Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20180425a' into staging

Migration pull for 2.13

Alexey Perevalov postcopy blocktime statistics
Xiao Guangrong's compression performance improvements

# gpg: Signature made Wed 25 Apr 2018 20:21:13 BST
# gpg:                using RSA key 0516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>"
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20180425a:
  migration: remove ram_save_compressed_page()
  migration: introduce save_normal_page()
  migration: move calling save_zero_page to the common place
  migration: move calling control_save_page to the common place
  migration: move some code to ram_save_host_page
  migration: introduce control_save_page()
  migration: detect compression and decompression errors
  migration: stop decompression to allocate and free memory frequently
  migration: stop compression to allocate and free memory frequently
  migration: stop compressing page in migration thread
  migration: add postcopy total blocktime into query-migrate
  migration: add blocktime calculation into migration-test
  migration: postcopy_blocktime documentation
  migration: calculate vCPU blocktime on dst side
  migration: add postcopy blocktime ctx into MigrationIncomingState
  migration: introduce postcopy-blocktime capability

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

11 files changed, 716 insertions, 215 deletions

diff --git a/docs/devel/migration.rst b/docs/devel/migration.rst
index e32b087..9342a8a 100644
--- a/docs/devel/migration.rst
+++ b/docs/devel/migration.rst
@@ -401,6 +401,20 @@ will now cause the transition from precopy to postcopy.
 It can be issued immediately after migration is started or any
 time later on.  Issuing it after the end of a migration is harmless.
 
+Blocktime is a postcopy live migration metric, intended to show how
+long the vCPU was in state of interruptable sleep due to pagefault.
+That metric is calculated both for all vCPUs as overlapped value, and
+separately for each vCPU. These values are calculated on destination
+side.  To enable postcopy blocktime calculation, enter following
+command on destination monitor:
+
+``migrate_set_capability postcopy-blocktime on``
+
+Postcopy blocktime can be retrieved by query-migrate qmp command.
+postcopy-blocktime value of qmp command will show overlapped blocking
+time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
+time per vCPU.
+
 .. note::
   During the postcopy phase, the bandwidth limits set using
   ``migrate_set_speed`` is ignored (to avoid delaying requested pages that
diff --git a/hmp.c b/hmp.c
index a25c7bd..898e25f 100644
--- a/hmp.c
+++ b/hmp.c
@@ -274,6 +274,21 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->cpu_throttle_percentage);
     }
 
+    if (info->has_postcopy_blocktime) {
+        monitor_printf(mon, "postcopy blocktime: %u\n",
+                       info->postcopy_blocktime);
+    }
+
+    if (info->has_postcopy_vcpu_blocktime) {
+        Visitor *v;
+        char *str;
+        v = string_output_visitor_new(false, &str);
+        visit_type_uint32List(v, NULL, &info->postcopy_vcpu_blocktime, NULL);
+        visit_complete(v, &str);
+        monitor_printf(mon, "postcopy vcpu blocktime: %s\n", str);
+        g_free(str);
+        visit_free(v);
+    }
     qapi_free_MigrationInfo(info);
     qapi_free_MigrationCapabilityStatusList(caps);
 }
diff --git a/migration/migration.c b/migration/migration.c
index 52a5092..0bdb28e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -630,14 +630,15 @@ static void populate_disk_info(MigrationInfo *info)
     }
 }
 
-MigrationInfo *qmp_query_migrate(Error **errp)
+static void fill_source_migration_info(MigrationInfo *info)
 {
-    MigrationInfo *info = g_malloc0(sizeof(*info));
     MigrationState *s = migrate_get_current();
 
     switch (s->state) {
     case MIGRATION_STATUS_NONE:
         /* no migration has happened ever */
+        /* do not overwrite destination migration status */
+        return;
         break;
     case MIGRATION_STATUS_SETUP:
         info->has_status = true;
@@ -688,8 +689,6 @@ MigrationInfo *qmp_query_migrate(Error **errp)
         break;
     }
     info->status = s->state;
-
-    return info;
 }
 
 /**
@@ -753,6 +752,41 @@ static bool migrate_caps_check(bool *cap_list,
     return true;
 }
 
+static void fill_destination_migration_info(MigrationInfo *info)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+
+    switch (mis->state) {
+    case MIGRATION_STATUS_NONE:
+        return;
+        break;
+    case MIGRATION_STATUS_SETUP:
+    case MIGRATION_STATUS_CANCELLING:
+    case MIGRATION_STATUS_CANCELLED:
+    case MIGRATION_STATUS_ACTIVE:
+    case MIGRATION_STATUS_POSTCOPY_ACTIVE:
+    case MIGRATION_STATUS_FAILED:
+    case MIGRATION_STATUS_COLO:
+        info->has_status = true;
+        break;
+    case MIGRATION_STATUS_COMPLETED:
+        info->has_status = true;
+        fill_destination_postcopy_migration_info(info);
+        break;
+    }
+    info->status = mis->state;
+}
+
+MigrationInfo *qmp_query_migrate(Error **errp)
+{
+    MigrationInfo *info = g_malloc0(sizeof(*info));
+
+    fill_destination_migration_info(info);
+    fill_source_migration_info(info);
+
+    return info;
+}
+
 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
                                   Error **errp)
 {
@@ -1541,6 +1575,15 @@ bool migrate_zero_blocks(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 }
 
+bool migrate_postcopy_blocktime(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME];
+}
+
 bool migrate_use_compression(void)
 {
     MigrationState *s;
diff --git a/migration/migration.h b/migration/migration.h
index 8d2f320..7c69598 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -22,6 +22,8 @@
 #include "hw/qdev.h"
 #include "io/channel.h"
 
+struct PostcopyBlocktimeContext;
+
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
@@ -65,10 +67,20 @@ struct MigrationIncomingState {
     /* The coroutine we should enter (back) after failover */
     Coroutine *migration_incoming_co;
     QemuSemaphore colo_incoming_sem;
+
+    /*
+     * PostcopyBlocktimeContext to keep information for postcopy
+     * live migration, to calculate vCPU block time
+     * */
+    struct PostcopyBlocktimeContext *blocktime_ctx;
 };
 
 MigrationIncomingState *migration_incoming_get_current(void);
 void migration_incoming_state_destroy(void);
+/*
+ * Functions to work with blocktime context
+ */
+void fill_destination_postcopy_migration_info(MigrationInfo *info);
 
 #define TYPE_MIGRATION "migration"
 
@@ -230,6 +242,7 @@ int migrate_compress_level(void);
 int migrate_compress_threads(void);
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
+bool migrate_postcopy_blocktime(void);
 
 /* Sending on the return path - generic and then for each message type */
 void migrate_send_rp_shut(MigrationIncomingState *mis,
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 4a0b33b..8ceeaa2 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -90,6 +90,103 @@ int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp)
 #include <sys/eventfd.h>
 #include <linux/userfaultfd.h>
 
+typedef struct PostcopyBlocktimeContext {
+    /* time when page fault initiated per vCPU */
+    uint32_t *page_fault_vcpu_time;
+    /* page address per vCPU */
+    uintptr_t *vcpu_addr;
+    uint32_t total_blocktime;
+    /* blocktime per vCPU */
+    uint32_t *vcpu_blocktime;
+    /* point in time when last page fault was initiated */
+    uint32_t last_begin;
+    /* number of vCPU are suspended */
+    int smp_cpus_down;
+    uint64_t start_time;
+
+    /*
+     * Handler for exit event, necessary for
+     * releasing whole blocktime_ctx
+     */
+    Notifier exit_notifier;
+} PostcopyBlocktimeContext;
+
+static void destroy_blocktime_context(struct PostcopyBlocktimeContext *ctx)
+{
+    g_free(ctx->page_fault_vcpu_time);
+    g_free(ctx->vcpu_addr);
+    g_free(ctx->vcpu_blocktime);
+    g_free(ctx);
+}
+
+static void migration_exit_cb(Notifier *n, void *data)
+{
+    PostcopyBlocktimeContext *ctx = container_of(n, PostcopyBlocktimeContext,
+                                                 exit_notifier);
+    destroy_blocktime_context(ctx);
+}
+
+static struct PostcopyBlocktimeContext *blocktime_context_new(void)
+{
+    PostcopyBlocktimeContext *ctx = g_new0(PostcopyBlocktimeContext, 1);
+    ctx->page_fault_vcpu_time = g_new0(uint32_t, smp_cpus);
+    ctx->vcpu_addr = g_new0(uintptr_t, smp_cpus);
+    ctx->vcpu_blocktime = g_new0(uint32_t, smp_cpus);
+
+    ctx->exit_notifier.notify = migration_exit_cb;
+    ctx->start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+    qemu_add_exit_notifier(&ctx->exit_notifier);
+    return ctx;
+}
+
+static uint32List *get_vcpu_blocktime_list(PostcopyBlocktimeContext *ctx)
+{
+    uint32List *list = NULL, *entry = NULL;
+    int i;
+
+    for (i = smp_cpus - 1; i >= 0; i--) {
+        entry = g_new0(uint32List, 1);
+        entry->value = ctx->vcpu_blocktime[i];
+        entry->next = list;
+        list = entry;
+    }
+
+    return list;
+}
+
+/*
+ * This function just populates MigrationInfo from postcopy's
+ * blocktime context. It will not populate MigrationInfo,
+ * unless postcopy-blocktime capability was set.
+ *
+ * @info: pointer to MigrationInfo to populate
+ */
+void fill_destination_postcopy_migration_info(MigrationInfo *info)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    PostcopyBlocktimeContext *bc = mis->blocktime_ctx;
+
+    if (!bc) {
+        return;
+    }
+
+    info->has_postcopy_blocktime = true;
+    info->postcopy_blocktime = bc->total_blocktime;
+    info->has_postcopy_vcpu_blocktime = true;
+    info->postcopy_vcpu_blocktime = get_vcpu_blocktime_list(bc);
+}
+
+static uint32_t get_postcopy_total_blocktime(void)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    PostcopyBlocktimeContext *bc = mis->blocktime_ctx;
+
+    if (!bc) {
+        return 0;
+    }
+
+    return bc->total_blocktime;
+}
 
 /**
  * receive_ufd_features: check userfault fd features, to request only supported
@@ -182,6 +279,19 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis)
         }
     }
 
+#ifdef UFFD_FEATURE_THREAD_ID
+    if (migrate_postcopy_blocktime() && mis &&
+        UFFD_FEATURE_THREAD_ID & supported_features) {
+        /* kernel supports that feature */
+        /* don't create blocktime_context if it exists */
+        if (!mis->blocktime_ctx) {
+            mis->blocktime_ctx = blocktime_context_new();
+        }
+
+        asked_features |= UFFD_FEATURE_THREAD_ID;
+    }
+#endif
+
     /*
      * request features, even if asked_features is 0, due to
      * kernel expects UFFD_API before UFFDIO_REGISTER, per
@@ -451,6 +561,9 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
         munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
         mis->postcopy_tmp_zero_page = NULL;
     }
+    trace_postcopy_ram_incoming_cleanup_blocktime(
+            get_postcopy_total_blocktime());
+
     trace_postcopy_ram_incoming_cleanup_exit();
     return 0;
 }
@@ -575,6 +688,148 @@ int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
     return 0;
 }
 
+static int get_mem_fault_cpu_index(uint32_t pid)
+{
+    CPUState *cpu_iter;
+
+    CPU_FOREACH(cpu_iter) {
+        if (cpu_iter->thread_id == pid) {
+            trace_get_mem_fault_cpu_index(cpu_iter->cpu_index, pid);
+            return cpu_iter->cpu_index;
+        }
+    }
+    trace_get_mem_fault_cpu_index(-1, pid);
+    return -1;
+}
+
+static uint32_t get_low_time_offset(PostcopyBlocktimeContext *dc)
+{
+    int64_t start_time_offset = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) -
+                                    dc->start_time;
+    return start_time_offset < 1 ? 1 : start_time_offset & UINT32_MAX;
+}
+
+/*
+ * This function is being called when pagefault occurs. It
+ * tracks down vCPU blocking time.
+ *
+ * @addr: faulted host virtual address
+ * @ptid: faulted process thread id
+ * @rb: ramblock appropriate to addr
+ */
+static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
+                                          RAMBlock *rb)
+{
+    int cpu, already_received;
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    PostcopyBlocktimeContext *dc = mis->blocktime_ctx;
+    uint32_t low_time_offset;
+
+    if (!dc || ptid == 0) {
+        return;
+    }
+    cpu = get_mem_fault_cpu_index(ptid);
+    if (cpu < 0) {
+        return;
+    }
+
+    low_time_offset = get_low_time_offset(dc);
+    if (dc->vcpu_addr[cpu] == 0) {
+        atomic_inc(&dc->smp_cpus_down);
+    }
+
+    atomic_xchg(&dc->last_begin, low_time_offset);
+    atomic_xchg(&dc->page_fault_vcpu_time[cpu], low_time_offset);
+    atomic_xchg(&dc->vcpu_addr[cpu], addr);
+
+    /* check it here, not at the begining of the function,
+     * due to, check could accur early than bitmap_set in
+     * qemu_ufd_copy_ioctl */
+    already_received = ramblock_recv_bitmap_test(rb, (void *)addr);
+    if (already_received) {
+        atomic_xchg(&dc->vcpu_addr[cpu], 0);
+        atomic_xchg(&dc->page_fault_vcpu_time[cpu], 0);
+        atomic_dec(&dc->smp_cpus_down);
+    }
+    trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu],
+                                        cpu, already_received);
+}
+
+/*
+ *  This function just provide calculated blocktime per cpu and trace it.
+ *  Total blocktime is calculated in mark_postcopy_blocktime_end.
+ *
+ *
+ * Assume we have 3 CPU
+ *
+ *      S1        E1           S1               E1
+ * -----***********------------xxx***************------------------------> CPU1
+ *
+ *             S2                E2
+ * ------------****************xxx---------------------------------------> CPU2
+ *
+ *                         S3            E3
+ * ------------------------****xxx********-------------------------------> CPU3
+ *
+ * We have sequence S1,S2,E1,S3,S1,E2,E3,E1
+ * S2,E1 - doesn't match condition due to sequence S1,S2,E1 doesn't include CPU3
+ * S3,S1,E2 - sequence includes all CPUs, in this case overlap will be S1,E2 -
+ *            it's a part of total blocktime.
+ * S1 - here is last_begin
+ * Legend of the picture is following:
+ *              * - means blocktime per vCPU
+ *              x - means overlapped blocktime (total blocktime)
+ *
+ * @addr: host virtual address
+ */
+static void mark_postcopy_blocktime_end(uintptr_t addr)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    PostcopyBlocktimeContext *dc = mis->blocktime_ctx;
+    int i, affected_cpu = 0;
+    bool vcpu_total_blocktime = false;
+    uint32_t read_vcpu_time, low_time_offset;
+
+    if (!dc) {
+        return;
+    }
+
+    low_time_offset = get_low_time_offset(dc);
+    /* lookup cpu, to clear it,
+     * that algorithm looks straighforward, but it's not
+     * optimal, more optimal algorithm is keeping tree or hash
+     * where key is address value is a list of  */
+    for (i = 0; i < smp_cpus; i++) {
+        uint32_t vcpu_blocktime = 0;
+
+        read_vcpu_time = atomic_fetch_add(&dc->page_fault_vcpu_time[i], 0);
+        if (atomic_fetch_add(&dc->vcpu_addr[i], 0) != addr ||
+            read_vcpu_time == 0) {
+            continue;
+        }
+        atomic_xchg(&dc->vcpu_addr[i], 0);
+        vcpu_blocktime = low_time_offset - read_vcpu_time;
+        affected_cpu += 1;
+        /* we need to know is that mark_postcopy_end was due to
+         * faulted page, another possible case it's prefetched
+         * page and in that case we shouldn't be here */
+        if (!vcpu_total_blocktime &&
+            atomic_fetch_add(&dc->smp_cpus_down, 0) == smp_cpus) {
+            vcpu_total_blocktime = true;
+        }
+        /* continue cycle, due to one page could affect several vCPUs */
+        dc->vcpu_blocktime[i] += vcpu_blocktime;
+    }
+
+    atomic_sub(&dc->smp_cpus_down, affected_cpu);
+    if (vcpu_total_blocktime) {
+        dc->total_blocktime += low_time_offset - atomic_fetch_add(
+                &dc->last_begin, 0);
+    }
+    trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime,
+                                      affected_cpu);
+}
+
 /*
  * Handle faults detected by the USERFAULT markings
  */
@@ -681,7 +936,12 @@ static void *postcopy_ram_fault_thread(void *opaque)
             rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
             trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
                                                 qemu_ram_get_idstr(rb),
-                                                rb_offset);
+                                                rb_offset,
+                                                msg.arg.pagefault.feat.ptid);
+            mark_postcopy_blocktime_begin(
+                    (uintptr_t)(msg.arg.pagefault.address),
+                                msg.arg.pagefault.feat.ptid, rb);
+
             /*
              * Send the request to the source - we want to request one
              * of our host page sizes (which is >= TPS)
@@ -829,6 +1089,8 @@ static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr,
     if (!ret) {
         ramblock_recv_bitmap_set_range(rb, host_addr,
                                        pagesize / qemu_target_page_size());
+        mark_postcopy_blocktime_end((uintptr_t)host_addr);
+
     }
     return ret;
 }
@@ -947,6 +1209,10 @@ void *postcopy_get_tmp_page(MigrationIncomingState *mis)
 
 #else
 /* No target OS support, stubs just fail */
+void fill_destination_postcopy_migration_info(MigrationInfo *info)
+{
+}
+
 bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
 {
     error_report("%s: No OS support", __func__);
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index bb63c77..0463f4c 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -658,8 +658,32 @@ uint64_t qemu_get_be64(QEMUFile *f)
     return v;
 }
 
-/* Compress size bytes of data start at p with specific compression
- * level and store the compressed data to the buffer of f.
+/* return the size after compression, or negative value on error */
+static int qemu_compress_data(z_stream *stream, uint8_t *dest, size_t dest_len,
+                              const uint8_t *source, size_t source_len)
+{
+    int err;
+
+    err = deflateReset(stream);
+    if (err != Z_OK) {
+        return -1;
+    }
+
+    stream->avail_in = source_len;
+    stream->next_in = (uint8_t *)source;
+    stream->avail_out = dest_len;
+    stream->next_out = dest;
+
+    err = deflate(stream, Z_FINISH);
+    if (err != Z_STREAM_END) {
+        return -1;
+    }
+
+    return stream->next_out - dest;
+}
+
+/* Compress size bytes of data start at p and store the compressed
+ * data to the buffer of f.
  *
  * When f is not writable, return -1 if f has no space to save the
  * compressed data.
@@ -667,9 +691,8 @@ uint64_t qemu_get_be64(QEMUFile *f)
  * do fflush first, if f still has no space to save the compressed
  * data, return -1.
  */
-
-ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size,
-                                  int level)
+ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
+                                  const uint8_t *p, size_t size)
 {
     ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
 
@@ -683,11 +706,13 @@ ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size,
             return -1;
         }
     }
-    if (compress2(f->buf + f->buf_index + sizeof(int32_t), (uLongf *)&blen,
-                  (Bytef *)p, size, level) != Z_OK) {
-        error_report("Compress Failed!");
-        return 0;
+
+    blen = qemu_compress_data(stream, f->buf + f->buf_index + sizeof(int32_t),
+                              blen, p, size);
+    if (blen < 0) {
+        return -1;
     }
+
     qemu_put_be32(f, blen);
     if (f->ops->writev_buffer) {
         add_to_iovec(f, f->buf + f->buf_index, blen, false);
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index f4f356a..2ccfcfb 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -25,6 +25,8 @@
 #ifndef MIGRATION_QEMU_FILE_H
 #define MIGRATION_QEMU_FILE_H
 
+#include <zlib.h>
+
 /* Read a chunk of data from a file at the given position.  The pos argument
  * can be ignored if the file is only be used for streaming.  The number of
  * bytes actually read should be returned.
@@ -132,8 +134,8 @@ bool qemu_file_is_writable(QEMUFile *f);
 
 size_t qemu_peek_buffer(QEMUFile *f, uint8_t **buf, size_t size, size_t offset);
 size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size);
-ssize_t qemu_put_compression_data(QEMUFile *f, const uint8_t *p, size_t size,
-                                  int level);
+ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
+                                  const uint8_t *p, size_t size);
 int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src);
 
 /*
diff --git a/migration/ram.c b/migration/ram.c
index 0e90efa..912810c 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -269,6 +269,10 @@ struct CompressParam {
     QemuCond cond;
     RAMBlock *block;
     ram_addr_t offset;
+
+    /* internally used fields */
+    z_stream stream;
+    uint8_t *originbuf;
 };
 typedef struct CompressParam CompressParam;
 
@@ -280,6 +284,7 @@ struct DecompressParam {
     void *des;
     uint8_t *compbuf;
     int len;
+    z_stream stream;
 };
 typedef struct DecompressParam DecompressParam;
 
@@ -294,13 +299,14 @@ static QemuCond comp_done_cond;
 /* The empty QEMUFileOps will be used by file in CompressParam */
 static const QEMUFileOps empty_ops = { };
 
+static QEMUFile *decomp_file;
 static DecompressParam *decomp_param;
 static QemuThread *decompress_threads;
 static QemuMutex decomp_done_lock;
 static QemuCond decomp_done_cond;
 
-static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
-                                ram_addr_t offset);
+static int do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
+                                ram_addr_t offset, uint8_t *source_buf);
 
 static void *do_data_compress(void *opaque)
 {
@@ -316,7 +322,8 @@ static void *do_data_compress(void *opaque)
             param->block = NULL;
             qemu_mutex_unlock(&param->mutex);
 
-            do_compress_ram_page(param->file, block, offset);
+            do_compress_ram_page(param->file, &param->stream, block, offset,
+                                 param->originbuf);
 
             qemu_mutex_lock(&comp_done_lock);
             param->done = true;
@@ -357,10 +364,20 @@ static void compress_threads_save_cleanup(void)
     terminate_compression_threads();
     thread_count = migrate_compress_threads();
     for (i = 0; i < thread_count; i++) {
+        /*
+         * we use it as a indicator which shows if the thread is
+         * properly init'd or not
+         */
+        if (!comp_param[i].file) {
+            break;
+        }
         qemu_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);
+        deflateEnd(&comp_param[i].stream);
+        g_free(comp_param[i].originbuf);
+        qemu_fclose(comp_param[i].file);
+        comp_param[i].file = NULL;
     }
     qemu_mutex_destroy(&comp_done_lock);
     qemu_cond_destroy(&comp_done_cond);
@@ -370,12 +387,12 @@ static void compress_threads_save_cleanup(void)
     comp_param = NULL;
 }
 
-static void compress_threads_save_setup(void)
+static int compress_threads_save_setup(void)
 {
     int i, thread_count;
 
     if (!migrate_use_compression()) {
-        return;
+        return 0;
     }
     thread_count = migrate_compress_threads();
     compress_threads = g_new0(QemuThread, thread_count);
@@ -383,6 +400,17 @@ static void compress_threads_save_setup(void)
     qemu_cond_init(&comp_done_cond);
     qemu_mutex_init(&comp_done_lock);
     for (i = 0; i < thread_count; i++) {
+        comp_param[i].originbuf = g_try_malloc(TARGET_PAGE_SIZE);
+        if (!comp_param[i].originbuf) {
+            goto exit;
+        }
+
+        if (deflateInit(&comp_param[i].stream,
+                        migrate_compress_level()) != Z_OK) {
+            g_free(comp_param[i].originbuf);
+            goto exit;
+        }
+
         /* comp_param[i].file is just used as a dummy buffer to save data,
          * set its ops to empty.
          */
@@ -395,6 +423,11 @@ static void compress_threads_save_setup(void)
                            do_data_compress, comp_param + i,
                            QEMU_THREAD_JOINABLE);
     }
+    return 0;
+
+exit:
+    compress_threads_save_cleanup();
+    return -1;
 }
 
 /* Multiple fd's */
@@ -941,6 +974,72 @@ static void ram_release_pages(const char *rbname, uint64_t offset, int pages)
     ram_discard_range(rbname, offset, pages << TARGET_PAGE_BITS);
 }
 
+/*
+ * @pages: the number of pages written by the control path,
+ *        < 0 - error
+ *        > 0 - number of pages written
+ *
+ * Return true if the pages has been saved, otherwise false is returned.
+ */
+static bool control_save_page(RAMState *rs, RAMBlock *block, ram_addr_t offset,
+                              int *pages)
+{
+    uint64_t bytes_xmit = 0;
+    int ret;
+
+    *pages = -1;
+    ret = ram_control_save_page(rs->f, block->offset, offset, TARGET_PAGE_SIZE,
+                                &bytes_xmit);
+    if (ret == RAM_SAVE_CONTROL_NOT_SUPP) {
+        return false;
+    }
+
+    if (bytes_xmit) {
+        ram_counters.transferred += bytes_xmit;
+        *pages = 1;
+    }
+
+    if (ret == RAM_SAVE_CONTROL_DELAYED) {
+        return true;
+    }
+
+    if (bytes_xmit > 0) {
+        ram_counters.normal++;
+    } else if (bytes_xmit == 0) {
+        ram_counters.duplicate++;
+    }
+
+    return true;
+}
+
+/*
+ * directly send the page to the stream
+ *
+ * Returns the number of pages written.
+ *
+ * @rs: current RAM state
+ * @block: block that contains the page we want to send
+ * @offset: offset inside the block for the page
+ * @buf: the page to be sent
+ * @async: send to page asyncly
+ */
+static int save_normal_page(RAMState *rs, RAMBlock *block, ram_addr_t offset,
+                            uint8_t *buf, bool async)
+{
+    ram_counters.transferred += save_page_header(rs, rs->f, block,
+                                                 offset | RAM_SAVE_FLAG_PAGE);
+    if (async) {
+        qemu_put_buffer_async(rs->f, buf, TARGET_PAGE_SIZE,
+                              migrate_release_ram() &
+                              migration_in_postcopy());
+    } else {
+        qemu_put_buffer(rs->f, buf, TARGET_PAGE_SIZE);
+    }
+    ram_counters.transferred += TARGET_PAGE_SIZE;
+    ram_counters.normal++;
+    return 1;
+}
+
 /**
  * ram_save_page: send the given page to the stream
  *
@@ -957,73 +1056,31 @@ static void ram_release_pages(const char *rbname, uint64_t offset, int pages)
 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;
+    ram_addr_t current_addr = block->offset + offset;
 
     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);
-        if (pages > 0) {
-            /* Must let xbzrle know, otherwise a previous (now 0'd) cached
-             * page would be stale
+    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
              */
-            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;
-            }
+            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++;
+        pages = save_normal_page(rs, block, offset, p, send_async);
     }
 
     XBZRLE_cache_unlock();
@@ -1031,8 +1088,8 @@ static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)
     return pages;
 }
 
-static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
-                                ram_addr_t offset)
+static int do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
+                                ram_addr_t offset, uint8_t *source_buf)
 {
     RAMState *rs = ram_state;
     int bytes_sent, blen;
@@ -1040,8 +1097,14 @@ static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
 
     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());
+
+    /*
+     * copy it to a internal buffer to avoid it being modified by VM
+     * so that we can catch up the error during compression and
+     * decompression
+     */
+    memcpy(source_buf, p, TARGET_PAGE_SIZE);
+    blen = qemu_put_compression_data(f, stream, source_buf, TARGET_PAGE_SIZE);
     if (blen < 0) {
         bytes_sent = 0;
         qemu_file_set_error(migrate_get_current()->to_dst_file, blen);
@@ -1122,83 +1185,6 @@ static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block,
 }
 
 /**
- * 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);
-            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);
-            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.
  *
@@ -1434,44 +1420,80 @@ err:
     return -1;
 }
 
+static bool save_page_use_compression(RAMState *rs)
+{
+    if (!migrate_use_compression()) {
+        return false;
+    }
+
+    /*
+     * If xbzrle is on, stop using the data compression after first
+     * round of migration even if compression is enabled. In theory,
+     * xbzrle can do better than compression.
+     */
+    if (rs->ram_bulk_stage || !migrate_use_xbzrle()) {
+        return true;
+    }
+
+    return false;
+}
+
 /**
  * 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;
+    RAMBlock *block = pss->block;
+    ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
+    int res;
 
-    /* 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 (control_save_page(rs, block, offset, &res)) {
+        return res;
+    }
+
+    /*
+     * 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 && save_page_use_compression(rs)) {
+            flush_compressed_data(rs);
+    }
+
+    res = save_zero_page(rs, block, offset);
+    if (res > 0) {
+        /* Must let xbzrle know, otherwise a previous (now 0'd) cached
+         * page would be stale
          */
-        if (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 (!save_page_use_compression(rs)) {
+            XBZRLE_cache_lock();
+            xbzrle_cache_zero_page(rs, block->offset + offset);
+            XBZRLE_cache_unlock();
         }
+        ram_release_pages(block->idstr, offset, res);
+        return res;
+    }
 
-        if (res < 0) {
-            return res;
-        }
-        if (pss->block->unsentmap) {
-            clear_bit(pss->page, pss->block->unsentmap);
-        }
+    /*
+     * Make sure the first page is sent out before other pages.
+     *
+     * we post it as normal page as compression will take much
+     * CPU resource.
+     */
+    if (block == rs->last_sent_block && save_page_use_compression(rs)) {
+        res = compress_page_with_multi_thread(rs, block, offset);
     }
 
-    return res;
+    return ram_save_page(rs, pss, last_stage);
 }
 
 /**
@@ -1500,12 +1522,22 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss,
         qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS;
 
     do {
+        /* Check the pages is dirty and if it is send it */
+        if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
+            pss->page++;
+            continue;
+        }
+
         tmppages = ram_save_target_page(rs, pss, last_stage);
         if (tmppages < 0) {
             return tmppages;
         }
 
         pages += tmppages;
+        if (pss->block->unsentmap) {
+            clear_bit(pss->page, pss->block->unsentmap);
+        }
+
         pss->page++;
     } while ((pss->page & (pagesize_bits - 1)) &&
              offset_in_ramblock(pss->block, pss->page << TARGET_PAGE_BITS));
@@ -2214,9 +2246,14 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     RAMState **rsp = opaque;
     RAMBlock *block;
 
+    if (compress_threads_save_setup()) {
+        return -1;
+    }
+
     /* migration has already setup the bitmap, reuse it. */
     if (!migration_in_colo_state()) {
         if (ram_init_all(rsp) != 0) {
+            compress_threads_save_cleanup();
             return -1;
         }
     }
@@ -2236,7 +2273,6 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     }
 
     rcu_read_unlock();
-    compress_threads_save_setup();
 
     ram_control_before_iterate(f, RAM_CONTROL_SETUP);
     ram_control_after_iterate(f, RAM_CONTROL_SETUP);
@@ -2501,12 +2537,37 @@ void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
     }
 }
 
+/* return the size after decompression, or negative value on error */
+static int
+qemu_uncompress_data(z_stream *stream, uint8_t *dest, size_t dest_len,
+                     const uint8_t *source, size_t source_len)
+{
+    int err;
+
+    err = inflateReset(stream);
+    if (err != Z_OK) {
+        return -1;
+    }
+
+    stream->avail_in = source_len;
+    stream->next_in = (uint8_t *)source;
+    stream->avail_out = dest_len;
+    stream->next_out = dest;
+
+    err = inflate(stream, Z_NO_FLUSH);
+    if (err != Z_STREAM_END) {
+        return -1;
+    }
+
+    return stream->total_out;
+}
+
 static void *do_data_decompress(void *opaque)
 {
     DecompressParam *param = opaque;
     unsigned long pagesize;
     uint8_t *des;
-    int len;
+    int len, ret;
 
     qemu_mutex_lock(&param->mutex);
     while (!param->quit) {
@@ -2517,13 +2578,13 @@ static void *do_data_decompress(void *opaque)
             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);
+
+            ret = qemu_uncompress_data(&param->stream, des, pagesize,
+                                       param->compbuf, len);
+            if (ret < 0) {
+                error_report("decompress data failed");
+                qemu_file_set_error(decomp_file, ret);
+            }
 
             qemu_mutex_lock(&decomp_done_lock);
             param->done = true;
@@ -2540,12 +2601,12 @@ static void *do_data_decompress(void *opaque)
     return NULL;
 }
 
-static void wait_for_decompress_done(void)
+static int wait_for_decompress_done(void)
 {
     int idx, thread_count;
 
     if (!migrate_use_compression()) {
-        return;
+        return 0;
     }
 
     thread_count = migrate_decompress_threads();
@@ -2556,30 +2617,7 @@ static void wait_for_decompress_done(void)
         }
     }
     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);
-    }
+    return qemu_file_get_error(decomp_file);
 }
 
 static void compress_threads_load_cleanup(void)
@@ -2591,21 +2629,70 @@ static void compress_threads_load_cleanup(void)
     }
     thread_count = migrate_decompress_threads();
     for (i = 0; i < thread_count; i++) {
+        /*
+         * we use it as a indicator which shows if the thread is
+         * properly init'd or not
+         */
+        if (!decomp_param[i].compbuf) {
+            break;
+        }
+
         qemu_mutex_lock(&decomp_param[i].mutex);
         decomp_param[i].quit = true;
         qemu_cond_signal(&decomp_param[i].cond);
         qemu_mutex_unlock(&decomp_param[i].mutex);
     }
     for (i = 0; i < thread_count; i++) {
+        if (!decomp_param[i].compbuf) {
+            break;
+        }
+
         qemu_thread_join(decompress_threads + i);
         qemu_mutex_destroy(&decomp_param[i].mutex);
         qemu_cond_destroy(&decomp_param[i].cond);
+        inflateEnd(&decomp_param[i].stream);
         g_free(decomp_param[i].compbuf);
+        decomp_param[i].compbuf = NULL;
     }
     g_free(decompress_threads);
     g_free(decomp_param);
     decompress_threads = NULL;
     decomp_param = NULL;
+    decomp_file = NULL;
+}
+
+static int compress_threads_load_setup(QEMUFile *f)
+{
+    int i, thread_count;
+
+    if (!migrate_use_compression()) {
+        return 0;
+    }
+
+    thread_count = migrate_decompress_threads();
+    decompress_threads = g_new0(QemuThread, thread_count);
+    decomp_param = g_new0(DecompressParam, thread_count);
+    qemu_mutex_init(&decomp_done_lock);
+    qemu_cond_init(&decomp_done_cond);
+    decomp_file = f;
+    for (i = 0; i < thread_count; i++) {
+        if (inflateInit(&decomp_param[i].stream) != Z_OK) {
+            goto exit;
+        }
+
+        decomp_param[i].compbuf = g_malloc0(compressBound(TARGET_PAGE_SIZE));
+        qemu_mutex_init(&decomp_param[i].mutex);
+        qemu_cond_init(&decomp_param[i].cond);
+        decomp_param[i].done = true;
+        decomp_param[i].quit = false;
+        qemu_thread_create(decompress_threads + i, "decompress",
+                           do_data_decompress, decomp_param + i,
+                           QEMU_THREAD_JOINABLE);
+    }
+    return 0;
+exit:
+    compress_threads_load_cleanup();
+    return -1;
 }
 
 static void decompress_data_with_multi_threads(QEMUFile *f,
@@ -2647,8 +2734,11 @@ static void decompress_data_with_multi_threads(QEMUFile *f,
  */
 static int ram_load_setup(QEMUFile *f, void *opaque)
 {
+    if (compress_threads_load_setup(f)) {
+        return -1;
+    }
+
     xbzrle_load_setup();
-    compress_threads_load_setup();
     ramblock_recv_map_init();
     return 0;
 }
@@ -2999,7 +3089,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
         }
     }
 
-    wait_for_decompress_done();
+    ret |= wait_for_decompress_done();
     rcu_read_unlock();
     trace_ram_load_complete(ret, seq_iter);
     return ret;
diff --git a/migration/trace-events b/migration/trace-events
index a180d7b..d6be74b 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -115,6 +115,8 @@ process_incoming_migration_co_end(int ret, int ps) "ret=%d postcopy-state=%d"
 process_incoming_migration_co_postcopy_end_main(void) ""
 migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
 migration_set_outgoing_channel(void *ioc, const char *ioctype, const char *hostname, void *err)  "ioc=%p ioctype=%s hostname=%s err=%p"
+mark_postcopy_blocktime_begin(uint64_t addr, void *dd, uint32_t time, int cpu, int received) "addr: 0x%" PRIx64 ", dd: %p, time: %u, cpu: %d, already_received: %d"
+mark_postcopy_blocktime_end(uint64_t addr, void *dd, uint32_t time, int affected_cpu) "addr: 0x%" PRIx64 ", dd: %p, time: %u, affected_cpu: %d"
 
 # migration/rdma.c
 qemu_rdma_accept_incoming_migration(void) ""
@@ -193,11 +195,12 @@ postcopy_ram_fault_thread_exit(void) ""
 postcopy_ram_fault_thread_fds_core(int baseufd, int quitfd) "ufd: %d quitfd: %d"
 postcopy_ram_fault_thread_fds_extra(size_t index, const char *name, int fd) "%zd/%s: %d"
 postcopy_ram_fault_thread_quit(void) ""
-postcopy_ram_fault_thread_request(uint64_t hostaddr, const char *ramblock, size_t offset) "Request for HVA=0x%" PRIx64 " rb=%s offset=0x%zx"
+postcopy_ram_fault_thread_request(uint64_t hostaddr, const char *ramblock, size_t offset, uint32_t pid) "Request for HVA=0x%" PRIx64 " rb=%s offset=0x%zx pid=%u"
 postcopy_ram_incoming_cleanup_closeuf(void) ""
 postcopy_ram_incoming_cleanup_entry(void) ""
 postcopy_ram_incoming_cleanup_exit(void) ""
 postcopy_ram_incoming_cleanup_join(void) ""
+postcopy_ram_incoming_cleanup_blocktime(uint64_t total) "total blocktime %" PRIu64
 postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_offset) "for %s in %s offset 0x%"PRIx64
 postcopy_request_shared_page_present(const char *sharer, const char *rb, uint64_t rb_offset) "%s already %s offset 0x%"PRIx64
 postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s"
@@ -206,6 +209,7 @@ save_xbzrle_page_skipping(void) ""
 save_xbzrle_page_overflow(void) ""
 ram_save_iterate_big_wait(uint64_t milliconds, int iterations) "big wait: %" PRIu64 " milliseconds, %d iterations"
 ram_load_complete(int ret, uint64_t seq_iter) "exit_code %d seq iteration %" PRIu64
+get_mem_fault_cpu_index(int cpu, uint32_t pid) "cpu: %d, pid: %u"
 
 # migration/exec.c
 migration_exec_outgoing(const char *cmd) "cmd=%s"
diff --git a/qapi/migration.json b/qapi/migration.json
index 9d0bf82..f3974c6 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -156,6 +156,13 @@
 #              @status is 'failed'. Clients should not attempt to parse the
 #              error strings. (Since 2.7)
 #
+# @postcopy-blocktime: total time when all vCPU were blocked during postcopy
+#           live migration (Since 2.13)
+#
+# @postcopy-vcpu-blocktime: list of the postcopy blocktime per vCPU (Since 2.13)
+#
+
+#
 # Since: 0.14.0
 ##
 { 'struct': 'MigrationInfo',
@@ -167,7 +174,9 @@
            '*downtime': 'int',
            '*setup-time': 'int',
            '*cpu-throttle-percentage': 'int',
-           '*error-desc': 'str'} }
+           '*error-desc': 'str',
+           '*postcopy-blocktime' : 'uint32',
+           '*postcopy-vcpu-blocktime': ['uint32']} }
 
 ##
 # @query-migrate:
@@ -354,16 +363,20 @@
 #
 # @x-multifd: Use more than one fd for migration (since 2.11)
 #
+#
 # @dirty-bitmaps: If enabled, QEMU will migrate named dirty bitmaps.
 #                 (since 2.12)
 #
+# @postcopy-blocktime: Calculate downtime for postcopy live migration
+#                     (since 2.13)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
            'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
            'block', 'return-path', 'pause-before-switchover', 'x-multifd',
-           'dirty-bitmaps' ] }
+           'dirty-bitmaps', 'postcopy-blocktime' ] }
 
 ##
 # @MigrationCapabilityStatus:
diff --git a/tests/migration-test.c b/tests/migration-test.c
index 422bf1a..dde7c46 100644
--- a/tests/migration-test.c
+++ b/tests/migration-test.c
@@ -26,6 +26,7 @@
 const unsigned start_address = 1024 * 1024;
 const unsigned end_address = 100 * 1024 * 1024;
 bool got_stop;
+static bool uffd_feature_thread_id;
 
 #if defined(__linux__)
 #include <sys/syscall.h>
@@ -55,6 +56,7 @@ static bool ufd_version_check(void)
         g_test_message("Skipping test: UFFDIO_API failed");
         return false;
     }
+    uffd_feature_thread_id = api_struct.features & UFFD_FEATURE_THREAD_ID;
 
     ioctl_mask = (__u64)1 << _UFFDIO_REGISTER |
                  (__u64)1 << _UFFDIO_UNREGISTER;
@@ -223,6 +225,16 @@ static uint64_t get_migration_pass(QTestState *who)
     return result;
 }
 
+static void read_blocktime(QTestState *who)
+{
+    QDict *rsp, *rsp_return;
+
+    rsp = wait_command(who, "{ 'execute': 'query-migrate' }");
+    rsp_return = qdict_get_qdict(rsp, "return");
+    g_assert(qdict_haskey(rsp_return, "postcopy-blocktime"));
+    QDECREF(rsp);
+}
+
 static void wait_for_migration_complete(QTestState *who)
 {
     while (true) {
@@ -533,6 +545,7 @@ static void test_migrate(void)
 
     migrate_set_capability(from, "postcopy-ram", "true");
     migrate_set_capability(to, "postcopy-ram", "true");
+    migrate_set_capability(to, "postcopy-blocktime", "true");
 
     /* We want to pick a speed slow enough that the test completes
      * quickly, but that it doesn't complete precopy even on a slow
@@ -559,6 +572,9 @@ static void test_migrate(void)
     wait_for_serial("dest_serial");
     wait_for_migration_complete(from);
 
+    if (uffd_feature_thread_id) {
+        read_blocktime(to);
+    }
     g_free(uri);
 
     test_migrate_end(from, to, true);