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qemu/migration/ram.c
Peter Xu 7d00ee6ad6 migration: provide ram_state_init() 
The old ram_state_init() is not really initializing the RAMState only,
but including lots of other stuff that is RAM-related.  Renaming it to
ram_init_all().  Instead, provide a real ram_state_init().

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2017-10-23 18:03:34 +02:00

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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 "qapi/qmp/qerror.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
* @errp: set *errp if the check failed, with reason
*/
int64_t xbzrle_cache_resize(int64_t new_size, Error **errp)
{
PageCache *new_cache;
int64_t ret;
/* Check for truncation */
if (new_size != (size_t)new_size) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"exceeding address space");
return -1;
}
/* Cache should not be larger than guest ram size */
if (new_size > ram_bytes_total()) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
"exceeds guest ram 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, errp);
if (!new_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_try_new0(RAMState, 1);
if (!*rsp) {
error_report("%s: Init ramstate fail", __func__);
return -1;
}
qemu_mutex_init(&(*rsp)->bitmap_mutex);
qemu_mutex_init(&(*rsp)->src_page_req_mutex);
QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
/*
* Count the total number of pages used by ram blocks not including any
* gaps due to alignment or unplugs.
*/
(*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
ram_state_reset(*rsp);
return 0;
}
static int ram_init_all(RAMState **rsp)
{
Error *local_err = NULL;
if (ram_state_init(rsp)) {
return -1;
}
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, &local_err);
if (!XBZRLE.cache) {
XBZRLE_cache_unlock();
error_report_err(local_err);
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();
/* 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);
}
}
}
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_init_all(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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