED_WAKEUP_CMD)
83 #define VMW_BALLOON_2M_ORDER (PMD_SHIFT - PAGE_SHIFT)
86 * 64-bit targets are only supported in 64-bit
89 #define VMW_BALLOON_CAPABILITIES (VMW_BALLOON_CAPABILITIES_COMMON \
90 | VMW_BALLOON_64_BIT_TARGET)
92 #define VMW_BALLOON_CAPABILITIES VMW_BALLOON_CAPABILITIES_COMMON
95 enum vmballoon_page_size_type {
98 VMW_BALLOON_LAST_SIZE = VMW_BALLOON_2M_PAGE
101 #define VMW_BALLOON_NUM_PAGE_SIZES (VMW_BALLOON_LAST_SIZE + 1)
103 static const char * const vmballoon_page_size_names[] = {
104 [VMW_BALLOON_4K_PAGE] = "4k",
105 [VMW_BALLOON_2M_PAGE] = "2M"
113 enum vmballoon_op_stat_type {
115 VMW_BALLOON_OP_FAIL_STAT
118 #define VMW_BALLOON_OP_STAT_TYPES (VMW_BALLOON_OP_FAIL_STAT + 1)
121 * enum vmballoon_cmd_type - backdoor commands.
123 * Availability of the commands is as followed:
125 * %VMW_BALLOON_CMD_START, %VMW_BALLOON_CMD_GET_TARGET and
126 * %VMW_BALLOON_CMD_GUEST_ID are always available.
128 * If the host reports %VMW_BALLOON_BASIC_CMDS are supported then
129 * %VMW_BALLOON_CMD_LOCK and %VMW_BALLOON_CMD_UNLOCK commands are available.
131 * If the host reports %VMW_BALLOON_BATCHED_CMDS are supported then
132 * %VMW_BALLOON_CMD_BATCHED_LOCK and VMW_BALLOON_CMD_BATCHED_UNLOCK commands
135 * If the host reports %VMW_BALLOON_BATCHED_2M_CMDS are supported then
136 * %VMW_BALLOON_CMD_BATCHED_2M_LOCK and %VMW_BALLOON_CMD_BATCHED_2M_UNLOCK
139 * If the host reports VMW_BALLOON_SIGNALLED_WAKEUP_CMD is supported then
140 * VMW_BALLOON_CMD_VMCI_DOORBELL_SET command is supported.
142 * @VMW_BALLOON_CMD_START: Communicating supported version with the hypervisor.
143 * @VMW_BALLOON_CMD_GET_TARGET: Gets the balloon target size.
144 * @VMW_BALLOON_CMD_LOCK: Informs the hypervisor about a ballooned page.
145 * @VMW_BALLOON_CMD_UNLOCK: Informs the hypervisor about a page that is about
146 * to be deflated from the balloon.
147 * @VMW_BALLOON_CMD_GUEST_ID: Informs the hypervisor about the type of OS that
149 * @VMW_BALLOON_CMD_BATCHED_LOCK: Inform the hypervisor about a batch of
150 * ballooned pages (up to 512).
151 * @VMW_BALLOON_CMD_BATCHED_UNLOCK: Inform the hypervisor about a batch of
152 * pages that are about to be deflated from the
153 * balloon (up to 512).
154 * @VMW_BALLOON_CMD_BATCHED_2M_LOCK: Similar to @VMW_BALLOON_CMD_BATCHED_LOCK
156 * @VMW_BALLOON_CMD_BATCHED_2M_UNLOCK: Similar to
157 * @VMW_BALLOON_CMD_BATCHED_UNLOCK for 2MB
159 * @VMW_BALLOON_CMD_VMCI_DOORBELL_SET: A command to set doorbell notification
160 * that would be invoked when the balloon
162 * @VMW_BALLOON_CMD_LAST: Value of the last command.
164 enum vmballoon_cmd_type {
165 VMW_BALLOON_CMD_START,
166 VMW_BALLOON_CMD_GET_TARGET,
167 VMW_BALLOON_CMD_LOCK,
168 VMW_BALLOON_CMD_UNLOCK,
169 VMW_BALLOON_CMD_GUEST_ID,
171 VMW_BALLOON_CMD_BATCHED_LOCK = 6,
172 VMW_BALLOON_CMD_BATCHED_UNLOCK,
173 VMW_BALLOON_CMD_BATCHED_2M_LOCK,
174 VMW_BALLOON_CMD_BATCHED_2M_UNLOCK,
175 VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
176 VMW_BALLOON_CMD_LAST = VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
179 #define VMW_BALLOON_CMD_NUM (VMW_BALLOON_CMD_LAST + 1)
181 enum vmballoon_error_codes {
183 VMW_BALLOON_ERROR_CMD_INVALID,
184 VMW_BALLOON_ERROR_PPN_INVALID,
185 VMW_BALLOON_ERROR_PPN_LOCKED,
186 VMW_BALLOON_ERROR_PPN_UNLOCKED,
187 VMW_BALLOON_ERROR_PPN_PINNED,
188 VMW_BALLOON_ERROR_PPN_NOTNEEDED,
189 VMW_BALLOON_ERROR_RESET,
190 VMW_BALLOON_ERROR_BUSY
193 #define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES (0x03000000)
195 #define VMW_BALLOON_CMD_WITH_TARGET_MASK \
196 ((1UL << VMW_BALLOON_CMD_GET_TARGET) | \
197 (1UL << VMW_BALLOON_CMD_LOCK) | \
198 (1UL << VMW_BALLOON_CMD_UNLOCK) | \
199 (1UL << VMW_BALLOON_CMD_BATCHED_LOCK) | \
200 (1UL << VMW_BALLOON_CMD_BATCHED_UNLOCK) | \
201 (1UL << VMW_BALLOON_CMD_BATCHED_2M_LOCK) | \
202 (1UL << VMW_BALLOON_CMD_BATCHED_2M_UNLOCK))
204 static const char * const vmballoon_cmd_names[] = {
205 [VMW_BALLOON_CMD_START] = "start",
206 [VMW_BALLOON_CMD_GET_TARGET] = "target",
207 [VMW_BALLOON_CMD_LOCK] = "lock",
208 [VMW_BALLOON_CMD_UNLOCK] = "unlock",
209 [VMW_BALLOON_CMD_GUEST_ID] = "guestType",
210 [VMW_BALLOON_CMD_BATCHED_LOCK] = "batchLock",
211 [VMW_BALLOON_CMD_BATCHED_UNLOCK] = "batchUnlock",
212 [VMW_BALLOON_CMD_BATCHED_2M_LOCK] = "2m-lock",
213 [VMW_BALLOON_CMD_BATCHED_2M_UNLOCK] = "2m-unlock",
214 [VMW_BALLOON_CMD_VMCI_DOORBELL_SET] = "doorbellSet"
217 enum vmballoon_stat_page {
218 VMW_BALLOON_PAGE_STAT_ALLOC,
219 VMW_BALLOON_PAGE_STAT_ALLOC_FAIL,
220 VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC,
221 VMW_BALLOON_PAGE_STAT_REFUSED_FREE,
222 VMW_BALLOON_PAGE_STAT_FREE,
223 VMW_BALLOON_PAGE_STAT_LAST = VMW_BALLOON_PAGE_STAT_FREE
226 #define VMW_BALLOON_PAGE_STAT_NUM (VMW_BALLOON_PAGE_STAT_LAST + 1)
228 enum vmballoon_stat_general {
229 VMW_BALLOON_STAT_TIMER,
230 VMW_BALLOON_STAT_DOORBELL,
231 VMW_BALLOON_STAT_RESET,
232 VMW_BALLOON_STAT_LAST = VMW_BALLOON_STAT_RESET
235 #define VMW_BALLOON_STAT_NUM (VMW_BALLOON_STAT_LAST + 1)
238 static DEFINE_STATIC_KEY_TRUE(vmw_balloon_batching);
239 static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled);
241 struct vmballoon_ctl {
242 struct list_head pages;
243 struct list_head refused_pages;
244 unsigned int n_refused_pages;
245 unsigned int n_pages;
246 enum vmballoon_page_size_type page_size;
247 enum vmballoon_op op;
250 struct vmballoon_page_size {
251 /* list of reserved physical pages */
252 struct list_head pages;
256 * struct vmballoon_batch_entry - a batch entry for lock or unlock.
258 * @status: the status of the operation, which is written by the hypervisor.
259 * @reserved: reserved for future use. Must be set to zero.
260 * @pfn: the physical frame number of the page to be locked or unlocked.
262 struct vmballoon_batch_entry {
264 u64 reserved : PAGE_SHIFT - 5;
269 struct vmballoon_page_size page_sizes[VMW_BALLOON_NUM_PAGE_SIZES];
272 * @max_page_size: maximum supported page size for ballooning.
274 * Protected by @conf_sem
276 enum vmballoon_page_size_type max_page_size;
279 * @size: balloon actual size in basic page size (frames).
281 * While we currently do not support size which is bigger than 32-bit,
282 * in preparation for future support, use 64-bits.
287 * @target: balloon target size in basic page size (frames).
289 * We do not protect the target under the assumption that setting the
290 * value is always done through a single write. If this assumption ever
291 * breaks, we would have to use X_ONCE for accesses, and suffer the less
292 * optimized code. Although we may read stale target value if multiple
293 * accesses happen at once, the performance impact should be minor.
295 unsigned long target;
298 * @reset_required: reset flag
300 * Setting this flag may introduce races, but the code is expected to
301 * handle them gracefully. In the worst case, another operation will
302 * fail as reset did not take place. Clearing the flag is done while
303 * holding @conf_sem for write.
308 * @capabilities: hypervisor balloon capabilities.
310 * Protected by @conf_sem.
312 unsigned long capabilities;
315 * @batch_page: pointer to communication batch page.
317 * When batching is used, batch_page points to a page, which holds up to
318 * %VMW_BALLOON_BATCH_MAX_PAGES entries for locking or unlocking.
320 struct vmballoon_batch_entry *batch_page;
323 * @batch_max_pages: maximum pages that can be locked/unlocked.
325 * Indicates the number of pages that the hypervisor can lock or unlock
326 * at once, according to whether batching is enabled. If batching is
327 * disabled, only a single page can be locked/unlock on each operation.
329 * Protected by @conf_sem.
331 unsigned int batch_max_pages;
334 * @page: page to be locked/unlocked by the hypervisor
336 * @page is only used when batching is disabled and a single page is
337 * reclaimed on each iteration.
339 * Protected by @comm_lock.
344 struct vmballoon_stats *stats;
346 #ifdef CONFIG_DEBUG_FS
347 /* debugfs file exporting statistics */
348 struct dentry *dbg_entry;
351 struct delayed_work dwork;
356 * Protected by @conf_sem.
358 struct vmci_handle vmci_doorbell;
361 * @conf_sem: semaphore to protect the configuration and the statistics.
363 struct rw_semaphore conf_sem;
366 * @comm_lock: lock to protect the communication with the host.
368 * Lock ordering: @conf_sem -> @comm_lock .
370 spinlock_t comm_lock;
373 static struct vmballoon balloon;
375 struct vmballoon_stats {
376 /* timer / doorbell operations */
377 atomic64_t general_stat[VMW_BALLOON_STAT_NUM];
379 /* allocation statistics for huge and small pages */
381 page_stat[VMW_BALLOON_PAGE_STAT_NUM][VMW_BALLOON_NUM_PAGE_SIZES];
383 /* Monitor operations: total operations, and failures */
384 atomic64_t ops[VMW_BALLOON_CMD_NUM][VMW_BALLOON_OP_STAT_TYPES];
387 static inline bool is_vmballoon_stats_on(void)
389 return IS_ENABLED(CONFIG_DEBUG_FS) &&
390 static_branch_unlikely(&balloon_stat_enabled);
393 static inline void vmballoon_stats_op_inc(struct vmballoon *b, unsigned int op,
394 enum vmballoon_op_stat_type type)
396 if (is_vmballoon_stats_on())
397 atomic64_inc(&b->stats->ops[op][type]);
400 static inline void vmballoon_stats_gen_inc(struct vmballoon *b,
401 enum vmballoon_stat_general stat)
403 if (is_vmballoon_stats_on())
404 atomic64_inc(&b->stats->general_stat[stat]);
407 static inline void vmballoon_stats_gen_add(struct vmballoon *b,
408 enum vmballoon_stat_general stat,
411 if (is_vmballoon_stats_on())
412 atomic64_add(val, &b->stats->general_stat[stat]);
415 static inline void vmballoon_stats_page_inc(struct vmballoon *b,
416 enum vmballoon_stat_page stat,
417 enum vmballoon_page_size_type size)
419 if (is_vmballoon_stats_on())
420 atomic64_inc(&b->stats->page_stat[stat][size]);
423 static inline void vmballoon_stats_page_add(struct vmballoon *b,
424 enum vmballoon_stat_page stat,
425 enum vmballoon_page_size_type size,
428 if (is_vmballoon_stats_on())
429 atomic64_add(val, &b->stats->page_stat[stat][size]);
432 static inline unsigned long
433 __vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1,
434 unsigned long arg2, unsigned long *result)
436 unsigned long status, dummy1, dummy2, dummy3, local_result;
438 vmballoon_stats_op_inc(b, cmd, VMW_BALLOON_OP_STAT);
440 asm volatile ("inl %%dx" :
446 "0"(VMW_BALLOON_HV_MAGIC),
448 "2"(VMW_BALLOON_HV_PORT),
453 /* update the result if needed */
455 *result = (cmd == VMW_BALLOON_CMD_START) ? dummy1 :
458 /* update target when applicable */
459 if (status == VMW_BALLOON_SUCCESS &&
460 ((1ul << cmd) & VMW_BALLOON_CMD_WITH_TARGET_MASK))
461 WRITE_ONCE(b->target, local_result);
463 if (status != VMW_BALLOON_SUCCESS &&
464 status != VMW_BALLOON_SUCCESS_WITH_CAPABILITIES) {
465 vmballoon_stats_op_inc(b, cmd, VMW_BALLOON_OP_FAIL_STAT);
466 pr_debug("%s: %s [0x%lx,0x%lx) failed, returned %ld\n",
467 __func__, vmballoon_cmd_names[cmd], arg1, arg2,
471 /* mark reset required accordingly */
472 if (status == VMW_BALLOON_ERROR_RESET)
473 b->reset_required = true;
478 static __always_inline unsigned long
479 vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1,
484 return __vmballoon_cmd(b, cmd, arg1, arg2, &dummy);
488 * Send "start" command to the host, communicating supported version
491 static int vmballoon_send_start(struct vmballoon *b, unsigned long req_caps)
493 unsigned long status, capabilities;
495 status = __vmballoon_cmd(b, VMW_BALLOON_CMD_START, req_caps, 0,
499 case VMW_BALLOON_SUCCESS_WITH_CAPABILITIES:
500 b->capabilities = capabilities;
502 case VMW_BALLOON_SUCCESS:
503 b->capabilities = VMW_BALLOON_BASIC_CMDS;
510 * 2MB pages are only supported with batching. If batching is for some
511 * reason disabled, do not use 2MB pages, since otherwise the legacy
512 * mechanism is used with 2MB pages, causing a failure.
514 b->max_page_size = VMW_BALLOON_4K_PAGE;
515 if ((b->capabilities & VMW_BALLOON_BATCHED_2M_CMDS) &&
516 (b->capabilities & VMW_BALLOON_BATCHED_CMDS))
517 b->max_page_size = VMW_BALLOON_2M_PAGE;
524 * vmballoon_send_guest_id - communicate guest type to the host.
526 * @b: pointer to the balloon.
528 * Communicate guest type to the host so that it can adjust ballooning
529 * algorithm to the one most appropriate for the guest. This command
530 * is normally issued after sending "start" command and is part of
531 * standard reset sequence.
533 * Return: zero on success or appropriate error code.
535 static int vmballoon_send_guest_id(struct vmballoon *b)
537 unsigned long status;
539 status = vmballoon_cmd(b, VMW_BALLOON_CMD_GUEST_ID,
540 VMW_BALLOON_GUEST_ID, 0);
542 return status == VMW_BALLOON_SUCCESS ? 0 : -EIO;
546 * vmballoon_page_order() - return the order of the page
547 * @page_size: the size of the page.
549 * Return: the allocation order.
552 unsigned int vmballoon_page_order(enum vmballoon_page_size_type page_size)
554 return page_size == VMW_BALLOON_2M_PAGE ? VMW_BALLOON_2M_ORDER : 0;
558 * vmballoon_page_in_frames() - returns the number of frames in a page.
559 * @page_size: the size of the page.
561 * Return: the number of 4k frames.
563 static inline unsigned int
564 vmballoon_page_in_frames(enum vmballoon_page_size_type page_size)
566 return 1 << vmballoon_page_order(page_size);
570 * vmballoon_send_get_target() - Retrieve desired balloon size from the host.
572 * @b: pointer to the balloon.
574 * Return: zero on success, EINVAL if limit does not fit in 32-bit, as required
575 * by the host-guest protocol and EIO if an error occurred in communicating with
578 static int vmballoon_send_get_target(struct vmballoon *b)
580 unsigned long status;
583 limit = totalram_pages();
585 /* Ensure limit fits in 32-bits if 64-bit targets are not supported */
586 if (!(b->capabilities & VMW_BALLOON_64_BIT_TARGET) &&
590 status = vmballoon_cmd(b, VMW_BALLOON_CMD_GET_TARGET, limit, 0);
592 return status == VMW_BALLOON_SUCCESS ? 0 : -EIO;
596 * vmballoon_alloc_page_list - allocates a list of pages.
598 * @b: pointer to the balloon.
599 * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
600 * @req_n_pages: the number of requested pages.
602 * Tries to allocate @req_n_pages. Add them to the list of balloon pages in
603 * @ctl.pages and updates @ctl.n_pages to reflect the number of pages.
605 * Return: zero on success or error code otherwise.
607 static int vmballoon_alloc_page_list(struct vmballoon *b,
608 struct vmballoon_ctl *ctl,
609 unsigned int req_n_pages)
614 for (i = 0; i < req_n_pages; i++) {
615 if (ctl->page_size == VMW_BALLOON_2M_PAGE)
616 page = alloc_pages(VMW_HUGE_PAGE_ALLOC_FLAGS,
617 VMW_BALLOON_2M_ORDER);
619 page = alloc_page(VMW_PAGE_ALLOC_FLAGS);
621 /* Update statistics */
622 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC,
626 /* Success. Add the page to the list and continue. */
627 list_add(&page->lru, &ctl->pages);
631 /* Allocation failed. Update statistics and stop. */
632 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC_FAIL,
639 return req_n_pages == ctl->n_pages ? 0 : -ENOMEM;
643 * vmballoon_handle_one_result - Handle lock/unlock result for a single page.
645 * @b: pointer for %struct vmballoon.
646 * @page: pointer for the page whose result should be handled.
647 * @page_size: size of the page.
648 * @status: status of the operation as provided by the hypervisor.
650 static int vmballoon_handle_one_result(struct vmballoon *b, struct page *page,
651 enum vmballoon_page_size_type page_size,
652 unsigned long status)
654 /* On success do nothing. The page is already on the balloon list. */
655 if (likely(status == VMW_BALLOON_SUCCESS))
658 pr_debug("%s: failed comm pfn %lx status %lu page_size %s\n", __func__,
659 page_to_pfn(page), status,
660 vmballoon_page_size_names[page_size]);
663 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC,
670 * vmballoon_status_page - returns the status of (un)lock operation
672 * @b: pointer to the balloon.
673 * @idx: index for the page for which the operation is performed.
674 * @p: pointer to where the page struct is returned.
676 * Following a lock or unlock operation, returns the status of the operation for
677 * an individual page. Provides the page that the operation was performed on on
678 * the @page argument.
680 * Returns: The status of a lock or unlock operation for an individual page.
682 static unsigned long vmballoon_status_page(struct vmballoon *b, int idx,
685 if (static_branch_likely(&vmw_balloon_batching)) {
687 *p = pfn_to_page(b->batch_page[idx].pfn);
688 return b->batch_page[idx].status;
691 /* non-batching mode */
695 * If a failure occurs, the indication will be provided in the status
696 * of the entire operation, which is considered before the individual
697 * page status. So for non-batching mode, the indication is always of
700 return VMW_BALLOON_SUCCESS;
704 * vmballoon_lock_op - notifies the host about inflated/deflated pages.
705 * @b: pointer to the balloon.
706 * @num_pages: number of inflated/deflated pages.
707 * @page_size: size of the page.
708 * @op: the type of operation (lock or unlock).
710 * Notify the host about page(s) that were ballooned (or removed from the
711 * balloon) so that host can use it without fear that guest will need it (or
712 * stop using them since the VM does). Host may reject some pages, we need to
713 * check the return value and maybe submit a different page. The pages that are
714 * inflated/deflated are pointed by @b->page.
716 * Return: result as provided by the hypervisor.
718 static unsigned long vmballoon_lock_op(struct vmballoon *b,
719 unsigned int num_pages,
720 enum vmballoon_page_size_type page_size,
721 enum vmballoon_op op)
723 unsigned long cmd, pfn;
725 lockdep_assert_held(&b->comm_lock);
727 if (static_branch_likely(&vmw_balloon_batching)) {
728 if (op == VMW_BALLOON_INFLATE)
729 cmd = page_size == VMW_BALLOON_2M_PAGE ?
730 VMW_BALLOON_CMD_BATCHED_2M_LOCK :
731 VMW_BALLOON_CMD_BATCHED_LOCK;
733 cmd = page_size == VMW_BALLOON_2M_PAGE ?
734 VMW_BALLOON_CMD_BATCHED_2M_UNLOCK :
735 VMW_BALLOON_CMD_BATCHED_UNLOCK;
737 pfn = PHYS_PFN(virt_to_phys(b->batch_page));
739 cmd = op == VMW_BALLOON_INFLATE ? VMW_BALLOON_CMD_LOCK :
740 VMW_BALLOON_CMD_UNLOCK;
741 pfn = page_to_pfn(b->page);
743 /* In non-batching mode, PFNs must fit in 32-bit */
744 if (unlikely(pfn != (u32)pfn))
745 return VMW_BALLOON_ERROR_PPN_INVALID;
748 return vmballoon_cmd(b, cmd, pfn, num_pages);
752 * vmballoon_add_page - adds a page towards lock/unlock operation.
754 * @b: pointer to the balloon.
755 * @idx: index of the page to be ballooned in this batch.
756 * @p: pointer to the page that is about to be ballooned.
758 * Adds the page to be ballooned. Must be called while holding @comm_lock.
760 static void vmballoon_add_page(struct vmballoon *b, unsigned int idx,
763 lockdep_assert_held(&b->comm_lock);
765 if (static_branch_likely(&vmw_balloon_batching))
766 b->batch_page[idx] = (struct vmballoon_batch_entry)
767 { .pfn = page_to_pfn(p) };
773 * vmballoon_lock - lock or unlock a batch of pages.
775 * @b: pointer to the balloon.
776 * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
778 * Notifies the host of about ballooned pages (after inflation or deflation,
779 * according to @ctl). If the host rejects the page put it on the
780 * @ctl refuse list. These refused page are then released when moving to the
781 * next size of pages.
783 * Note that we neither free any @page here nor put them back on the ballooned
784 * pages list. Instead we queue it for later processing. We do that for several
785 * reasons. First, we do not want to free the page under the lock. Second, it
786 * allows us to unify the handling of lock and unlock. In the inflate case, the
787 * caller will check if there are too many refused pages and release them.
788 * Although it is not identical to the past behavior, it should not affect
791 static int vmballoon_lock(struct vmballoon *b, struct vmballoon_ctl *ctl)
793 unsigned long batch_status;
795 unsigned int i, num_pages;
797 num_pages = ctl->n_pages;
801 /* communication with the host is done under the communication lock */
802 spin_lock(&b->comm_lock);
805 list_for_each_entry(page, &ctl->pages, lru)
806 vmballoon_add_page(b, i++, page);
808 batch_status = vmballoon_lock_op(b, ctl->n_pages, ctl->page_size,
812 * Iterate over the pages in the provided list. Since we are changing
813 * @ctl->n_pages we are saving the original value in @num_pages and
814 * use this value to bound the loop.
816 for (i = 0; i < num_pages; i++) {
817 unsigned long status;
819 status = vmballoon_status_page(b, i, &page);
822 * Failure of the whole batch overrides a single operation
825 if (batch_status != VMW_BALLOON_SUCCESS)
826 status = batch_status;
828 /* Continue if no error happened */
829 if (!vmballoon_handle_one_result(b, page, ctl->page_size,
834 * Error happened. Move the pages to the refused list and update
837 list_move(&page->lru, &ctl->refused_pages);
839 ctl->n_refused_pages++;
842 spin_unlock(&b->comm_lock);
844 return batch_status == VMW_BALLOON_SUCCESS ? 0 : -EIO;
848 * vmballoon_release_page_list() - Releases a page list
850 * @page_list: list of pages to release.
851 * @n_pages: pointer to the number of pages.
852 * @page_size: whether the pages in the list are 2MB (or else 4KB).
854 * Releases the list of pages and zeros the number of pages.
856 static void vmballoon_release_page_list(struct list_head *page_list,
858 enum vmballoon_page_size_type page_size)
860 struct page *page, *tmp;
862 list_for_each_entry_safe(page, tmp, page_list, lru) {
863 list_del(&page->lru);
864 __free_pages(page, vmballoon_page_order(page_size));
872 * Release pages that were allocated while attempting to inflate the
873 * balloon but were refused by the host for one reason or another.
875 static void vmballoon_release_refused_pages(struct vmballoon *b,
876 struct vmballoon_ctl *ctl)
878 vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_FREE,
881 vmballoon_release_page_list(&ctl->refused_pages, &ctl->n_refused_pages,
886 * vmballoon_change - retrieve the required balloon change
888 * @b: pointer for the balloon.
890 * Return: the required change for the balloon size. A positive number
891 * indicates inflation, a negative number indicates a deflation.
893 static int64_t vmballoon_change(struct vmballoon *b)
895 int64_t size, target;
897 size = atomic64_read(&b->size);
898 target = READ_ONCE(b->target);
901 * We must cast first because of int sizes
902 * Otherwise we might get huge positives instead of negatives
905 if (b->reset_required)
908 /* consider a 2MB slack on deflate, unless the balloon is emptied */
909 if (target < size && target != 0 &&
910 size - target < vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE))
913 return target - size;
917 * vmballoon_enqueue_page_list() - Enqueues list of pages after inflation.
919 * @b: pointer to balloon.
920 * @pages: list of pages to enqueue.
921 * @n_pages: pointer to number of pages in list. The value is zeroed.
922 * @page_size: whether the pages are 2MB or 4KB pages.
924 * Enqueues the provides list of pages in the ballooned page list, clears the
925 * list and zeroes the number of pages that was provided.
927 static void vmballoon_enqueue_page_list(struct vmballoon *b,
928 struct list_head *pages,
929 unsigned int *n_pages,
930 enum vmballoon_page_size_type page_size)
932 struct vmballoon_page_size *page_size_info = &b->page_sizes[page_size];
934 list_splice_init(pages, &page_size_info->pages);
939 * vmballoon_dequeue_page_list() - Dequeues page lists for deflation.
941 * @b: pointer to balloon.
942 * @pages: list of pages to enqueue.
943 * @n_pages: pointer to number of pages in list. The value is zeroed.
944 * @page_size: whether the pages are 2MB or 4KB pages.
945 * @n_req_pages: the number of requested pages.
947 * Dequeues the number of requested pages from the balloon for deflation. The
948 * number of dequeued pages may be lower, if not enough pages in the requested
949 * size are available.
951 static void vmballoon_dequeue_page_list(struct vmballoon *b,
952 struct list_head *pages,
953 unsigned int *n_pages,
954 enum vmballoon_page_size_type page_size,
955 unsigned int n_req_pages)
957 struct vmballoon_page_size *page_size_info = &b->page_sizes[page_size];
958 struct page *page, *tmp;
961 list_for_each_entry_safe(page, tmp, &page_size_info->pages, lru) {
962 list_move(&page->lru, pages);
963 if (++i == n_req_pages)
970 * vmballoon_inflate() - Inflate the balloon towards its target size.
972 * @b: pointer to the balloon.
974 static void vmballoon_inflate(struct vmballoon *b)
976 int64_t to_inflate_frames;
977 struct vmballoon_ctl ctl = {
978 .pages = LIST_HEAD_INIT(ctl.pages),
979 .refused_pages = LIST_HEAD_INIT(ctl.refused_pages),
980 .page_size = b->max_page_size,
981 .op = VMW_BALLOON_INFLATE
984 while ((to_inflate_frames = vmballoon_change(b)) > 0) {
985 unsigned int to_inflate_pages, page_in_frames;
986 int alloc_error, lock_error = 0;
988 VM_BUG_ON(!list_empty(&ctl.pages));
989 VM_BUG_ON(ctl.n_pages != 0);
991 page_in_frames = vmballoon_page_in_frames(ctl.page_size);
993 to_inflate_pages = min_t(unsigned long, b->batch_max_pages,
994 DIV_ROUND_UP_ULL(to_inflate_frames,
997 /* Start by allocating */
998 alloc_error = vmballoon_alloc_page_list(b, &ctl,
1001 /* Actually lock the pages by telling the hypervisor */
1002 lock_error = vmballoon_lock(b, &ctl);
1005 * If an error indicates that something serious went wrong,
1006 * stop the inflation.
1011 /* Update the balloon size */
1012 atomic64_add(ctl.n_pages * page_in_frames, &b->size);
1014 vmballoon_enqueue_page_list(b, &ctl.pages, &ctl.n_pages,
1018 * If allocation failed or the number of refused pages exceeds
1019 * the maximum allowed, move to the next page size.
1022 ctl.n_refused_pages >= VMW_BALLOON_MAX_REFUSED) {
1023 if (ctl.page_size == VMW_BALLOON_4K_PAGE)
1027 * Ignore errors from locking as we now switch to 4k
1028 * pages and we might get different errors.
1030 vmballoon_release_refused_pages(b, &ctl);
1038 * Release pages that were allocated while attempting to inflate the
1039 * balloon but were refused by the host for one reason or another,
1040 * and update the statistics.
1042 if (ctl.n_refused_pages != 0)
1043 vmballoon_release_refused_pages(b, &ctl);
1047 * vmballoon_deflate() - Decrease the size of the balloon.
1049 * @b: pointer to the balloon
1050 * @n_frames: the number of frames to deflate. If zero, automatically
1051 * calculated according to the target size.
1052 * @coordinated: whether to coordinate with the host
1054 * Decrease the size of the balloon allowing guest to use more memory.
1056 * Return: The number of deflated frames (i.e., basic page size units)
1058 static unsigned long vmballoon_deflate(struct vmballoon *b, uint64_t n_frames,
1061 unsigned long deflated_frames = 0;
1062 unsigned long tried_frames = 0;
1063 struct vmballoon_ctl ctl = {
1064 .pages = LIST_HEAD_INIT(ctl.pages),
1065 .refused_pages = LIST_HEAD_INIT(ctl.refused_pages),
1066 .page_size = VMW_BALLOON_4K_PAGE,
1067 .op = VMW_BALLOON_DEFLATE
1070 /* free pages to reach target */
1072 unsigned int to_deflate_pages, n_unlocked_frames;
1073 unsigned int page_in_frames;
1074 int64_t to_deflate_frames;
1077 page_in_frames = vmballoon_page_in_frames(ctl.page_size);
1079 VM_BUG_ON(!list_empty(&ctl.pages));
1080 VM_BUG_ON(ctl.n_pages);
1081 VM_BUG_ON(!list_empty(&ctl.refused_pages));
1082 VM_BUG_ON(ctl.n_refused_pages);
1085 * If we were requested a specific number of frames, we try to
1086 * deflate this number of frames. Otherwise, deflation is
1087 * performed according to the target and balloon size.
1089 to_deflate_frames = n_frames ? n_frames - tried_frames :
1090 -vmballoon_change(b);
1092 /* break if no work to do */
1093 if (to_deflate_frames <= 0)
1097 * Calculate the number of frames based on current page size,
1098 * but limit the deflated frames to a single chunk
1100 to_deflate_pages = min_t(unsigned long, b->batch_max_pages,
1101 DIV_ROUND_UP_ULL(to_deflate_frames,
1104 /* First take the pages from the balloon pages. */
1105 vmballoon_dequeue_page_list(b, &ctl.pages, &ctl.n_pages,
1106 ctl.page_size, to_deflate_pages);
1109 * Before pages are moving to the refused list, count their
1110 * frames as frames that we tried to deflate.
1112 tried_frames += ctl.n_pages * page_in_frames;
1115 * Unlock the pages by communicating with the hypervisor if the
1116 * communication is coordinated (i.e., not pop). We ignore the
1117 * return code. Instead we check if all the pages we manage to
1118 * unlock all the pages. If we failed, we will move to the next
1119 * page size, and would eventually try again later.
1122 vmballoon_lock(b, &ctl);
1125 * Check if we deflated enough. We will move to the next page
1126 * size if we did not manage to do so. This calculation takes
1127 * place now, as once the pages are released, the number of
1130 deflated_all = (ctl.n_pages == to_deflate_pages);
1132 /* Update local and global counters */
1133 n_unlocked_frames = ctl.n_pages * page_in_frames;
1134 atomic64_sub(n_unlocked_frames, &b->size);
1135 deflated_frames += n_unlocked_frames;
1137 vmballoon_stats_page_add(b, VMW_BALLOON_PAGE_STAT_FREE,
1138 ctl.page_size, ctl.n_pages);
1140 /* free the ballooned pages */
1141 vmballoon_release_page_list(&ctl.pages, &ctl.n_pages,
1144 /* Return the refused pages to the ballooned list. */
1145 vmballoon_enqueue_page_list(b, &ctl.refused_pages,
1146 &ctl.n_refused_pages,
1149 /* If we failed to unlock all the pages, move to next size. */
1150 if (!deflated_all) {
1151 if (ctl.page_size == b->max_page_size)
1159 return deflated_frames;
1163 * vmballoon_deinit_batching - disables batching mode.
1165 * @b: pointer to &struct vmballoon.
1167 * Disables batching, by deallocating the page for communication with the
1168 * hypervisor and disabling the static key to indicate that batching is off.
1170 static void vmballoon_deinit_batching(struct vmballoon *b)
1172 free_page((unsigned long)b->batch_page);
1173 b->batch_page = NULL;
1174 static_branch_disable(&vmw_balloon_batching);
1175 b->batch_max_pages = 1;
1179 * vmballoon_init_batching - enable batching mode.
1181 * @b: pointer to &struct vmballoon.
1183 * Enables batching, by allocating a page for communication with the hypervisor
1184 * and enabling the static_key to use batching.
1186 * Return: zero on success or an appropriate error-code.
1188 static int vmballoon_init_batching(struct vmballoon *b)
1192 page = alloc_page(GFP_KERNEL | __GFP_ZERO);
1196 b->batch_page = page_address(page);
1197 b->batch_max_pages = PAGE_SIZE / sizeof(struct vmballoon_batch_entry);
1199 static_branch_enable(&vmw_balloon_batching);
1205 * Receive notification and resize balloon
1207 static void vmballoon_doorbell(void *client_data)
1209 struct vmballoon *b = client_data;
1211 vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_DOORBELL);
1213 mod_delayed_work(system_freezable_wq, &b->dwork, 0);
1217 * Clean up vmci doorbell
1219 static void vmballoon_vmci_cleanup(struct vmballoon *b)
1221 vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
1222 VMCI_INVALID_ID, VMCI_INVALID_ID);
1224 if (!vmci_handle_is_invalid(b->vmci_doorbell)) {
1225 vmci_doorbell_destroy(b->vmci_doorbell);
1226 b->vmci_doorbell = VMCI_INVALID_HANDLE;
1231 * vmballoon_vmci_init - Initialize vmci doorbell.
1233 * @b: pointer to the balloon.
1235 * Return: zero on success or when wakeup command not supported. Error-code
1238 * Initialize vmci doorbell, to get notified as soon as balloon changes.
1240 static int vmballoon_vmci_init(struct vmballoon *b)
1242 unsigned long error;
1244 if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) == 0)
1247 error = vmci_doorbell_create(&b->vmci_doorbell, VMCI_FLAG_DELAYED_CB,
1248 VMCI_PRIVILEGE_FLAG_RESTRICTED,
1249 vmballoon_doorbell, b);
1251 if (error != VMCI_SUCCESS)
1254 error = __vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
1255 b->vmci_doorbell.context,
1256 b->vmci_doorbell.resource, NULL);
1258 if (error != VMW_BALLOON_SUCCESS)
1263 vmballoon_vmci_cleanup(b);
1268 * vmballoon_pop - Quickly release all pages allocate for the balloon.
1270 * @b: pointer to the balloon.
1272 * This function is called when host decides to "reset" balloon for one reason
1273 * or another. Unlike normal "deflate" we do not (shall not) notify host of the
1274 * pages being released.
1276 static void vmballoon_pop(struct vmballoon *b)
1280 while ((size = atomic64_read(&b->size)))
1281 vmballoon_deflate(b, size, false);
1285 * Perform standard reset sequence by popping the balloon (in case it
1286 * is not empty) and then restarting protocol. This operation normally
1287 * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
1289 static void vmballoon_reset(struct vmballoon *b)
1293 down_write(&b->conf_sem);
1295 vmballoon_vmci_cleanup(b);
1297 /* free all pages, skipping monitor unlock */
1300 if (vmballoon_send_start(b, VMW_BALLOON_CAPABILITIES))
1303 if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) {
1304 if (vmballoon_init_batching(b)) {
1306 * We failed to initialize batching, inform the monitor
1307 * about it by sending a null capability.
1309 * The guest will retry in one second.
1311 vmballoon_send_start(b, 0);
1314 } else if ((b->capabilities & VMW_BALLOON_BASIC_CMDS) != 0) {
1315 vmballoon_deinit_batching(b);
1318 vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_RESET);
1319 b->reset_required = false;
1321 error = vmballoon_vmci_init(b);
1323 pr_err("failed to initialize vmci doorbell\n");
1325 if (vmballoon_send_guest_id(b))
1326 pr_err("failed to send guest ID to the host\n");
1328 up_write(&b->conf_sem);
1332 * vmballoon_work - periodic balloon worker for reset, inflation and deflation.
1334 * @work: pointer to the &work_struct which is provided by the workqueue.
1336 * Resets the protocol if needed, gets the new size and adjusts balloon as
1337 * needed. Repeat in 1 sec.
1339 static void vmballoon_work(struct work_struct *work)
1341 struct delayed_work *dwork = to_delayed_work(work);
1342 struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
1345 if (b->reset_required)
1348 down_read(&b->conf_sem);
1351 * Update the stats while holding the semaphore to ensure that
1352 * @stats_enabled is consistent with whether the stats are actually
1355 vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_TIMER);
1357 if (!vmballoon_send_get_target(b))
1358 change = vmballoon_change(b);
1361 pr_debug("%s - size: %llu, target %lu\n", __func__,
1362 atomic64_read(&b->size), READ_ONCE(b->target));
1365 vmballoon_inflate(b);
1366 else /* (change < 0) */
1367 vmballoon_deflate(b, 0, true);
1370 up_read(&b->conf_sem);
1373 * We are using a freezable workqueue so that balloon operations are
1374 * stopped while the system transitions to/from sleep/hibernation.
1376 queue_delayed_work(system_freezable_wq,
1377 dwork, round_jiffies_relative(HZ));
1384 #ifdef CONFIG_DEBUG_FS
1386 static const char * const vmballoon_stat_page_names[] = {
1387 [VMW_BALLOON_PAGE_STAT_ALLOC] = "alloc",
1388 [VMW_BALLOON_PAGE_STAT_ALLOC_FAIL] = "allocFail",
1389 [VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC] = "errAlloc",
1390 [VMW_BALLOON_PAGE_STAT_REFUSED_FREE] = "errFree",
1391 [VMW_BALLOON_PAGE_STAT_FREE] = "free"
1394 static const char * const vmballoon_stat_names[] = {
1395 [VMW_BALLOON_STAT_TIMER] = "timer",
1396 [VMW_BALLOON_STAT_DOORBELL] = "doorbell",
1397 [VMW_BALLOON_STAT_RESET] = "reset",
1400 static int vmballoon_enable_stats(struct vmballoon *b)
1404 down_write(&b->conf_sem);
1406 /* did we somehow race with another reader which enabled stats? */
1410 b->stats = kzalloc(sizeof(*b->stats), GFP_KERNEL);
1413 /* allocation failed */
1417 static_key_enable(&balloon_stat_enabled.key);
1419 up_write(&b->conf_sem);
1424 * vmballoon_debug_show - shows statistics of balloon operations.
1425 * @f: pointer to the &struct seq_file.
1428 * Provides the statistics that can be accessed in vmmemctl in the debugfs.
1429 * To avoid the overhead - mainly that of memory - of collecting the statistics,
1430 * we only collect statistics after the first time the counters are read.
1432 * Return: zero on success or an error code.
1434 static int vmballoon_debug_show(struct seq_file *f, void *offset)
1436 struct vmballoon *b = f->private;
1439 /* enables stats if they are disabled */
1441 int r = vmballoon_enable_stats(b);
1447 /* format capabilities info */
1448 seq_printf(f, "%-22s: %#16x\n", "balloon capabilities",
1449 VMW_BALLOON_CAPABILITIES);
1450 seq_printf(f, "%-22s: %#16lx\n", "used capabilities", b->capabilities);
1451 seq_printf(f, "%-22s: %16s\n", "is resetting",
1452 b->reset_required ? "y" : "n");
1454 /* format size info */
1455 seq_printf(f, "%-22s: %16lu\n", "target", READ_ONCE(b->target));
1456 seq_printf(f, "%-22s: %16llu\n", "current", atomic64_read(&b->size));
1458 for (i = 0; i < VMW_BALLOON_CMD_NUM; i++) {
1459 if (vmballoon_cmd_names[i] == NULL)
1462 seq_printf(f, "%-22s: %16llu (%llu failed)\n",
1463 vmballoon_cmd_names[i],
1464 atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_STAT]),
1465 atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_FAIL_STAT]));
1468 for (i = 0; i < VMW_BALLOON_STAT_NUM; i++)
1469 seq_printf(f, "%-22s: %16llu\n",
1470 vmballoon_stat_names[i],
1471 atomic64_read(&b->stats->general_stat[i]));
1473 for (i = 0; i < VMW_BALLOON_PAGE_STAT_NUM; i++) {
1474 for (j = 0; j < VMW_BALLOON_NUM_PAGE_SIZES; j++)
1475 seq_printf(f, "%-18s(%s): %16llu\n",
1476 vmballoon_stat_page_names[i],
1477 vmballoon_page_size_names[j],
1478 atomic64_read(&b->stats->page_stat[i][j]));
1484 DEFINE_SHOW_ATTRIBUTE(vmballoon_debug);
1486 static int __init vmballoon_debugfs_init(struct vmballoon *b)
1490 b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
1491 &vmballoon_debug_fops);
1492 if (IS_ERR(b->dbg_entry)) {
1493 error = PTR_ERR(b->dbg_entry);
1494 pr_err("failed to create debugfs entry, error: %d\n", error);
1501 static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
1503 static_key_disable(&balloon_stat_enabled.key);
1504 debugfs_remove(b->dbg_entry);
1511 static inline int vmballoon_debugfs_init(struct vmballoon *b)
1516 static inline void vmballoon_debugfs_exit(struct vmballoon *b)
1520 #endif /* CONFIG_DEBUG_FS */
1522 static int __init vmballoon_init(void)
1524 enum vmballoon_page_size_type page_size;
1528 * Check if we are running on VMware's hypervisor and bail out
1531 if (x86_hyper_type != X86_HYPER_VMWARE)
1534 for (page_size = VMW_BALLOON_4K_PAGE;
1535 page_size <= VMW_BALLOON_LAST_SIZE; page_size++)
1536 INIT_LIST_HEAD(&balloon.page_sizes[page_size].pages);
1539 INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
1541 error = vmballoon_debugfs_init(&balloon);
1545 spin_lock_init(&balloon.comm_lock);
1546 init_rwsem(&balloon.conf_sem);
1547 balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
1548 balloon.batch_page = NULL;
1549 balloon.page = NULL;
1550 balloon.reset_required = true;
1552 queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
1558 * Using late_initcall() instead of module_init() allows the balloon to use the
1559 * VMCI doorbell even when the balloon is built into the kernel. Otherwise the
1560 * VMCI is probed only after the balloon is initialized. If the balloon is used
1561 * as a module, late_initcall() is equivalent to module_init().
1563 late_initcall(vmballoon_init);
1565 static void __exit vmballoon_exit(void)
1567 vmballoon_vmci_cleanup(&balloon);
1568 cancel_delayed_work_sync(&balloon.dwork);
1570 vmballoon_debugfs_exit(&balloon);
1573 * Deallocate all reserved memory, and reset connection with monitor.
1574 * Reset connection before deallocating memory to avoid potential for
1575 * additional spurious resets from guest touching deallocated pages.
1577 vmballoon_send_start(&balloon, 0);
1578 vmballoon_pop(&balloon);
1580 module_exit(vmballoon_exit);