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qemu / qemu / c59716fc5b62734052d26baa06b62467c0d3c125 / . / migration / ram.c
blob: 0ef68798d236c09922887e847eabcce2f1f0e530 [file] [log] [blame]
/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2011-2015 Red Hat Inc
*
* Authors:
* Juan Quintela <quintela@redhat.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "qemu/cutils.h"
#include "qemu/bitops.h"
#include "qemu/bitmap.h"
#include "qemu/main-loop.h"
#include "xbzrle.h"
#include "ram.h"
#include "migration.h"
#include "migration/register.h"
#include "migration/misc.h"
#include "qemu-file.h"
#include "postcopy-ram.h"
#include "page_cache.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qapi/qapi-types-migration.h"
#include "qapi/qapi-events-migration.h"
#include "qapi/qmp/qerror.h"
#include "trace.h"
#include "exec/ram_addr.h"
#include "exec/target_page.h"
#include "qemu/rcu_queue.h"
#include "migration/colo.h"
#include "block.h"
#include "sysemu/sysemu.h"
#include "savevm.h"
#include "qemu/iov.h"
#include "multifd.h"
/***********************************************************/
/* ram save/restore */
/* RAM_SAVE_FLAG_ZERO used to be named RAM_SAVE_FLAG_COMPRESS, it
* worked for pages that where filled with the same char. We switched
* it to only search for the zero value. And to avoid confusion with
* RAM_SSAVE_FLAG_COMPRESS_PAGE just rename it.
*/
#define RAM_SAVE_FLAG_FULL 0x01 /* Obsolete, not used anymore */
#define RAM_SAVE_FLAG_ZERO 0x02
#define RAM_SAVE_FLAG_MEM_SIZE 0x04
#define RAM_SAVE_FLAG_PAGE 0x08
#define RAM_SAVE_FLAG_EOS 0x10
#define RAM_SAVE_FLAG_CONTINUE 0x20
#define RAM_SAVE_FLAG_XBZRLE 0x40
/* 0x80 is reserved in migration.h start with 0x100 next */
#define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100
static inline bool is_zero_range(uint8_t *p, uint64_t size)
{
return buffer_is_zero(p, size);
}
XBZRLECacheStats xbzrle_counters;
/* struct contains XBZRLE cache and a static page
used by the compression */
static struct {
/* buffer used for XBZRLE encoding */
uint8_t *encoded_buf;
/* buffer for storing page content */
uint8_t *current_buf;
/* Cache for XBZRLE, Protected by lock. */
PageCache *cache;
QemuMutex lock;
/* it will store a page full of zeros */
uint8_t *zero_target_page;
/* buffer used for XBZRLE decoding */
uint8_t *decoded_buf;
} XBZRLE;
static void XBZRLE_cache_lock(void)
{
if (migrate_use_xbzrle())
qemu_mutex_lock(&XBZRLE.lock);
}
static void XBZRLE_cache_unlock(void)
{
if (migrate_use_xbzrle())
qemu_mutex_unlock(&XBZRLE.lock);
}
/**
* xbzrle_cache_resize: resize the xbzrle cache
*
* This function is called from qmp_migrate_set_cache_size in main
* thread, possibly while a migration is in progress. A running
* migration may be using the cache and might finish during this call,
* hence changes to the cache are protected by XBZRLE.lock().
*
* Returns 0 for success or -1 for error
*
* @new_size: new cache size
* @errp: set *errp if the check failed, with reason
*/
int xbzrle_cache_resize(int64_t new_size, Error **errp)
{
PageCache *new_cache;
int64_t ret = 0;
/* Check for truncation */
if (new_size != (size_t)new_size) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"exceeding address space");
return -1;
}
if (new_size == migrate_xbzrle_cache_size()) {
/* nothing to do */
return 0;
}
XBZRLE_cache_lock();
if (XBZRLE.cache != NULL) {
new_cache = cache_init(new_size, TARGET_PAGE_SIZE, errp);
if (!new_cache) {
ret = -1;
goto out;
}
cache_fini(XBZRLE.cache);
XBZRLE.cache = new_cache;
}
out:
XBZRLE_cache_unlock();
return ret;
}
static bool ramblock_is_ignored(RAMBlock *block)
{
return !qemu_ram_is_migratable(block) ||
(migrate_ignore_shared() && qemu_ram_is_shared(block));
}
/* Should be holding either ram_list.mutex, or the RCU lock. */
#define RAMBLOCK_FOREACH_NOT_IGNORED(block) \
INTERNAL_RAMBLOCK_FOREACH(block) \
if (ramblock_is_ignored(block)) {} else
#define RAMBLOCK_FOREACH_MIGRATABLE(block) \
INTERNAL_RAMBLOCK_FOREACH(block) \
if (!qemu_ram_is_migratable(block)) {} else
#undef RAMBLOCK_FOREACH
int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque)
{
RAMBlock *block;
int ret = 0;
RCU_READ_LOCK_GUARD();
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
ret = func(block, opaque);
if (ret) {
break;
}
}
return ret;
}
static void ramblock_recv_map_init(void)
{
RAMBlock *rb;
RAMBLOCK_FOREACH_NOT_IGNORED(rb) {
assert(!rb->receivedmap);
rb->receivedmap = bitmap_new(rb->max_length >> qemu_target_page_bits());
}
}
int ramblock_recv_bitmap_test(RAMBlock *rb, void *host_addr)
{
return test_bit(ramblock_recv_bitmap_offset(host_addr, rb),
rb->receivedmap);
}
bool ramblock_recv_bitmap_test_byte_offset(RAMBlock *rb, uint64_t byte_offset)
{
return test_bit(byte_offset >> TARGET_PAGE_BITS, rb->receivedmap);
}
void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr)
{
set_bit_atomic(ramblock_recv_bitmap_offset(host_addr, rb), rb->receivedmap);
}
void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr,
size_t nr)
{
bitmap_set_atomic(rb->receivedmap,
ramblock_recv_bitmap_offset(host_addr, rb),
nr);
}
#define RAMBLOCK_RECV_BITMAP_ENDING (0x0123456789abcdefULL)
/*
* Format: bitmap_size (8 bytes) + whole_bitmap (N bytes).
*
* Returns >0 if success with sent bytes, or <0 if error.
*/
int64_t ramblock_recv_bitmap_send(QEMUFile *file,
const char *block_name)
{
RAMBlock *block = qemu_ram_block_by_name(block_name);
unsigned long *le_bitmap, nbits;
uint64_t size;
if (!block) {
error_report("%s: invalid block name: %s", __func__, block_name);
return -1;
}
nbits = block->used_length >> TARGET_PAGE_BITS;
/*
* Make sure the tmp bitmap buffer is big enough, e.g., on 32bit
* machines we may need 4 more bytes for padding (see below
* comment). So extend it a bit before hand.
*/
le_bitmap = bitmap_new(nbits + BITS_PER_LONG);
/*
* Always use little endian when sending the bitmap. This is
* required that when source and destination VMs are not using the
* same endianess. (Note: big endian won't work.)
*/
bitmap_to_le(le_bitmap, block->receivedmap, nbits);
/* Size of the bitmap, in bytes */
size = DIV_ROUND_UP(nbits, 8);
/*
* size is always aligned to 8 bytes for 64bit machines, but it
* may not be true for 32bit machines. We need this padding to
* make sure the migration can survive even between 32bit and
* 64bit machines.
*/
size = ROUND_UP(size, 8);
qemu_put_be64(file, size);
qemu_put_buffer(file, (const uint8_t *)le_bitmap, size);
/*
* Mark as an end, in case the middle part is screwed up due to
* some "misterious" reason.
*/
qemu_put_be64(file, RAMBLOCK_RECV_BITMAP_ENDING);
qemu_fflush(file);
g_free(le_bitmap);
if (qemu_file_get_error(file)) {
return qemu_file_get_error(file);
}
return size + sizeof(size);
}
/*
* An outstanding page request, on the source, having been received
* and queued
*/
struct RAMSrcPageRequest {
RAMBlock *rb;
hwaddr offset;
hwaddr len;
QSIMPLEQ_ENTRY(RAMSrcPageRequest) next_req;
};
/* State of RAM for migration */
struct RAMState {
/* QEMUFile used for this migration */
QEMUFile *f;
/* Last block that we have visited searching for dirty pages */
RAMBlock *last_seen_block;
/* Last block from where we have sent data */
RAMBlock *last_sent_block;
/* Last dirty target page we have sent */
ram_addr_t last_page;
/* last ram version we have seen */
uint32_t last_version;
/* We are in the first round */
bool ram_bulk_stage;
/* The free page optimization is enabled */
bool fpo_enabled;
/* How many times we have dirty too many pages */
int dirty_rate_high_cnt;
/* these variables are used for bitmap sync */
/* last time we did a full bitmap_sync */
int64_t time_last_bitmap_sync;
/* bytes transferred at start_time */
uint64_t bytes_xfer_prev;
/* number of dirty pages since start_time */
uint64_t num_dirty_pages_period;
/* xbzrle misses since the beginning of the period */
uint64_t xbzrle_cache_miss_prev;
/* compression statistics since the beginning of the period */
/* amount of count that no free thread to compress data */
uint64_t compress_thread_busy_prev;
/* amount bytes after compression */
uint64_t compressed_size_prev;
/* amount of compressed pages */
uint64_t compress_pages_prev;
/* total handled target pages at the beginning of period */
uint64_t target_page_count_prev;
/* total handled target pages since start */
uint64_t target_page_count;
/* number of dirty bits in the bitmap */
uint64_t migration_dirty_pages;
/* Protects modification of the bitmap and migration dirty pages */
QemuMutex bitmap_mutex;
/* The RAMBlock used in the last src_page_requests */
RAMBlock *last_req_rb;
/* Queue of outstanding page requests from the destination */
QemuMutex src_page_req_mutex;
QSIMPLEQ_HEAD(, RAMSrcPageRequest) src_page_requests;
};
typedef struct RAMState RAMState;
static RAMState *ram_state;
static NotifierWithReturnList precopy_notifier_list;
void precopy_infrastructure_init(void)
{
notifier_with_return_list_init(&precopy_notifier_list);
}
void precopy_add_notifier(NotifierWithReturn *n)
{
notifier_with_return_list_add(&precopy_notifier_list, n);
}
void precopy_remove_notifier(NotifierWithReturn *n)
{
notifier_with_return_remove(n);
}
int precopy_notify(PrecopyNotifyReason reason, Error **errp)
{
PrecopyNotifyData pnd;
pnd.reason = reason;
pnd.errp = errp;
return notifier_with_return_list_notify(&precopy_notifier_list, &pnd);
}
void precopy_enable_free_page_optimization(void)
{
if (!ram_state) {
return;
}
ram_state->fpo_enabled = true;
}
uint64_t ram_bytes_remaining(void)
{
return ram_state ? (ram_state->migration_dirty_pages * TARGET_PAGE_SIZE) :
0;
}
MigrationStats ram_counters;
/* used by the search for pages to send */
struct PageSearchStatus {
/* Current block being searched */
RAMBlock *block;
/* Current page to search from */
unsigned long page;
/* Set once we wrap around */
bool complete_round;
};
typedef struct PageSearchStatus PageSearchStatus;
CompressionStats compression_counters;
struct CompressParam {
bool done;
bool quit;
bool zero_page;
QEMUFile *file;
QemuMutex mutex;
QemuCond cond;
RAMBlock *block;
ram_addr_t offset;
/* internally used fields */
z_stream stream;
uint8_t *originbuf;
};
typedef struct CompressParam CompressParam;
struct DecompressParam {
bool done;
bool quit;
QemuMutex mutex;
QemuCond cond;
void *des;
uint8_t *compbuf;
int len;
z_stream stream;
};
typedef struct DecompressParam DecompressParam;
static CompressParam *comp_param;
static QemuThread *compress_threads;
/* comp_done_cond is used to wake up the migration thread when
* one of the compression threads has finished the compression.
* comp_done_lock is used to co-work with comp_done_cond.
*/
static QemuMutex comp_done_lock;
static QemuCond comp_done_cond;
/* The empty QEMUFileOps will be used by file in CompressParam */
static const QEMUFileOps empty_ops = { };
static QEMUFile *decomp_file;
static DecompressParam *decomp_param;
static QemuThread *decompress_threads;
static QemuMutex decomp_done_lock;
static QemuCond decomp_done_cond;
static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
ram_addr_t offset, uint8_t *source_buf);
static void *do_data_compress(void *opaque)
{
CompressParam *param = opaque;
RAMBlock *block;
ram_addr_t offset;
bool zero_page;
qemu_mutex_lock(&param->mutex);
while (!param->quit) {
if (param->block) {
block = param->block;
offset = param->offset;
param->block = NULL;
qemu_mutex_unlock(&param->mutex);
zero_page = do_compress_ram_page(param->file, &param->stream,
block, offset, param->originbuf);
qemu_mutex_lock(&comp_done_lock);
param->done = true;
param->zero_page = zero_page;
qemu_cond_signal(&comp_done_cond);
qemu_mutex_unlock(&comp_done_lock);
qemu_mutex_lock(&param->mutex);
} else {
qemu_cond_wait(&param->cond, &param->mutex);
}
}
qemu_mutex_unlock(&param->mutex);
return NULL;
}
static void compress_threads_save_cleanup(void)
{
int i, thread_count;
if (!migrate_use_compression() || !comp_param) {
return;
}
thread_count = migrate_compress_threads();
for (i = 0; i < thread_count; i++) {
/*
* we use it as a indicator which shows if the thread is
* properly init'd or not
*/
if (!comp_param[i].file) {
break;
}
qemu_mutex_lock(&comp_param[i].mutex);
comp_param[i].quit = true;
qemu_cond_signal(&comp_param[i].cond);
qemu_mutex_unlock(&comp_param[i].mutex);
qemu_thread_join(compress_threads + i);
qemu_mutex_destroy(&comp_param[i].mutex);
qemu_cond_destroy(&comp_param[i].cond);
deflateEnd(&comp_param[i].stream);
g_free(comp_param[i].originbuf);
qemu_fclose(comp_param[i].file);
comp_param[i].file = NULL;
}
qemu_mutex_destroy(&comp_done_lock);
qemu_cond_destroy(&comp_done_cond);
g_free(compress_threads);
g_free(comp_param);
compress_threads = NULL;
comp_param = NULL;
}
static int compress_threads_save_setup(void)
{
int i, thread_count;
if (!migrate_use_compression()) {
return 0;
}
thread_count = migrate_compress_threads();
compress_threads = g_new0(QemuThread, thread_count);
comp_param = g_new0(CompressParam, thread_count);
qemu_cond_init(&comp_done_cond);
qemu_mutex_init(&comp_done_lock);
for (i = 0; i < thread_count; i++) {
comp_param[i].originbuf = g_try_malloc(TARGET_PAGE_SIZE);
if (!comp_param[i].originbuf) {
goto exit;
}
if (deflateInit(&comp_param[i].stream,
migrate_compress_level()) != Z_OK) {
g_free(comp_param[i].originbuf);
goto exit;
}
/* comp_param[i].file is just used as a dummy buffer to save data,
* set its ops to empty.
*/
comp_param[i].file = qemu_fopen_ops(NULL, &empty_ops);
comp_param[i].done = true;
comp_param[i].quit = false;
qemu_mutex_init(&comp_param[i].mutex);
qemu_cond_init(&comp_param[i].cond);
qemu_thread_create(compress_threads + i, "compress",
do_data_compress, comp_param + i,
QEMU_THREAD_JOINABLE);
}
return 0;
exit:
compress_threads_save_cleanup();
return -1;
}
/**
* save_page_header: write page header to wire
*
* If this is the 1st block, it also writes the block identification
*
* Returns the number of bytes written
*
* @f: QEMUFile where to send the data
* @block: block that contains the page we want to send
* @offset: offset inside the block for the page
* in the lower bits, it contains flags
*/
static size_t save_page_header(RAMState *rs, QEMUFile *f, RAMBlock *block,
ram_addr_t offset)
{
size_t size, len;
if (block == rs->last_sent_block) {
offset |= RAM_SAVE_FLAG_CONTINUE;
}
qemu_put_be64(f, offset);
size = 8;
if (!(offset & RAM_SAVE_FLAG_CONTINUE)) {
len = strlen(block->idstr);
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *)block->idstr, len);
size += 1 + len;
rs->last_sent_block = block;
}
return size;
}
/**
* mig_throttle_guest_down: throotle down the guest
*
* Reduce amount of guest cpu execution to hopefully slow down memory
* writes. If guest dirty memory rate is reduced below the rate at
* which we can transfer pages to the destination then we should be
* able to complete migration. Some workloads dirty memory way too
* fast and will not effectively converge, even with auto-converge.
*/
static void mig_throttle_guest_down(void)
{
MigrationState *s = migrate_get_current();
uint64_t pct_initial = s->parameters.cpu_throttle_initial;
uint64_t pct_icrement = s->parameters.cpu_throttle_increment;
int pct_max = s->parameters.max_cpu_throttle;
/* We have not started throttling yet. Let's start it. */
if (!cpu_throttle_active()) {
cpu_throttle_set(pct_initial);
} else {
/* Throttling already on, just increase the rate */
cpu_throttle_set(MIN(cpu_throttle_get_percentage() + pct_icrement,
pct_max));
}
}
/**
* xbzrle_cache_zero_page: insert a zero page in the XBZRLE cache
*
* @rs: current RAM state
* @current_addr: address for the zero page
*
* Update the xbzrle cache to reflect a page that's been sent as all 0.
* The important thing is that a stale (not-yet-0'd) page be replaced
* by the new data.
* As a bonus, if the page wasn't in the cache it gets added so that
* when a small write is made into the 0'd page it gets XBZRLE sent.
*/
static void xbzrle_cache_zero_page(RAMState *rs, ram_addr_t current_addr)
{
if (rs->ram_bulk_stage || !migrate_use_xbzrle()) {
return;
}
/* We don't care if this fails to allocate a new cache page
* as long as it updated an old one */
cache_insert(XBZRLE.cache, current_addr, XBZRLE.zero_target_page,
ram_counters.dirty_sync_count);
}
#define ENCODING_FLAG_XBZRLE 0x1
/**
* save_xbzrle_page: compress and send current page
*
* Returns: 1 means that we wrote the page
* 0 means that page is identical to the one already sent
* -1 means that xbzrle would be longer than normal
*
* @rs: current RAM state
* @current_data: pointer to the address of the page contents
* @current_addr: addr of the page
* @block: block that contains the page we want to send
* @offset: offset inside the block for the page
* @last_stage: if we are at the completion stage
*/
static int save_xbzrle_page(RAMState *rs, uint8_t **current_data,
ram_addr_t current_addr, RAMBlock *block,
ram_addr_t offset, bool last_stage)
{
int encoded_len = 0, bytes_xbzrle;
uint8_t *prev_cached_page;
if (!cache_is_cached(XBZRLE.cache, current_addr,
ram_counters.dirty_sync_count)) {
xbzrle_counters.cache_miss++;
if (!last_stage) {
if (cache_insert(XBZRLE.cache, current_addr, *current_data,
ram_counters.dirty_sync_count) == -1) {
return -1;
} else {
/* update *current_data when the page has been
inserted into cache */
*current_data = get_cached_data(XBZRLE.cache, current_addr);
}
}
return -1;
}
prev_cached_page = get_cached_data(XBZRLE.cache, current_addr);
/* save current buffer into memory */
memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE);
/* XBZRLE encoding (if there is no overflow) */
encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf,
TARGET_PAGE_SIZE, XBZRLE.encoded_buf,
TARGET_PAGE_SIZE);
/*
* Update the cache contents, so that it corresponds to the data
* sent, in all cases except where we skip the page.
*/
if (!last_stage && encoded_len != 0) {
memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE);
/*
* In the case where we couldn't compress, ensure that the caller
* sends the data from the cache, since the guest might have
* changed the RAM since we copied it.
*/
*current_data = prev_cached_page;
}
if (encoded_len == 0) {
trace_save_xbzrle_page_skipping();
return 0;
} else if (encoded_len == -1) {
trace_save_xbzrle_page_overflow();
xbzrle_counters.overflow++;
return -1;
}
/* Send XBZRLE based compressed page */
bytes_xbzrle = save_page_header(rs, rs->f, block,
offset | RAM_SAVE_FLAG_XBZRLE);
qemu_put_byte(rs->f, ENCODING_FLAG_XBZRLE);
qemu_put_be16(rs->f, encoded_len);
qemu_put_buffer(rs->f, XBZRLE.encoded_buf, encoded_len);
bytes_xbzrle += encoded_len + 1 + 2;
xbzrle_counters.pages++;
xbzrle_counters.bytes += bytes_xbzrle;
ram_counters.transferred += bytes_xbzrle;
return 1;
}
/**
* migration_bitmap_find_dirty: find the next dirty page from start
*
* Returns the page offset within memory region of the start of a dirty page
*
* @rs: current RAM state
* @rb: RAMBlock where to search for dirty pages
* @start: page where we start the search
*/
static inline
unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb,
unsigned long start)
{
unsigned long size = rb->used_length >> TARGET_PAGE_BITS;
unsigned long *bitmap = rb->bmap;
unsigned long next;
if (ramblock_is_ignored(rb)) {
return size;
}
/*
* When the free page optimization is enabled, we need to check the bitmap
* to send the non-free pages rather than all the pages in the bulk stage.
*/
if (!rs->fpo_enabled && rs->ram_bulk_stage && start > 0) {
next = start + 1;
} else {
next = find_next_bit(bitmap, size, start);
}
return next;
}
static inline bool migration_bitmap_clear_dirty(RAMState *rs,
RAMBlock *rb,
unsigned long page)
{
bool ret;
qemu_mutex_lock(&rs->bitmap_mutex);
/*
* Clear dirty bitmap if needed. This _must_ be called before we
* send any of the page in the chunk because we need to make sure
* we can capture further page content changes when we sync dirty
* log the next time. So as long as we are going to send any of
* the page in the chunk we clear the remote dirty bitmap for all.
* Clearing it earlier won't be a problem, but too late will.
*/
if (rb->clear_bmap && clear_bmap_test_and_clear(rb, page)) {
uint8_t shift = rb->clear_bmap_shift;
hwaddr size = 1ULL << (TARGET_PAGE_BITS + shift);
hwaddr start = (((ram_addr_t)page) << TARGET_PAGE_BITS) & (-size);
/*
* CLEAR_BITMAP_SHIFT_MIN should always guarantee this... this
* can make things easier sometimes since then start address
* of the small chunk will always be 64 pages aligned so the
* bitmap will always be aligned to unsigned long. We should
* even be able to remove this restriction but I'm simply
* keeping it.
*/
assert(shift >= 6);
trace_migration_bitmap_clear_dirty(rb->idstr, start, size, page);
memory_region_clear_dirty_bitmap(rb->mr, start, size);
}
ret = test_and_clear_bit(page, rb->bmap);
if (ret) {
rs->migration_dirty_pages--;
}
qemu_mutex_unlock(&rs->bitmap_mutex);
return ret;
}
/* Called with RCU critical section */
static void ramblock_sync_dirty_bitmap(RAMState *rs, RAMBlock *rb)
{
rs->migration_dirty_pages +=
cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length,
&rs->num_dirty_pages_period);
}
/**
* ram_pagesize_summary: calculate all the pagesizes of a VM
*
* Returns a summary bitmap of the page sizes of all RAMBlocks
*
* For VMs with just normal pages this is equivalent to the host page
* size. If it's got some huge pages then it's the OR of all the
* different page sizes.
*/
uint64_t ram_pagesize_summary(void)
{
RAMBlock *block;
uint64_t summary = 0;
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
summary |= block->page_size;
}
return summary;
}
uint64_t ram_get_total_transferred_pages(void)
{
return ram_counters.normal + ram_counters.duplicate +
compression_counters.pages + xbzrle_counters.pages;
}
static void migration_update_rates(RAMState *rs, int64_t end_time)
{
uint64_t page_count = rs->target_page_count - rs->target_page_count_prev;
double compressed_size;
/* calculate period counters */
ram_counters.dirty_pages_rate = rs->num_dirty_pages_period * 1000
/ (end_time - rs->time_last_bitmap_sync);
if (!page_count) {
return;
}
if (migrate_use_xbzrle()) {
xbzrle_counters.cache_miss_rate = (double)(xbzrle_counters.cache_miss -
rs->xbzrle_cache_miss_prev) / page_count;
rs->xbzrle_cache_miss_prev = xbzrle_counters.cache_miss;
}
if (migrate_use_compression()) {
compression_counters.busy_rate = (double)(compression_counters.busy -
rs->compress_thread_busy_prev) / page_count;
rs->compress_thread_busy_prev = compression_counters.busy;
compressed_size = compression_counters.compressed_size -
rs->compressed_size_prev;
if (compressed_size) {
double uncompressed_size = (compression_counters.pages -
rs->compress_pages_prev) * TARGET_PAGE_SIZE;
/* Compression-Ratio = Uncompressed-size / Compressed-size */
compression_counters.compression_rate =
uncompressed_size / compressed_size;
rs->compress_pages_prev = compression_counters.pages;
rs->compressed_size_prev = compression_counters.compressed_size;
}
}
}
static void migration_bitmap_sync(RAMState *rs)
{
RAMBlock *block;
int64_t end_time;
uint64_t bytes_xfer_now;
ram_counters.dirty_sync_count++;
if (!rs->time_last_bitmap_sync) {
rs->time_last_bitmap_sync = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
}
trace_migration_bitmap_sync_start();
memory_global_dirty_log_sync();
qemu_mutex_lock(&rs->bitmap_mutex);
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
ramblock_sync_dirty_bitmap(rs, block);
}
ram_counters.remaining = ram_bytes_remaining();
}
qemu_mutex_unlock(&rs->bitmap_mutex);
memory_global_after_dirty_log_sync();
trace_migration_bitmap_sync_end(rs->num_dirty_pages_period);
end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
/* more than 1 second = 1000 millisecons */
if (end_time > rs->time_last_bitmap_sync + 1000) {
bytes_xfer_now = ram_counters.transferred;
/* During block migration the auto-converge logic incorrectly detects
* that ram migration makes no progress. Avoid this by disabling the
* throttling logic during the bulk phase of block migration. */
if (migrate_auto_converge() && !blk_mig_bulk_active()) {
/* The following detection logic can be refined later. For now:
Check to see if the dirtied bytes is 50% more than the approx.
amount of bytes that just got transferred since the last time we
were in this routine. If that happens twice, start or increase
throttling */
if ((rs->num_dirty_pages_period * TARGET_PAGE_SIZE >
(bytes_xfer_now - rs->bytes_xfer_prev) / 2) &&
(++rs->dirty_rate_high_cnt >= 2)) {
trace_migration_throttle();
rs->dirty_rate_high_cnt = 0;
mig_throttle_guest_down();
}
}
migration_update_rates(rs, end_time);
rs->target_page_count_prev = rs->target_page_count;
/* reset period counters */
rs->time_last_bitmap_sync = end_time;
rs->num_dirty_pages_period = 0;
rs->bytes_xfer_prev = bytes_xfer_now;
}
if (migrate_use_events()) {
qapi_event_send_migration_pass(ram_counters.dirty_sync_count);
}
}
static void migration_bitmap_sync_precopy(RAMState *rs)
{
Error *local_err = NULL;
/*
* The current notifier usage is just an optimization to migration, so we
* don't stop the normal migration process in the error case.
*/
if (precopy_notify(PRECOPY_NOTIFY_BEFORE_BITMAP_SYNC, &local_err)) {
error_report_err(local_err);
}
migration_bitmap_sync(rs);
if (precopy_notify(PRECOPY_NOTIFY_AFTER_BITMAP_SYNC, &local_err)) {
error_report_err(local_err);
}
}
/**
* save_zero_page_to_file: send the zero page to the file
*
* Returns the size of data written to the file, 0 means the page is not
* a zero page
*
* @rs: current RAM state
* @file: the file where the data is saved
* @block: block that contains the page we want to send
* @offset: offset inside the block for the page
*/
static int save_zero_page_to_file(RAMState *rs, QEMUFile *file,
RAMBlock *block, ram_addr_t offset)
{
uint8_t *p = block->host + offset;
int len = 0;
if (is_zero_range(p, TARGET_PAGE_SIZE)) {
len += save_page_header(rs, file, block, offset | RAM_SAVE_FLAG_ZERO);
qemu_put_byte(file, 0);
len += 1;
}
return len;
}
/**
* save_zero_page: send the zero page to the stream
*
* Returns the number of pages written.
*
* @rs: current RAM state
* @block: block that contains the page we want to send
* @offset: offset inside the block for the page
*/
static int save_zero_page(RAMState *rs, RAMBlock *block, ram_addr_t offset)
{
int len = save_zero_page_to_file(rs, rs->f, block, offset);
if (len) {
ram_counters.duplicate++;
ram_counters.transferred += len;
return 1;
}
return -1;
}
static void ram_release_pages(const char *rbname, uint64_t offset, int pages)
{
if (!migrate_release_ram() || !migration_in_postcopy()) {
return;
}
ram_discard_range(rbname, offset, ((ram_addr_t)pages) << TARGET_PAGE_BITS);
}
/*
* @pages: the number of pages written by the control path,
* < 0 - error
* > 0 - number of pages written
*
* Return true if the pages has been saved, otherwise false is returned.
*/
static bool control_save_page(RAMState *rs, RAMBlock *block, ram_addr_t offset,
int *pages)
{
uint64_t bytes_xmit = 0;
int ret;
*pages = -1;
ret = ram_control_save_page(rs->f, block->offset, offset, TARGET_PAGE_SIZE,
&bytes_xmit);
if (ret == RAM_SAVE_CONTROL_NOT_SUPP) {
return false;
}
if (bytes_xmit) {
ram_counters.transferred += bytes_xmit;
*pages = 1;
}
if (ret == RAM_SAVE_CONTROL_DELAYED) {
return true;
}
if (bytes_xmit > 0) {
ram_counters.normal++;
} else if (bytes_xmit == 0) {
ram_counters.duplicate++;
}
return true;
}
/*
* directly send the page to the stream
*
* Returns the number of pages written.
*
* @rs: current RAM state
* @block: block that contains the page we want to send
* @offset: offset inside the block for the page
* @buf: the page to be sent
* @async: send to page asyncly
*/
static int save_normal_page(RAMState *rs, RAMBlock *block, ram_addr_t offset,
uint8_t *buf, bool async)
{
ram_counters.transferred += save_page_header(rs, rs->f, block,
offset | RAM_SAVE_FLAG_PAGE);
if (async) {
qemu_put_buffer_async(rs->f, buf, TARGET_PAGE_SIZE,
migrate_release_ram() &
migration_in_postcopy());
} else {
qemu_put_buffer(rs->f, buf, TARGET_PAGE_SIZE);
}
ram_counters.transferred += TARGET_PAGE_SIZE;
ram_counters.normal++;
return 1;
}
/**
* ram_save_page: send the given page to the stream
*
* Returns the number of pages written.
* < 0 - error
* >=0 - Number of pages written - this might legally be 0
* if xbzrle noticed the page was the same.
*
* @rs: current RAM state
* @block: block that contains the page we want to send
* @offset: offset inside the block for the page
* @last_stage: if we are at the completion stage
*/
static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)
{
int pages = -1;
uint8_t *p;
bool send_async = true;
RAMBlock *block = pss->block;
ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
ram_addr_t current_addr = block->offset + offset;
p = block->host + offset;
trace_ram_save_page(block->idstr, (uint64_t)offset, p);
XBZRLE_cache_lock();
if (!rs->ram_bulk_stage && !migration_in_postcopy() &&
migrate_use_xbzrle()) {
pages = save_xbzrle_page(rs, &p, current_addr, block,
offset, last_stage);
if (!last_stage) {
/* Can't send this cached data async, since the cache page
* might get updated before it gets to the wire
*/
send_async = false;
}
}
/* XBZRLE overflow or normal page */
if (pages == -1) {
pages = save_normal_page(rs, block, offset, p, send_async);
}
XBZRLE_cache_unlock();
return pages;
}
static int ram_save_multifd_page(RAMState *rs, RAMBlock *block,
ram_addr_t offset)
{
if (multifd_queue_page(rs->f, block, offset) < 0) {
return -1;
}
ram_counters.normal++;
return 1;
}
static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
ram_addr_t offset, uint8_t *source_buf)
{
RAMState *rs = ram_state;
uint8_t *p = block->host + (offset & TARGET_PAGE_MASK);
bool zero_page = false;
int ret;
if (save_zero_page_to_file(rs, f, block, offset)) {
zero_page = true;
goto exit;
}
save_page_header(rs, f, block, offset | RAM_SAVE_FLAG_COMPRESS_PAGE);
/*
* copy it to a internal buffer to avoid it being modified by VM
* so that we can catch up the error during compression and
* decompression
*/
memcpy(source_buf, p, TARGET_PAGE_SIZE);
ret = qemu_put_compression_data(f, stream, source_buf, TARGET_PAGE_SIZE);
if (ret < 0) {
qemu_file_set_error(migrate_get_current()->to_dst_file, ret);
error_report("compressed data failed!");
return false;
}
exit:
ram_release_pages(block->idstr, offset & TARGET_PAGE_MASK, 1);
return zero_page;
}
static void
update_compress_thread_counts(const CompressParam *param, int bytes_xmit)
{
ram_counters.transferred += bytes_xmit;
if (param->zero_page) {
ram_counters.duplicate++;
return;
}
/* 8 means a header with RAM_SAVE_FLAG_CONTINUE. */
compression_counters.compressed_size += bytes_xmit - 8;
compression_counters.pages++;
}
static bool save_page_use_compression(RAMState *rs);
static void flush_compressed_data(RAMState *rs)
{
int idx, len, thread_count;
if (!save_page_use_compression(rs)) {
return;
}
thread_count = migrate_compress_threads();
qemu_mutex_lock(&comp_done_lock);
for (idx = 0; idx < thread_count; idx++) {
while (!comp_param[idx].done) {
qemu_cond_wait(&comp_done_cond, &comp_done_lock);
}
}
qemu_mutex_unlock(&comp_done_lock);
for (idx = 0; idx < thread_count; idx++) {
qemu_mutex_lock(&comp_param[idx].mutex);
if (!comp_param[idx].quit) {
len = qemu_put_qemu_file(rs->f, comp_param[idx].file);
/*
* it's safe to fetch zero_page without holding comp_done_lock
* as there is no further request submitted to the thread,
* i.e, the thread should be waiting for a request at this point.
*/
update_compress_thread_counts(&comp_param[idx], len);
}
qemu_mutex_unlock(&comp_param[idx].mutex);
}
}
static inline void set_compress_params(CompressParam *param, RAMBlock *block,
ram_addr_t offset)
{
param->block = block;
param->offset = offset;
}
static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block,
ram_addr_t offset)
{
int idx, thread_count, bytes_xmit = -1, pages = -1;
bool wait = migrate_compress_wait_thread();
thread_count = migrate_compress_threads();
qemu_mutex_lock(&comp_done_lock);
retry:
for (idx = 0; idx < thread_count; idx++) {
if (comp_param[idx].done) {
comp_param[idx].done = false;
bytes_xmit = qemu_put_qemu_file(rs->f, comp_param[idx].file);
qemu_mutex_lock(&comp_param[idx].mutex);
set_compress_params(&comp_param[idx], block, offset);
qemu_cond_signal(&comp_param[idx].cond);
qemu_mutex_unlock(&comp_param[idx].mutex);
pages = 1;
update_compress_thread_counts(&comp_param[idx], bytes_xmit);
break;
}
}
/*
* wait for the free thread if the user specifies 'compress-wait-thread',
* otherwise we will post the page out in the main thread as normal page.
*/
if (pages < 0 && wait) {
qemu_cond_wait(&comp_done_cond, &comp_done_lock);
goto retry;
}
qemu_mutex_unlock(&comp_done_lock);
return pages;
}
/**
* find_dirty_block: find the next dirty page and update any state
* associated with the search process.
*
* Returns true if a page is found
*
* @rs: current RAM state
* @pss: data about the state of the current dirty page scan
* @again: set to false if the search has scanned the whole of RAM
*/
static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss, bool *again)
{
pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page);
if (pss->complete_round && pss->block == rs->last_seen_block &&
pss->page >= rs->last_page) {
/*
* We've been once around the RAM and haven't found anything.
* Give up.
*/
*again = false;
return false;
}
if ((((ram_addr_t)pss->page) << TARGET_PAGE_BITS)
>= pss->block->used_length) {
/* Didn't find anything in this RAM Block */
pss->page = 0;
pss->block = QLIST_NEXT_RCU(pss->block, next);
if (!pss->block) {
/*
* If memory migration starts over, we will meet a dirtied page
* which may still exists in compression threads's ring, so we
* should flush the compressed data to make sure the new page
* is not overwritten by the old one in the destination.
*
* Also If xbzrle is on, stop using the data compression at this
* point. In theory, xbzrle can do better than compression.
*/
flush_compressed_data(rs);
/* Hit the end of the list */
pss->block = QLIST_FIRST_RCU(&ram_list.blocks);
/* Flag that we've looped */
pss->complete_round = true;
rs->ram_bulk_stage = false;
}
/* Didn't find anything this time, but try again on the new block */
*again = true;
return false;
} else {
/* Can go around again, but... */
*again = true;
/* We've found something so probably don't need to */
return true;
}
}
/**
* unqueue_page: gets a page of the queue
*
* Helper for 'get_queued_page' - gets a page off the queue
*
* Returns the block of the page (or NULL if none available)
*
* @rs: current RAM state
* @offset: used to return the offset within the RAMBlock
*/
static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t *offset)
{
RAMBlock *block = NULL;
if (QSIMPLEQ_EMPTY_ATOMIC(&rs->src_page_requests)) {
return NULL;
}
qemu_mutex_lock(&rs->src_page_req_mutex);
if (!QSIMPLEQ_EMPTY(&rs->src_page_requests)) {
struct RAMSrcPageRequest *entry =
QSIMPLEQ_FIRST(&rs->src_page_requests);
block = entry->rb;
*offset = entry->offset;
if (entry->len > TARGET_PAGE_SIZE) {
entry->len -= TARGET_PAGE_SIZE;
entry->offset += TARGET_PAGE_SIZE;
} else {
memory_region_unref(block->mr);
QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req);
g_free(entry);
migration_consume_urgent_request();
}
}
qemu_mutex_unlock(&rs->src_page_req_mutex);
return block;
}
/**
* get_queued_page: unqueue a page from the postcopy requests
*
* Skips pages that are already sent (!dirty)
*
* Returns true if a queued page is found
*
* @rs: current RAM state
* @pss: data about the state of the current dirty page scan
*/
static bool get_queued_page(RAMState *rs, PageSearchStatus *pss)
{
RAMBlock *block;
ram_addr_t offset;
bool dirty;
do {
block = unqueue_page(rs, &offset);
/*
* We're sending this page, and since it's postcopy nothing else
* will dirty it, and we must make sure it doesn't get sent again
* even if this queue request was received after the background
* search already sent it.
*/
if (block) {
unsigned long page;
page = offset >> TARGET_PAGE_BITS;
dirty = test_bit(page, block->bmap);
if (!dirty) {
trace_get_queued_page_not_dirty(block->idstr, (uint64_t)offset,
page);
} else {
trace_get_queued_page(block->idstr, (uint64_t)offset, page);
}
}
} while (block && !dirty);
if (block) {
/*
* As soon as we start servicing pages out of order, then we have
* to kill the bulk stage, since the bulk stage assumes
* in (migration_bitmap_find_and_reset_dirty) that every page is
* dirty, that's no longer true.
*/
rs->ram_bulk_stage = false;
/*
* We want the background search to continue from the queued page
* since the guest is likely to want other pages near to the page
* it just requested.
*/
pss->block = block;
pss->page = offset >> TARGET_PAGE_BITS;
/*
* This unqueued page would break the "one round" check, even is
* really rare.
*/
pss->complete_round = false;
}
return !!block;
}
/**
* migration_page_queue_free: drop any remaining pages in the ram
* request queue
*
* It should be empty at the end anyway, but in error cases there may
* be some left. in case that there is any page left, we drop it.
*
*/
static void migration_page_queue_free(RAMState *rs)
{
struct RAMSrcPageRequest *mspr, *next_mspr;
/* This queue generally should be empty - but in the case of a failed
* migration might have some droppings in.
*/
RCU_READ_LOCK_GUARD();
QSIMPLEQ_FOREACH_SAFE(mspr, &rs->src_page_requests, next_req, next_mspr) {
memory_region_unref(mspr->rb->mr);
QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req);
g_free(mspr);
}
}
/**
* ram_save_queue_pages: queue the page for transmission
*
* A request from postcopy destination for example.
*
* Returns zero on success or negative on error
*
* @rbname: Name of the RAMBLock of the request. NULL means the
* same that last one.
* @start: starting address from the start of the RAMBlock
* @len: length (in bytes) to send
*/
int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len)
{
RAMBlock *ramblock;
RAMState *rs = ram_state;
ram_counters.postcopy_requests++;
RCU_READ_LOCK_GUARD();
if (!rbname) {
/* Reuse last RAMBlock */
ramblock = rs->last_req_rb;
if (!ramblock) {
/*
* Shouldn't happen, we can't reuse the last RAMBlock if
* it's the 1st request.
*/
error_report("ram_save_queue_pages no previous block");
return -1;
}
} else {
ramblock = qemu_ram_block_by_name(rbname);
if (!ramblock) {
/* We shouldn't be asked for a non-existent RAMBlock */
error_report("ram_save_queue_pages no block '%s'", rbname);
return -1;
}
rs->last_req_rb = ramblock;
}
trace_ram_save_queue_pages(ramblock->idstr, start, len);
if (start+len > ramblock->used_length) {
error_report("%s request overrun start=" RAM_ADDR_FMT " len="
RAM_ADDR_FMT " blocklen=" RAM_ADDR_FMT,
__func__, start, len, ramblock->used_length);
return -1;
}
struct RAMSrcPageRequest *new_entry =
g_malloc0(sizeof(struct RAMSrcPageRequest));
new_entry->rb = ramblock;
new_entry->offset = start;
new_entry->len = len;
memory_region_ref(ramblock->mr);
qemu_mutex_lock(&rs->src_page_req_mutex);
QSIMPLEQ_INSERT_TAIL(&rs->src_page_requests, new_entry, next_req);
migration_make_urgent_request();
qemu_mutex_unlock(&rs->src_page_req_mutex);
return 0;
}
static bool save_page_use_compression(RAMState *rs)
{
if (!migrate_use_compression()) {
return false;
}
/*
* If xbzrle is on, stop using the data compression after first
* round of migration even if compression is enabled. In theory,
* xbzrle can do better than compression.
*/
if (rs->ram_bulk_stage || !migrate_use_xbzrle()) {
return true;
}
return false;
}
/*
* try to compress the page before posting it out, return true if the page
* has been properly handled by compression, otherwise needs other
* paths to handle it
*/
static bool save_compress_page(RAMState *rs, RAMBlock *block, ram_addr_t offset)
{
if (!save_page_use_compression(rs)) {
return false;
}
/*
* When starting the process of a new block, the first page of
* the block should be sent out before other pages in the same
* block, and all the pages in last block should have been sent
* out, keeping this order is important, because the 'cont' flag
* is used to avoid resending the block name.
*
* We post the fist page as normal page as compression will take
* much CPU resource.
*/
if (block != rs->last_sent_block) {
flush_compressed_data(rs);
return false;
}
if (compress_page_with_multi_thread(rs, block, offset) > 0) {
return true;
}
compression_counters.busy++;
return false;
}
/**
* ram_save_target_page: save one target page
*
* Returns the number of pages written
*
* @rs: current RAM state
* @pss: data about the page we want to send
* @last_stage: if we are at the completion stage
*/
static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
bool last_stage)
{
RAMBlock *block = pss->block;
ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
int res;
if (control_save_page(rs, block, offset, &res)) {
return res;
}
if (save_compress_page(rs, block, offset)) {
return 1;
}
res = save_zero_page(rs, block, offset);
if (res > 0) {
/* Must let xbzrle know, otherwise a previous (now 0'd) cached
* page would be stale
*/
if (!save_page_use_compression(rs)) {
XBZRLE_cache_lock();
xbzrle_cache_zero_page(rs, block->offset + offset);
XBZRLE_cache_unlock();
}
ram_release_pages(block->idstr, offset, res);
return res;
}
/*
* Do not use multifd for:
* 1. Compression as the first page in the new block should be posted out
* before sending the compressed page
* 2. In postcopy as one whole host page should be placed
*/
if (!save_page_use_compression(rs) && migrate_use_multifd()
&& !migration_in_postcopy()) {
return ram_save_multifd_page(rs, block, offset);
}
return ram_save_page(rs, pss, last_stage);
}
/**
* ram_save_host_page: save a whole host page
*
* Starting at *offset send pages up to the end of the current host
* page. It's valid for the initial offset to point into the middle of
* a host page in which case the remainder of the hostpage is sent.
* Only dirty target pages are sent. Note that the host page size may
* be a huge page for this block.
* The saving stops at the boundary of the used_length of the block
* if the RAMBlock isn't a multiple of the host page size.
*
* Returns the number of pages written or negative on error
*
* @rs: current RAM state
* @ms: current migration state
* @pss: data about the page we want to send
* @last_stage: if we are at the completion stage
*/
static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss,
bool last_stage)
{
int tmppages, pages = 0;
size_t pagesize_bits =
qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS;
if (ramblock_is_ignored(pss->block)) {
error_report("block %s should not be migrated !", pss->block->idstr);
return 0;
}
do {
/* Check the pages is dirty and if it is send it */
if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
pss->page++;
continue;
}
tmppages = ram_save_target_page(rs, pss, last_stage);
if (tmppages < 0) {
return tmppages;
}
pages += tmppages;
pss->page++;
/* Allow rate limiting to happen in the middle of huge pages */
migration_rate_limit();
} while ((pss->page & (pagesize_bits - 1)) &&
offset_in_ramblock(pss->block,
((ram_addr_t)pss->page) << TARGET_PAGE_BITS));
/* The offset we leave with is the last one we looked at */
pss->page--;
return pages;
}
/**
* ram_find_and_save_block: finds a dirty page and sends it to f
*
* Called within an RCU critical section.
*
* Returns the number of pages written where zero means no dirty pages,
* or negative on error
*
* @rs: current RAM state
* @last_stage: if we are at the completion stage
*
* On systems where host-page-size > target-page-size it will send all the
* pages in a host page that are dirty.
*/
static int ram_find_and_save_block(RAMState *rs, bool last_stage)
{
PageSearchStatus pss;
int pages = 0;
bool again, found;
/* No dirty page as there is zero RAM */
if (!ram_bytes_total()) {
return pages;
}
pss.block = rs->last_seen_block;
pss.page = rs->last_page;
pss.complete_round = false;
if (!pss.block) {
pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
}
do {
again = true;
found = get_queued_page(rs, &pss);
if (!found) {
/* priority queue empty, so just search for something dirty */
found = find_dirty_block(rs, &pss, &again);
}
if (found) {
pages = ram_save_host_page(rs, &pss, last_stage);
}
} while (!pages && again);
rs->last_seen_block = pss.block;
rs->last_page = pss.page;
return pages;
}
void acct_update_position(QEMUFile *f, size_t size, bool zero)
{
uint64_t pages = size / TARGET_PAGE_SIZE;
if (zero) {
ram_counters.duplicate += pages;
} else {
ram_counters.normal += pages;
ram_counters.transferred += size;
qemu_update_position(f, size);
}
}
static uint64_t ram_bytes_total_common(bool count_ignored)
{
RAMBlock *block;
uint64_t total = 0;
RCU_READ_LOCK_GUARD();
if (count_ignored) {
RAMBLOCK_FOREACH_MIGRATABLE(block) {
total += block->used_length;
}
} else {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
total += block->used_length;
}
}
return total;
}
uint64_t ram_bytes_total(void)
{
return ram_bytes_total_common(false);
}
static void xbzrle_load_setup(void)
{
XBZRLE.decoded_buf = g_malloc(TARGET_PAGE_SIZE);
}
static void xbzrle_load_cleanup(void)
{
g_free(XBZRLE.decoded_buf);
XBZRLE.decoded_buf = NULL;
}
static void ram_state_cleanup(RAMState **rsp)
{
if (*rsp) {
migration_page_queue_free(*rsp);
qemu_mutex_destroy(&(*rsp)->bitmap_mutex);
qemu_mutex_destroy(&(*rsp)->src_page_req_mutex);
g_free(*rsp);
*rsp = NULL;
}
}
static void xbzrle_cleanup(void)
{
XBZRLE_cache_lock();
if (XBZRLE.cache) {
cache_fini(XBZRLE.cache);
g_free(XBZRLE.encoded_buf);
g_free(XBZRLE.current_buf);
g_free(XBZRLE.zero_target_page);
XBZRLE.cache = NULL;
XBZRLE.encoded_buf = NULL;
XBZRLE.current_buf = NULL;
XBZRLE.zero_target_page = NULL;
}
XBZRLE_cache_unlock();
}
static void ram_save_cleanup(void *opaque)
{
RAMState **rsp = opaque;
RAMBlock *block;
/* caller have hold iothread lock or is in a bh, so there is
* no writing race against the migration bitmap
*/
memory_global_dirty_log_stop();
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
g_free(block->clear_bmap);
block->clear_bmap = NULL;
g_free(block->bmap);
block->bmap = NULL;
}
xbzrle_cleanup();
compress_threads_save_cleanup();
ram_state_cleanup(rsp);
}
static void ram_state_reset(RAMState *rs)
{
rs->last_seen_block = NULL;
rs->last_sent_block = NULL;
rs->last_page = 0;
rs->last_version = ram_list.version;
rs->ram_bulk_stage = true;
rs->fpo_enabled = false;
}
#define MAX_WAIT 50 /* ms, half buffered_file limit */
/*
* 'expected' is the value you expect the bitmap mostly to be full
* of; it won't bother printing lines that are all this value.
* If 'todump' is null the migration bitmap is dumped.
*/
void ram_debug_dump_bitmap(unsigned long *todump, bool expected,
unsigned long pages)
{
int64_t cur;
int64_t linelen = 128;
char linebuf[129];
for (cur = 0; cur < pages; cur += linelen) {
int64_t curb;
bool found = false;
/*
* Last line; catch the case where the line length
* is longer than remaining ram
*/
if (cur + linelen > pages) {
linelen = pages - cur;
}
for (curb = 0; curb < linelen; curb++) {
bool thisbit = test_bit(cur + curb, todump);
linebuf[curb] = thisbit ? '1' : '.';
found = found || (thisbit != expected);
}
if (found) {
linebuf[curb] = '\0';
fprintf(stderr, "0x%08" PRIx64 " : %s\n", cur, linebuf);
}
}
}
/* **** functions for postcopy ***** */
void ram_postcopy_migrated_memory_release(MigrationState *ms)
{
struct RAMBlock *block;
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
unsigned long *bitmap = block->bmap;
unsigned long range = block->used_length >> TARGET_PAGE_BITS;
unsigned long run_start = find_next_zero_bit(bitmap, range, 0);
while (run_start < range) {
unsigned long run_end = find_next_bit(bitmap, range, run_start + 1);
ram_discard_range(block->idstr,
((ram_addr_t)run_start) << TARGET_PAGE_BITS,
((ram_addr_t)(run_end - run_start))
<< TARGET_PAGE_BITS);
run_start = find_next_zero_bit(bitmap, range, run_end + 1);
}
}
}
/**
* postcopy_send_discard_bm_ram: discard a RAMBlock
*
* Returns zero on success
*
* Callback from postcopy_each_ram_send_discard for each RAMBlock
*
* @ms: current migration state
* @block: RAMBlock to discard
*/
static int postcopy_send_discard_bm_ram(MigrationState *ms, RAMBlock *block)
{
unsigned long end = block->used_length >> TARGET_PAGE_BITS;
unsigned long current;
unsigned long *bitmap = block->bmap;
for (current = 0; current < end; ) {
unsigned long one = find_next_bit(bitmap, end, current);
unsigned long zero, discard_length;
if (one >= end) {
break;
}
zero = find_next_zero_bit(bitmap, end, one + 1);
if (zero >= end) {
discard_length = end - one;
} else {
discard_length = zero - one;
}
postcopy_discard_send_range(ms, one, discard_length);
current = one + discard_length;
}
return 0;
}
/**
* postcopy_each_ram_send_discard: discard all RAMBlocks
*
* Returns 0 for success or negative for error
*
* Utility for the outgoing postcopy code.
* Calls postcopy_send_discard_bm_ram for each RAMBlock
* passing it bitmap indexes and name.
* (qemu_ram_foreach_block ends up passing unscaled lengths
* which would mean postcopy code would have to deal with target page)
*
* @ms: current migration state
*/
static int postcopy_each_ram_send_discard(MigrationState *ms)
{
struct RAMBlock *block;
int ret;
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
postcopy_discard_send_init(ms, block->idstr);
/*
* Postcopy sends chunks of bitmap over the wire, but it
* just needs indexes at this point, avoids it having
* target page specific code.
*/
ret = postcopy_send_discard_bm_ram(ms, block);
postcopy_discard_send_finish(ms);
if (ret) {
return ret;
}
}
return 0;
}
/**
* postcopy_chunk_hostpages_pass: canonicalize bitmap in hostpages
*
* Helper for postcopy_chunk_hostpages; it's called twice to
* canonicalize the two bitmaps, that are similar, but one is
* inverted.
*
* Postcopy requires that all target pages in a hostpage are dirty or
* clean, not a mix. This function canonicalizes the bitmaps.
*
* @ms: current migration state
* @block: block that contains the page we want to canonicalize
*/
static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block)
{
RAMState *rs = ram_state;
unsigned long *bitmap = block->bmap;
unsigned int host_ratio = block->page_size / TARGET_PAGE_SIZE;
unsigned long pages = block->used_length >> TARGET_PAGE_BITS;
unsigned long run_start;
if (block->page_size == TARGET_PAGE_SIZE) {
/* Easy case - TPS==HPS for a non-huge page RAMBlock */
return;
}
/* Find a dirty page */
run_start = find_next_bit(bitmap, pages, 0);
while (run_start < pages) {
/*
* If the start of this run of pages is in the middle of a host
* page, then we need to fixup this host page.
*/
if (QEMU_IS_ALIGNED(run_start, host_ratio)) {
/* Find the end of this run */
run_start = find_next_zero_bit(bitmap, pages, run_start + 1);
/*
* If the end isn't at the start of a host page, then the
* run doesn't finish at the end of a host page
* and we need to discard.
*/
}
if (!QEMU_IS_ALIGNED(run_start, host_ratio)) {
unsigned long page;
unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
host_ratio);
run_start = QEMU_ALIGN_UP(run_start, host_ratio);
/* Clean up the bitmap */
for (page = fixup_start_addr;
page < fixup_start_addr + host_ratio; page++) {
/*
* Remark them as dirty, updating the count for any pages
* that weren't previously dirty.
*/
rs->migration_dirty_pages += !test_and_set_bit(page, bitmap);
}
}
/* Find the next dirty page for the next iteration */
run_start = find_next_bit(bitmap, pages, run_start);
}
}
/**
* postcopy_chunk_hostpages: discard any partially sent host page
*
* Utility for the outgoing postcopy code.
*
* Discard any partially sent host-page size chunks, mark any partially
* dirty host-page size chunks as all dirty. In this case the host-page
* is the host-page for the particular RAMBlock, i.e. it might be a huge page
*
* Returns zero on success
*
* @ms: current migration state
* @block: block we want to work with
*/
static int postcopy_chunk_hostpages(MigrationState *ms, RAMBlock *block)
{
postcopy_discard_send_init(ms, block->idstr);
/*
* Ensure that all partially dirty host pages are made fully dirty.
*/
postcopy_chunk_hostpages_pass(ms, block);
postcopy_discard_send_finish(ms);
return 0;
}
/**
* ram_postcopy_send_discard_bitmap: transmit the discard bitmap
*
* Returns zero on success
*
* Transmit the set of pages to be discarded after precopy to the target
* these are pages that:
* a) Have been previously transmitted but are now dirty again
* b) Pages that have never been transmitted, this ensures that
* any pages on the destination that have been mapped by background
* tasks get discarded (transparent huge pages is the specific concern)
* Hopefully this is pretty sparse
*
* @ms: current migration state
*/
int ram_postcopy_send_discard_bitmap(MigrationState *ms)
{
RAMState *rs = ram_state;
RAMBlock *block;
int ret;
RCU_READ_LOCK_GUARD();
/* This should be our last sync, the src is now paused */
migration_bitmap_sync(rs);
/* Easiest way to make sure we don't resume in the middle of a host-page */
rs->last_seen_block = NULL;
rs->last_sent_block = NULL;
rs->last_page = 0;
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
/* Deal with TPS != HPS and huge pages */
ret = postcopy_chunk_hostpages(ms, block);
if (ret) {
return ret;
}
#ifdef DEBUG_POSTCOPY
ram_debug_dump_bitmap(block->bmap, true,
block->used_length >> TARGET_PAGE_BITS);
#endif
}
trace_ram_postcopy_send_discard_bitmap();
ret = postcopy_each_ram_send_discard(ms);
return ret;
}
/**
* ram_discard_range: discard dirtied pages at the beginning of postcopy
*
* Returns zero on success
*
* @rbname: name of the RAMBlock of the request. NULL means the
* same that last one.
* @start: RAMBlock starting page
* @length: RAMBlock size
*/
int ram_discard_range(const char *rbname, uint64_t start, size_t length)
{
trace_ram_discard_range(rbname, start, length);
RCU_READ_LOCK_GUARD();
RAMBlock *rb = qemu_ram_block_by_name(rbname);
if (!rb) {
error_report("ram_discard_range: Failed to find block '%s'", rbname);
return -1;
}
/*
* On source VM, we don't need to update the received bitmap since
* we don't even have one.
*/
if (rb->receivedmap) {
bitmap_clear(rb->receivedmap, start >> qemu_target_page_bits(),
length >> qemu_target_page_bits());
}
return ram_block_discard_range(rb, start, length);
}
/*
* For every allocation, we will try not to crash the VM if the
* allocation failed.
*/
static int xbzrle_init(void)
{
Error *local_err = NULL;
if (!migrate_use_xbzrle()) {
return 0;
}
XBZRLE_cache_lock();
XBZRLE.zero_target_page = g_try_malloc0(TARGET_PAGE_SIZE);
if (!XBZRLE.zero_target_page) {
error_report("%s: Error allocating zero page", __func__);
goto err_out;
}
XBZRLE.cache = cache_init(migrate_xbzrle_cache_size(),
TARGET_PAGE_SIZE, &local_err);
if (!XBZRLE.cache) {
error_report_err(local_err);
goto free_zero_page;
}
XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE);
if (!XBZRLE.encoded_buf) {
error_report("%s: Error allocating encoded_buf", __func__);
goto free_cache;
}
XBZRLE.current_buf = g_try_malloc(TARGET_PAGE_SIZE);
if (!XBZRLE.current_buf) {
error_report("%s: Error allocating current_buf", __func__);
goto free_encoded_buf;
}
/* We are all good */
XBZRLE_cache_unlock();
return 0;
free_encoded_buf:
g_free(XBZRLE.encoded_buf);
XBZRLE.encoded_buf = NULL;
free_cache:
cache_fini(XBZRLE.cache);
XBZRLE.cache = NULL;
free_zero_page:
g_free(XBZRLE.zero_target_page);
XBZRLE.zero_target_page = NULL;
err_out:
XBZRLE_cache_unlock();
return -ENOMEM;
}
static int ram_state_init(RAMState **rsp)
{
*rsp = g_try_new0(RAMState, 1);
if (!*rsp) {
error_report("%s: Init ramstate fail", __func__);
return -1;
}
qemu_mutex_init(&(*rsp)->bitmap_mutex);
qemu_mutex_init(&(*rsp)->src_page_req_mutex);
QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
/*
* Count the total number of pages used by ram blocks not including any
* gaps due to alignment or unplugs.
* This must match with the initial values of dirty bitmap.
*/
(*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
ram_state_reset(*rsp);
return 0;
}
static void ram_list_init_bitmaps(void)
{
MigrationState *ms = migrate_get_current();
RAMBlock *block;
unsigned long pages;
uint8_t shift;
/* Skip setting bitmap if there is no RAM */
if (ram_bytes_total()) {
shift = ms->clear_bitmap_shift;
if (shift > CLEAR_BITMAP_SHIFT_MAX) {
error_report("clear_bitmap_shift (%u) too big, using "
"max value (%u)", shift, CLEAR_BITMAP_SHIFT_MAX);
shift = CLEAR_BITMAP_SHIFT_MAX;
} else if (shift < CLEAR_BITMAP_SHIFT_MIN) {
error_report("clear_bitmap_shift (%u) too small, using "
"min value (%u)", shift, CLEAR_BITMAP_SHIFT_MIN);
shift = CLEAR_BITMAP_SHIFT_MIN;
}
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
pages = block->max_length >> TARGET_PAGE_BITS;
/*
* The initial dirty bitmap for migration must be set with all
* ones to make sure we'll migrate every guest RAM page to
* destination.
* Here we set RAMBlock.bmap all to 1 because when rebegin a
* new migration after a failed migration, ram_list.
* dirty_memory[DIRTY_MEMORY_MIGRATION] don't include the whole
* guest memory.
*/
block->bmap = bitmap_new(pages);
bitmap_set(block->bmap, 0, pages);
block->clear_bmap_shift = shift;
block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));
}
}
}
static void ram_init_bitmaps(RAMState *rs)
{
/* For memory_global_dirty_log_start below. */
qemu_mutex_lock_iothread();
qemu_mutex_lock_ramlist();
WITH_RCU_READ_LOCK_GUARD() {
ram_list_init_bitmaps();
memory_global_dirty_log_start();
migration_bitmap_sync_precopy(rs);
}
qemu_mutex_unlock_ramlist();
qemu_mutex_unlock_iothread();
}
static int ram_init_all(RAMState **rsp)
{
if (ram_state_init(rsp)) {
return -1;
}
if (xbzrle_init()) {
ram_state_cleanup(rsp);
return -1;
}
ram_init_bitmaps(*rsp);
return 0;
}
static void ram_state_resume_prepare(RAMState *rs, QEMUFile *out)
{
RAMBlock *block;
uint64_t pages = 0;
/*
* Postcopy is not using xbzrle/compression, so no need for that.
* Also, since source are already halted, we don't need to care
* about dirty page logging as well.
*/
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
pages += bitmap_count_one(block->bmap,
block->used_length >> TARGET_PAGE_BITS);
}
/* This may not be aligned with current bitmaps. Recalculate. */
rs->migration_dirty_pages = pages;
rs->last_seen_block = NULL;
rs->last_sent_block = NULL;
rs->last_page = 0;
rs->last_version = ram_list.version;
/*
* Disable the bulk stage, otherwise we'll resend the whole RAM no
* matter what we have sent.
*/
rs->ram_bulk_stage = false;
/* Update RAMState cache of output QEMUFile */
rs->f = out;
trace_ram_state_resume_prepare(pages);
}
/*
* This function clears bits of the free pages reported by the caller from the
* migration dirty bitmap. @addr is the host address corresponding to the
* start of the continuous guest free pages, and @len is the total bytes of
* those pages.
*/
void qemu_guest_free_page_hint(void *addr, size_t len)
{
RAMBlock *block;
ram_addr_t offset;
size_t used_len, start, npages;
MigrationState *s = migrate_get_current();
/* This function is currently expected to be used during live migration */
if (!migration_is_setup_or_active(s->state)) {
return;
}
for (; len > 0; len -= used_len, addr += used_len) {
block = qemu_ram_block_from_host(addr, false, &offset);
if (unlikely(!block || offset >= block->used_length)) {
/*
* The implementation might not support RAMBlock resize during
* live migration, but it could happen in theory with future
* updates. So we add a check here to capture that case.
*/
error_report_once("%s unexpected error", __func__);
return;
}
if (len <= block->used_length - offset) {
used_len = len;
} else {
used_len = block->used_length - offset;
}
start = offset >> TARGET_PAGE_BITS;
npages = used_len >> TARGET_PAGE_BITS;
qemu_mutex_lock(&ram_state->bitmap_mutex);
ram_state->migration_dirty_pages -=
bitmap_count_one_with_offset(block->bmap, start, npages);
bitmap_clear(block->bmap, start, npages);
qemu_mutex_unlock(&ram_state->bitmap_mutex);
}
}
/*
* Each of ram_save_setup, ram_save_iterate and ram_save_complete has
* long-running RCU critical section. When rcu-reclaims in the code
* start to become numerous it will be necessary to reduce the
* granularity of these critical sections.
*/
/**
* ram_save_setup: Setup RAM for migration
*
* Returns zero to indicate success and negative for error
*
* @f: QEMUFile where to send the data
* @opaque: RAMState pointer
*/
static int ram_save_setup(QEMUFile *f, void *opaque)
{
RAMState **rsp = opaque;
RAMBlock *block;
if (compress_threads_save_setup()) {
return -1;
}
/* migration has already setup the bitmap, reuse it. */
if (!migration_in_colo_state()) {
if (ram_init_all(rsp) != 0) {
compress_threads_save_cleanup();
return -1;
}
}
(*rsp)->f = f;
WITH_RCU_READ_LOCK_GUARD() {
qemu_put_be64(f, ram_bytes_total_common(true) | RAM_SAVE_FLAG_MEM_SIZE);
RAMBLOCK_FOREACH_MIGRATABLE(block) {
qemu_put_byte(f, strlen(block->idstr));
qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));
qemu_put_be64(f, block->used_length);
if (migrate_postcopy_ram() && block->page_size !=
qemu_host_page_size) {
qemu_put_be64(f, block->page_size);
}
if (migrate_ignore_shared()) {
qemu_put_be64(f, block->mr->addr);
}
}
}
ram_control_before_iterate(f, RAM_CONTROL_SETUP);
ram_control_after_iterate(f, RAM_CONTROL_SETUP);
multifd_send_sync_main(f);
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
qemu_fflush(f);
return 0;
}
/**
* ram_save_iterate: iterative stage for migration
*
* Returns zero to indicate success and negative for error
*
* @f: QEMUFile where to send the data
* @opaque: RAMState pointer
*/
static int ram_save_iterate(QEMUFile *f, void *opaque)
{
RAMState **temp = opaque;
RAMState *rs = *temp;
int ret = 0;
int i;
int64_t t0;
int done = 0;
if (blk_mig_bulk_active()) {
/* Avoid transferring ram during bulk phase of block migration as
* the bulk phase will usually take a long time and transferring
* ram updates during that time is pointless. */
goto out;
}
WITH_RCU_READ_LOCK_GUARD() {
if (ram_list.version != rs->last_version) {
ram_state_reset(rs);
}
/* Read version before ram_list.blocks */
smp_rmb();
ram_control_before_iterate(f, RAM_CONTROL_ROUND);
t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
i = 0;
while ((ret = qemu_file_rate_limit(f)) == 0 ||
!QSIMPLEQ_EMPTY(&rs->src_page_requests)) {
int pages;
if (qemu_file_get_error(f)) {
break;
}
pages = ram_find_and_save_block(rs, false);
/* no more pages to sent */
if (pages == 0) {
done = 1;
break;
}
if (pages < 0) {
qemu_file_set_error(f, pages);
break;
}
rs->target_page_count += pages;
/*
* During postcopy, it is necessary to make sure one whole host
* page is sent in one chunk.
*/
if (migrate_postcopy_ram()) {
flush_compressed_data(rs);
}
/*
* we want to check in the 1st loop, just in case it was the 1st
* time and we had to sync the dirty bitmap.
* qemu_clock_get_ns() is a bit expensive, so we only check each
* some iterations
*/
if ((i & 63) == 0) {
uint64_t t1 = (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - t0) /
1000000;
if (t1 > MAX_WAIT) {
trace_ram_save_iterate_big_wait(t1, i);
break;
}
}
i++;
}
}
/*
* Must occur before EOS (or any QEMUFile operation)
* because of RDMA protocol.
*/
ram_control_after_iterate(f, RAM_CONTROL_ROUND);
out:
if (ret >= 0
&& migration_is_setup_or_active(migrate_get_current()->state)) {
multifd_send_sync_main(rs->f);
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
qemu_fflush(f);
ram_counters.transferred += 8;
ret = qemu_file_get_error(f);
}
if (ret < 0) {
return ret;
}
return done;
}
/**
* ram_save_complete: function called to send the remaining amount of ram
*
* Returns zero to indicate success or negative on error
*
* Called with iothread lock
*
* @f: QEMUFile where to send the data
* @opaque: RAMState pointer
*/
static int ram_save_complete(QEMUFile *f, void *opaque)
{
RAMState **temp = opaque;
RAMState *rs = *temp;
int ret = 0;
WITH_RCU_READ_LOCK_GUARD() {
if (!migration_in_postcopy()) {
migration_bitmap_sync_precopy(rs);
}
ram_control_before_iterate(f, RAM_CONTROL_FINISH);
/* try transferring iterative blocks of memory */
/* flush all remaining blocks regardless of rate limiting */
while (true) {
int pages;
pages = ram_find_and_save_block(rs, !migration_in_colo_state());
/* no more blocks to sent */
if (pages == 0) {
break;
}
if (pages < 0) {
ret = pages;
break;
}
}
flush_compressed_data(rs);
ram_control_after_iterate(f, RAM_CONTROL_FINISH);
}
if (ret >= 0) {
multifd_send_sync_main(rs->f);
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
qemu_fflush(f);
}
return ret;
}
static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
uint64_t *res_precopy_only,
uint64_t *res_compatible,
uint64_t *res_postcopy_only)
{
RAMState **temp = opaque;
RAMState *rs = *temp;
uint64_t remaining_size;
remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
if (!migration_in_postcopy() &&
remaining_size < max_size) {
qemu_mutex_lock_iothread();
WITH_RCU_READ_LOCK_GUARD() {
migration_bitmap_sync_precopy(rs);
}
qemu_mutex_unlock_iothread();
remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
}
if (migrate_postcopy_ram()) {
/* We can do postcopy, and all the data is postcopiable */
*res_compatible += remaining_size;
} else {
*res_precopy_only += remaining_size;
}
}
static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
{
unsigned int xh_len;
int xh_flags;
uint8_t *loaded_data;
/* extract RLE header */
xh_flags = qemu_get_byte(f);
xh_len = qemu_get_be16(f);
if (xh_flags != ENCODING_FLAG_XBZRLE) {
error_report("Failed to load XBZRLE page - wrong compression!");
return -1;
}
if (xh_len > TARGET_PAGE_SIZE) {
error_report("Failed to load XBZRLE page - len overflow!");
return -1;
}
loaded_data = XBZRLE.decoded_buf;
/* load data and decode */
/* it can change loaded_data to point to an internal buffer */
qemu_get_buffer_in_place(f, &loaded_data, xh_len);
/* decode RLE */
if (xbzrle_decode_buffer(loaded_data, xh_len, host,
TARGET_PAGE_SIZE) == -1) {
error_report("Failed to load XBZRLE page - decode error!");
return -1;
}
return 0;
}
/**
* ram_block_from_stream: read a RAMBlock id from the migration stream
*
* Must be called from within a rcu critical section.
*
* Returns a pointer from within the RCU-protected ram_list.
*
* @f: QEMUFile where to read the data from
* @flags: Page flags (mostly to see if it's a continuation of previous block)
*/
static inline RAMBlock *ram_block_from_stream(QEMUFile *f, int flags)
{
static RAMBlock *block = NULL;
char id[256];
uint8_t len;
if (flags & RAM_SAVE_FLAG_CONTINUE) {
if (!block) {
error_report("Ack, bad migration stream!");
return NULL;
}
return block;
}
len = qemu_get_byte(f);
qemu_get_buffer(f, (uint8_t *)id, len);
id[len] = 0;
block = qemu_ram_block_by_name(id);
if (!block) {
error_report("Can't find block %s", id);
return NULL;
}
if (ramblock_is_ignored(block)) {
error_report("block %s should not be migrated !", id);
return NULL;
}
return block;
}
static inline void *host_from_ram_block_offset(RAMBlock *block,
ram_addr_t offset)
{
if (!offset_in_ramblock(block, offset)) {
return NULL;
}
return block->host + offset;
}
static inline void *colo_cache_from_block_offset(RAMBlock *block,
ram_addr_t offset)
{
if (!offset_in_ramblock(block, offset)) {
return NULL;
}
if (!block->colo_cache) {
error_report("%s: colo_cache is NULL in block :%s",
__func__, block->idstr);
return NULL;
}
/*
* During colo checkpoint, we need bitmap of these migrated pages.
* It help us to decide which pages in ram cache should be flushed
* into VM's RAM later.
*/
if (!test_and_set_bit(offset >> TARGET_PAGE_BITS, block->bmap)) {
ram_state->migration_dirty_pages++;
}
return block->colo_cache + offset;
}
/**
* ram_handle_compressed: handle the zero page case
*
* If a page (or a whole RDMA chunk) has been
* determined to be zero, then zap it.
*
* @host: host address for the zero page
* @ch: what the page is filled from. We only support zero
* @size: size of the zero page
*/
void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
{
if (ch != 0 || !is_zero_range(host, size)) {
memset(host, ch, size);
}
}
/* return the size after decompression, or negative value on error */
static int
qemu_uncompress_data(z_stream *stream, uint8_t *dest, size_t dest_len,
const uint8_t *source, size_t source_len)
{
int err;
err = inflateReset(stream);
if (err != Z_OK) {
return -1;
}
stream->avail_in = source_len;
stream->next_in = (uint8_t *)source;
stream->avail_out = dest_len;
stream->next_out = dest;
err = inflate(stream, Z_NO_FLUSH);
if (err != Z_STREAM_END) {
return -1;
}
return stream->total_out;
}
static void *do_data_decompress(void *opaque)
{
DecompressParam *param = opaque;
unsigned long pagesize;
uint8_t *des;
int len, ret;
qemu_mutex_lock(&param->mutex);
while (!param->quit) {
if (param->des) {
des = param->des;
len = param->len;
param->des = 0;
qemu_mutex_unlock(&param->mutex);
pagesize = TARGET_PAGE_SIZE;
ret = qemu_uncompress_data(&param->stream, des, pagesize,
param->compbuf, len);
if (ret < 0 && migrate_get_current()->decompress_error_check) {
error_report("decompress data failed");
qemu_file_set_error(decomp_file, ret);
}
qemu_mutex_lock(&decomp_done_lock);
param->done = true;
qemu_cond_signal(&decomp_done_cond);
qemu_mutex_unlock(&decomp_done_lock);
qemu_mutex_lock(&param->mutex);
} else {
qemu_cond_wait(&param->cond, &param->mutex);
}
}
qemu_mutex_unlock(&param->mutex);
return NULL;
}
static int wait_for_decompress_done(void)
{
int idx, thread_count;
if (!migrate_use_compression()) {
return 0;
}
thread_count = migrate_decompress_threads();
qemu_mutex_lock(&decomp_done_lock);
for (idx = 0; idx < thread_count; idx++) {
while (!decomp_param[idx].done) {
qemu_cond_wait(&decomp_done_cond, &decomp_done_lock);
}
}
qemu_mutex_unlock(&decomp_done_lock);
return qemu_file_get_error(decomp_file);
}
static void compress_threads_load_cleanup(void)
{
int i, thread_count;
if (!migrate_use_compression()) {
return;
}
thread_count = migrate_decompress_threads();
for (i = 0; i < thread_count; i++) {
/*
* we use it as a indicator which shows if the thread is
* properly init'd or not
*/
if (!decomp_param[i].compbuf) {
break;
}
qemu_mutex_lock(&decomp_param[i].mutex);
decomp_param[i].quit = true;
qemu_cond_signal(&decomp_param[i].cond);
qemu_mutex_unlock(&decomp_param[i].mutex);
}
for (i = 0; i < thread_count; i++) {
if (!decomp_param[i].compbuf) {
break;
}
qemu_thread_join(decompress_threads + i);
qemu_mutex_destroy(&decomp_param[i].mutex);
qemu_cond_destroy(&decomp_param[i].cond);
inflateEnd(&decomp_param[i].stream);
g_free(decomp_param[i].compbuf);
decomp_param[i].compbuf = NULL;
}
g_free(decompress_threads);
g_free(decomp_param);
decompress_threads = NULL;
decomp_param = NULL;
decomp_file = NULL;
}
static int compress_threads_load_setup(QEMUFile *f)
{
int i, thread_count;
if (!migrate_use_compression()) {
return 0;
}
thread_count = migrate_decompress_threads();
decompress_threads = g_new0(QemuThread, thread_count);
decomp_param = g_new0(DecompressParam, thread_count);
qemu_mutex_init(&decomp_done_lock);
qemu_cond_init(&decomp_done_cond);
decomp_file = f;
for (i = 0; i < thread_count; i++) {
if (inflateInit(&decomp_param[i].stream) != Z_OK) {
goto exit;
}
decomp_param[i].compbuf = g_malloc0(compressBound(TARGET_PAGE_SIZE));
qemu_mutex_init(&decomp_param[i].mutex);
qemu_cond_init(&decomp_param[i].cond);
decomp_param[i].done = true;
decomp_param[i].quit = false;
qemu_thread_create(decompress_threads + i, "decompress",
do_data_decompress, decomp_param + i,
QEMU_THREAD_JOINABLE);
}
return 0;
exit:
compress_threads_load_cleanup();
return -1;
}
static void decompress_data_with_multi_threads(QEMUFile *f,
void *host, int len)
{
int idx, thread_count;
thread_count = migrate_decompress_threads();
qemu_mutex_lock(&decomp_done_lock);
while (true) {
for (idx = 0; idx < thread_count; idx++) {
if (decomp_param[idx].done) {
decomp_param[idx].done = false;
qemu_mutex_lock(&decomp_param[idx].mutex);
qemu_get_buffer(f, decomp_param[idx].compbuf, len);
decomp_param[idx].des = host;
decomp_param[idx].len = len;
qemu_cond_signal(&decomp_param[idx].cond);
qemu_mutex_unlock(&decomp_param[idx].mutex);
break;
}
}
if (idx < thread_count) {
break;
} else {
qemu_cond_wait(&decomp_done_cond, &decomp_done_lock);
}
}
qemu_mutex_unlock(&decomp_done_lock);
}
/*
* colo cache: this is for secondary VM, we cache the whole
* memory of the secondary VM, it is need to hold the global lock
* to call this helper.
*/
int colo_init_ram_cache(void)
{
RAMBlock *block;
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
block->colo_cache = qemu_anon_ram_alloc(block->used_length,
NULL,
false);
if (!block->colo_cache) {
error_report("%s: Can't alloc memory for COLO cache of block %s,"
"size 0x" RAM_ADDR_FMT, __func__, block->idstr,
block->used_length);
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
if (block->colo_cache) {
qemu_anon_ram_free(block->colo_cache, block->used_length);
block->colo_cache = NULL;
}
}
return -errno;
}
memcpy(block->colo_cache, block->host, block->used_length);
}
}
/*
* Record the dirty pages that sent by PVM, we use this dirty bitmap together
* with to decide which page in cache should be flushed into SVM's RAM. Here
* we use the same name 'ram_bitmap' as for migration.
*/
if (ram_bytes_total()) {
RAMBlock *block;
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
unsigned long pages = block->max_length >> TARGET_PAGE_BITS;
block->bmap = bitmap_new(pages);
bitmap_set(block->bmap, 0, pages);
}
}
ram_state = g_new0(RAMState, 1);
ram_state->migration_dirty_pages = 0;
qemu_mutex_init(&ram_state->bitmap_mutex);
memory_global_dirty_log_start();
return 0;
}
/* It is need to hold the global lock to call this helper */
void colo_release_ram_cache(void)
{
RAMBlock *block;
memory_global_dirty_log_stop();
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
g_free(block->bmap);
block->bmap = NULL;
}
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
if (block->colo_cache) {
qemu_anon_ram_free(block->colo_cache, block->used_length);
block->colo_cache = NULL;
}
}
}
qemu_mutex_destroy(&ram_state->bitmap_mutex);
g_free(ram_state);
ram_state = NULL;
}
/**
* ram_load_setup: Setup RAM for migration incoming side
*
* Returns zero to indicate success and negative for error
*
* @f: QEMUFile where to receive the data
* @opaque: RAMState pointer
*/
static int ram_load_setup(QEMUFile *f, void *opaque)
{
if (compress_threads_load_setup(f)) {
return -1;
}
xbzrle_load_setup();
ramblock_recv_map_init();
return 0;
}
static int ram_load_cleanup(void *opaque)
{
RAMBlock *rb;
RAMBLOCK_FOREACH_NOT_IGNORED(rb) {
qemu_ram_block_writeback(rb);
}
xbzrle_load_cleanup();
compress_threads_load_cleanup();
RAMBLOCK_FOREACH_NOT_IGNORED(rb) {
g_free(rb->receivedmap);
rb->receivedmap = NULL;
}
return 0;
}
/**
* ram_postcopy_incoming_init: allocate postcopy data structures
*
* Returns 0 for success and negative if there was one error
*
* @mis: current migration incoming state
*
* Allocate data structures etc needed by incoming migration with
* postcopy-ram. postcopy-ram's similarly names
* postcopy_ram_incoming_init does the work.
*/
int ram_postcopy_incoming_init(MigrationIncomingState *mis)
{
return postcopy_ram_incoming_init(mis);
}
/**
* ram_load_postcopy: load a page in postcopy case
*
* Returns 0 for success or -errno in case of error
*
* Called in postcopy mode by ram_load().
* rcu_read_lock is taken prior to this being called.
*
* @f: QEMUFile where to send the data
*/
static int ram_load_postcopy(QEMUFile *f)
{
int flags = 0, ret = 0;
bool place_needed = false;
bool matches_target_page_size = false;
MigrationIncomingState *mis = migration_incoming_get_current();
/* Temporary page that is later 'placed' */
void *postcopy_host_page = mis->postcopy_tmp_page;
void *this_host = NULL;
bool all_zero = false;
int target_pages = 0;
while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) {
ram_addr_t addr;
void *host = NULL;
void *page_buffer = NULL;
void *place_source = NULL;
RAMBlock *block = NULL;
uint8_t ch;
int len;
addr = qemu_get_be64(f);
/*
* If qemu file error, we should stop here, and then "addr"
* may be invalid
*/
ret = qemu_file_get_error(f);
if (ret) {
break;
}
flags = addr & ~TARGET_PAGE_MASK;
addr &= TARGET_PAGE_MASK;
trace_ram_load_postcopy_loop((uint64_t)addr, flags);
place_needed = false;
if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE)) {
block = ram_block_from_stream(f, flags);
host = host_from_ram_block_offset(block, addr);
if (!host) {
error_report("Illegal RAM offset " RAM_ADDR_FMT, addr);
ret = -EINVAL;
break;
}
target_pages++;
matches_target_page_size = block->page_size == TARGET_PAGE_SIZE;
/*
* Postcopy requires that we place whole host pages atomically;
* these may be huge pages for RAMBlocks that are backed by
* hugetlbfs.
* To make it atomic, the data is read into a temporary page
* that's moved into place later.
* The migration protocol uses, possibly smaller, target-pages
* however the source ensures it always sends all the components
* of a host page in one chunk.
*/
page_buffer = postcopy_host_page +
((uintptr_t)host & (block->page_size - 1));
/* If all TP are zero then we can optimise the place */
if (target_pages == 1) {
all_zero = true;
this_host = (void *)QEMU_ALIGN_DOWN((uintptr_t)host,
block->page_size);
} else {
/* not the 1st TP within the HP */
if (QEMU_ALIGN_DOWN((uintptr_t)host, block->page_size) !=
(uintptr_t)this_host) {
error_report("Non-same host page %p/%p",
host, this_host);
ret = -EINVAL;
break;
}
}
/*
* If it's the last part of a host page then we place the host
* page
*/
if (target_pages == (block->page_size / TARGET_PAGE_SIZE)) {
place_needed = true;
target_pages = 0;
}
place_source = postcopy_host_page;
}
switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
case RAM_SAVE_FLAG_ZERO:
ch = qemu_get_byte(f);
/*
* Can skip to set page_buffer when
* this is a zero page and (block->page_size == TARGET_PAGE_SIZE).
*/
if (ch || !matches_target_page_size) {
memset(page_buffer, ch, TARGET_PAGE_SIZE);
}
if (ch) {
all_zero = false;
}
break;
case RAM_SAVE_FLAG_PAGE:
all_zero = false;
if (!matches_target_page_size) {
/* For huge pages, we always use temporary buffer */
qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE);
} else {
/*
* For small pages that matches target page size, we
* avoid the qemu_file copy. Instead we directly use
* the buffer of QEMUFile to place the page. Note: we
* cannot do any QEMUFile operation before using that
* buffer to make sure the buffer is valid when
* placing the page.
*/
qemu_get_buffer_in_place(f, (uint8_t **)&place_source,
TARGET_PAGE_SIZE);
}
break;
case RAM_SAVE_FLAG_COMPRESS_PAGE:
all_zero = false;
len = qemu_get_be32(f);
if (len < 0 || len > compressBound(TARGET_PAGE_SIZE)) {
error_report("Invalid compressed data length: %d", len);
ret = -EINVAL;
break;
}
decompress_data_with_multi_threads(f, page_buffer, len);
break;
case RAM_SAVE_FLAG_EOS:
/* normal exit */
multifd_recv_sync_main();
break;
default:
error_report("Unknown combination of migration flags: %#x"
" (postcopy mode)", flags);
ret = -EINVAL;
break;
}
/* Got the whole host page, wait for decompress before placing. */
if (place_needed) {
ret |= wait_for_decompress_done();
}
/* Detect for any possible file errors */
if (!ret && qemu_file_get_error(f)) {
ret = qemu_file_get_error(f);
}
if (!ret && place_needed) {
/* This gets called at the last target page in the host page */
void *place_dest = (void *)QEMU_ALIGN_DOWN((uintptr_t)host,
block->page_size);
if (all_zero) {
ret = postcopy_place_page_zero(mis, place_dest,
block);
} else {
ret = postcopy_place_page(mis, place_dest,
place_source, block);
}
}
}
return ret;
}
static bool postcopy_is_advised(void)
{
PostcopyState ps = postcopy_state_get();
return ps >= POSTCOPY_INCOMING_ADVISE && ps < POSTCOPY_INCOMING_END;
}
static bool postcopy_is_running(void)
{
PostcopyState ps = postcopy_state_get();
return ps >= POSTCOPY_INCOMING_LISTENING && ps < POSTCOPY_INCOMING_END;
}
/*
* Flush content of RAM cache into SVM's memory.
* Only flush the pages that be dirtied by PVM or SVM or both.
*/
static void colo_flush_ram_cache(void)
{
RAMBlock *block = NULL;
void *dst_host;
void *src_host;
unsigned long offset = 0;
memory_global_dirty_log_sync();
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
ramblock_sync_dirty_bitmap(ram_state, block);
}
}
trace_colo_flush_ram_cache_begin(ram_state->migration_dirty_pages);
WITH_RCU_READ_LOCK_GUARD() {
block = QLIST_FIRST_RCU(&ram_list.blocks);
while (block) {
offset = migration_bitmap_find_dirty(ram_state, block, offset);
if (((ram_addr_t)offset) << TARGET_PAGE_BITS
>= block->used_length) {
offset = 0;
block = QLIST_NEXT_RCU(block, next);
} else {
migration_bitmap_clear_dirty(ram_state, block, offset);
dst_host = block->host
+ (((ram_addr_t)offset) << TARGET_PAGE_BITS);
src_host = block->colo_cache
+ (((ram_addr_t)offset) << TARGET_PAGE_BITS);
memcpy(dst_host, src_host, TARGET_PAGE_SIZE);
}
}
}
trace_colo_flush_ram_cache_end();
}
/**
* ram_load_precopy: load pages in precopy case
*
* Returns 0 for success or -errno in case of error
*
* Called in precopy mode by ram_load().
* rcu_read_lock is taken prior to this being called.
*
* @f: QEMUFile where to send the data
*/
static int ram_load_precopy(QEMUFile *f)
{
int flags = 0, ret = 0, invalid_flags = 0, len = 0, i = 0;
/* ADVISE is earlier, it shows the source has the postcopy capability on */
bool postcopy_advised = postcopy_is_advised();
if (!migrate_use_compression()) {
invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE;
}
while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) {
ram_addr_t addr, total_ram_bytes;
void *host = NULL;
uint8_t ch;
/*
* Yield periodically to let main loop run, but an iteration of
* the main loop is expensive, so do it each some iterations
*/
if ((i & 32767) == 0 && qemu_in_coroutine()) {
aio_co_schedule(qemu_get_current_aio_context(),
qemu_coroutine_self());
qemu_coroutine_yield();
}
i++;
addr = qemu_get_be64(f);
flags = addr & ~TARGET_PAGE_MASK;
addr &= TARGET_PAGE_MASK;
if (flags & invalid_flags) {
if (flags & invalid_flags & RAM_SAVE_FLAG_COMPRESS_PAGE) {
error_report("Received an unexpected compressed page");
}
ret = -EINVAL;
break;
}
if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
RAMBlock *block = ram_block_from_stream(f, flags);
/*
* After going into COLO, we should load the Page into colo_cache.
*/
if (migration_incoming_in_colo_state()) {
host = colo_cache_from_block_offset(block, addr);
} else {
host = host_from_ram_block_offset(block, addr);
}
if (!host) {
error_report("Illegal RAM offset " RAM_ADDR_FMT, addr);
ret = -EINVAL;
break;
}
if (!migration_incoming_in_colo_state()) {
ramblock_recv_bitmap_set(block, host);
}
trace_ram_load_loop(block->idstr, (uint64_t)addr, flags, host);
}
switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
case RAM_SAVE_FLAG_MEM_SIZE:
/* Synchronize RAM block list */
total_ram_bytes = addr;
while (!ret && total_ram_bytes) {
RAMBlock *block;
char id[256];
ram_addr_t length;
len = qemu_get_byte(f);
qemu_get_buffer(f, (uint8_t *)id, len);
id[len] = 0;
length = qemu_get_be64(f);
block = qemu_ram_block_by_name(id);
if (block && !qemu_ram_is_migratable(block)) {
error_report("block %s should not be migrated !", id);
ret = -EINVAL;
} else if (block) {
if (length != block->used_length) {
Error *local_err = NULL;
ret = qemu_ram_resize(block, length,
&local_err);
if (local_err) {
error_report_err(local_err);
}
}
/* For postcopy we need to check hugepage sizes match */
if (postcopy_advised &&
block->page_size != qemu_host_page_size) {
uint64_t remote_page_size = qemu_get_be64(f);
if (remote_page_size != block->page_size) {
error_report("Mismatched RAM page size %s "
"(local) %zd != %" PRId64,
id, block->page_size,
remote_page_size);
ret = -EINVAL;
}
}
if (migrate_ignore_shared()) {
hwaddr addr = qemu_get_be64(f);
if (ramblock_is_ignored(block) &&
block->mr->addr != addr) {
error_report("Mismatched GPAs for block %s "
"%" PRId64 "!= %" PRId64,
id, (uint64_t)addr,
(uint64_t)block->mr->addr);
ret = -EINVAL;
}
}
ram_control_load_hook(f, RAM_CONTROL_BLOCK_REG,
block->idstr);
} else {
error_report("Unknown ramblock \"%s\", cannot "
"accept migration", id);
ret = -EINVAL;
}
total_ram_bytes -= length;
}
break;
case RAM_SAVE_FLAG_ZERO:
ch = qemu_get_byte(f);
ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
break;
case RAM_SAVE_FLAG_PAGE:
qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
break;
case RAM_SAVE_FLAG_COMPRESS_PAGE:
len = qemu_get_be32(f);
if (len < 0 || len > compressBound(TARGET_PAGE_SIZE)) {
error_report("Invalid compressed data length: %d", len);
ret = -EINVAL;
break;
}
decompress_data_with_multi_threads(f, host, len);
break;
case RAM_SAVE_FLAG_XBZRLE:
if (load_xbzrle(f, addr, host) < 0) {
error_report("Failed to decompress XBZRLE page at "
RAM_ADDR_FMT, addr);
ret = -EINVAL;
break;
}
break;
case RAM_SAVE_FLAG_EOS:
/* normal exit */
multifd_recv_sync_main();
break;
default:
if (flags & RAM_SAVE_FLAG_HOOK) {
ram_control_load_hook(f, RAM_CONTROL_HOOK, NULL);
} else {
error_report("Unknown combination of migration flags: %#x",
flags);
ret = -EINVAL;
}
}
if (!ret) {
ret = qemu_file_get_error(f);
}
}
ret |= wait_for_decompress_done();
return ret;
}
static int ram_load(QEMUFile *f, void *opaque, int version_id)
{
int ret = 0;
static uint64_t seq_iter;
/*
* If system is running in postcopy mode, page inserts to host memory must
* be atomic
*/
bool postcopy_running = postcopy_is_running();
seq_iter++;
if (version_id != 4) {
return -EINVAL;
}
/*
* This RCU critical section can be very long running.
* When RCU reclaims in the code start to become numerous,
* it will be necessary to reduce the granularity of this
* critical section.
*/
WITH_RCU_READ_LOCK_GUARD() {
if (postcopy_running) {
ret = ram_load_postcopy(f);
} else {
ret = ram_load_precopy(f);
}
}
trace_ram_load_complete(ret, seq_iter);
if (!ret && migration_incoming_in_colo_state()) {
colo_flush_ram_cache();
}
return ret;
}
static bool ram_has_postcopy(void *opaque)
{
RAMBlock *rb;
RAMBLOCK_FOREACH_NOT_IGNORED(rb) {
if (ramblock_is_pmem(rb)) {
info_report("Block: %s, host: %p is a nvdimm memory, postcopy"
"is not supported now!", rb->idstr, rb->host);
return false;
}
}
return migrate_postcopy_ram();
}
/* Sync all the dirty bitmap with destination VM. */
static int ram_dirty_bitmap_sync_all(MigrationState *s, RAMState *rs)
{
RAMBlock *block;
QEMUFile *file = s->to_dst_file;
int ramblock_count = 0;
trace_ram_dirty_bitmap_sync_start();
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
qemu_savevm_send_recv_bitmap(file, block->idstr);
trace_ram_dirty_bitmap_request(block->idstr);
ramblock_count++;
}
trace_ram_dirty_bitmap_sync_wait();
/* Wait until all the ramblocks' dirty bitmap synced */
while (ramblock_count--) {
qemu_sem_wait(&s->rp_state.rp_sem);
}
trace_ram_dirty_bitmap_sync_complete();
return 0;
}
static void ram_dirty_bitmap_reload_notify(MigrationState *s)
{
qemu_sem_post(&s->rp_state.rp_sem);
}
/*
* Read the received bitmap, revert it as the initial dirty bitmap.
* This is only used when the postcopy migration is paused but wants
* to resume from a middle point.
*/
int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *block)
{
int ret = -EINVAL;
QEMUFile *file = s->rp_state.from_dst_file;
unsigned long *le_bitmap, nbits = block->used_length >> TARGET_PAGE_BITS;
uint64_t local_size = DIV_ROUND_UP(nbits, 8);
uint64_t size, end_mark;
trace_ram_dirty_bitmap_reload_begin(block->idstr);
if (s->state != MIGRATION_STATUS_POSTCOPY_RECOVER) {
error_report("%s: incorrect state %s", __func__,
MigrationStatus_str(s->state));
return -EINVAL;
}
/*
* Note: see comments in ramblock_recv_bitmap_send() on why we
* need the endianess convertion, and the paddings.
*/
local_size = ROUND_UP(local_size, 8);
/* Add paddings */
le_bitmap = bitmap_new(nbits + BITS_PER_LONG);
size = qemu_get_be64(file);
/* The size of the bitmap should match with our ramblock */
if (size != local_size) {
error_report("%s: ramblock '%s' bitmap size mismatch "
"(0x%"PRIx64" != 0x%"PRIx64")", __func__,
block->idstr, size, local_size);
ret = -EINVAL;
goto out;
}
size = qemu_get_buffer(file, (uint8_t *)le_bitmap, local_size);
end_mark = qemu_get_be64(file);
ret = qemu_file_get_error(file);
if (ret || size != local_size) {
error_report("%s: read bitmap failed for ramblock '%s': %d"
" (size 0x%"PRIx64", got: 0x%"PRIx64")",
__func__, block->idstr, ret, local_size, size);
ret = -EIO;
goto out;
}
if (end_mark != RAMBLOCK_RECV_BITMAP_ENDING) {
error_report("%s: ramblock '%s' end mark incorrect: 0x%"PRIu64,
__func__, block->idstr, end_mark);
ret = -EINVAL;
goto out;
}
/*
* Endianess convertion. We are during postcopy (though paused).
* The dirty bitmap won't change. We can directly modify it.
*/
bitmap_from_le(block->bmap, le_bitmap, nbits);
/*
* What we received is "received bitmap". Revert it as the initial
* dirty bitmap for this ramblock.
*/
bitmap_complement(block->bmap, block->bmap, nbits);
trace_ram_dirty_bitmap_reload_complete(block->idstr);
/*
* We succeeded to sync bitmap for current ramblock. If this is
* the last one to sync, we need to notify the main send thread.
*/
ram_dirty_bitmap_reload_notify(s);
ret = 0;
out:
g_free(le_bitmap);
return ret;
}
static int ram_resume_prepare(MigrationState *s, void *opaque)
{
RAMState *rs = *(RAMState **)opaque;
int ret;
ret = ram_dirty_bitmap_sync_all(s, rs);
if (ret) {
return ret;
}
ram_state_resume_prepare(rs, s->to_dst_file);
return 0;
}
static SaveVMHandlers savevm_ram_handlers = {
.save_setup = ram_save_setup,
.save_live_iterate = ram_save_iterate,
.save_live_complete_postcopy = ram_save_complete,
.save_live_complete_precopy = ram_save_complete,
.has_postcopy = ram_has_postcopy,
.save_live_pending = ram_save_pending,
.load_state = ram_load,
.save_cleanup = ram_save_cleanup,
.load_setup = ram_load_setup,
.load_cleanup = ram_load_cleanup,
.resume_prepare = ram_resume_prepare,
};
void ram_mig_init(void)
{
qemu_mutex_init(&XBZRLE.lock);
register_savevm_live("ram", 0, 4, &savevm_ram_handlers, &ram_state);
}