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WSL2-Linux-Kernel/drivers/misc/vmw_balloon.c

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// 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/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/mount.h>
#include <linux/pseudo_fs.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;
#ifdef CONFIG_DEBUG_FS
/* debugfs file exporting statistics */
struct dentry *dbg_entry;
#endif
/**
* @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("failed to initialize vmci doorbell\n");
if (vmballoon_send_guest_id(b))
pr_err("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);
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)
{
b->dbg_entry = 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_remove(b->dbg_entry);
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
static int vmballoon_init_fs_context(struct fs_context *fc)
{
return init_pseudo(fc, BALLOON_VMW_MAGIC) ? 0 : -ENOMEM;
}
static struct file_system_type vmballoon_fs = {
.name = "balloon-vmware",
.init_fs_context = vmballoon_init_fs_context,
.kill_sb = kill_anon_super,
};
static struct vfsmount *vmballoon_mnt;
/**
* 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_deinit() - removes compaction related data.
*
* @b: pointer to the balloon.
*/
static void vmballoon_compaction_deinit(struct vmballoon *b)
{
if (!IS_ERR(b->b_dev_info.inode))
iput(b->b_dev_info.inode);
b->b_dev_info.inode = NULL;
kern_unmount(vmballoon_mnt);
vmballoon_mnt = NULL;
}
/**
* 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 int vmballoon_compaction_init(struct vmballoon *b)
{
vmballoon_mnt = kern_mount(&vmballoon_fs);
if (IS_ERR(vmballoon_mnt))
return PTR_ERR(vmballoon_mnt);
b->b_dev_info.migratepage = vmballoon_migratepage;
b->b_dev_info.inode = alloc_anon_inode(vmballoon_mnt->mnt_sb);
if (IS_ERR(b->b_dev_info.inode))
return PTR_ERR(b->b_dev_info.inode);
b->b_dev_info.inode->i_mapping->a_ops = &balloon_aops;
return 0;
}
#else /* CONFIG_BALLOON_COMPACTION */
static void vmballoon_compaction_deinit(struct vmballoon *b)
{
}
static int vmballoon_compaction_init(struct vmballoon *b)
{
return 0;
}
#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);
error = vmballoon_compaction_init(&balloon);
if (error)
goto fail;
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);
vmballoon_compaction_deinit(&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);
/* Only once we popped the balloon, compaction can be deinit */
vmballoon_compaction_deinit(&balloon);
}
module_exit(vmballoon_exit);
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