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qemu-e2k/migration/ram.c
Dr. David Alan Gilbert a82d593b61 Page request: Consume pages off the post-copy queue 
When transmitting RAM pages, consume pages that have been queued by
MIG_RPCOMM_REQPAGE commands and send them ahead of normal page scanning.

Note:
  a) After a queued page the linear walk carries on from after the
unqueued page; there is a reasonable chance that the destination
was about to ask for other closeby pages anyway.

  b) We have to be careful of any assumptions that the page walking
code makes, in particular it does some short cuts on its first linear
walk that break as soon as we do a queued page.

  c) We have to be careful to not break up host-page size chunks, since
this makes it harder to place the pages on the destination.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2015-11-10 15:00:27 +01:00

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/*
* 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 <stdint.h>
#include <zlib.h>
#include "qemu/bitops.h"
#include "qemu/bitmap.h"
#include "qemu/timer.h"
#include "qemu/main-loop.h"
#include "migration/migration.h"
#include "migration/postcopy-ram.h"
#include "exec/address-spaces.h"
#include "migration/page_cache.h"
#include "qemu/error-report.h"
#include "trace.h"
#include "exec/ram_addr.h"
#include "qemu/rcu_queue.h"
#ifdef DEBUG_MIGRATION_RAM
#define DPRINTF(fmt, ...) \
do { fprintf(stdout, "migration_ram: " fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) \
do { } while (0)
#endif
static int dirty_rate_high_cnt;
static uint64_t bitmap_sync_count;
/***********************************************************/
/* ram save/restore */
#define RAM_SAVE_FLAG_FULL 0x01 /* Obsolete, not used anymore */
#define RAM_SAVE_FLAG_COMPRESS 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 const uint8_t ZERO_TARGET_PAGE[TARGET_PAGE_SIZE];
static inline bool is_zero_range(uint8_t *p, uint64_t size)
{
return buffer_find_nonzero_offset(p, size) == size;
}
/* 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;
} XBZRLE;
/* buffer used for XBZRLE decoding */
static uint8_t *xbzrle_decoded_buf;
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);
}
/*
* called from qmp_migrate_set_cache_size in main thread, possibly while
* a migration is in progress.
* A running migration maybe using the cache and might finish during this
* call, hence changes to the cache are protected by XBZRLE.lock().
*/
int64_t xbzrle_cache_resize(int64_t new_size)
{
PageCache *new_cache;
int64_t ret;
if (new_size < TARGET_PAGE_SIZE) {
return -1;
}
XBZRLE_cache_lock();
if (XBZRLE.cache != NULL) {
if (pow2floor(new_size) == migrate_xbzrle_cache_size()) {
goto out_new_size;
}
new_cache = cache_init(new_size / TARGET_PAGE_SIZE,
TARGET_PAGE_SIZE);
if (!new_cache) {
error_report("Error creating cache");
ret = -1;
goto out;
}
cache_fini(XBZRLE.cache);
XBZRLE.cache = new_cache;
}
out_new_size:
ret = pow2floor(new_size);
out:
XBZRLE_cache_unlock();
return ret;
}
/* accounting for migration statistics */
typedef struct AccountingInfo {
uint64_t dup_pages;
uint64_t skipped_pages;
uint64_t norm_pages;
uint64_t iterations;
uint64_t xbzrle_bytes;
uint64_t xbzrle_pages;
uint64_t xbzrle_cache_miss;
double xbzrle_cache_miss_rate;
uint64_t xbzrle_overflows;
} AccountingInfo;
static AccountingInfo acct_info;
static void acct_clear(void)
{
memset(&acct_info, 0, sizeof(acct_info));
}
uint64_t dup_mig_bytes_transferred(void)
{
return acct_info.dup_pages * TARGET_PAGE_SIZE;
}
uint64_t dup_mig_pages_transferred(void)
{
return acct_info.dup_pages;
}
uint64_t skipped_mig_bytes_transferred(void)
{
return acct_info.skipped_pages * TARGET_PAGE_SIZE;
}
uint64_t skipped_mig_pages_transferred(void)
{
return acct_info.skipped_pages;
}
uint64_t norm_mig_bytes_transferred(void)
{
return acct_info.norm_pages * TARGET_PAGE_SIZE;
}
uint64_t norm_mig_pages_transferred(void)
{
return acct_info.norm_pages;
}
uint64_t xbzrle_mig_bytes_transferred(void)
{
return acct_info.xbzrle_bytes;
}
uint64_t xbzrle_mig_pages_transferred(void)
{
return acct_info.xbzrle_pages;
}
uint64_t xbzrle_mig_pages_cache_miss(void)
{
return acct_info.xbzrle_cache_miss;
}
double xbzrle_mig_cache_miss_rate(void)
{
return acct_info.xbzrle_cache_miss_rate;
}
uint64_t xbzrle_mig_pages_overflow(void)
{
return acct_info.xbzrle_overflows;
}
/* This is the last block that we have visited serching for dirty pages
*/
static RAMBlock *last_seen_block;
/* This is the last block from where we have sent data */
static RAMBlock *last_sent_block;
static ram_addr_t last_offset;
static QemuMutex migration_bitmap_mutex;
static uint64_t migration_dirty_pages;
static uint32_t last_version;
static bool ram_bulk_stage;
/* used by the search for pages to send */
struct PageSearchStatus {
/* Current block being searched */
RAMBlock *block;
/* Current offset to search from */
ram_addr_t offset;
/* Set once we wrap around */
bool complete_round;
};
typedef struct PageSearchStatus PageSearchStatus;
static struct BitmapRcu {
struct rcu_head rcu;
/* Main migration bitmap */
unsigned long *bmap;
/* bitmap of pages that haven't been sent even once
* only maintained and used in postcopy at the moment
* where it's used to send the dirtymap at the start
* of the postcopy phase
*/
unsigned long *unsentmap;
} *migration_bitmap_rcu;
struct CompressParam {
bool start;
bool done;
QEMUFile *file;
QemuMutex mutex;
QemuCond cond;
RAMBlock *block;
ram_addr_t offset;
};
typedef struct CompressParam CompressParam;
struct DecompressParam {
bool start;
QemuMutex mutex;
QemuCond cond;
void *des;
uint8 *compbuf;
int len;
};
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 bool compression_switch;
static bool quit_comp_thread;
static bool quit_decomp_thread;
static DecompressParam *decomp_param;
static QemuThread *decompress_threads;
static uint8_t *compressed_data_buf;
static int do_compress_ram_page(CompressParam *param);
static void *do_data_compress(void *opaque)
{
CompressParam *param = opaque;
while (!quit_comp_thread) {
qemu_mutex_lock(&param->mutex);
/* Re-check the quit_comp_thread in case of
* terminate_compression_threads is called just before
* qemu_mutex_lock(&param->mutex) and after
* while(!quit_comp_thread), re-check it here can make
* sure the compression thread terminate as expected.
*/
while (!param->start && !quit_comp_thread) {
qemu_cond_wait(&param->cond, &param->mutex);
}
if (!quit_comp_thread) {
do_compress_ram_page(param);
}
param->start = false;
qemu_mutex_unlock(&param->mutex);
qemu_mutex_lock(comp_done_lock);
param->done = true;
qemu_cond_signal(comp_done_cond);
qemu_mutex_unlock(comp_done_lock);
}
return NULL;
}
static inline void terminate_compression_threads(void)
{
int idx, thread_count;
thread_count = migrate_compress_threads();
quit_comp_thread = true;
for (idx = 0; idx < thread_count; idx++) {
qemu_mutex_lock(&comp_param[idx].mutex);
qemu_cond_signal(&comp_param[idx].cond);
qemu_mutex_unlock(&comp_param[idx].mutex);
}
}
void migrate_compress_threads_join(void)
{
int i, thread_count;
if (!migrate_use_compression()) {
return;
}
terminate_compression_threads();
thread_count = migrate_compress_threads();
for (i = 0; i < thread_count; i++) {
qemu_thread_join(compress_threads + i);
qemu_fclose(comp_param[i].file);
qemu_mutex_destroy(&comp_param[i].mutex);
qemu_cond_destroy(&comp_param[i].cond);
}
qemu_mutex_destroy(comp_done_lock);
qemu_cond_destroy(comp_done_cond);
g_free(compress_threads);
g_free(comp_param);
g_free(comp_done_cond);
g_free(comp_done_lock);
compress_threads = NULL;
comp_param = NULL;
comp_done_cond = NULL;
comp_done_lock = NULL;
}
void migrate_compress_threads_create(void)
{
int i, thread_count;
if (!migrate_use_compression()) {
return;
}
quit_comp_thread = false;
compression_switch = true;
thread_count = migrate_compress_threads();
compress_threads = g_new0(QemuThread, thread_count);
comp_param = g_new0(CompressParam, thread_count);
comp_done_cond = g_new0(QemuCond, 1);
comp_done_lock = g_new0(QemuMutex, 1);
qemu_cond_init(comp_done_cond);
qemu_mutex_init(comp_done_lock);
for (i = 0; i < thread_count; i++) {
/* com_param[i].file is just used as a dummy buffer to save data, set
* it's ops to empty.
*/
comp_param[i].file = qemu_fopen_ops(NULL, &empty_ops);
comp_param[i].done = true;
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);
}
}
/**
* save_page_header: Write page header to wire
*
* If this is the 1st block, it also writes the block identification
*
* Returns: 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(QEMUFile *f, RAMBlock *block, ram_addr_t offset)
{
size_t size, len;
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;
}
return size;
}
/* 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[MIGRATION_PARAMETER_X_CPU_THROTTLE_INITIAL];
uint64_t pct_icrement =
s->parameters[MIGRATION_PARAMETER_X_CPU_THROTTLE_INCREMENT];
/* 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(cpu_throttle_get_percentage() + pct_icrement);
}
}
/* 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(ram_addr_t current_addr)
{
if (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, ZERO_TARGET_PAGE,
bitmap_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
*
* @f: QEMUFile where to send the data
* @current_data:
* @current_addr:
* @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
* @bytes_transferred: increase it with the number of transferred bytes
*/
static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data,
ram_addr_t current_addr, RAMBlock *block,
ram_addr_t offset, bool last_stage,
uint64_t *bytes_transferred)
{
int encoded_len = 0, bytes_xbzrle;
uint8_t *prev_cached_page;
if (!cache_is_cached(XBZRLE.cache, current_addr, bitmap_sync_count)) {
acct_info.xbzrle_cache_miss++;
if (!last_stage) {
if (cache_insert(XBZRLE.cache, current_addr, *current_data,
bitmap_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);
if (encoded_len == 0) {
DPRINTF("Skipping unmodified page\n");
return 0;
} else if (encoded_len == -1) {
DPRINTF("Overflow\n");
acct_info.xbzrle_overflows++;
/* update data in the cache */
if (!last_stage) {
memcpy(prev_cached_page, *current_data, TARGET_PAGE_SIZE);
*current_data = prev_cached_page;
}
return -1;
}
/* we need to update the data in the cache, in order to get the same data */
if (!last_stage) {
memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE);
}
/* Send XBZRLE based compressed page */
bytes_xbzrle = save_page_header(f, block, offset | RAM_SAVE_FLAG_XBZRLE);
qemu_put_byte(f, ENCODING_FLAG_XBZRLE);
qemu_put_be16(f, encoded_len);
qemu_put_buffer(f, XBZRLE.encoded_buf, encoded_len);
bytes_xbzrle += encoded_len + 1 + 2;
acct_info.xbzrle_pages++;
acct_info.xbzrle_bytes += bytes_xbzrle;
*bytes_transferred += bytes_xbzrle;
return 1;
}
/* Called with rcu_read_lock() to protect migration_bitmap
* rb: The RAMBlock to search for dirty pages in
* start: Start address (typically so we can continue from previous page)
* ram_addr_abs: Pointer into which to store the address of the dirty page
* within the global ram_addr space
*
* Returns: byte offset within memory region of the start of a dirty page
*/
static inline
ram_addr_t migration_bitmap_find_dirty(RAMBlock *rb,
ram_addr_t start,
ram_addr_t *ram_addr_abs)
{
unsigned long base = rb->offset >> TARGET_PAGE_BITS;
unsigned long nr = base + (start >> TARGET_PAGE_BITS);
uint64_t rb_size = rb->used_length;
unsigned long size = base + (rb_size >> TARGET_PAGE_BITS);
unsigned long *bitmap;
unsigned long next;
bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
if (ram_bulk_stage && nr > base) {
next = nr + 1;
} else {
next = find_next_bit(bitmap, size, nr);
}
*ram_addr_abs = next << TARGET_PAGE_BITS;
return (next - base) << TARGET_PAGE_BITS;
}
static inline bool migration_bitmap_clear_dirty(ram_addr_t addr)
{
bool ret;
int nr = addr >> TARGET_PAGE_BITS;
unsigned long *bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
ret = test_and_clear_bit(nr, bitmap);
if (ret) {
migration_dirty_pages--;
}
return ret;
}
static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length)
{
unsigned long *bitmap;
bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
migration_dirty_pages +=
cpu_physical_memory_sync_dirty_bitmap(bitmap, start, length);
}
/* Fix me: there are too many global variables used in migration process. */
static int64_t start_time;
static int64_t bytes_xfer_prev;
static int64_t num_dirty_pages_period;
static uint64_t xbzrle_cache_miss_prev;
static uint64_t iterations_prev;
static void migration_bitmap_sync_init(void)
{
start_time = 0;
bytes_xfer_prev = 0;
num_dirty_pages_period = 0;
xbzrle_cache_miss_prev = 0;
iterations_prev = 0;
}
/* Called with iothread lock held, to protect ram_list.dirty_memory[] */
static void migration_bitmap_sync(void)
{
RAMBlock *block;
uint64_t num_dirty_pages_init = migration_dirty_pages;
MigrationState *s = migrate_get_current();
int64_t end_time;
int64_t bytes_xfer_now;
bitmap_sync_count++;
if (!bytes_xfer_prev) {
bytes_xfer_prev = ram_bytes_transferred();
}
if (!start_time) {
start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
}
trace_migration_bitmap_sync_start();
address_space_sync_dirty_bitmap(&address_space_memory);
qemu_mutex_lock(&migration_bitmap_mutex);
rcu_read_lock();
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
migration_bitmap_sync_range(block->offset, block->used_length);
}
rcu_read_unlock();
qemu_mutex_unlock(&migration_bitmap_mutex);
trace_migration_bitmap_sync_end(migration_dirty_pages
- num_dirty_pages_init);
num_dirty_pages_period += migration_dirty_pages - num_dirty_pages_init;
end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
/* more than 1 second = 1000 millisecons */
if (end_time > start_time + 1000) {
if (migrate_auto_converge()) {
/* 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 */
bytes_xfer_now = ram_bytes_transferred();
if (s->dirty_pages_rate &&
(num_dirty_pages_period * TARGET_PAGE_SIZE >
(bytes_xfer_now - bytes_xfer_prev)/2) &&
(dirty_rate_high_cnt++ >= 2)) {
trace_migration_throttle();
dirty_rate_high_cnt = 0;
mig_throttle_guest_down();
}
bytes_xfer_prev = bytes_xfer_now;
}
if (migrate_use_xbzrle()) {
if (iterations_prev != acct_info.iterations) {
acct_info.xbzrle_cache_miss_rate =
(double)(acct_info.xbzrle_cache_miss -
xbzrle_cache_miss_prev) /
(acct_info.iterations - iterations_prev);
}
iterations_prev = acct_info.iterations;
xbzrle_cache_miss_prev = acct_info.xbzrle_cache_miss;
}
s->dirty_pages_rate = num_dirty_pages_period * 1000
/ (end_time - start_time);
s->dirty_bytes_rate = s->dirty_pages_rate * TARGET_PAGE_SIZE;
start_time = end_time;
num_dirty_pages_period = 0;
}
s->dirty_sync_count = bitmap_sync_count;
}
/**
* save_zero_page: Send the zero page to the stream
*
* Returns: Number of pages 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
* @p: pointer to the page
* @bytes_transferred: increase it with the number of transferred bytes
*/
static int save_zero_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset,
uint8_t *p, uint64_t *bytes_transferred)
{
int pages = -1;
if (is_zero_range(p, TARGET_PAGE_SIZE)) {
acct_info.dup_pages++;
*bytes_transferred += save_page_header(f, block,
offset | RAM_SAVE_FLAG_COMPRESS);
qemu_put_byte(f, 0);
*bytes_transferred += 1;
pages = 1;
}
return pages;
}
/**
* ram_save_page: Send the given page to the stream
*
* Returns: Number of pages 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
* @last_stage: if we are at the completion stage
* @bytes_transferred: increase it with the number of transferred bytes
*/
static int ram_save_page(QEMUFile *f, RAMBlock* block, ram_addr_t offset,
bool last_stage, uint64_t *bytes_transferred)
{
int pages = -1;
uint64_t bytes_xmit;
ram_addr_t current_addr;
uint8_t *p;
int ret;
bool send_async = true;
p = block->host + offset;
/* In doubt sent page as normal */
bytes_xmit = 0;
ret = ram_control_save_page(f, block->offset,
offset, TARGET_PAGE_SIZE, &bytes_xmit);
if (bytes_xmit) {
*bytes_transferred += bytes_xmit;
pages = 1;
}
XBZRLE_cache_lock();
current_addr = block->offset + offset;
if (block == last_sent_block) {
offset |= RAM_SAVE_FLAG_CONTINUE;
}
if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
if (ret != RAM_SAVE_CONTROL_DELAYED) {
if (bytes_xmit > 0) {
acct_info.norm_pages++;
} else if (bytes_xmit == 0) {
acct_info.dup_pages++;
}
}
} else {
pages = save_zero_page(f, block, offset, p, bytes_transferred);
if (pages > 0) {
/* Must let xbzrle know, otherwise a previous (now 0'd) cached
* page would be stale
*/
xbzrle_cache_zero_page(current_addr);
} else if (!ram_bulk_stage && migrate_use_xbzrle()) {
pages = save_xbzrle_page(f, &p, current_addr, block,
offset, last_stage, bytes_transferred);
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) {
*bytes_transferred += save_page_header(f, block,
offset | RAM_SAVE_FLAG_PAGE);
if (send_async) {
qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
} else {
qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
}
*bytes_transferred += TARGET_PAGE_SIZE;
pages = 1;
acct_info.norm_pages++;
}
XBZRLE_cache_unlock();
return pages;
}
static int do_compress_ram_page(CompressParam *param)
{
int bytes_sent, blen;
uint8_t *p;
RAMBlock *block = param->block;
ram_addr_t offset = param->offset;
p = block->host + (offset & TARGET_PAGE_MASK);
bytes_sent = save_page_header(param->file, block, offset |
RAM_SAVE_FLAG_COMPRESS_PAGE);
blen = qemu_put_compression_data(param->file, p, TARGET_PAGE_SIZE,
migrate_compress_level());
bytes_sent += blen;
return bytes_sent;
}
static inline void start_compression(CompressParam *param)
{
param->done = false;
qemu_mutex_lock(&param->mutex);
param->start = true;
qemu_cond_signal(&param->cond);
qemu_mutex_unlock(&param->mutex);
}
static inline void start_decompression(DecompressParam *param)
{
qemu_mutex_lock(&param->mutex);
param->start = true;
qemu_cond_signal(&param->cond);
qemu_mutex_unlock(&param->mutex);
}
static uint64_t bytes_transferred;
static void flush_compressed_data(QEMUFile *f)
{
int idx, len, thread_count;
if (!migrate_use_compression()) {
return;
}
thread_count = migrate_compress_threads();
for (idx = 0; idx < thread_count; idx++) {
if (!comp_param[idx].done) {
qemu_mutex_lock(comp_done_lock);
while (!comp_param[idx].done && !quit_comp_thread) {
qemu_cond_wait(comp_done_cond, comp_done_lock);
}
qemu_mutex_unlock(comp_done_lock);
}
if (!quit_comp_thread) {
len = qemu_put_qemu_file(f, comp_param[idx].file);
bytes_transferred += len;
}
}
}
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(QEMUFile *f, RAMBlock *block,
ram_addr_t offset,
uint64_t *bytes_transferred)
{
int idx, thread_count, bytes_xmit = -1, pages = -1;
thread_count = migrate_compress_threads();
qemu_mutex_lock(comp_done_lock);
while (true) {
for (idx = 0; idx < thread_count; idx++) {
if (comp_param[idx].done) {
bytes_xmit = qemu_put_qemu_file(f, comp_param[idx].file);
set_compress_params(&comp_param[idx], block, offset);
start_compression(&comp_param[idx]);
pages = 1;
acct_info.norm_pages++;
*bytes_transferred += bytes_xmit;
break;
}
}
if (pages > 0) {
break;
} else {
qemu_cond_wait(comp_done_cond, comp_done_lock);
}
}
qemu_mutex_unlock(comp_done_lock);
return pages;
}
/**
* ram_save_compressed_page: compress the given page and send it to the stream
*
* Returns: Number of pages 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
* @last_stage: if we are at the completion stage
* @bytes_transferred: increase it with the number of transferred bytes
*/
static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block,
ram_addr_t offset, bool last_stage,
uint64_t *bytes_transferred)
{
int pages = -1;
uint64_t bytes_xmit;
uint8_t *p;
int ret;
p = block->host + offset;
bytes_xmit = 0;
ret = ram_control_save_page(f, block->offset,
offset, TARGET_PAGE_SIZE, &bytes_xmit);
if (bytes_xmit) {
*bytes_transferred += bytes_xmit;
pages = 1;
}
if (block == last_sent_block) {
offset |= RAM_SAVE_FLAG_CONTINUE;
}
if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
if (ret != RAM_SAVE_CONTROL_DELAYED) {
if (bytes_xmit > 0) {
acct_info.norm_pages++;
} else if (bytes_xmit == 0) {
acct_info.dup_pages++;
}
}
} else {
/* 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.
*/
if (block != last_sent_block) {
flush_compressed_data(f);
pages = save_zero_page(f, block, offset, p, bytes_transferred);
if (pages == -1) {
set_compress_params(&comp_param[0], block, offset);
/* Use the qemu thread to compress the data to make sure the
* first page is sent out before other pages
*/
bytes_xmit = do_compress_ram_page(&comp_param[0]);
acct_info.norm_pages++;
qemu_put_qemu_file(f, comp_param[0].file);
*bytes_transferred += bytes_xmit;
pages = 1;
}
} else {
pages = save_zero_page(f, block, offset, p, bytes_transferred);
if (pages == -1) {
pages = compress_page_with_multi_thread(f, block, offset,
bytes_transferred);
}
}
}
return pages;
}
/*
* Find the next dirty page and update any state associated with
* the search process.
*
* Returns: True if a page is found
*
* @f: Current migration stream.
* @pss: Data about the state of the current dirty page scan.
* @*again: Set to false if the search has scanned the whole of RAM
* *ram_addr_abs: Pointer into which to store the address of the dirty page
* within the global ram_addr space
*/
static bool find_dirty_block(QEMUFile *f, PageSearchStatus *pss,
bool *again, ram_addr_t *ram_addr_abs)
{
pss->offset = migration_bitmap_find_dirty(pss->block, pss->offset,
ram_addr_abs);
if (pss->complete_round && pss->block == last_seen_block &&
pss->offset >= last_offset) {
/*
* We've been once around the RAM and haven't found anything.
* Give up.
*/
*again = false;
return false;
}
if (pss->offset >= pss->block->used_length) {
/* Didn't find anything in this RAM Block */
pss->offset = 0;
pss->block = QLIST_NEXT_RCU(pss->block, next);
if (!pss->block) {
/* Hit the end of the list */
pss->block = QLIST_FIRST_RCU(&ram_list.blocks);
/* Flag that we've looped */
pss->complete_round = true;
ram_bulk_stage = false;
if (migrate_use_xbzrle()) {
/* If xbzrle is on, stop using the data compression at this
* point. In theory, xbzrle can do better than compression.
*/
flush_compressed_data(f);
compression_switch = 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;
}
}
/*
* Helper for 'get_queued_page' - gets a page off the queue
* ms: MigrationState in
* *offset: Used to return the offset within the RAMBlock
* ram_addr_abs: global offset in the dirty/sent bitmaps
*
* Returns: block (or NULL if none available)
*/
static RAMBlock *unqueue_page(MigrationState *ms, ram_addr_t *offset,
ram_addr_t *ram_addr_abs)
{
RAMBlock *block = NULL;
qemu_mutex_lock(&ms->src_page_req_mutex);
if (!QSIMPLEQ_EMPTY(&ms->src_page_requests)) {
struct MigrationSrcPageRequest *entry =
QSIMPLEQ_FIRST(&ms->src_page_requests);
block = entry->rb;
*offset = entry->offset;
*ram_addr_abs = (entry->offset + entry->rb->offset) &
TARGET_PAGE_MASK;
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(&ms->src_page_requests, next_req);
g_free(entry);
}
}
qemu_mutex_unlock(&ms->src_page_req_mutex);
return block;
}
/*
* Unqueue a page from the queue fed by postcopy page requests; skips pages
* that are already sent (!dirty)
*
* ms: MigrationState in
* pss: PageSearchStatus structure updated with found block/offset
* ram_addr_abs: global offset in the dirty/sent bitmaps
*
* Returns: true if a queued page is found
*/
static bool get_queued_page(MigrationState *ms, PageSearchStatus *pss,
ram_addr_t *ram_addr_abs)
{
RAMBlock *block;
ram_addr_t offset;
bool dirty;
do {
block = unqueue_page(ms, &offset, ram_addr_abs);
/*
* 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 *bitmap;
bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
dirty = test_bit(*ram_addr_abs >> TARGET_PAGE_BITS, bitmap);
if (!dirty) {
trace_get_queued_page_not_dirty(
block->idstr, (uint64_t)offset,
(uint64_t)*ram_addr_abs,
test_bit(*ram_addr_abs >> TARGET_PAGE_BITS,
atomic_rcu_read(&migration_bitmap_rcu)->unsentmap));
} else {
trace_get_queued_page(block->idstr,
(uint64_t)offset,
(uint64_t)*ram_addr_abs);
}
}
} 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.
*/
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->offset = offset;
}
return !!block;
}
/**
* flush_page_queue: Flush 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.
*
* ms: MigrationState
*/
void flush_page_queue(MigrationState *ms)
{
struct MigrationSrcPageRequest *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();
QSIMPLEQ_FOREACH_SAFE(mspr, &ms->src_page_requests, next_req, next_mspr) {
memory_region_unref(mspr->rb->mr);
QSIMPLEQ_REMOVE_HEAD(&ms->src_page_requests, next_req);
g_free(mspr);
}
rcu_read_unlock();
}
/**
* Queue the pages for transmission, e.g. a request from postcopy destination
* ms: MigrationStatus in which the queue is held
* rbname: The RAMBlock the request is for - may be NULL (to mean reuse last)
* start: Offset from the start of the RAMBlock
* len: Length (in bytes) to send
* Return: 0 on success
*/
int ram_save_queue_pages(MigrationState *ms, const char *rbname,
ram_addr_t start, ram_addr_t len)
{
RAMBlock *ramblock;
rcu_read_lock();
if (!rbname) {
/* Reuse last RAMBlock */
ramblock = ms->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");
goto err;
}
} 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);
goto err;
}
ms->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=%zx len=%zx blocklen=%zx",
__func__, start, len, ramblock->used_length);
goto err;
}
struct MigrationSrcPageRequest *new_entry =
g_malloc0(sizeof(struct MigrationSrcPageRequest));
new_entry->rb = ramblock;
new_entry->offset = start;
new_entry->len = len;
memory_region_ref(ramblock->mr);
qemu_mutex_lock(&ms->src_page_req_mutex);
QSIMPLEQ_INSERT_TAIL(&ms->src_page_requests, new_entry, next_req);
qemu_mutex_unlock(&ms->src_page_req_mutex);
rcu_read_unlock();
return 0;
err:
rcu_read_unlock();
return -1;
}
/**
* ram_save_target_page: Save one target page
*
*
* @f: QEMUFile where to send the data
* @block: pointer to 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
* @bytes_transferred: increase it with the number of transferred bytes
* @dirty_ram_abs: Address of the start of the dirty page in ram_addr_t space
*
* Returns: Number of pages written.
*/
static int ram_save_target_page(MigrationState *ms, QEMUFile *f,
RAMBlock *block, ram_addr_t offset,
bool last_stage,
uint64_t *bytes_transferred,
ram_addr_t dirty_ram_abs)
{
int res = 0;
/* Check the pages is dirty and if it is send it */
if (migration_bitmap_clear_dirty(dirty_ram_abs)) {
unsigned long *unsentmap;
if (compression_switch && migrate_use_compression()) {
res = ram_save_compressed_page(f, block, offset,
last_stage,
bytes_transferred);
} else {
res = ram_save_page(f, block, offset, last_stage,
bytes_transferred);
}
if (res < 0) {
return res;
}
unsentmap = atomic_rcu_read(&migration_bitmap_rcu)->unsentmap;
if (unsentmap) {
clear_bit(dirty_ram_abs >> TARGET_PAGE_BITS, unsentmap);
}
}
return res;
}
/**
* ram_save_host_page: Starting at *offset send pages upto 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.
*
* Returns: Number of pages written.
*
* @f: QEMUFile where to send the data
* @block: pointer to block that contains the page we want to send
* @offset: offset inside the block for the page; updated to last target page
* sent
* @last_stage: if we are at the completion stage
* @bytes_transferred: increase it with the number of transferred bytes
* @dirty_ram_abs: Address of the start of the dirty page in ram_addr_t space
*/
static int ram_save_host_page(MigrationState *ms, QEMUFile *f, RAMBlock *block,
ram_addr_t *offset, bool last_stage,
uint64_t *bytes_transferred,
ram_addr_t dirty_ram_abs)
{
int tmppages, pages = 0;
do {
tmppages = ram_save_target_page(ms, f, block, *offset, last_stage,
bytes_transferred, dirty_ram_abs);
if (tmppages < 0) {
return tmppages;
}
pages += tmppages;
*offset += TARGET_PAGE_SIZE;
dirty_ram_abs += TARGET_PAGE_SIZE;
} while (*offset & (qemu_host_page_size - 1));
/* The offset we leave with is the last one we looked at */
*offset -= TARGET_PAGE_SIZE;
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
* 0 means no dirty pages
*
* @f: QEMUFile where to send the data
* @last_stage: if we are at the completion stage
* @bytes_transferred: increase it with the number of transferred bytes
*
* 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(QEMUFile *f, bool last_stage,
uint64_t *bytes_transferred)
{
PageSearchStatus pss;
MigrationState *ms = migrate_get_current();
int pages = 0;
bool again, found;
ram_addr_t dirty_ram_abs; /* Address of the start of the dirty page in
ram_addr_t space */
pss.block = last_seen_block;
pss.offset = last_offset;
pss.complete_round = false;
if (!pss.block) {
pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
}
do {
again = true;
found = get_queued_page(ms, &pss, &dirty_ram_abs);
if (!found) {
/* priority queue empty, so just search for something dirty */
found = find_dirty_block(f, &pss, &again, &dirty_ram_abs);
}
if (found) {
pages = ram_save_host_page(ms, f, pss.block, &pss.offset,
last_stage, bytes_transferred,
dirty_ram_abs);
}
} while (!pages && again);
last_seen_block = pss.block;
last_offset = pss.offset;
return pages;
}
void acct_update_position(QEMUFile *f, size_t size, bool zero)
{
uint64_t pages = size / TARGET_PAGE_SIZE;
if (zero) {
acct_info.dup_pages += pages;
} else {
acct_info.norm_pages += pages;
bytes_transferred += size;
qemu_update_position(f, size);
}
}
static ram_addr_t ram_save_remaining(void)
{
return migration_dirty_pages;
}
uint64_t ram_bytes_remaining(void)
{
return ram_save_remaining() * TARGET_PAGE_SIZE;
}
uint64_t ram_bytes_transferred(void)
{
return bytes_transferred;
}
uint64_t ram_bytes_total(void)
{
RAMBlock *block;
uint64_t total = 0;
rcu_read_lock();
QLIST_FOREACH_RCU(block, &ram_list.blocks, next)
total += block->used_length;
rcu_read_unlock();
return total;
}
void free_xbzrle_decoded_buf(void)
{
g_free(xbzrle_decoded_buf);
xbzrle_decoded_buf = NULL;
}
static void migration_bitmap_free(struct BitmapRcu *bmap)
{
g_free(bmap->bmap);
g_free(bmap->unsentmap);
g_free(bmap);
}
static void ram_migration_cleanup(void *opaque)
{
/* caller have hold iothread lock or is in a bh, so there is
* no writing race against this migration_bitmap
*/
struct BitmapRcu *bitmap = migration_bitmap_rcu;
atomic_rcu_set(&migration_bitmap_rcu, NULL);
if (bitmap) {
memory_global_dirty_log_stop();
call_rcu(bitmap, migration_bitmap_free, rcu);
}
XBZRLE_cache_lock();
if (XBZRLE.cache) {
cache_fini(XBZRLE.cache);
g_free(XBZRLE.encoded_buf);
g_free(XBZRLE.current_buf);
XBZRLE.cache = NULL;
XBZRLE.encoded_buf = NULL;
XBZRLE.current_buf = NULL;
}
XBZRLE_cache_unlock();
}
static void reset_ram_globals(void)
{
last_seen_block = NULL;
last_sent_block = NULL;
last_offset = 0;
last_version = ram_list.version;
ram_bulk_stage = true;
}
#define MAX_WAIT 50 /* ms, half buffered_file limit */
void migration_bitmap_extend(ram_addr_t old, ram_addr_t new)
{
/* called in qemu main thread, so there is
* no writing race against this migration_bitmap
*/
if (migration_bitmap_rcu) {
struct BitmapRcu *old_bitmap = migration_bitmap_rcu, *bitmap;
bitmap = g_new(struct BitmapRcu, 1);
bitmap->bmap = bitmap_new(new);
/* prevent migration_bitmap content from being set bit
* by migration_bitmap_sync_range() at the same time.
* it is safe to migration if migration_bitmap is cleared bit
* at the same time.
*/
qemu_mutex_lock(&migration_bitmap_mutex);
bitmap_copy(bitmap->bmap, old_bitmap->bmap, old);
bitmap_set(bitmap->bmap, old, new - old);
/* We don't have a way to safely extend the sentmap
* with RCU; so mark it as missing, entry to postcopy
* will fail.
*/
bitmap->unsentmap = NULL;
atomic_rcu_set(&migration_bitmap_rcu, bitmap);
qemu_mutex_unlock(&migration_bitmap_mutex);
migration_dirty_pages += new - old;
call_rcu(old_bitmap, migration_bitmap_free, rcu);
}
}
/*
* '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)
{
int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;
int64_t cur;
int64_t linelen = 128;
char linebuf[129];
if (!todump) {
todump = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
}
for (cur = 0; cur < ram_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 > ram_pages) {
linelen = ram_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 ***** */
/*
* Callback from postcopy_each_ram_send_discard for each RAMBlock
* Note: At this point the 'unsentmap' is the processed bitmap combined
* with the dirtymap; so a '1' means it's either dirty or unsent.
* start,length: Indexes into the bitmap for the first bit
* representing the named block and length in target-pages
*/
static int postcopy_send_discard_bm_ram(MigrationState *ms,
PostcopyDiscardState *pds,
unsigned long start,
unsigned long length)
{
unsigned long end = start + length; /* one after the end */
unsigned long current;
unsigned long *unsentmap;
unsentmap = atomic_rcu_read(&migration_bitmap_rcu)->unsentmap;
for (current = start; current < end; ) {
unsigned long one = find_next_bit(unsentmap, end, current);
if (one <= end) {
unsigned long zero = find_next_zero_bit(unsentmap, end, one + 1);
unsigned long discard_length;
if (zero >= end) {
discard_length = end - one;
} else {
discard_length = zero - one;
}
postcopy_discard_send_range(ms, pds, one, discard_length);
current = one + discard_length;
} else {
current = one;
}
}
return 0;
}
/*
* Utility for the outgoing postcopy code.
* Calls postcopy_send_discard_bm_ram for each RAMBlock
* passing it bitmap indexes and name.
* Returns: 0 on success
* (qemu_ram_foreach_block ends up passing unscaled lengths
* which would mean postcopy code would have to deal with target page)
*/
static int postcopy_each_ram_send_discard(MigrationState *ms)
{
struct RAMBlock *block;
int ret;
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
unsigned long first = block->offset >> TARGET_PAGE_BITS;
PostcopyDiscardState *pds = postcopy_discard_send_init(ms,
first,
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, pds, first,
block->used_length >> TARGET_PAGE_BITS);
postcopy_discard_send_finish(ms, pds);
if (ret) {
return ret;
}
}
return 0;
}
/*
* 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
*/
int ram_postcopy_send_discard_bitmap(MigrationState *ms)
{
int ret;
unsigned long *bitmap, *unsentmap;
rcu_read_lock();
/* This should be our last sync, the src is now paused */
migration_bitmap_sync();
unsentmap = atomic_rcu_read(&migration_bitmap_rcu)->unsentmap;
if (!unsentmap) {
/* We don't have a safe way to resize the sentmap, so
* if the bitmap was resized it will be NULL at this
* point.
*/
error_report("migration ram resized during precopy phase");
rcu_read_unlock();
return -EINVAL;
}
/*
* Update the unsentmap to be unsentmap = unsentmap | dirty
*/
bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
bitmap_or(unsentmap, unsentmap, bitmap,
last_ram_offset() >> TARGET_PAGE_BITS);
trace_ram_postcopy_send_discard_bitmap();
#ifdef DEBUG_POSTCOPY
ram_debug_dump_bitmap(unsentmap, true);
#endif
ret = postcopy_each_ram_send_discard(ms);
rcu_read_unlock();
return ret;
}
/*
* At the start of the postcopy phase of migration, any now-dirty
* precopied pages are discarded.
*
* start, length describe a byte address range within the RAMBlock
*
* Returns 0 on success.
*/
int ram_discard_range(MigrationIncomingState *mis,
const char *block_name,
uint64_t start, size_t length)
{
int ret = -1;
rcu_read_lock();
RAMBlock *rb = qemu_ram_block_by_name(block_name);
if (!rb) {
error_report("ram_discard_range: Failed to find block '%s'",
block_name);
goto err;
}
uint8_t *host_startaddr = rb->host + start;
if ((uintptr_t)host_startaddr & (qemu_host_page_size - 1)) {
error_report("ram_discard_range: Unaligned start address: %p",
host_startaddr);
goto err;
}
if ((start + length) <= rb->used_length) {
uint8_t *host_endaddr = host_startaddr + length;
if ((uintptr_t)host_endaddr & (qemu_host_page_size - 1)) {
error_report("ram_discard_range: Unaligned end address: %p",
host_endaddr);
goto err;
}
ret = postcopy_ram_discard_range(mis, host_startaddr, length);
} else {
error_report("ram_discard_range: Overrun block '%s' (%" PRIu64
"/%zu/%zu)",
block_name, start, length, rb->used_length);
}
err:
rcu_read_unlock();
return ret;
}
/* 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.
*/
static int ram_save_setup(QEMUFile *f, void *opaque)
{
RAMBlock *block;
int64_t ram_bitmap_pages; /* Size of bitmap in pages, including gaps */
dirty_rate_high_cnt = 0;
bitmap_sync_count = 0;
migration_bitmap_sync_init();
qemu_mutex_init(&migration_bitmap_mutex);
if (migrate_use_xbzrle()) {
XBZRLE_cache_lock();
XBZRLE.cache = cache_init(migrate_xbzrle_cache_size() /
TARGET_PAGE_SIZE,
TARGET_PAGE_SIZE);
if (!XBZRLE.cache) {
XBZRLE_cache_unlock();
error_report("Error creating cache");
return -1;
}
XBZRLE_cache_unlock();
/* We prefer not to abort if there is no memory */
XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE);
if (!XBZRLE.encoded_buf) {
error_report("Error allocating encoded_buf");
return -1;
}
XBZRLE.current_buf = g_try_malloc(TARGET_PAGE_SIZE);
if (!XBZRLE.current_buf) {
error_report("Error allocating current_buf");
g_free(XBZRLE.encoded_buf);
XBZRLE.encoded_buf = NULL;
return -1;
}
acct_clear();
}
/* iothread lock needed for ram_list.dirty_memory[] */
qemu_mutex_lock_iothread();
qemu_mutex_lock_ramlist();
rcu_read_lock();
bytes_transferred = 0;
reset_ram_globals();
ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS;
migration_bitmap_rcu = g_new0(struct BitmapRcu, 1);
migration_bitmap_rcu->bmap = bitmap_new(ram_bitmap_pages);
bitmap_set(migration_bitmap_rcu->bmap, 0, ram_bitmap_pages);
if (migrate_postcopy_ram()) {
migration_bitmap_rcu->unsentmap = bitmap_new(ram_bitmap_pages);
bitmap_set(migration_bitmap_rcu->unsentmap, 0, ram_bitmap_pages);
}
/*
* Count the total number of pages used by ram blocks not including any
* gaps due to alignment or unplugs.
*/
migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
memory_global_dirty_log_start();
migration_bitmap_sync();
qemu_mutex_unlock_ramlist();
qemu_mutex_unlock_iothread();
qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
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);
}
rcu_read_unlock();
ram_control_before_iterate(f, RAM_CONTROL_SETUP);
ram_control_after_iterate(f, RAM_CONTROL_SETUP);
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
return 0;
}
static int ram_save_iterate(QEMUFile *f, void *opaque)
{
int ret;
int i;
int64_t t0;
int pages_sent = 0;
rcu_read_lock();
if (ram_list.version != last_version) {
reset_ram_globals();
}
/* 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) {
int pages;
pages = ram_find_and_save_block(f, false, &bytes_transferred);
/* no more pages to sent */
if (pages == 0) {
break;
}
pages_sent += pages;
acct_info.iterations++;
/* 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_get_clock_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) {
DPRINTF("big wait: %" PRIu64 " milliseconds, %d iterations\n",
t1, i);
break;
}
}
i++;
}
flush_compressed_data(f);
rcu_read_unlock();
/*
* Must occur before EOS (or any QEMUFile operation)
* because of RDMA protocol.
*/
ram_control_after_iterate(f, RAM_CONTROL_ROUND);
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
bytes_transferred += 8;
ret = qemu_file_get_error(f);
if (ret < 0) {
return ret;
}
return pages_sent;
}
/* Called with iothread lock */
static int ram_save_complete(QEMUFile *f, void *opaque)
{
rcu_read_lock();
migration_bitmap_sync();
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(f, true, &bytes_transferred);
/* no more blocks to sent */
if (pages == 0) {
break;
}
}
flush_compressed_data(f);
ram_control_after_iterate(f, RAM_CONTROL_FINISH);
rcu_read_unlock();
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
return 0;
}
static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
uint64_t *non_postcopiable_pending,
uint64_t *postcopiable_pending)
{
uint64_t remaining_size;
remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;
if (remaining_size < max_size) {
qemu_mutex_lock_iothread();
rcu_read_lock();
migration_bitmap_sync();
rcu_read_unlock();
qemu_mutex_unlock_iothread();
remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;
}
/* We can do postcopy, and all the data is postcopiable */
*postcopiable_pending += remaining_size;
}
static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
{
unsigned int xh_len;
int xh_flags;
if (!xbzrle_decoded_buf) {
xbzrle_decoded_buf = g_malloc(TARGET_PAGE_SIZE);
}
/* 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;
}
/* load data and decode */
qemu_get_buffer(f, xbzrle_decoded_buf, xh_len);
/* decode RLE */
if (xbzrle_decode_buffer(xbzrle_decoded_buf, xh_len, host,
TARGET_PAGE_SIZE) == -1) {
error_report("Failed to load XBZRLE page - decode error!");
return -1;
}
return 0;
}
/* Must be called from within a rcu critical section.
* Returns a pointer from within the RCU-protected ram_list.
*/
static inline void *host_from_stream_offset(QEMUFile *f,
ram_addr_t offset,
int flags)
{
static RAMBlock *block = NULL;
char id[256];
uint8_t len;
if (flags & RAM_SAVE_FLAG_CONTINUE) {
if (!block || block->max_length <= offset) {
error_report("Ack, bad migration stream!");
return NULL;
}
return block->host + offset;
}
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 && block->max_length > offset) {
return block->host + offset;
}
error_report("Can't find block %s", id);
return NULL;
}
/*
* If a page (or a whole RDMA chunk) has been
* determined to be zero, then zap it.
*/
void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
{
if (ch != 0 || !is_zero_range(host, size)) {
memset(host, ch, size);
}
}
static void *do_data_decompress(void *opaque)
{
DecompressParam *param = opaque;
unsigned long pagesize;
while (!quit_decomp_thread) {
qemu_mutex_lock(&param->mutex);
while (!param->start && !quit_decomp_thread) {
qemu_cond_wait(&param->cond, &param->mutex);
pagesize = TARGET_PAGE_SIZE;
if (!quit_decomp_thread) {
/* uncompress() will return failed in some case, especially
* when the page is dirted when doing the compression, it's
* not a problem because the dirty page will be retransferred
* and uncompress() won't break the data in other pages.
*/
uncompress((Bytef *)param->des, &pagesize,
(const Bytef *)param->compbuf, param->len);
}
param->start = false;
}
qemu_mutex_unlock(&param->mutex);
}
return NULL;
}
void migrate_decompress_threads_create(void)
{
int i, thread_count;
thread_count = migrate_decompress_threads();
decompress_threads = g_new0(QemuThread, thread_count);
decomp_param = g_new0(DecompressParam, thread_count);
compressed_data_buf = g_malloc0(compressBound(TARGET_PAGE_SIZE));
quit_decomp_thread = false;
for (i = 0; i < thread_count; i++) {
qemu_mutex_init(&decomp_param[i].mutex);
qemu_cond_init(&decomp_param[i].cond);
decomp_param[i].compbuf = g_malloc0(compressBound(TARGET_PAGE_SIZE));
qemu_thread_create(decompress_threads + i, "decompress",
do_data_decompress, decomp_param + i,
QEMU_THREAD_JOINABLE);
}
}
void migrate_decompress_threads_join(void)
{
int i, thread_count;
quit_decomp_thread = true;
thread_count = migrate_decompress_threads();
for (i = 0; i < thread_count; i++) {
qemu_mutex_lock(&decomp_param[i].mutex);
qemu_cond_signal(&decomp_param[i].cond);
qemu_mutex_unlock(&decomp_param[i].mutex);
}
for (i = 0; i < thread_count; i++) {
qemu_thread_join(decompress_threads + i);
qemu_mutex_destroy(&decomp_param[i].mutex);
qemu_cond_destroy(&decomp_param[i].cond);
g_free(decomp_param[i].compbuf);
}
g_free(decompress_threads);
g_free(decomp_param);
g_free(compressed_data_buf);
decompress_threads = NULL;
decomp_param = NULL;
compressed_data_buf = NULL;
}
static void decompress_data_with_multi_threads(uint8_t *compbuf,
void *host, int len)
{
int idx, thread_count;
thread_count = migrate_decompress_threads();
while (true) {
for (idx = 0; idx < thread_count; idx++) {
if (!decomp_param[idx].start) {
memcpy(decomp_param[idx].compbuf, compbuf, len);
decomp_param[idx].des = host;
decomp_param[idx].len = len;
start_decompression(&decomp_param[idx]);
break;
}
}
if (idx < thread_count) {
break;
}
}
}
/*
* 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)
{
size_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;
return postcopy_ram_incoming_init(mis, ram_pages);
}
static int ram_load(QEMUFile *f, void *opaque, int version_id)
{
int flags = 0, ret = 0;
static uint64_t seq_iter;
int len = 0;
seq_iter++;
if (version_id != 4) {
ret = -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.
*/
rcu_read_lock();
while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) {
ram_addr_t addr, total_ram_bytes;
void *host = NULL;
uint8_t ch;
addr = qemu_get_be64(f);
flags = addr & ~TARGET_PAGE_MASK;
addr &= TARGET_PAGE_MASK;
if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
host = host_from_stream_offset(f, addr, flags);
if (!host) {
error_report("Illegal RAM offset " RAM_ADDR_FMT, addr);
ret = -EINVAL;
break;
}
}
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) {
if (length != block->used_length) {
Error *local_err = NULL;
ret = qemu_ram_resize(block->offset, length,
&local_err);
if (local_err) {
error_report_err(local_err);
}
}
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_COMPRESS:
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;
}
qemu_get_buffer(f, compressed_data_buf, len);
decompress_data_with_multi_threads(compressed_data_buf, 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 */
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);
}
}
rcu_read_unlock();
DPRINTF("Completed load of VM with exit code %d seq iteration "
"%" PRIu64 "\n", ret, seq_iter);
return ret;
}
static SaveVMHandlers savevm_ram_handlers = {
.save_live_setup = ram_save_setup,
.save_live_iterate = ram_save_iterate,
.save_live_complete_postcopy = ram_save_complete,
.save_live_complete_precopy = ram_save_complete,
.save_live_pending = ram_save_pending,
.load_state = ram_load,
.cleanup = ram_migration_cleanup,
};
void ram_mig_init(void)
{
qemu_mutex_init(&XBZRLE.lock);
register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, NULL);
}
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