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9ac78b6171
qemu/migration/ram.c
Peter Lieven 9ac78b6171 migration: disable auto-converge during bulk block migration 
auto-converge and block migration currently do not play well together.
During block migration the auto-converge logic detects that ram
migration makes no progress and thus throttles down the vm until
it nearly stalls completely. Avoid this by disabling the throttling
logic during the bulk phase of the block migration.

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-Id: <1506421996-12513-1-git-send-email-pl@kamp.de>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2017-09-27 11:27:14 +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 "qemu/osdep.h"
#include "cpu.h"
#include <zlib.h>
#include "qapi-event.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 "migration/page_cache.h"
#include "qemu/error-report.h"
#include "trace.h"
#include "exec/ram_addr.h"
#include "qemu/rcu_queue.h"
#include "migration/colo.h"
#include "migration/block.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 the new_size or negative in case of error.
*
* @new_size: new cache size
*/
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;
}
/*
* 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;
/* 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;
/* number of iterations at the beginning of period */
uint64_t iterations_prev;
/* Iterations since start */
uint64_t iterations;
/* number of dirty bits in the bitmap */
uint64_t migration_dirty_pages;
/* protects modification of the bitmap */
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(src_page_requests, RAMSrcPageRequest) src_page_requests;
};
typedef struct RAMState RAMState;
static RAMState *ram_state;
uint64_t ram_bytes_remaining(void)
{
return ram_state->migration_dirty_pages * TARGET_PAGE_SIZE;
}
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;
struct CompressParam {
bool done;
bool quit;
QEMUFile *file;
QemuMutex mutex;
QemuCond cond;
RAMBlock *block;
ram_addr_t offset;
};
typedef struct CompressParam CompressParam;
struct DecompressParam {
bool done;
bool quit;
QemuMutex mutex;
QemuCond cond;
void *des;
uint8_t *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 DecompressParam *decomp_param;
static QemuThread *decompress_threads;
static QemuMutex decomp_done_lock;
static QemuCond decomp_done_cond;
static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
ram_addr_t offset);
static void *do_data_compress(void *opaque)
{
CompressParam *param = opaque;
RAMBlock *block;
ram_addr_t offset;
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);
do_compress_ram_page(param->file, block, offset);
qemu_mutex_lock(&comp_done_lock);
param->done = true;
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 inline void terminate_compression_threads(void)
{
int idx, thread_count;
thread_count = migrate_compress_threads();
for (idx = 0; idx < thread_count; idx++) {
qemu_mutex_lock(&comp_param[idx].mutex);
comp_param[idx].quit = true;
qemu_cond_signal(&comp_param[idx].cond);
qemu_mutex_unlock(&comp_param[idx].mutex);
}
}
static void compress_threads_save_cleanup(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);
compress_threads = NULL;
comp_param = NULL;
}
static void compress_threads_save_setup(void)
{
int i, thread_count;
if (!migrate_use_compression()) {
return;
}
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].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);
}
}
/* Multiple fd's */
struct MultiFDSendParams {
uint8_t id;
char *name;
QemuThread thread;
QemuSemaphore sem;
QemuMutex mutex;
bool quit;
};
typedef struct MultiFDSendParams MultiFDSendParams;
struct {
MultiFDSendParams *params;
/* number of created threads */
int count;
} *multifd_send_state;
static void terminate_multifd_send_threads(Error *errp)
{
int i;
for (i = 0; i < multifd_send_state->count; i++) {
MultiFDSendParams *p = &multifd_send_state->params[i];
qemu_mutex_lock(&p->mutex);
p->quit = true;
qemu_sem_post(&p->sem);
qemu_mutex_unlock(&p->mutex);
}
}
int multifd_save_cleanup(Error **errp)
{
int i;
int ret = 0;
if (!migrate_use_multifd()) {
return 0;
}
terminate_multifd_send_threads(NULL);
for (i = 0; i < multifd_send_state->count; i++) {
MultiFDSendParams *p = &multifd_send_state->params[i];
qemu_thread_join(&p->thread);
qemu_mutex_destroy(&p->mutex);
qemu_sem_destroy(&p->sem);
g_free(p->name);
p->name = NULL;
}
g_free(multifd_send_state->params);
multifd_send_state->params = NULL;
g_free(multifd_send_state);
multifd_send_state = NULL;
return ret;
}
static void *multifd_send_thread(void *opaque)
{
MultiFDSendParams *p = opaque;
while (true) {
qemu_mutex_lock(&p->mutex);
if (p->quit) {
qemu_mutex_unlock(&p->mutex);
break;
}
qemu_mutex_unlock(&p->mutex);
qemu_sem_wait(&p->sem);
}
return NULL;
}
int multifd_save_setup(void)
{
int thread_count;
uint8_t i;
if (!migrate_use_multifd()) {
return 0;
}
thread_count = migrate_multifd_channels();
multifd_send_state = g_malloc0(sizeof(*multifd_send_state));
multifd_send_state->params = g_new0(MultiFDSendParams, thread_count);
multifd_send_state->count = 0;
for (i = 0; i < thread_count; i++) {
MultiFDSendParams *p = &multifd_send_state->params[i];
qemu_mutex_init(&p->mutex);
qemu_sem_init(&p->sem, 0);
p->quit = false;
p->id = i;
p->name = g_strdup_printf("multifdsend_%d", i);
qemu_thread_create(&p->thread, p->name, multifd_send_thread, p,
QEMU_THREAD_JOINABLE);
multifd_send_state->count++;
}
return 0;
}
struct MultiFDRecvParams {
uint8_t id;
char *name;
QemuThread thread;
QemuSemaphore sem;
QemuMutex mutex;
bool quit;
};
typedef struct MultiFDRecvParams MultiFDRecvParams;
struct {
MultiFDRecvParams *params;
/* number of created threads */
int count;
} *multifd_recv_state;
static void terminate_multifd_recv_threads(Error *errp)
{
int i;
for (i = 0; i < multifd_recv_state->count; i++) {
MultiFDRecvParams *p = &multifd_recv_state->params[i];
qemu_mutex_lock(&p->mutex);
p->quit = true;
qemu_sem_post(&p->sem);
qemu_mutex_unlock(&p->mutex);
}
}
int multifd_load_cleanup(Error **errp)
{
int i;
int ret = 0;
if (!migrate_use_multifd()) {
return 0;
}
terminate_multifd_recv_threads(NULL);
for (i = 0; i < multifd_recv_state->count; i++) {
MultiFDRecvParams *p = &multifd_recv_state->params[i];
qemu_thread_join(&p->thread);
qemu_mutex_destroy(&p->mutex);
qemu_sem_destroy(&p->sem);
g_free(p->name);
p->name = NULL;
}
g_free(multifd_recv_state->params);
multifd_recv_state->params = NULL;
g_free(multifd_recv_state);
multifd_recv_state = NULL;
return ret;
}
static void *multifd_recv_thread(void *opaque)
{
MultiFDRecvParams *p = opaque;
while (true) {
qemu_mutex_lock(&p->mutex);
if (p->quit) {
qemu_mutex_unlock(&p->mutex);
break;
}
qemu_mutex_unlock(&p->mutex);
qemu_sem_wait(&p->sem);
}
return NULL;
}
int multifd_load_setup(void)
{
int thread_count;
uint8_t i;
if (!migrate_use_multifd()) {
return 0;
}
thread_count = migrate_multifd_channels();
multifd_recv_state = g_malloc0(sizeof(*multifd_recv_state));
multifd_recv_state->params = g_new0(MultiFDRecvParams, thread_count);
multifd_recv_state->count = 0;
for (i = 0; i < thread_count; i++) {
MultiFDRecvParams *p = &multifd_recv_state->params[i];
qemu_mutex_init(&p->mutex);
qemu_sem_init(&p->sem, 0);
p->quit = false;
p->id = i;
p->name = g_strdup_printf("multifdrecv_%d", i);
qemu_thread_create(&p->thread, p->name, multifd_recv_thread, p,
QEMU_THREAD_JOINABLE);
multifd_recv_state->count++;
}
return 0;
}
/**
* 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;
/* 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);
}
}
/**
* 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);
if (encoded_len == 0) {
trace_save_xbzrle_page_skipping();
return 0;
} else if (encoded_len == -1) {
trace_save_xbzrle_page_overflow();
xbzrle_counters.overflow++;
/* 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(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
*
* Called with rcu_read_lock() to protect migration_bitmap
*
* Returns the byte 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 (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;
ret = test_and_clear_bit(page, rb->bmap);
if (ret) {
rs->migration_dirty_pages--;
}
return ret;
}
static void migration_bitmap_sync_range(RAMState *rs, RAMBlock *rb,
ram_addr_t start, ram_addr_t length)
{
rs->migration_dirty_pages +=
cpu_physical_memory_sync_dirty_bitmap(rb, start, 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(block) {
summary |= block->page_size;
}
return summary;
}
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);
rcu_read_lock();
RAMBLOCK_FOREACH(block) {
migration_bitmap_sync_range(rs, block, 0, block->used_length);
}
rcu_read_unlock();
qemu_mutex_unlock(&rs->bitmap_mutex);
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) {
/* calculate period counters */
ram_counters.dirty_pages_rate = rs->num_dirty_pages_period * 1000
/ (end_time - rs->time_last_bitmap_sync);
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();
}
}
if (migrate_use_xbzrle()) {
if (rs->iterations_prev != rs->iterations) {
xbzrle_counters.cache_miss_rate =
(double)(xbzrle_counters.cache_miss -
rs->xbzrle_cache_miss_prev) /
(rs->iterations - rs->iterations_prev);
}
rs->iterations_prev = rs->iterations;
rs->xbzrle_cache_miss_prev = xbzrle_counters.cache_miss;
}
/* 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, NULL);
}
}
/**
* 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
* @p: pointer to the page
*/
static int save_zero_page(RAMState *rs, RAMBlock *block, ram_addr_t offset,
uint8_t *p)
{
int pages = -1;
if (is_zero_range(p, TARGET_PAGE_SIZE)) {
ram_counters.duplicate++;
ram_counters.transferred +=
save_page_header(rs, rs->f, block, offset | RAM_SAVE_FLAG_ZERO);
qemu_put_byte(rs->f, 0);
ram_counters.transferred += 1;
pages = 1;
}
return pages;
}
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, pages << TARGET_PAGE_BITS);
}
/**
* 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;
uint64_t bytes_xmit;
ram_addr_t current_addr;
uint8_t *p;
int ret;
bool send_async = true;
RAMBlock *block = pss->block;
ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
p = block->host + offset;
trace_ram_save_page(block->idstr, (uint64_t)offset, p);
/* In doubt sent page as normal */
bytes_xmit = 0;
ret = ram_control_save_page(rs->f, block->offset,
offset, TARGET_PAGE_SIZE, &bytes_xmit);
if (bytes_xmit) {
ram_counters.transferred += bytes_xmit;
pages = 1;
}
XBZRLE_cache_lock();
current_addr = block->offset + offset;
if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
if (ret != RAM_SAVE_CONTROL_DELAYED) {
if (bytes_xmit > 0) {
ram_counters.normal++;
} else if (bytes_xmit == 0) {
ram_counters.duplicate++;
}
}
} else {
pages = save_zero_page(rs, block, offset, p);
if (pages > 0) {
/* Must let xbzrle know, otherwise a previous (now 0'd) cached
* page would be stale
*/
xbzrle_cache_zero_page(rs, current_addr);
ram_release_pages(block->idstr, offset, pages);
} else 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) {
ram_counters.transferred +=
save_page_header(rs, rs->f, block, offset | RAM_SAVE_FLAG_PAGE);
if (send_async) {
qemu_put_buffer_async(rs->f, p, TARGET_PAGE_SIZE,
migrate_release_ram() &
migration_in_postcopy());
} else {
qemu_put_buffer(rs->f, p, TARGET_PAGE_SIZE);
}
ram_counters.transferred += TARGET_PAGE_SIZE;
pages = 1;
ram_counters.normal++;
}
XBZRLE_cache_unlock();
return pages;
}
static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
ram_addr_t offset)
{
RAMState *rs = ram_state;
int bytes_sent, blen;
uint8_t *p = block->host + (offset & TARGET_PAGE_MASK);
bytes_sent = save_page_header(rs, f, block, offset |
RAM_SAVE_FLAG_COMPRESS_PAGE);
blen = qemu_put_compression_data(f, p, TARGET_PAGE_SIZE,
migrate_compress_level());
if (blen < 0) {
bytes_sent = 0;
qemu_file_set_error(migrate_get_current()->to_dst_file, blen);
error_report("compressed data failed!");
} else {
bytes_sent += blen;
ram_release_pages(block->idstr, offset & TARGET_PAGE_MASK, 1);
}
return bytes_sent;
}
static void flush_compressed_data(RAMState *rs)
{
int idx, len, thread_count;
if (!migrate_use_compression()) {
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);
ram_counters.transferred += 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;
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) {
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;
ram_counters.normal++;
ram_counters.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 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
* @last_stage: if we are at the completion stage
*/
static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
bool last_stage)
{
int pages = -1;
uint64_t bytes_xmit = 0;
uint8_t *p;
int ret, blen;
RAMBlock *block = pss->block;
ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
p = block->host + offset;
ret = ram_control_save_page(rs->f, block->offset,
offset, TARGET_PAGE_SIZE, &bytes_xmit);
if (bytes_xmit) {
ram_counters.transferred += bytes_xmit;
pages = 1;
}
if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
if (ret != RAM_SAVE_CONTROL_DELAYED) {
if (bytes_xmit > 0) {
ram_counters.normal++;
} else if (bytes_xmit == 0) {
ram_counters.duplicate++;
}
}
} 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 != rs->last_sent_block) {
flush_compressed_data(rs);
pages = save_zero_page(rs, block, offset, p);
if (pages == -1) {
/* Make sure the first page is sent out before other pages */
bytes_xmit = save_page_header(rs, rs->f, block, offset |
RAM_SAVE_FLAG_COMPRESS_PAGE);
blen = qemu_put_compression_data(rs->f, p, TARGET_PAGE_SIZE,
migrate_compress_level());
if (blen > 0) {
ram_counters.transferred += bytes_xmit + blen;
ram_counters.normal++;
pages = 1;
} else {
qemu_file_set_error(rs->f, blen);
error_report("compressed data failed!");
}
}
if (pages > 0) {
ram_release_pages(block->idstr, offset, pages);
}
} else {
pages = save_zero_page(rs, block, offset, p);
if (pages == -1) {
pages = compress_page_with_multi_thread(rs, block, offset);
} else {
ram_release_pages(block->idstr, offset, pages);
}
}
}
return pages;
}
/**
* find_dirty_block: find the next dirty page and update any state
* associated with the search process.
*
* Returns 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 ((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) {
/* 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;
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(rs);
}
}
/* 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;
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);
}
}
qemu_mutex_unlock(&rs->src_page_req_mutex);
return block;
}
/**
* get_queued_page: unqueue a page from the postocpy requests
*
* Skips pages that are already sent (!dirty)
*
* Returns 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, test_bit(page, block->unsentmap));
} 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;
}
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();
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);
}
rcu_read_unlock();
}
/**
* 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();
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");
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;
}
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);
goto err;
}
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);
qemu_mutex_unlock(&rs->src_page_req_mutex);
rcu_read_unlock();
return 0;
err:
rcu_read_unlock();
return -1;
}
/**
* ram_save_target_page: save one target page
*
* Returns the number of pages written
*
* @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_target_page(RAMState *rs, PageSearchStatus *pss,
bool last_stage)
{
int res = 0;
/* Check the pages is dirty and if it is send it */
if (migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
/*
* 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 (migrate_use_compression() &&
(rs->ram_bulk_stage || !migrate_use_xbzrle())) {
res = ram_save_compressed_page(rs, pss, last_stage);
} else {
res = ram_save_page(rs, pss, last_stage);
}
if (res < 0) {
return res;
}
if (pss->block->unsentmap) {
clear_bit(pss->page, pss->block->unsentmap);
}
}
return res;
}
/**
* 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;
do {
tmppages = ram_save_target_page(rs, pss, last_stage);
if (tmppages < 0) {
return tmppages;
}
pages += tmppages;
pss->page++;
} while ((pss->page & (pagesize_bits - 1)) &&
offset_in_ramblock(pss->block, 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
*
* @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);
}
}
uint64_t ram_bytes_total(void)
{
RAMBlock *block;
uint64_t total = 0;
rcu_read_lock();
RAMBLOCK_FOREACH(block) {
total += block->used_length;
}
rcu_read_unlock();
return total;
}
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_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 this migration_bitmap
*/
memory_global_dirty_log_stop();
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
g_free(block->bmap);
block->bmap = NULL;
g_free(block->unsentmap);
block->unsentmap = NULL;
}
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();
migration_page_queue_free(*rsp);
compress_threads_save_cleanup();
g_free(*rsp);
*rsp = NULL;
}
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;
}
#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(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, run_start << TARGET_PAGE_BITS,
(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
* Note: At this point the 'unsentmap' is the processed bitmap combined
* with the dirtymap; so a '1' means it's either dirty or unsent.
*
* @ms: current migration state
* @pds: state for postcopy
* @start: RAMBlock starting page
* @length: RAMBlock size
*/
static int postcopy_send_discard_bm_ram(MigrationState *ms,
PostcopyDiscardState *pds,
RAMBlock *block)
{
unsigned long end = block->used_length >> TARGET_PAGE_BITS;
unsigned long current;
unsigned long *unsentmap = block->unsentmap;
for (current = 0; 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;
}
if (discard_length) {
postcopy_discard_send_range(ms, pds, one, discard_length);
}
current = one + discard_length;
} else {
current = one;
}
}
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(block) {
PostcopyDiscardState *pds =
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, pds, block);
postcopy_discard_send_finish(ms, pds);
if (ret) {
return ret;
}
}
return 0;
}
/**
* postcopy_chunk_hostpages_pass: canocalize 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
* @unsent_pass: if true we need to canonicalize partially unsent host pages
* otherwise we need to canonicalize partially dirty host pages
* @block: block that contains the page we want to canonicalize
* @pds: state for postcopy
*/
static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
RAMBlock *block,
PostcopyDiscardState *pds)
{
RAMState *rs = ram_state;
unsigned long *bitmap = block->bmap;
unsigned long *unsentmap = block->unsentmap;
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;
}
if (unsent_pass) {
/* Find a sent page */
run_start = find_next_zero_bit(unsentmap, pages, 0);
} else {
/* Find a dirty page */
run_start = find_next_bit(bitmap, pages, 0);
}
while (run_start < pages) {
bool do_fixup = false;
unsigned long fixup_start_addr;
unsigned long host_offset;
/*
* If the start of this run of pages is in the middle of a host
* page, then we need to fixup this host page.
*/
host_offset = run_start % host_ratio;
if (host_offset) {
do_fixup = true;
run_start -= host_offset;
fixup_start_addr = run_start;
/* For the next pass */
run_start = run_start + host_ratio;
} else {
/* Find the end of this run */
unsigned long run_end;
if (unsent_pass) {
run_end = find_next_bit(unsentmap, pages, run_start + 1);
} else {
run_end = 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.
*/
host_offset = run_end % host_ratio;
if (host_offset) {
do_fixup = true;
fixup_start_addr = run_end - host_offset;
/*
* This host page has gone, the next loop iteration starts
* from after the fixup
*/
run_start = fixup_start_addr + host_ratio;
} else {
/*
* No discards on this iteration, next loop starts from
* next sent/dirty page
*/
run_start = run_end + 1;
}
}
if (do_fixup) {
unsigned long page;
/* Tell the destination to discard this page */
if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) {
/* For the unsent_pass we:
* discard partially sent pages
* For the !unsent_pass (dirty) we:
* discard partially dirty pages that were sent
* (any partially sent pages were already discarded
* by the previous unsent_pass)
*/
postcopy_discard_send_range(ms, pds, fixup_start_addr,
host_ratio);
}
/* Clean up the bitmap */
for (page = fixup_start_addr;
page < fixup_start_addr + host_ratio; page++) {
/* All pages in this host page are now not sent */
set_bit(page, unsentmap);
/*
* 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);
}
}
if (unsent_pass) {
/* Find the next sent page for the next iteration */
run_start = find_next_zero_bit(unsentmap, pages, run_start);
} else {
/* Find the next dirty page for the next iteration */
run_start = find_next_bit(bitmap, pages, run_start);
}
}
}
/**
* postcopy_chuck_hostpages: discrad 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)
{
PostcopyDiscardState *pds =
postcopy_discard_send_init(ms, block->idstr);
/* First pass: Discard all partially sent host pages */
postcopy_chunk_hostpages_pass(ms, true, block, pds);
/*
* Second pass: Ensure that all partially dirty host pages are made
* fully dirty.
*/
postcopy_chunk_hostpages_pass(ms, false, block, pds);
postcopy_discard_send_finish(ms, pds);
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();
/* 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;
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
unsigned long pages = block->used_length >> TARGET_PAGE_BITS;
unsigned long *bitmap = block->bmap;
unsigned long *unsentmap = block->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;
}
/* Deal with TPS != HPS and huge pages */
ret = postcopy_chunk_hostpages(ms, block);
if (ret) {
rcu_read_unlock();
return ret;
}
/*
* Update the unsentmap to be unsentmap = unsentmap | dirty
*/
bitmap_or(unsentmap, unsentmap, bitmap, pages);
#ifdef DEBUG_POSTCOPY
ram_debug_dump_bitmap(unsentmap, true, pages);
#endif
}
trace_ram_postcopy_send_discard_bitmap();
ret = postcopy_each_ram_send_discard(ms);
rcu_read_unlock();
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)
{
int ret = -1;
trace_ram_discard_range(rbname, start, length);
rcu_read_lock();
RAMBlock *rb = qemu_ram_block_by_name(rbname);
if (!rb) {
error_report("ram_discard_range: Failed to find block '%s'", rbname);
goto err;
}
ret = ram_block_discard_range(rb, start, length);
err:
rcu_read_unlock();
return ret;
}
static int ram_state_init(RAMState **rsp)
{
*rsp = g_new0(RAMState, 1);
qemu_mutex_init(&(*rsp)->bitmap_mutex);
qemu_mutex_init(&(*rsp)->src_page_req_mutex);
QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
if (migrate_use_xbzrle()) {
XBZRLE_cache_lock();
XBZRLE.zero_target_page = g_malloc0(TARGET_PAGE_SIZE);
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");
g_free(*rsp);
*rsp = NULL;
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");
g_free(*rsp);
*rsp = NULL;
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;
g_free(*rsp);
*rsp = NULL;
return -1;
}
}
/* For memory_global_dirty_log_start below. */
qemu_mutex_lock_iothread();
qemu_mutex_lock_ramlist();
rcu_read_lock();
ram_state_reset(*rsp);
/* Skip setting bitmap if there is no RAM */
if (ram_bytes_total()) {
RAMBlock *block;
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
unsigned long pages = block->max_length >> TARGET_PAGE_BITS;
block->bmap = bitmap_new(pages);
bitmap_set(block->bmap, 0, pages);
if (migrate_postcopy_ram()) {
block->unsentmap = bitmap_new(pages);
bitmap_set(block->unsentmap, 0, pages);
}
}
}
/*
* Count the total number of pages used by ram blocks not including any
* gaps due to alignment or unplugs.
*/
(*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
memory_global_dirty_log_start();
migration_bitmap_sync(*rsp);
qemu_mutex_unlock_ramlist();
qemu_mutex_unlock_iothread();
rcu_read_unlock();
return 0;
}
/*
* 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;
/* migration has already setup the bitmap, reuse it. */
if (!migration_in_colo_state()) {
if (ram_state_init(rsp) != 0) {
return -1;
}
}
(*rsp)->f = f;
rcu_read_lock();
qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
RAMBLOCK_FOREACH(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);
}
}
rcu_read_unlock();
compress_threads_save_setup();
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;
}
/**
* 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;
int i;
int64_t t0;
int done = 0;
rcu_read_lock();
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) {
int pages;
pages = ram_find_and_save_block(rs, false);
/* no more pages to sent */
if (pages == 0) {
done = 1;
break;
}
rs->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) {
trace_ram_save_iterate_big_wait(t1, i);
break;
}
}
i++;
}
flush_compressed_data(rs);
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);
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
*
* 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;
rcu_read_lock();
if (!migration_in_postcopy()) {
migration_bitmap_sync(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;
}
}
flush_compressed_data(rs);
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)
{
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();
rcu_read_lock();
migration_bitmap_sync(rs);
rcu_read_unlock();
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 */
*postcopiable_pending += remaining_size;
} else {
*non_postcopiable_pending += 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;
}
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;
}
/**
* 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);
}
}
static void *do_data_decompress(void *opaque)
{
DecompressParam *param = opaque;
unsigned long pagesize;
uint8_t *des;
int len;
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;
/* 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 *)des, &pagesize,
(const Bytef *)param->compbuf, len);
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 void wait_for_decompress_done(void)
{
int idx, thread_count;
if (!migrate_use_compression()) {
return;
}
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);
}
static void compress_threads_load_setup(void)
{
int i, thread_count;
if (!migrate_use_compression()) {
return;
}
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);
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));
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);
}
}
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++) {
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++) {
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);
decompress_threads = NULL;
decomp_param = NULL;
}
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);
}
/**
* 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)
{
xbzrle_load_setup();
compress_threads_load_setup();
return 0;
}
static int ram_load_cleanup(void *opaque)
{
xbzrle_load_cleanup();
compress_threads_load_cleanup();
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)
{
unsigned long ram_pages = last_ram_page();
return postcopy_ram_incoming_init(mis, ram_pages);
}
/**
* 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 matching_page_sizes = false;
MigrationIncomingState *mis = migration_incoming_get_current();
/* Temporary page that is later 'placed' */
void *postcopy_host_page = postcopy_get_tmp_page(mis);
void *last_host = NULL;
bool all_zero = false;
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;
addr = qemu_get_be64(f);
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)) {
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;
}
matching_page_sizes = 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 order.
*/
page_buffer = postcopy_host_page +
((uintptr_t)host & (block->page_size - 1));
/* If all TP are zero then we can optimise the place */
if (!((uintptr_t)host & (block->page_size - 1))) {
all_zero = true;
} else {
/* not the 1st TP within the HP */
if (host != (last_host + TARGET_PAGE_SIZE)) {
error_report("Non-sequential target page %p/%p",
host, last_host);
ret = -EINVAL;
break;
}
}
/*
* If it's the last part of a host page then we place the host
* page
*/
place_needed = (((uintptr_t)host + TARGET_PAGE_SIZE) &
(block->page_size - 1)) == 0;
place_source = postcopy_host_page;
}
last_host = host;
switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
case RAM_SAVE_FLAG_ZERO:
ch = qemu_get_byte(f);
memset(page_buffer, ch, TARGET_PAGE_SIZE);
if (ch) {
all_zero = false;
}
break;
case RAM_SAVE_FLAG_PAGE:
all_zero = false;
if (!place_needed || !matching_page_sizes) {
qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE);
} else {
/* Avoids the qemu_file copy during postcopy, which is
* going to do a copy later; can only do it when we
* do this read in one go (matching page sizes)
*/
qemu_get_buffer_in_place(f, (uint8_t **)&place_source,
TARGET_PAGE_SIZE);
}
break;
case RAM_SAVE_FLAG_EOS:
/* normal exit */
break;
default:
error_report("Unknown combination of migration flags: %#x"
" (postcopy mode)", flags);
ret = -EINVAL;
}
if (place_needed) {
/* This gets called at the last target page in the host page */
void *place_dest = host + TARGET_PAGE_SIZE - block->page_size;
if (all_zero) {
ret = postcopy_place_page_zero(mis, place_dest,
block->page_size);
} else {
ret = postcopy_place_page(mis, place_dest,
place_source, block->page_size);
}
}
if (!ret) {
ret = qemu_file_get_error(f);
}
}
return ret;
}
static int ram_load(QEMUFile *f, void *opaque, int version_id)
{
int flags = 0, ret = 0, invalid_flags = 0;
static uint64_t seq_iter;
int len = 0;
/*
* If system is running in postcopy mode, page inserts to host memory must
* be atomic
*/
bool postcopy_running = postcopy_state_get() >= POSTCOPY_INCOMING_LISTENING;
/* ADVISE is earlier, it shows the source has the postcopy capability on */
bool postcopy_advised = postcopy_state_get() >= POSTCOPY_INCOMING_ADVISE;
seq_iter++;
if (version_id != 4) {
ret = -EINVAL;
}
if (!migrate_use_compression()) {
invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE;
}
/* 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();
if (postcopy_running) {
ret = ram_load_postcopy(f);
}
while (!postcopy_running && !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 & 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);
host = host_from_ram_block_offset(block, addr);
if (!host) {
error_report("Illegal RAM offset " RAM_ADDR_FMT, addr);
ret = -EINVAL;
break;
}
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) {
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;
}
}
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 */
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);
}
}
wait_for_decompress_done();
rcu_read_unlock();
trace_ram_load_complete(ret, seq_iter);
return ret;
}
static bool ram_has_postcopy(void *opaque)
{
return migrate_postcopy_ram();
}
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,
};
void ram_mig_init(void)
{
qemu_mutex_init(&XBZRLE.lock);
register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, &ram_state);
}
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