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Diffstat (limited to 'drivers/misc/vmw_balloon.c')
| -rw-r--r-- | drivers/misc/vmw_balloon.c | 1937 |
1 files changed, 1937 insertions, 0 deletions
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c new file mode 100644 index 000000000..9ce9b9e0e --- /dev/null +++ b/drivers/misc/vmw_balloon.c @@ -0,0 +1,1937 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * VMware Balloon driver. + * + * Copyright (C) 2000-2018, VMware, Inc. All Rights Reserved. + * + * This is VMware physical memory management driver for Linux. The driver + * acts like a "balloon" that can be inflated to reclaim physical pages by + * reserving them in the guest and invalidating them in the monitor, + * freeing up the underlying machine pages so they can be allocated to + * other guests. The balloon can also be deflated to allow the guest to + * use more physical memory. Higher level policies can control the sizes + * of balloons in VMs in order to manage physical memory resources. + */ + +//#define DEBUG +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/types.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/vmalloc.h> +#include <linux/sched.h> +#include <linux/module.h> +#include <linux/workqueue.h> +#include <linux/debugfs.h> +#include <linux/seq_file.h> +#include <linux/rwsem.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/balloon_compaction.h> +#include <linux/vmw_vmci_defs.h> +#include <linux/vmw_vmci_api.h> +#include <asm/hypervisor.h> + +MODULE_AUTHOR("VMware, Inc."); +MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver"); +MODULE_ALIAS("dmi:*:svnVMware*:*"); +MODULE_ALIAS("vmware_vmmemctl"); +MODULE_LICENSE("GPL"); + +static bool __read_mostly vmwballoon_shrinker_enable; +module_param(vmwballoon_shrinker_enable, bool, 0444); +MODULE_PARM_DESC(vmwballoon_shrinker_enable, + "Enable non-cooperative out-of-memory protection. Disabled by default as it may degrade performance."); + +/* Delay in seconds after shrink before inflation. */ +#define VMBALLOON_SHRINK_DELAY (5) + +/* Maximum number of refused pages we accumulate during inflation cycle */ +#define VMW_BALLOON_MAX_REFUSED 16 + +/* Magic number for the balloon mount-point */ +#define BALLOON_VMW_MAGIC 0x0ba11007 + +/* + * Hypervisor communication port definitions. + */ +#define VMW_BALLOON_HV_PORT 0x5670 +#define VMW_BALLOON_HV_MAGIC 0x456c6d6f +#define VMW_BALLOON_GUEST_ID 1 /* Linux */ + +enum vmwballoon_capabilities { + /* + * Bit 0 is reserved and not associated to any capability. + */ + VMW_BALLOON_BASIC_CMDS = (1 << 1), + VMW_BALLOON_BATCHED_CMDS = (1 << 2), + VMW_BALLOON_BATCHED_2M_CMDS = (1 << 3), + VMW_BALLOON_SIGNALLED_WAKEUP_CMD = (1 << 4), + VMW_BALLOON_64_BIT_TARGET = (1 << 5) +}; + +#define VMW_BALLOON_CAPABILITIES_COMMON (VMW_BALLOON_BASIC_CMDS \ + | VMW_BALLOON_BATCHED_CMDS \ + | VMW_BALLOON_BATCHED_2M_CMDS \ + | VMW_BALLOON_SIGNALLED_WAKEUP_CMD) + +#define VMW_BALLOON_2M_ORDER (PMD_SHIFT - PAGE_SHIFT) + +/* + * 64-bit targets are only supported in 64-bit + */ +#ifdef CONFIG_64BIT +#define VMW_BALLOON_CAPABILITIES (VMW_BALLOON_CAPABILITIES_COMMON \ + | VMW_BALLOON_64_BIT_TARGET) +#else +#define VMW_BALLOON_CAPABILITIES VMW_BALLOON_CAPABILITIES_COMMON +#endif + +enum vmballoon_page_size_type { + VMW_BALLOON_4K_PAGE, + VMW_BALLOON_2M_PAGE, + VMW_BALLOON_LAST_SIZE = VMW_BALLOON_2M_PAGE +}; + +#define VMW_BALLOON_NUM_PAGE_SIZES (VMW_BALLOON_LAST_SIZE + 1) + +static const char * const vmballoon_page_size_names[] = { + [VMW_BALLOON_4K_PAGE] = "4k", + [VMW_BALLOON_2M_PAGE] = "2M" +}; + +enum vmballoon_op { + VMW_BALLOON_INFLATE, + VMW_BALLOON_DEFLATE +}; + +enum vmballoon_op_stat_type { + VMW_BALLOON_OP_STAT, + VMW_BALLOON_OP_FAIL_STAT +}; + +#define VMW_BALLOON_OP_STAT_TYPES (VMW_BALLOON_OP_FAIL_STAT + 1) + +/** + * enum vmballoon_cmd_type - backdoor commands. + * + * Availability of the commands is as followed: + * + * %VMW_BALLOON_CMD_START, %VMW_BALLOON_CMD_GET_TARGET and + * %VMW_BALLOON_CMD_GUEST_ID are always available. + * + * If the host reports %VMW_BALLOON_BASIC_CMDS are supported then + * %VMW_BALLOON_CMD_LOCK and %VMW_BALLOON_CMD_UNLOCK commands are available. + * + * If the host reports %VMW_BALLOON_BATCHED_CMDS are supported then + * %VMW_BALLOON_CMD_BATCHED_LOCK and VMW_BALLOON_CMD_BATCHED_UNLOCK commands + * are available. + * + * If the host reports %VMW_BALLOON_BATCHED_2M_CMDS are supported then + * %VMW_BALLOON_CMD_BATCHED_2M_LOCK and %VMW_BALLOON_CMD_BATCHED_2M_UNLOCK + * are supported. + * + * If the host reports VMW_BALLOON_SIGNALLED_WAKEUP_CMD is supported then + * VMW_BALLOON_CMD_VMCI_DOORBELL_SET command is supported. + * + * @VMW_BALLOON_CMD_START: Communicating supported version with the hypervisor. + * @VMW_BALLOON_CMD_GET_TARGET: Gets the balloon target size. + * @VMW_BALLOON_CMD_LOCK: Informs the hypervisor about a ballooned page. + * @VMW_BALLOON_CMD_UNLOCK: Informs the hypervisor about a page that is about + * to be deflated from the balloon. + * @VMW_BALLOON_CMD_GUEST_ID: Informs the hypervisor about the type of OS that + * runs in the VM. + * @VMW_BALLOON_CMD_BATCHED_LOCK: Inform the hypervisor about a batch of + * ballooned pages (up to 512). + * @VMW_BALLOON_CMD_BATCHED_UNLOCK: Inform the hypervisor about a batch of + * pages that are about to be deflated from the + * balloon (up to 512). + * @VMW_BALLOON_CMD_BATCHED_2M_LOCK: Similar to @VMW_BALLOON_CMD_BATCHED_LOCK + * for 2MB pages. + * @VMW_BALLOON_CMD_BATCHED_2M_UNLOCK: Similar to + * @VMW_BALLOON_CMD_BATCHED_UNLOCK for 2MB + * pages. + * @VMW_BALLOON_CMD_VMCI_DOORBELL_SET: A command to set doorbell notification + * that would be invoked when the balloon + * size changes. + * @VMW_BALLOON_CMD_LAST: Value of the last command. + */ +enum vmballoon_cmd_type { + VMW_BALLOON_CMD_START, + VMW_BALLOON_CMD_GET_TARGET, + VMW_BALLOON_CMD_LOCK, + VMW_BALLOON_CMD_UNLOCK, + VMW_BALLOON_CMD_GUEST_ID, + /* No command 5 */ + VMW_BALLOON_CMD_BATCHED_LOCK = 6, + VMW_BALLOON_CMD_BATCHED_UNLOCK, + VMW_BALLOON_CMD_BATCHED_2M_LOCK, + VMW_BALLOON_CMD_BATCHED_2M_UNLOCK, + VMW_BALLOON_CMD_VMCI_DOORBELL_SET, + VMW_BALLOON_CMD_LAST = VMW_BALLOON_CMD_VMCI_DOORBELL_SET, +}; + +#define VMW_BALLOON_CMD_NUM (VMW_BALLOON_CMD_LAST + 1) + +enum vmballoon_error_codes { + VMW_BALLOON_SUCCESS, + VMW_BALLOON_ERROR_CMD_INVALID, + VMW_BALLOON_ERROR_PPN_INVALID, + VMW_BALLOON_ERROR_PPN_LOCKED, + VMW_BALLOON_ERROR_PPN_UNLOCKED, + VMW_BALLOON_ERROR_PPN_PINNED, + VMW_BALLOON_ERROR_PPN_NOTNEEDED, + VMW_BALLOON_ERROR_RESET, + VMW_BALLOON_ERROR_BUSY +}; + +#define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES (0x03000000) + +#define VMW_BALLOON_CMD_WITH_TARGET_MASK \ + ((1UL << VMW_BALLOON_CMD_GET_TARGET) | \ + (1UL << VMW_BALLOON_CMD_LOCK) | \ + (1UL << VMW_BALLOON_CMD_UNLOCK) | \ + (1UL << VMW_BALLOON_CMD_BATCHED_LOCK) | \ + (1UL << VMW_BALLOON_CMD_BATCHED_UNLOCK) | \ + (1UL << VMW_BALLOON_CMD_BATCHED_2M_LOCK) | \ + (1UL << VMW_BALLOON_CMD_BATCHED_2M_UNLOCK)) + +static const char * const vmballoon_cmd_names[] = { + [VMW_BALLOON_CMD_START] = "start", + [VMW_BALLOON_CMD_GET_TARGET] = "target", + [VMW_BALLOON_CMD_LOCK] = "lock", + [VMW_BALLOON_CMD_UNLOCK] = "unlock", + [VMW_BALLOON_CMD_GUEST_ID] = "guestType", + [VMW_BALLOON_CMD_BATCHED_LOCK] = "batchLock", + [VMW_BALLOON_CMD_BATCHED_UNLOCK] = "batchUnlock", + [VMW_BALLOON_CMD_BATCHED_2M_LOCK] = "2m-lock", + [VMW_BALLOON_CMD_BATCHED_2M_UNLOCK] = "2m-unlock", + [VMW_BALLOON_CMD_VMCI_DOORBELL_SET] = "doorbellSet" +}; + +enum vmballoon_stat_page { + VMW_BALLOON_PAGE_STAT_ALLOC, + VMW_BALLOON_PAGE_STAT_ALLOC_FAIL, + VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC, + VMW_BALLOON_PAGE_STAT_REFUSED_FREE, + VMW_BALLOON_PAGE_STAT_FREE, + VMW_BALLOON_PAGE_STAT_LAST = VMW_BALLOON_PAGE_STAT_FREE +}; + +#define VMW_BALLOON_PAGE_STAT_NUM (VMW_BALLOON_PAGE_STAT_LAST + 1) + +enum vmballoon_stat_general { + VMW_BALLOON_STAT_TIMER, + VMW_BALLOON_STAT_DOORBELL, + VMW_BALLOON_STAT_RESET, + VMW_BALLOON_STAT_SHRINK, + VMW_BALLOON_STAT_SHRINK_FREE, + VMW_BALLOON_STAT_LAST = VMW_BALLOON_STAT_SHRINK_FREE +}; + +#define VMW_BALLOON_STAT_NUM (VMW_BALLOON_STAT_LAST + 1) + +static DEFINE_STATIC_KEY_TRUE(vmw_balloon_batching); +static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled); + +struct vmballoon_ctl { + struct list_head pages; + struct list_head refused_pages; + struct list_head prealloc_pages; + unsigned int n_refused_pages; + unsigned int n_pages; + enum vmballoon_page_size_type page_size; + enum vmballoon_op op; +}; + +/** + * struct vmballoon_batch_entry - a batch entry for lock or unlock. + * + * @status: the status of the operation, which is written by the hypervisor. + * @reserved: reserved for future use. Must be set to zero. + * @pfn: the physical frame number of the page to be locked or unlocked. + */ +struct vmballoon_batch_entry { + u64 status : 5; + u64 reserved : PAGE_SHIFT - 5; + u64 pfn : 52; +} __packed; + +struct vmballoon { + /** + * @max_page_size: maximum supported page size for ballooning. + * + * Protected by @conf_sem + */ + enum vmballoon_page_size_type max_page_size; + + /** + * @size: balloon actual size in basic page size (frames). + * + * While we currently do not support size which is bigger than 32-bit, + * in preparation for future support, use 64-bits. + */ + atomic64_t size; + + /** + * @target: balloon target size in basic page size (frames). + * + * We do not protect the target under the assumption that setting the + * value is always done through a single write. If this assumption ever + * breaks, we would have to use X_ONCE for accesses, and suffer the less + * optimized code. Although we may read stale target value if multiple + * accesses happen at once, the performance impact should be minor. + */ + unsigned long target; + + /** + * @reset_required: reset flag + * + * Setting this flag may introduce races, but the code is expected to + * handle them gracefully. In the worst case, another operation will + * fail as reset did not take place. Clearing the flag is done while + * holding @conf_sem for write. + */ + bool reset_required; + + /** + * @capabilities: hypervisor balloon capabilities. + * + * Protected by @conf_sem. + */ + unsigned long capabilities; + + /** + * @batch_page: pointer to communication batch page. + * + * When batching is used, batch_page points to a page, which holds up to + * %VMW_BALLOON_BATCH_MAX_PAGES entries for locking or unlocking. + */ + struct vmballoon_batch_entry *batch_page; + + /** + * @batch_max_pages: maximum pages that can be locked/unlocked. + * + * Indicates the number of pages that the hypervisor can lock or unlock + * at once, according to whether batching is enabled. If batching is + * disabled, only a single page can be locked/unlock on each operation. + * + * Protected by @conf_sem. + */ + unsigned int batch_max_pages; + + /** + * @page: page to be locked/unlocked by the hypervisor + * + * @page is only used when batching is disabled and a single page is + * reclaimed on each iteration. + * + * Protected by @comm_lock. + */ + struct page *page; + + /** + * @shrink_timeout: timeout until the next inflation. + * + * After an shrink event, indicates the time in jiffies after which + * inflation is allowed again. Can be written concurrently with reads, + * so must use READ_ONCE/WRITE_ONCE when accessing. + */ + unsigned long shrink_timeout; + + /* statistics */ + struct vmballoon_stats *stats; + + /** + * @b_dev_info: balloon device information descriptor. + */ + struct balloon_dev_info b_dev_info; + + struct delayed_work dwork; + + /** + * @huge_pages - list of the inflated 2MB pages. + * + * Protected by @b_dev_info.pages_lock . + */ + struct list_head huge_pages; + + /** + * @vmci_doorbell. + * + * Protected by @conf_sem. + */ + struct vmci_handle vmci_doorbell; + + /** + * @conf_sem: semaphore to protect the configuration and the statistics. + */ + struct rw_semaphore conf_sem; + + /** + * @comm_lock: lock to protect the communication with the host. + * + * Lock ordering: @conf_sem -> @comm_lock . + */ + spinlock_t comm_lock; + + /** + * @shrinker: shrinker interface that is used to avoid over-inflation. + */ + struct shrinker shrinker; + + /** + * @shrinker_registered: whether the shrinker was registered. + * + * The shrinker interface does not handle gracefully the removal of + * shrinker that was not registered before. This indication allows to + * simplify the unregistration process. + */ + bool shrinker_registered; +}; + +static struct vmballoon balloon; + +struct vmballoon_stats { + /* timer / doorbell operations */ + atomic64_t general_stat[VMW_BALLOON_STAT_NUM]; + + /* allocation statistics for huge and small pages */ + atomic64_t + page_stat[VMW_BALLOON_PAGE_STAT_NUM][VMW_BALLOON_NUM_PAGE_SIZES]; + + /* Monitor operations: total operations, and failures */ + atomic64_t ops[VMW_BALLOON_CMD_NUM][VMW_BALLOON_OP_STAT_TYPES]; +}; + +static inline bool is_vmballoon_stats_on(void) +{ + return IS_ENABLED(CONFIG_DEBUG_FS) && + static_branch_unlikely(&balloon_stat_enabled); +} + +static inline void vmballoon_stats_op_inc(struct vmballoon *b, unsigned int op, + enum vmballoon_op_stat_type type) +{ + if (is_vmballoon_stats_on()) + atomic64_inc(&b->stats->ops[op][type]); +} + +static inline void vmballoon_stats_gen_inc(struct vmballoon *b, + enum vmballoon_stat_general stat) +{ + if (is_vmballoon_stats_on()) + atomic64_inc(&b->stats->general_stat[stat]); +} + +static inline void vmballoon_stats_gen_add(struct vmballoon *b, + enum vmballoon_stat_general stat, + unsigned int val) +{ + if (is_vmballoon_stats_on()) + atomic64_add(val, &b->stats->general_stat[stat]); +} + +static inline void vmballoon_stats_page_inc(struct vmballoon *b, + enum vmballoon_stat_page stat, + enum vmballoon_page_size_type size) +{ + if (is_vmballoon_stats_on()) + atomic64_inc(&b->stats->page_stat[stat][size]); +} + +static inline void vmballoon_stats_page_add(struct vmballoon *b, + enum vmballoon_stat_page stat, + enum vmballoon_page_size_type size, + unsigned int val) +{ + if (is_vmballoon_stats_on()) + atomic64_add(val, &b->stats->page_stat[stat][size]); +} + +static inline unsigned long +__vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1, + unsigned long arg2, unsigned long *result) +{ + unsigned long status, dummy1, dummy2, dummy3, local_result; + + vmballoon_stats_op_inc(b, cmd, VMW_BALLOON_OP_STAT); + + asm volatile ("inl %%dx" : + "=a"(status), + "=c"(dummy1), + "=d"(dummy2), + "=b"(local_result), + "=S"(dummy3) : + "0"(VMW_BALLOON_HV_MAGIC), + "1"(cmd), + "2"(VMW_BALLOON_HV_PORT), + "3"(arg1), + "4"(arg2) : + "memory"); + + /* update the result if needed */ + if (result) + *result = (cmd == VMW_BALLOON_CMD_START) ? dummy1 : + local_result; + + /* update target when applicable */ + if (status == VMW_BALLOON_SUCCESS && + ((1ul << cmd) & VMW_BALLOON_CMD_WITH_TARGET_MASK)) + WRITE_ONCE(b->target, local_result); + + if (status != VMW_BALLOON_SUCCESS && + status != VMW_BALLOON_SUCCESS_WITH_CAPABILITIES) { + vmballoon_stats_op_inc(b, cmd, VMW_BALLOON_OP_FAIL_STAT); + pr_debug("%s: %s [0x%lx,0x%lx) failed, returned %ld\n", + __func__, vmballoon_cmd_names[cmd], arg1, arg2, + status); + } + + /* mark reset required accordingly */ + if (status == VMW_BALLOON_ERROR_RESET) + b->reset_required = true; + + return status; +} + +static __always_inline unsigned long +vmballoon_cmd(struct vmballoon *b, unsigned long cmd, unsigned long arg1, + unsigned long arg2) +{ + unsigned long dummy; + + return __vmballoon_cmd(b, cmd, arg1, arg2, &dummy); +} + +/* + * Send "start" command to the host, communicating supported version + * of the protocol. + */ +static int vmballoon_send_start(struct vmballoon *b, unsigned long req_caps) +{ + unsigned long status, capabilities; + + status = __vmballoon_cmd(b, VMW_BALLOON_CMD_START, req_caps, 0, + &capabilities); + + switch (status) { + case VMW_BALLOON_SUCCESS_WITH_CAPABILITIES: + b->capabilities = capabilities; + break; + case VMW_BALLOON_SUCCESS: + b->capabilities = VMW_BALLOON_BASIC_CMDS; + break; + default: + return -EIO; + } + + /* + * 2MB pages are only supported with batching. If batching is for some + * reason disabled, do not use 2MB pages, since otherwise the legacy + * mechanism is used with 2MB pages, causing a failure. + */ + b->max_page_size = VMW_BALLOON_4K_PAGE; + if ((b->capabilities & VMW_BALLOON_BATCHED_2M_CMDS) && + (b->capabilities & VMW_BALLOON_BATCHED_CMDS)) + b->max_page_size = VMW_BALLOON_2M_PAGE; + + + return 0; +} + +/** + * vmballoon_send_guest_id - communicate guest type to the host. + * + * @b: pointer to the balloon. + * + * Communicate guest type to the host so that it can adjust ballooning + * algorithm to the one most appropriate for the guest. This command + * is normally issued after sending "start" command and is part of + * standard reset sequence. + * + * Return: zero on success or appropriate error code. + */ +static int vmballoon_send_guest_id(struct vmballoon *b) +{ + unsigned long status; + + status = vmballoon_cmd(b, VMW_BALLOON_CMD_GUEST_ID, + VMW_BALLOON_GUEST_ID, 0); + + return status == VMW_BALLOON_SUCCESS ? 0 : -EIO; +} + +/** + * vmballoon_page_order() - return the order of the page + * @page_size: the size of the page. + * + * Return: the allocation order. + */ +static inline +unsigned int vmballoon_page_order(enum vmballoon_page_size_type page_size) +{ + return page_size == VMW_BALLOON_2M_PAGE ? VMW_BALLOON_2M_ORDER : 0; +} + +/** + * vmballoon_page_in_frames() - returns the number of frames in a page. + * @page_size: the size of the page. + * + * Return: the number of 4k frames. + */ +static inline unsigned int +vmballoon_page_in_frames(enum vmballoon_page_size_type page_size) +{ + return 1 << vmballoon_page_order(page_size); +} + +/** + * vmballoon_mark_page_offline() - mark a page as offline + * @page: pointer for the page. + * @page_size: the size of the page. + */ +static void +vmballoon_mark_page_offline(struct page *page, + enum vmballoon_page_size_type page_size) +{ + int i; + + for (i = 0; i < vmballoon_page_in_frames(page_size); i++) + __SetPageOffline(page + i); +} + +/** + * vmballoon_mark_page_online() - mark a page as online + * @page: pointer for the page. + * @page_size: the size of the page. + */ +static void +vmballoon_mark_page_online(struct page *page, + enum vmballoon_page_size_type page_size) +{ + int i; + + for (i = 0; i < vmballoon_page_in_frames(page_size); i++) + __ClearPageOffline(page + i); +} + +/** + * vmballoon_send_get_target() - Retrieve desired balloon size from the host. + * + * @b: pointer to the balloon. + * + * Return: zero on success, EINVAL if limit does not fit in 32-bit, as required + * by the host-guest protocol and EIO if an error occurred in communicating with + * the host. + */ +static int vmballoon_send_get_target(struct vmballoon *b) +{ + unsigned long status; + unsigned long limit; + + limit = totalram_pages(); + + /* Ensure limit fits in 32-bits if 64-bit targets are not supported */ + if (!(b->capabilities & VMW_BALLOON_64_BIT_TARGET) && + limit != (u32)limit) + return -EINVAL; + + status = vmballoon_cmd(b, VMW_BALLOON_CMD_GET_TARGET, limit, 0); + + return status == VMW_BALLOON_SUCCESS ? 0 : -EIO; +} + +/** + * vmballoon_alloc_page_list - allocates a list of pages. + * + * @b: pointer to the balloon. + * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation. + * @req_n_pages: the number of requested pages. + * + * Tries to allocate @req_n_pages. Add them to the list of balloon pages in + * @ctl.pages and updates @ctl.n_pages to reflect the number of pages. + * + * Return: zero on success or error code otherwise. + */ +static int vmballoon_alloc_page_list(struct vmballoon *b, + struct vmballoon_ctl *ctl, + unsigned int req_n_pages) +{ + struct page *page; + unsigned int i; + + for (i = 0; i < req_n_pages; i++) { + /* + * First check if we happen to have pages that were allocated + * before. This happens when 2MB page rejected during inflation + * by the hypervisor, and then split into 4KB pages. + */ + if (!list_empty(&ctl->prealloc_pages)) { + page = list_first_entry(&ctl->prealloc_pages, + struct page, lru); + list_del(&page->lru); + } else { + if (ctl->page_size == VMW_BALLOON_2M_PAGE) + page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN| + __GFP_NOMEMALLOC, VMW_BALLOON_2M_ORDER); + else + page = balloon_page_alloc(); + + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC, + ctl->page_size); + } + + if (page) { + /* Success. Add the page to the list and continue. */ + list_add(&page->lru, &ctl->pages); + continue; + } + + /* Allocation failed. Update statistics and stop. */ + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC_FAIL, + ctl->page_size); + break; + } + + ctl->n_pages = i; + + return req_n_pages == ctl->n_pages ? 0 : -ENOMEM; +} + +/** + * vmballoon_handle_one_result - Handle lock/unlock result for a single page. + * + * @b: pointer for %struct vmballoon. + * @page: pointer for the page whose result should be handled. + * @page_size: size of the page. + * @status: status of the operation as provided by the hypervisor. + */ +static int vmballoon_handle_one_result(struct vmballoon *b, struct page *page, + enum vmballoon_page_size_type page_size, + unsigned long status) +{ + /* On success do nothing. The page is already on the balloon list. */ + if (likely(status == VMW_BALLOON_SUCCESS)) + return 0; + + pr_debug("%s: failed comm pfn %lx status %lu page_size %s\n", __func__, + page_to_pfn(page), status, + vmballoon_page_size_names[page_size]); + + /* Error occurred */ + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC, + page_size); + + return -EIO; +} + +/** + * vmballoon_status_page - returns the status of (un)lock operation + * + * @b: pointer to the balloon. + * @idx: index for the page for which the operation is performed. + * @p: pointer to where the page struct is returned. + * + * Following a lock or unlock operation, returns the status of the operation for + * an individual page. Provides the page that the operation was performed on on + * the @page argument. + * + * Returns: The status of a lock or unlock operation for an individual page. + */ +static unsigned long vmballoon_status_page(struct vmballoon *b, int idx, + struct page **p) +{ + if (static_branch_likely(&vmw_balloon_batching)) { + /* batching mode */ + *p = pfn_to_page(b->batch_page[idx].pfn); + return b->batch_page[idx].status; + } + + /* non-batching mode */ + *p = b->page; + + /* + * If a failure occurs, the indication will be provided in the status + * of the entire operation, which is considered before the individual + * page status. So for non-batching mode, the indication is always of + * success. + */ + return VMW_BALLOON_SUCCESS; +} + +/** + * vmballoon_lock_op - notifies the host about inflated/deflated pages. + * @b: pointer to the balloon. + * @num_pages: number of inflated/deflated pages. + * @page_size: size of the page. + * @op: the type of operation (lock or unlock). + * + * Notify the host about page(s) that were ballooned (or removed from the + * balloon) so that host can use it without fear that guest will need it (or + * stop using them since the VM does). Host may reject some pages, we need to + * check the return value and maybe submit a different page. The pages that are + * inflated/deflated are pointed by @b->page. + * + * Return: result as provided by the hypervisor. + */ +static unsigned long vmballoon_lock_op(struct vmballoon *b, + unsigned int num_pages, + enum vmballoon_page_size_type page_size, + enum vmballoon_op op) +{ + unsigned long cmd, pfn; + + lockdep_assert_held(&b->comm_lock); + + if (static_branch_likely(&vmw_balloon_batching)) { + if (op == VMW_BALLOON_INFLATE) + cmd = page_size == VMW_BALLOON_2M_PAGE ? + VMW_BALLOON_CMD_BATCHED_2M_LOCK : + VMW_BALLOON_CMD_BATCHED_LOCK; + else + cmd = page_size == VMW_BALLOON_2M_PAGE ? + VMW_BALLOON_CMD_BATCHED_2M_UNLOCK : + VMW_BALLOON_CMD_BATCHED_UNLOCK; + + pfn = PHYS_PFN(virt_to_phys(b->batch_page)); + } else { + cmd = op == VMW_BALLOON_INFLATE ? VMW_BALLOON_CMD_LOCK : + VMW_BALLOON_CMD_UNLOCK; + pfn = page_to_pfn(b->page); + + /* In non-batching mode, PFNs must fit in 32-bit */ + if (unlikely(pfn != (u32)pfn)) + return VMW_BALLOON_ERROR_PPN_INVALID; + } + + return vmballoon_cmd(b, cmd, pfn, num_pages); +} + +/** + * vmballoon_add_page - adds a page towards lock/unlock operation. + * + * @b: pointer to the balloon. + * @idx: index of the page to be ballooned in this batch. + * @p: pointer to the page that is about to be ballooned. + * + * Adds the page to be ballooned. Must be called while holding @comm_lock. + */ +static void vmballoon_add_page(struct vmballoon *b, unsigned int idx, + struct page *p) +{ + lockdep_assert_held(&b->comm_lock); + + if (static_branch_likely(&vmw_balloon_batching)) + b->batch_page[idx] = (struct vmballoon_batch_entry) + { .pfn = page_to_pfn(p) }; + else + b->page = p; +} + +/** + * vmballoon_lock - lock or unlock a batch of pages. + * + * @b: pointer to the balloon. + * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation. + * + * Notifies the host of about ballooned pages (after inflation or deflation, + * according to @ctl). If the host rejects the page put it on the + * @ctl refuse list. These refused page are then released when moving to the + * next size of pages. + * + * Note that we neither free any @page here nor put them back on the ballooned + * pages list. Instead we queue it for later processing. We do that for several + * reasons. First, we do not want to free the page under the lock. Second, it + * allows us to unify the handling of lock and unlock. In the inflate case, the + * caller will check if there are too many refused pages and release them. + * Although it is not identical to the past behavior, it should not affect + * performance. + */ +static int vmballoon_lock(struct vmballoon *b, struct vmballoon_ctl *ctl) +{ + unsigned long batch_status; + struct page *page; + unsigned int i, num_pages; + + num_pages = ctl->n_pages; + if (num_pages == 0) + return 0; + + /* communication with the host is done under the communication lock */ + spin_lock(&b->comm_lock); + + i = 0; + list_for_each_entry(page, &ctl->pages, lru) + vmballoon_add_page(b, i++, page); + + batch_status = vmballoon_lock_op(b, ctl->n_pages, ctl->page_size, + ctl->op); + + /* + * Iterate over the pages in the provided list. Since we are changing + * @ctl->n_pages we are saving the original value in @num_pages and + * use this value to bound the loop. + */ + for (i = 0; i < num_pages; i++) { + unsigned long status; + + status = vmballoon_status_page(b, i, &page); + + /* + * Failure of the whole batch overrides a single operation + * results. + */ + if (batch_status != VMW_BALLOON_SUCCESS) + status = batch_status; + + /* Continue if no error happened */ + if (!vmballoon_handle_one_result(b, page, ctl->page_size, + status)) + continue; + + /* + * Error happened. Move the pages to the refused list and update + * the pages number. + */ + list_move(&page->lru, &ctl->refused_pages); + ctl->n_pages--; + ctl->n_refused_pages++; + } + + spin_unlock(&b->comm_lock); + + return batch_status == VMW_BALLOON_SUCCESS ? 0 : -EIO; +} + +/** + * vmballoon_release_page_list() - Releases a page list + * + * @page_list: list of pages to release. + * @n_pages: pointer to the number of pages. + * @page_size: whether the pages in the list are 2MB (or else 4KB). + * + * Releases the list of pages and zeros the number of pages. + */ +static void vmballoon_release_page_list(struct list_head *page_list, + int *n_pages, + enum vmballoon_page_size_type page_size) +{ + struct page *page, *tmp; + + list_for_each_entry_safe(page, tmp, page_list, lru) { + list_del(&page->lru); + __free_pages(page, vmballoon_page_order(page_size)); + } + + if (n_pages) + *n_pages = 0; +} + + +/* + * Release pages that were allocated while attempting to inflate the + * balloon but were refused by the host for one reason or another. + */ +static void vmballoon_release_refused_pages(struct vmballoon *b, + struct vmballoon_ctl *ctl) +{ + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_REFUSED_FREE, + ctl->page_size); + + vmballoon_release_page_list(&ctl->refused_pages, &ctl->n_refused_pages, + ctl->page_size); +} + +/** + * vmballoon_change - retrieve the required balloon change + * + * @b: pointer for the balloon. + * + * Return: the required change for the balloon size. A positive number + * indicates inflation, a negative number indicates a deflation. + */ +static int64_t vmballoon_change(struct vmballoon *b) +{ + int64_t size, target; + + size = atomic64_read(&b->size); + target = READ_ONCE(b->target); + + /* + * We must cast first because of int sizes + * Otherwise we might get huge positives instead of negatives + */ + + if (b->reset_required) + return 0; + + /* consider a 2MB slack on deflate, unless the balloon is emptied */ + if (target < size && target != 0 && + size - target < vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE)) + return 0; + + /* If an out-of-memory recently occurred, inflation is disallowed. */ + if (target > size && time_before(jiffies, READ_ONCE(b->shrink_timeout))) + return 0; + + return target - size; +} + +/** + * vmballoon_enqueue_page_list() - Enqueues list of pages after inflation. + * + * @b: pointer to balloon. + * @pages: list of pages to enqueue. + * @n_pages: pointer to number of pages in list. The value is zeroed. + * @page_size: whether the pages are 2MB or 4KB pages. + * + * Enqueues the provides list of pages in the ballooned page list, clears the + * list and zeroes the number of pages that was provided. + */ +static void vmballoon_enqueue_page_list(struct vmballoon *b, + struct list_head *pages, + unsigned int *n_pages, + enum vmballoon_page_size_type page_size) +{ + unsigned long flags; + struct page *page; + + if (page_size == VMW_BALLOON_4K_PAGE) { + balloon_page_list_enqueue(&b->b_dev_info, pages); + } else { + /* + * Keep the huge pages in a local list which is not available + * for the balloon compaction mechanism. + */ + spin_lock_irqsave(&b->b_dev_info.pages_lock, flags); + + list_for_each_entry(page, pages, lru) { + vmballoon_mark_page_offline(page, VMW_BALLOON_2M_PAGE); + } + + list_splice_init(pages, &b->huge_pages); + __count_vm_events(BALLOON_INFLATE, *n_pages * + vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE)); + spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags); + } + + *n_pages = 0; +} + +/** + * vmballoon_dequeue_page_list() - Dequeues page lists for deflation. + * + * @b: pointer to balloon. + * @pages: list of pages to enqueue. + * @n_pages: pointer to number of pages in list. The value is zeroed. + * @page_size: whether the pages are 2MB or 4KB pages. + * @n_req_pages: the number of requested pages. + * + * Dequeues the number of requested pages from the balloon for deflation. The + * number of dequeued pages may be lower, if not enough pages in the requested + * size are available. + */ +static void vmballoon_dequeue_page_list(struct vmballoon *b, + struct list_head *pages, + unsigned int *n_pages, + enum vmballoon_page_size_type page_size, + unsigned int n_req_pages) +{ + struct page *page, *tmp; + unsigned int i = 0; + unsigned long flags; + + /* In the case of 4k pages, use the compaction infrastructure */ + if (page_size == VMW_BALLOON_4K_PAGE) { + *n_pages = balloon_page_list_dequeue(&b->b_dev_info, pages, + n_req_pages); + return; + } + + /* 2MB pages */ + spin_lock_irqsave(&b->b_dev_info.pages_lock, flags); + list_for_each_entry_safe(page, tmp, &b->huge_pages, lru) { + vmballoon_mark_page_online(page, VMW_BALLOON_2M_PAGE); + + list_move(&page->lru, pages); + if (++i == n_req_pages) + break; + } + + __count_vm_events(BALLOON_DEFLATE, + i * vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE)); + spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags); + *n_pages = i; +} + +/** + * vmballoon_split_refused_pages() - Split the 2MB refused pages to 4k. + * + * If inflation of 2MB pages was denied by the hypervisor, it is likely to be + * due to one or few 4KB pages. These 2MB pages may keep being allocated and + * then being refused. To prevent this case, this function splits the refused + * pages into 4KB pages and adds them into @prealloc_pages list. + * + * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation. + */ +static void vmballoon_split_refused_pages(struct vmballoon_ctl *ctl) +{ + struct page *page, *tmp; + unsigned int i, order; + + order = vmballoon_page_order(ctl->page_size); + + list_for_each_entry_safe(page, tmp, &ctl->refused_pages, lru) { + list_del(&page->lru); + split_page(page, order); + for (i = 0; i < (1 << order); i++) + list_add(&page[i].lru, &ctl->prealloc_pages); + } + ctl->n_refused_pages = 0; +} + +/** + * vmballoon_inflate() - Inflate the balloon towards its target size. + * + * @b: pointer to the balloon. + */ +static void vmballoon_inflate(struct vmballoon *b) +{ + int64_t to_inflate_frames; + struct vmballoon_ctl ctl = { + .pages = LIST_HEAD_INIT(ctl.pages), + .refused_pages = LIST_HEAD_INIT(ctl.refused_pages), + .prealloc_pages = LIST_HEAD_INIT(ctl.prealloc_pages), + .page_size = b->max_page_size, + .op = VMW_BALLOON_INFLATE + }; + + while ((to_inflate_frames = vmballoon_change(b)) > 0) { + unsigned int to_inflate_pages, page_in_frames; + int alloc_error, lock_error = 0; + + VM_BUG_ON(!list_empty(&ctl.pages)); + VM_BUG_ON(ctl.n_pages != 0); + + page_in_frames = vmballoon_page_in_frames(ctl.page_size); + + to_inflate_pages = min_t(unsigned long, b->batch_max_pages, + DIV_ROUND_UP_ULL(to_inflate_frames, + page_in_frames)); + + /* Start by allocating */ + alloc_error = vmballoon_alloc_page_list(b, &ctl, + to_inflate_pages); + + /* Actually lock the pages by telling the hypervisor */ + lock_error = vmballoon_lock(b, &ctl); + + /* + * If an error indicates that something serious went wrong, + * stop the inflation. + */ + if (lock_error) + break; + + /* Update the balloon size */ + atomic64_add(ctl.n_pages * page_in_frames, &b->size); + + vmballoon_enqueue_page_list(b, &ctl.pages, &ctl.n_pages, + ctl.page_size); + + /* + * If allocation failed or the number of refused pages exceeds + * the maximum allowed, move to the next page size. + */ + if (alloc_error || + ctl.n_refused_pages >= VMW_BALLOON_MAX_REFUSED) { + if (ctl.page_size == VMW_BALLOON_4K_PAGE) + break; + + /* + * Split the refused pages to 4k. This will also empty + * the refused pages list. + */ + vmballoon_split_refused_pages(&ctl); + ctl.page_size--; + } + + cond_resched(); + } + + /* + * Release pages that were allocated while attempting to inflate the + * balloon but were refused by the host for one reason or another, + * and update the statistics. + */ + if (ctl.n_refused_pages != 0) + vmballoon_release_refused_pages(b, &ctl); + + vmballoon_release_page_list(&ctl.prealloc_pages, NULL, ctl.page_size); +} + +/** + * vmballoon_deflate() - Decrease the size of the balloon. + * + * @b: pointer to the balloon + * @n_frames: the number of frames to deflate. If zero, automatically + * calculated according to the target size. + * @coordinated: whether to coordinate with the host + * + * Decrease the size of the balloon allowing guest to use more memory. + * + * Return: The number of deflated frames (i.e., basic page size units) + */ +static unsigned long vmballoon_deflate(struct vmballoon *b, uint64_t n_frames, + bool coordinated) +{ + unsigned long deflated_frames = 0; + unsigned long tried_frames = 0; + struct vmballoon_ctl ctl = { + .pages = LIST_HEAD_INIT(ctl.pages), + .refused_pages = LIST_HEAD_INIT(ctl.refused_pages), + .page_size = VMW_BALLOON_4K_PAGE, + .op = VMW_BALLOON_DEFLATE + }; + + /* free pages to reach target */ + while (true) { + unsigned int to_deflate_pages, n_unlocked_frames; + unsigned int page_in_frames; + int64_t to_deflate_frames; + bool deflated_all; + + page_in_frames = vmballoon_page_in_frames(ctl.page_size); + + VM_BUG_ON(!list_empty(&ctl.pages)); + VM_BUG_ON(ctl.n_pages); + VM_BUG_ON(!list_empty(&ctl.refused_pages)); + VM_BUG_ON(ctl.n_refused_pages); + + /* + * If we were requested a specific number of frames, we try to + * deflate this number of frames. Otherwise, deflation is + * performed according to the target and balloon size. + */ + to_deflate_frames = n_frames ? n_frames - tried_frames : + -vmballoon_change(b); + + /* break if no work to do */ + if (to_deflate_frames <= 0) + break; + + /* + * Calculate the number of frames based on current page size, + * but limit the deflated frames to a single chunk + */ + to_deflate_pages = min_t(unsigned long, b->batch_max_pages, + DIV_ROUND_UP_ULL(to_deflate_frames, + page_in_frames)); + + /* First take the pages from the balloon pages. */ + vmballoon_dequeue_page_list(b, &ctl.pages, &ctl.n_pages, + ctl.page_size, to_deflate_pages); + + /* + * Before pages are moving to the refused list, count their + * frames as frames that we tried to deflate. + */ + tried_frames += ctl.n_pages * page_in_frames; + + /* + * Unlock the pages by communicating with the hypervisor if the + * communication is coordinated (i.e., not pop). We ignore the + * return code. Instead we check if all the pages we manage to + * unlock all the pages. If we failed, we will move to the next + * page size, and would eventually try again later. + */ + if (coordinated) + vmballoon_lock(b, &ctl); + + /* + * Check if we deflated enough. We will move to the next page + * size if we did not manage to do so. This calculation takes + * place now, as once the pages are released, the number of + * pages is zeroed. + */ + deflated_all = (ctl.n_pages == to_deflate_pages); + + /* Update local and global counters */ + n_unlocked_frames = ctl.n_pages * page_in_frames; + atomic64_sub(n_unlocked_frames, &b->size); + deflated_frames += n_unlocked_frames; + + vmballoon_stats_page_add(b, VMW_BALLOON_PAGE_STAT_FREE, + ctl.page_size, ctl.n_pages); + + /* free the ballooned pages */ + vmballoon_release_page_list(&ctl.pages, &ctl.n_pages, + ctl.page_size); + + /* Return the refused pages to the ballooned list. */ + vmballoon_enqueue_page_list(b, &ctl.refused_pages, + &ctl.n_refused_pages, + ctl.page_size); + + /* If we failed to unlock all the pages, move to next size. */ + if (!deflated_all) { + if (ctl.page_size == b->max_page_size) + break; + ctl.page_size++; + } + + cond_resched(); + } + + return deflated_frames; +} + +/** + * vmballoon_deinit_batching - disables batching mode. + * + * @b: pointer to &struct vmballoon. + * + * Disables batching, by deallocating the page for communication with the + * hypervisor and disabling the static key to indicate that batching is off. + */ +static void vmballoon_deinit_batching(struct vmballoon *b) +{ + free_page((unsigned long)b->batch_page); + b->batch_page = NULL; + static_branch_disable(&vmw_balloon_batching); + b->batch_max_pages = 1; +} + +/** + * vmballoon_init_batching - enable batching mode. + * + * @b: pointer to &struct vmballoon. + * + * Enables batching, by allocating a page for communication with the hypervisor + * and enabling the static_key to use batching. + * + * Return: zero on success or an appropriate error-code. + */ +static int vmballoon_init_batching(struct vmballoon *b) +{ + struct page *page; + + page = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + return -ENOMEM; + + b->batch_page = page_address(page); + b->batch_max_pages = PAGE_SIZE / sizeof(struct vmballoon_batch_entry); + + static_branch_enable(&vmw_balloon_batching); + + return 0; +} + +/* + * Receive notification and resize balloon + */ +static void vmballoon_doorbell(void *client_data) +{ + struct vmballoon *b = client_data; + + vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_DOORBELL); + + mod_delayed_work(system_freezable_wq, &b->dwork, 0); +} + +/* + * Clean up vmci doorbell + */ +static void vmballoon_vmci_cleanup(struct vmballoon *b) +{ + vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET, + VMCI_INVALID_ID, VMCI_INVALID_ID); + + if (!vmci_handle_is_invalid(b->vmci_doorbell)) { + vmci_doorbell_destroy(b->vmci_doorbell); + b->vmci_doorbell = VMCI_INVALID_HANDLE; + } +} + +/** + * vmballoon_vmci_init - Initialize vmci doorbell. + * + * @b: pointer to the balloon. + * + * Return: zero on success or when wakeup command not supported. Error-code + * otherwise. + * + * Initialize vmci doorbell, to get notified as soon as balloon changes. + */ +static int vmballoon_vmci_init(struct vmballoon *b) +{ + unsigned long error; + + if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) == 0) + return 0; + + error = vmci_doorbell_create(&b->vmci_doorbell, VMCI_FLAG_DELAYED_CB, + VMCI_PRIVILEGE_FLAG_RESTRICTED, + vmballoon_doorbell, b); + + if (error != VMCI_SUCCESS) + goto fail; + + error = __vmballoon_cmd(b, VMW_BALLOON_CMD_VMCI_DOORBELL_SET, + b->vmci_doorbell.context, + b->vmci_doorbell.resource, NULL); + + if (error != VMW_BALLOON_SUCCESS) + goto fail; + + return 0; +fail: + vmballoon_vmci_cleanup(b); + return -EIO; +} + +/** + * vmballoon_pop - Quickly release all pages allocate for the balloon. + * + * @b: pointer to the balloon. + * + * This function is called when host decides to "reset" balloon for one reason + * or another. Unlike normal "deflate" we do not (shall not) notify host of the + * pages being released. + */ +static void vmballoon_pop(struct vmballoon *b) +{ + unsigned long size; + + while ((size = atomic64_read(&b->size))) + vmballoon_deflate(b, size, false); +} + +/* + * Perform standard reset sequence by popping the balloon (in case it + * is not empty) and then restarting protocol. This operation normally + * happens when host responds with VMW_BALLOON_ERROR_RESET to a command. + */ +static void vmballoon_reset(struct vmballoon *b) +{ + int error; + + down_write(&b->conf_sem); + + vmballoon_vmci_cleanup(b); + + /* free all pages, skipping monitor unlock */ + vmballoon_pop(b); + + if (vmballoon_send_start(b, VMW_BALLOON_CAPABILITIES)) + goto unlock; + + if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) { + if (vmballoon_init_batching(b)) { + /* + * We failed to initialize batching, inform the monitor + * about it by sending a null capability. + * + * The guest will retry in one second. + */ + vmballoon_send_start(b, 0); + goto unlock; + } + } else if ((b->capabilities & VMW_BALLOON_BASIC_CMDS) != 0) { + vmballoon_deinit_batching(b); + } + + vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_RESET); + b->reset_required = false; + + error = vmballoon_vmci_init(b); + if (error) + pr_err_once("failed to initialize vmci doorbell\n"); + + if (vmballoon_send_guest_id(b)) + pr_err_once("failed to send guest ID to the host\n"); + +unlock: + up_write(&b->conf_sem); +} + +/** + * vmballoon_work - periodic balloon worker for reset, inflation and deflation. + * + * @work: pointer to the &work_struct which is provided by the workqueue. + * + * Resets the protocol if needed, gets the new size and adjusts balloon as + * needed. Repeat in 1 sec. + */ +static void vmballoon_work(struct work_struct *work) +{ + struct delayed_work *dwork = to_delayed_work(work); + struct vmballoon *b = container_of(dwork, struct vmballoon, dwork); + int64_t change = 0; + + if (b->reset_required) + vmballoon_reset(b); + + down_read(&b->conf_sem); + + /* + * Update the stats while holding the semaphore to ensure that + * @stats_enabled is consistent with whether the stats are actually + * enabled + */ + vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_TIMER); + + if (!vmballoon_send_get_target(b)) + change = vmballoon_change(b); + + if (change != 0) { + pr_debug("%s - size: %llu, target %lu\n", __func__, + atomic64_read(&b->size), READ_ONCE(b->target)); + + if (change > 0) + vmballoon_inflate(b); + else /* (change < 0) */ + vmballoon_deflate(b, 0, true); + } + + up_read(&b->conf_sem); + + /* + * We are using a freezable workqueue so that balloon operations are + * stopped while the system transitions to/from sleep/hibernation. + */ + queue_delayed_work(system_freezable_wq, + dwork, round_jiffies_relative(HZ)); + +} + +/** + * vmballoon_shrinker_scan() - deflate the balloon due to memory pressure. + * @shrinker: pointer to the balloon shrinker. + * @sc: page reclaim information. + * + * Returns: number of pages that were freed during deflation. + */ +static unsigned long vmballoon_shrinker_scan(struct shrinker *shrinker, + struct shrink_control *sc) +{ + struct vmballoon *b = &balloon; + unsigned long deflated_frames; + + pr_debug("%s - size: %llu", __func__, atomic64_read(&b->size)); + + vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_SHRINK); + + /* + * If the lock is also contended for read, we cannot easily reclaim and + * we bail out. + */ + if (!down_read_trylock(&b->conf_sem)) + return 0; + + deflated_frames = vmballoon_deflate(b, sc->nr_to_scan, true); + + vmballoon_stats_gen_add(b, VMW_BALLOON_STAT_SHRINK_FREE, + deflated_frames); + + /* + * Delay future inflation for some time to mitigate the situations in + * which balloon continuously grows and shrinks. Use WRITE_ONCE() since + * the access is asynchronous. + */ + WRITE_ONCE(b->shrink_timeout, jiffies + HZ * VMBALLOON_SHRINK_DELAY); + + up_read(&b->conf_sem); + + return deflated_frames; +} + +/** + * vmballoon_shrinker_count() - return the number of ballooned pages. + * @shrinker: pointer to the balloon shrinker. + * @sc: page reclaim information. + * + * Returns: number of 4k pages that are allocated for the balloon and can + * therefore be reclaimed under pressure. + */ +static unsigned long vmballoon_shrinker_count(struct shrinker *shrinker, + struct shrink_control *sc) +{ + struct vmballoon *b = &balloon; + + return atomic64_read(&b->size); +} + +static void vmballoon_unregister_shrinker(struct vmballoon *b) +{ + if (b->shrinker_registered) + unregister_shrinker(&b->shrinker); + b->shrinker_registered = false; +} + +static int vmballoon_register_shrinker(struct vmballoon *b) +{ + int r; + + /* Do nothing if the shrinker is not enabled */ + if (!vmwballoon_shrinker_enable) + return 0; + + b->shrinker.scan_objects = vmballoon_shrinker_scan; + b->shrinker.count_objects = vmballoon_shrinker_count; + b->shrinker.seeks = DEFAULT_SEEKS; + + r = register_shrinker(&b->shrinker, "vmw-balloon"); + + if (r == 0) + b->shrinker_registered = true; + + return r; +} + +/* + * DEBUGFS Interface + */ +#ifdef CONFIG_DEBUG_FS + +static const char * const vmballoon_stat_page_names[] = { + [VMW_BALLOON_PAGE_STAT_ALLOC] = "alloc", + [VMW_BALLOON_PAGE_STAT_ALLOC_FAIL] = "allocFail", + [VMW_BALLOON_PAGE_STAT_REFUSED_ALLOC] = "errAlloc", + [VMW_BALLOON_PAGE_STAT_REFUSED_FREE] = "errFree", + [VMW_BALLOON_PAGE_STAT_FREE] = "free" +}; + +static const char * const vmballoon_stat_names[] = { + [VMW_BALLOON_STAT_TIMER] = "timer", + [VMW_BALLOON_STAT_DOORBELL] = "doorbell", + [VMW_BALLOON_STAT_RESET] = "reset", + [VMW_BALLOON_STAT_SHRINK] = "shrink", + [VMW_BALLOON_STAT_SHRINK_FREE] = "shrinkFree" +}; + +static int vmballoon_enable_stats(struct vmballoon *b) +{ + int r = 0; + + down_write(&b->conf_sem); + + /* did we somehow race with another reader which enabled stats? */ + if (b->stats) + goto out; + + b->stats = kzalloc(sizeof(*b->stats), GFP_KERNEL); + + if (!b->stats) { + /* allocation failed */ + r = -ENOMEM; + goto out; + } + static_key_enable(&balloon_stat_enabled.key); +out: + up_write(&b->conf_sem); + return r; +} + +/** + * vmballoon_debug_show - shows statistics of balloon operations. + * @f: pointer to the &struct seq_file. + * @offset: ignored. + * + * Provides the statistics that can be accessed in vmmemctl in the debugfs. + * To avoid the overhead - mainly that of memory - of collecting the statistics, + * we only collect statistics after the first time the counters are read. + * + * Return: zero on success or an error code. + */ +static int vmballoon_debug_show(struct seq_file *f, void *offset) +{ + struct vmballoon *b = f->private; + int i, j; + + /* enables stats if they are disabled */ + if (!b->stats) { + int r = vmballoon_enable_stats(b); + + if (r) + return r; + } + + /* format capabilities info */ + seq_printf(f, "%-22s: %#16x\n", "balloon capabilities", + VMW_BALLOON_CAPABILITIES); + seq_printf(f, "%-22s: %#16lx\n", "used capabilities", b->capabilities); + seq_printf(f, "%-22s: %16s\n", "is resetting", + b->reset_required ? "y" : "n"); + + /* format size info */ + seq_printf(f, "%-22s: %16lu\n", "target", READ_ONCE(b->target)); + seq_printf(f, "%-22s: %16llu\n", "current", atomic64_read(&b->size)); + + for (i = 0; i < VMW_BALLOON_CMD_NUM; i++) { + if (vmballoon_cmd_names[i] == NULL) + continue; + + seq_printf(f, "%-22s: %16llu (%llu failed)\n", + vmballoon_cmd_names[i], + atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_STAT]), + atomic64_read(&b->stats->ops[i][VMW_BALLOON_OP_FAIL_STAT])); + } + + for (i = 0; i < VMW_BALLOON_STAT_NUM; i++) + seq_printf(f, "%-22s: %16llu\n", + vmballoon_stat_names[i], + atomic64_read(&b->stats->general_stat[i])); + + for (i = 0; i < VMW_BALLOON_PAGE_STAT_NUM; i++) { + for (j = 0; j < VMW_BALLOON_NUM_PAGE_SIZES; j++) + seq_printf(f, "%-18s(%s): %16llu\n", + vmballoon_stat_page_names[i], + vmballoon_page_size_names[j], + atomic64_read(&b->stats->page_stat[i][j])); + } + + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(vmballoon_debug); + +static void __init vmballoon_debugfs_init(struct vmballoon *b) +{ + debugfs_create_file("vmmemctl", S_IRUGO, NULL, b, + &vmballoon_debug_fops); +} + +static void __exit vmballoon_debugfs_exit(struct vmballoon *b) +{ + static_key_disable(&balloon_stat_enabled.key); + debugfs_lookup_and_remove("vmmemctl", NULL); + kfree(b->stats); + b->stats = NULL; +} + +#else + +static inline void vmballoon_debugfs_init(struct vmballoon *b) +{ +} + +static inline void vmballoon_debugfs_exit(struct vmballoon *b) +{ +} + +#endif /* CONFIG_DEBUG_FS */ + + +#ifdef CONFIG_BALLOON_COMPACTION +/** + * vmballoon_migratepage() - migrates a balloon page. + * @b_dev_info: balloon device information descriptor. + * @newpage: the page to which @page should be migrated. + * @page: a ballooned page that should be migrated. + * @mode: migration mode, ignored. + * + * This function is really open-coded, but that is according to the interface + * that balloon_compaction provides. + * + * Return: zero on success, -EAGAIN when migration cannot be performed + * momentarily, and -EBUSY if migration failed and should be retried + * with that specific page. + */ +static int vmballoon_migratepage(struct balloon_dev_info *b_dev_info, + struct page *newpage, struct page *page, + enum migrate_mode mode) +{ + unsigned long status, flags; + struct vmballoon *b; + int ret; + + b = container_of(b_dev_info, struct vmballoon, b_dev_info); + + /* + * If the semaphore is taken, there is ongoing configuration change + * (i.e., balloon reset), so try again. + */ + if (!down_read_trylock(&b->conf_sem)) + return -EAGAIN; + + spin_lock(&b->comm_lock); + /* + * We must start by deflating and not inflating, as otherwise the + * hypervisor may tell us that it has enough memory and the new page is + * not needed. Since the old page is isolated, we cannot use the list + * interface to unlock it, as the LRU field is used for isolation. + * Instead, we use the native interface directly. + */ + vmballoon_add_page(b, 0, page); + status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE, + VMW_BALLOON_DEFLATE); + + if (status == VMW_BALLOON_SUCCESS) + status = vmballoon_status_page(b, 0, &page); + + /* + * If a failure happened, let the migration mechanism know that it + * should not retry. + */ + if (status != VMW_BALLOON_SUCCESS) { + spin_unlock(&b->comm_lock); + ret = -EBUSY; + goto out_unlock; + } + + /* + * The page is isolated, so it is safe to delete it without holding + * @pages_lock . We keep holding @comm_lock since we will need it in a + * second. + */ + balloon_page_delete(page); + + put_page(page); + + /* Inflate */ + vmballoon_add_page(b, 0, newpage); + status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE, + VMW_BALLOON_INFLATE); + + if (status == VMW_BALLOON_SUCCESS) + status = vmballoon_status_page(b, 0, &newpage); + + spin_unlock(&b->comm_lock); + + if (status != VMW_BALLOON_SUCCESS) { + /* + * A failure happened. While we can deflate the page we just + * inflated, this deflation can also encounter an error. Instead + * we will decrease the size of the balloon to reflect the + * change and report failure. + */ + atomic64_dec(&b->size); + ret = -EBUSY; + } else { + /* + * Success. Take a reference for the page, and we will add it to + * the list after acquiring the lock. + */ + get_page(newpage); + ret = MIGRATEPAGE_SUCCESS; + } + + /* Update the balloon list under the @pages_lock */ + spin_lock_irqsave(&b->b_dev_info.pages_lock, flags); + + /* + * On inflation success, we already took a reference for the @newpage. + * If we succeed just insert it to the list and update the statistics + * under the lock. + */ + if (ret == MIGRATEPAGE_SUCCESS) { + balloon_page_insert(&b->b_dev_info, newpage); + __count_vm_event(BALLOON_MIGRATE); + } + + /* + * We deflated successfully, so regardless to the inflation success, we + * need to reduce the number of isolated_pages. + */ + b->b_dev_info.isolated_pages--; + spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags); + +out_unlock: + up_read(&b->conf_sem); + return ret; +} + +/** + * vmballoon_compaction_init() - initialized compaction for the balloon. + * + * @b: pointer to the balloon. + * + * If during the initialization a failure occurred, this function does not + * perform cleanup. The caller must call vmballoon_compaction_deinit() in this + * case. + * + * Return: zero on success or error code on failure. + */ +static __init void vmballoon_compaction_init(struct vmballoon *b) +{ + b->b_dev_info.migratepage = vmballoon_migratepage; +} + +#else /* CONFIG_BALLOON_COMPACTION */ +static inline void vmballoon_compaction_init(struct vmballoon *b) +{ +} +#endif /* CONFIG_BALLOON_COMPACTION */ + +static int __init vmballoon_init(void) +{ + int error; + + /* + * Check if we are running on VMware's hypervisor and bail out + * if we are not. + */ + if (x86_hyper_type != X86_HYPER_VMWARE) + return -ENODEV; + + INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work); + + error = vmballoon_register_shrinker(&balloon); + if (error) + goto fail; + + /* + * Initialization of compaction must be done after the call to + * balloon_devinfo_init() . + */ + balloon_devinfo_init(&balloon.b_dev_info); + vmballoon_compaction_init(&balloon); + + INIT_LIST_HEAD(&balloon.huge_pages); + spin_lock_init(&balloon.comm_lock); + init_rwsem(&balloon.conf_sem); + balloon.vmci_doorbell = VMCI_INVALID_HANDLE; + balloon.batch_page = NULL; + balloon.page = NULL; + balloon.reset_required = true; + + queue_delayed_work(system_freezable_wq, &balloon.dwork, 0); + + vmballoon_debugfs_init(&balloon); + + return 0; +fail: + vmballoon_unregister_shrinker(&balloon); + return error; +} + +/* + * Using late_initcall() instead of module_init() allows the balloon to use the + * VMCI doorbell even when the balloon is built into the kernel. Otherwise the + * VMCI is probed only after the balloon is initialized. If the balloon is used + * as a module, late_initcall() is equivalent to module_init(). + */ +late_initcall(vmballoon_init); + +static void __exit vmballoon_exit(void) +{ + vmballoon_unregister_shrinker(&balloon); + vmballoon_vmci_cleanup(&balloon); + cancel_delayed_work_sync(&balloon.dwork); + + vmballoon_debugfs_exit(&balloon); + + /* + * Deallocate all reserved memory, and reset connection with monitor. + * Reset connection before deallocating memory to avoid potential for + * additional spurious resets from guest touching deallocated pages. + */ + vmballoon_send_start(&balloon, 0); + vmballoon_pop(&balloon); +} +module_exit(vmballoon_exit); |