Merge remote-tracking branch 'remotes/jasowang/tags/net-pull-request' into staging

# gpg: Signature made Fri 19 Oct 2018 04:16:03 BST
# gpg:                using RSA key EF04965B398D6211
# gpg: Good signature from "Jason Wang (Jason Wang on RedHat) <jasowang@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 215D 46F4 8246 689E C77F  3562 EF04 965B 398D 6211

* remotes/jasowang/tags/net-pull-request: (26 commits)
  qemu-options: Fix bad "macaddr" property in the documentation
  e1000: indicate dropped packets in HW counters
  net: ignore packet size greater than INT_MAX
  pcnet: fix possible buffer overflow
  rtl8139: fix possible out of bound access
  ne2000: fix possible out of bound access in ne2000_receive
  clean up callback when del virtqueue
  docs: Add COLO status diagram to COLO-FT.txt
  COLO: quick failover process by kick COLO thread
  COLO: notify net filters about checkpoint/failover event
  filter-rewriter: handle checkpoint and failover event
  filter: Add handle_event method for NetFilterClass
  COLO: flush host dirty ram from cache
  savevm: split the process of different stages for loadvm/savevm
  qapi: Add new command to query colo status
  qapi/migration.json: Rename COLO unknown mode to none mode.
  qmp event: Add COLO_EXIT event to notify users while exited COLO
  COLO: Flush memory data from ram cache
  ram/COLO: Record the dirty pages that SVM received
  COLO: Load dirty pages into SVM's RAM cache firstly
  ...

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

30 files changed, 958 insertions, 152 deletions

diff --git a/docs/COLO-FT.txt b/docs/COLO-FT.txt
index 70cfb9ce7d..6302469d0e 100644
--- a/docs/COLO-FT.txt
+++ b/docs/COLO-FT.txt
@@ -110,6 +110,40 @@ Note:
 HeartBeat has not been implemented yet, so you need to trigger failover process
 by using 'x-colo-lost-heartbeat' command.
 
+== COLO operation status ==
+
++-----------------+
+|                 |
+|    Start COLO   |
+|                 |
++--------+--------+
+         |
+         |  Main qmp command:
+         |  migrate-set-capabilities with x-colo
+         |  migrate
+         |
+         v
++--------+--------+
+|                 |
+|  COLO running   |
+|                 |
++--------+--------+
+         |
+         |  Main qmp command:
+         |  x-colo-lost-heartbeat
+         |  or
+         |  some error happened
+         v
++--------+--------+
+|                 |  send qmp event:
+|  COLO failover  |  COLO_EXIT
+|                 |
++-----------------+
+
+COLO use the qmp command to switch and report operation status.
+The diagram just shows the main qmp command, you can get the detail
+in test procedure.
+
 == Test procedure ==
 1. Startup qemu
 Primary:
diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index 13a9494a8d..5e144cb4e4 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -36,6 +36,7 @@
 #include "qemu/range.h"
 
 #include "e1000x_common.h"
+#include "trace.h"
 
 static const uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 
@@ -847,6 +848,15 @@ static uint64_t rx_desc_base(E1000State *s)
     return (bah << 32) + bal;
 }
 
+static void
+e1000_receiver_overrun(E1000State *s, size_t size)
+{
+    trace_e1000_receiver_overrun(size, s->mac_reg[RDH], s->mac_reg[RDT]);
+    e1000x_inc_reg_if_not_full(s->mac_reg, RNBC);
+    e1000x_inc_reg_if_not_full(s->mac_reg, MPC);
+    set_ics(s, 0, E1000_ICS_RXO);
+}
+
 static ssize_t
 e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
 {
@@ -916,8 +926,8 @@ e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
     desc_offset = 0;
     total_size = size + e1000x_fcs_len(s->mac_reg);
     if (!e1000_has_rxbufs(s, total_size)) {
-            set_ics(s, 0, E1000_ICS_RXO);
-            return -1;
+        e1000_receiver_overrun(s, total_size);
+        return -1;
     }
     do {
         desc_size = total_size - desc_offset;
@@ -969,7 +979,7 @@ e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
             rdh_start >= s->mac_reg[RDLEN] / sizeof(desc)) {
             DBGOUT(RXERR, "RDH wraparound @%x, RDT %x, RDLEN %x\n",
                    rdh_start, s->mac_reg[RDT], s->mac_reg[RDLEN]);
-            set_ics(s, 0, E1000_ICS_RXO);
+            e1000_receiver_overrun(s, total_size);
             return -1;
         }
     } while (desc_offset < total_size);
diff --git a/hw/net/ne2000.c b/hw/net/ne2000.c
index 07d79e317f..869518ee06 100644
--- a/hw/net/ne2000.c
+++ b/hw/net/ne2000.c
@@ -174,7 +174,7 @@ static int ne2000_buffer_full(NE2000State *s)
 ssize_t ne2000_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
 {
     NE2000State *s = qemu_get_nic_opaque(nc);
-    int size = size_;
+    size_t size = size_;
     uint8_t *p;
     unsigned int total_len, next, avail, len, index, mcast_idx;
     uint8_t buf1[60];
@@ -182,7 +182,7 @@ ssize_t ne2000_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
         { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
 #if defined(DEBUG_NE2000)
-    printf("NE2000: received len=%d\n", size);
+    printf("NE2000: received len=%zu\n", size);
 #endif
 
     if (s->cmd & E8390_STOP || ne2000_buffer_full(s))
diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
index 0c44554168..d9ba04bdfc 100644
--- a/hw/net/pcnet.c
+++ b/hw/net/pcnet.c
@@ -988,14 +988,14 @@ ssize_t pcnet_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
     uint8_t buf1[60];
     int remaining;
     int crc_err = 0;
-    int size = size_;
+    size_t size = size_;
 
     if (CSR_DRX(s) || CSR_STOP(s) || CSR_SPND(s) || !size ||
         (CSR_LOOP(s) && !s->looptest)) {
         return -1;
     }
 #ifdef PCNET_DEBUG
-    printf("pcnet_receive size=%d\n", size);
+    printf("pcnet_receive size=%zu\n", size);
 #endif
 
     /* if too small buffer, then expand it */
diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index 46daa16202..2342a095e3 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -817,7 +817,7 @@ static ssize_t rtl8139_do_receive(NetClientState *nc, const uint8_t *buf, size_t
     RTL8139State *s = qemu_get_nic_opaque(nc);
     PCIDevice *d = PCI_DEVICE(s);
     /* size is the length of the buffer passed to the driver */
-    int size = size_;
+    size_t size = size_;
     const uint8_t *dot1q_buf = NULL;
 
     uint32_t packet_header = 0;
@@ -826,7 +826,7 @@ static ssize_t rtl8139_do_receive(NetClientState *nc, const uint8_t *buf, size_t
     static const uint8_t broadcast_macaddr[6] =
         { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
-    DPRINTF(">>> received len=%d\n", size);
+    DPRINTF(">>> received len=%zu\n", size);
 
     /* test if board clock is stopped */
     if (!s->clock_enabled)
@@ -1035,7 +1035,7 @@ static ssize_t rtl8139_do_receive(NetClientState *nc, const uint8_t *buf, size_t
 
         if (size+4 > rx_space)
         {
-            DPRINTF("C+ Rx mode : descriptor %d size %d received %d + 4\n",
+            DPRINTF("C+ Rx mode : descriptor %d size %d received %zu + 4\n",
                 descriptor, rx_space, size);
 
             s->IntrStatus |= RxOverflow;
@@ -1148,7 +1148,7 @@ static ssize_t rtl8139_do_receive(NetClientState *nc, const uint8_t *buf, size_t
         if (avail != 0 && RX_ALIGN(size + 8) >= avail)
         {
             DPRINTF("rx overflow: rx buffer length %d head 0x%04x "
-                "read 0x%04x === available 0x%04x need 0x%04x\n",
+                "read 0x%04x === available 0x%04x need 0x%04zx\n",
                 s->RxBufferSize, s->RxBufAddr, s->RxBufPtr, avail, size + 8);
 
             s->IntrStatus |= RxOverflow;
diff --git a/hw/net/trace-events b/hw/net/trace-events
index c1dea4b156..9d49f62fa1 100644
--- a/hw/net/trace-events
+++ b/hw/net/trace-events
@@ -98,6 +98,9 @@ net_rx_pkt_rss_ip6_ex(void) "Calculating IPv6/EX RSS  hash"
 net_rx_pkt_rss_hash(size_t rss_length, uint32_t rss_hash) "RSS hash for %zu bytes: 0x%X"
 net_rx_pkt_rss_add_chunk(void* ptr, size_t size, size_t input_offset) "Add RSS chunk %p, %zu bytes, RSS input offset %zu bytes"
 
+# hw/net/e1000.c
+e1000_receiver_overrun(size_t s, uint32_t rdh, uint32_t rdt) "Receiver overrun: dropped packet of %zu bytes, RDH=%u, RDT=%u"
+
 # hw/net/e1000x_common.c
 e1000x_rx_can_recv_disabled(bool link_up, bool rx_enabled, bool pci_master) "link_up: %d, rx_enabled %d, pci_master %d"
 e1000x_vlan_is_vlan_pkt(bool is_vlan_pkt, uint16_t eth_proto, uint16_t vet) "Is VLAN packet: %d, ETH proto: 0x%X, VET: 0x%X"
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 4e61944f14..4136d239dd 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1611,6 +1611,8 @@ void virtio_del_queue(VirtIODevice *vdev, int n)
 
     vdev->vq[n].vring.num = 0;
     vdev->vq[n].vring.num_default = 0;
+    vdev->vq[n].handle_output = NULL;
+    vdev->vq[n].handle_aio_output = NULL;
 }
 
 static void virtio_set_isr(VirtIODevice *vdev, int value)
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 3abb639056..9ecd911c3e 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -27,6 +27,7 @@ struct RAMBlock {
     struct rcu_head rcu;
     struct MemoryRegion *mr;
     uint8_t *host;
+    uint8_t *colo_cache; /* For colo, VM's ram cache */
     ram_addr_t offset;
     ram_addr_t used_length;
     ram_addr_t max_length;
diff --git a/include/migration/colo.h b/include/migration/colo.h
index 2fe48ad353..99ce17aca7 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -16,14 +16,21 @@
 #include "qemu-common.h"
 #include "qapi/qapi-types-migration.h"
 
+enum colo_event {
+    COLO_EVENT_NONE,
+    COLO_EVENT_CHECKPOINT,
+    COLO_EVENT_FAILOVER,
+};
+
 void colo_info_init(void);
 
 void migrate_start_colo_process(MigrationState *s);
 bool migration_in_colo_state(void);
 
 /* loadvm */
-bool migration_incoming_enable_colo(void);
-void migration_incoming_exit_colo(void);
+void migration_incoming_enable_colo(void);
+void migration_incoming_disable_colo(void);
+bool migration_incoming_colo_enabled(void);
 void *colo_process_incoming_thread(void *opaque);
 bool migration_incoming_in_colo_state(void);
 
diff --git a/include/net/filter.h b/include/net/filter.h
index 435acd6f82..49da666ac0 100644
--- a/include/net/filter.h
+++ b/include/net/filter.h
@@ -38,6 +38,8 @@ typedef ssize_t (FilterReceiveIOV)(NetFilterState *nc,
 
 typedef void (FilterStatusChanged) (NetFilterState *nf, Error **errp);
 
+typedef void (FilterHandleEvent) (NetFilterState *nf, int event, Error **errp);
+
 typedef struct NetFilterClass {
     ObjectClass parent_class;
 
@@ -45,6 +47,7 @@ typedef struct NetFilterClass {
     FilterSetup *setup;
     FilterCleanup *cleanup;
     FilterStatusChanged *status_changed;
+    FilterHandleEvent *handle_event;
     /* mandatory */
     FilterReceiveIOV *receive_iov;
 } NetFilterClass;
@@ -77,4 +80,6 @@ ssize_t qemu_netfilter_pass_to_next(NetClientState *sender,
                                     int iovcnt,
                                     void *opaque);
 
+void colo_notify_filters_event(int event, Error **errp);
+
 #endif /* QEMU_NET_FILTER_H */
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index c83ec47ba8..a4f3bafd86 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,6 +1,6 @@
 common-obj-y += migration.o socket.o fd.o exec.o
 common-obj-y += tls.o channel.o savevm.o
-common-obj-y += colo-comm.o colo.o colo-failover.o
+common-obj-y += colo.o colo-failover.o
 common-obj-y += vmstate.o vmstate-types.o page_cache.o
 common-obj-y += qemu-file.o global_state.o
 common-obj-y += qemu-file-channel.o
diff --git a/migration/colo-comm.c b/migration/colo-comm.c
deleted file mode 100644
index df26e4dfe7..0000000000
--- a/migration/colo-comm.c
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
- * (a.k.a. Fault Tolerance or Continuous Replication)
- *
- * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
- * Copyright (c) 2016 FUJITSU LIMITED
- * Copyright (c) 2016 Intel Corporation
- *
- * This work is licensed under the terms of the GNU GPL, version 2 or
- * later. See the COPYING file in the top-level directory.
- *
- */
-
-#include "qemu/osdep.h"
-#include "migration.h"
-#include "migration/colo.h"
-#include "migration/vmstate.h"
-#include "trace.h"
-
-typedef struct {
-     bool colo_requested;
-} COLOInfo;
-
-static COLOInfo colo_info;
-
-COLOMode get_colo_mode(void)
-{
-    if (migration_in_colo_state()) {
-        return COLO_MODE_PRIMARY;
-    } else if (migration_incoming_in_colo_state()) {
-        return COLO_MODE_SECONDARY;
-    } else {
-        return COLO_MODE_UNKNOWN;
-    }
-}
-
-static int colo_info_pre_save(void *opaque)
-{
-    COLOInfo *s = opaque;
-
-    s->colo_requested = migrate_colo_enabled();
-
-    return 0;
-}
-
-static bool colo_info_need(void *opaque)
-{
-   return migrate_colo_enabled();
-}
-
-static const VMStateDescription colo_state = {
-    .name = "COLOState",
-    .version_id = 1,
-    .minimum_version_id = 1,
-    .pre_save = colo_info_pre_save,
-    .needed = colo_info_need,
-    .fields = (VMStateField[]) {
-        VMSTATE_BOOL(colo_requested, COLOInfo),
-        VMSTATE_END_OF_LIST()
-    },
-};
-
-void colo_info_init(void)
-{
-    vmstate_register(NULL, 0, &colo_state, &colo_info);
-}
-
-bool migration_incoming_enable_colo(void)
-{
-    return colo_info.colo_requested;
-}
-
-void migration_incoming_exit_colo(void)
-{
-    colo_info.colo_requested = false;
-}
diff --git a/migration/colo-failover.c b/migration/colo-failover.c
index 0ae0c41221..4854a96c92 100644
--- a/migration/colo-failover.c
+++ b/migration/colo-failover.c
@@ -77,7 +77,7 @@ FailoverStatus failover_get_state(void)
 
 void qmp_x_colo_lost_heartbeat(Error **errp)
 {
-    if (get_colo_mode() == COLO_MODE_UNKNOWN) {
+    if (get_colo_mode() == COLO_MODE_NONE) {
         error_setg(errp, QERR_FEATURE_DISABLED, "colo");
         return;
     }
diff --git a/migration/colo.c b/migration/colo.c
index 88936f5962..956ac236b7 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -25,8 +25,16 @@
 #include "qemu/error-report.h"
 #include "migration/failover.h"
 #include "replication.h"
+#include "net/colo-compare.h"
+#include "net/colo.h"
+#include "block/block.h"
+#include "qapi/qapi-events-migration.h"
+#include "qapi/qmp/qerror.h"
+#include "sysemu/cpus.h"
+#include "net/filter.h"
 
 static bool vmstate_loading;
+static Notifier packets_compare_notifier;
 
 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
 
@@ -53,6 +61,7 @@ static void secondary_vm_do_failover(void)
 {
     int old_state;
     MigrationIncomingState *mis = migration_incoming_get_current();
+    Error *local_err = NULL;
 
     /* Can not do failover during the process of VM's loading VMstate, Or
      * it will break the secondary VM.
@@ -70,6 +79,17 @@ static void secondary_vm_do_failover(void)
     migrate_set_state(&mis->state, MIGRATION_STATUS_COLO,
                       MIGRATION_STATUS_COMPLETED);
 
+    replication_stop_all(true, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+    }
+
+    /* Notify all filters of all NIC to do checkpoint */
+    colo_notify_filters_event(COLO_EVENT_FAILOVER, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+    }
+
     if (!autostart) {
         error_report("\"-S\" qemu option will be ignored in secondary side");
         /* recover runstate to normal migration finish state */
@@ -107,9 +127,15 @@ static void primary_vm_do_failover(void)
 {
     MigrationState *s = migrate_get_current();
     int old_state;
+    Error *local_err = NULL;
 
     migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
                       MIGRATION_STATUS_COMPLETED);
+    /*
+     * kick COLO thread which might wait at
+     * qemu_sem_wait(&s->colo_checkpoint_sem).
+     */
+    colo_checkpoint_notify(migrate_get_current());
 
     /*
      * Wake up COLO thread which may blocked in recv() or send(),
@@ -130,10 +156,28 @@ static void primary_vm_do_failover(void)
                      FailoverStatus_str(old_state));
         return;
     }
+
+    replication_stop_all(true, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+        local_err = NULL;
+    }
+
     /* Notify COLO thread that failover work is finished */
     qemu_sem_post(&s->colo_exit_sem);
 }
 
+COLOMode get_colo_mode(void)
+{
+    if (migration_in_colo_state()) {
+        return COLO_MODE_PRIMARY;
+    } else if (migration_incoming_in_colo_state()) {
+        return COLO_MODE_SECONDARY;
+    } else {
+        return COLO_MODE_NONE;
+    }
+}
+
 void colo_do_failover(MigrationState *s)
 {
     /* Make sure VM stopped while failover happened. */
@@ -207,6 +251,26 @@ void qmp_xen_colo_do_checkpoint(Error **errp)
 #endif
 }
 
+COLOStatus *qmp_query_colo_status(Error **errp)
+{
+    COLOStatus *s = g_new0(COLOStatus, 1);
+
+    s->mode = get_colo_mode();
+
+    switch (failover_get_state()) {
+    case FAILOVER_STATUS_NONE:
+        s->reason = COLO_EXIT_REASON_NONE;
+        break;
+    case FAILOVER_STATUS_REQUIRE:
+        s->reason = COLO_EXIT_REASON_REQUEST;
+        break;
+    default:
+        s->reason = COLO_EXIT_REASON_ERROR;
+    }
+
+    return s;
+}
+
 static void colo_send_message(QEMUFile *f, COLOMessage msg,
                               Error **errp)
 {
@@ -343,21 +407,42 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
         goto out;
     }
 
+    colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT, &local_err);
+    if (local_err) {
+        goto out;
+    }
+
     /* Disable block migration */
     migrate_set_block_enabled(false, &local_err);
-    qemu_savevm_state_header(fb);
-    qemu_savevm_state_setup(fb);
     qemu_mutex_lock_iothread();
-    qemu_savevm_state_complete_precopy(fb, false, false);
-    qemu_mutex_unlock_iothread();
-
-    qemu_fflush(fb);
+    replication_do_checkpoint_all(&local_err);
+    if (local_err) {
+        qemu_mutex_unlock_iothread();
+        goto out;
+    }
 
     colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
     if (local_err) {
+        qemu_mutex_unlock_iothread();
+        goto out;
+    }
+    /* Note: device state is saved into buffer */
+    ret = qemu_save_device_state(fb);
+
+    qemu_mutex_unlock_iothread();
+    if (ret < 0) {
         goto out;
     }
     /*
+     * Only save VM's live state, which not including device state.
+     * TODO: We may need a timeout mechanism to prevent COLO process
+     * to be blocked here.
+     */
+    qemu_savevm_live_state(s->to_dst_file);
+
+    qemu_fflush(fb);
+
+    /*
      * We need the size of the VMstate data in Secondary side,
      * With which we can decide how much data should be read.
      */
@@ -400,6 +485,11 @@ out:
     return ret;
 }
 
+static void colo_compare_notify_checkpoint(Notifier *notifier, void *data)
+{
+    colo_checkpoint_notify(data);
+}
+
 static void colo_process_checkpoint(MigrationState *s)
 {
     QIOChannelBuffer *bioc;
@@ -416,6 +506,9 @@ static void colo_process_checkpoint(MigrationState *s)
         goto out;
     }
 
+    packets_compare_notifier.notify = colo_compare_notify_checkpoint;
+    colo_compare_register_notifier(&packets_compare_notifier);
+
     /*
      * Wait for Secondary finish loading VM states and enter COLO
      * restore.
@@ -430,6 +523,12 @@ static void colo_process_checkpoint(MigrationState *s)
     object_unref(OBJECT(bioc));
 
     qemu_mutex_lock_iothread();
+    replication_start_all(REPLICATION_MODE_PRIMARY, &local_err);
+    if (local_err) {
+        qemu_mutex_unlock_iothread();
+        goto out;
+    }
+
     vm_start();
     qemu_mutex_unlock_iothread();
     trace_colo_vm_state_change("stop", "run");
@@ -445,6 +544,9 @@ static void colo_process_checkpoint(MigrationState *s)
 
         qemu_sem_wait(&s->colo_checkpoint_sem);
 
+        if (s->state != MIGRATION_STATUS_COLO) {
+            goto out;
+        }
         ret = colo_do_checkpoint_transaction(s, bioc, fb);
         if (ret < 0) {
             goto out;
@@ -461,11 +563,38 @@ out:
         qemu_fclose(fb);
     }
 
-    timer_del(s->colo_delay_timer);
+    /*
+     * There are only two reasons we can get here, some error happened
+     * or the user triggered failover.
+     */
+    switch (failover_get_state()) {
+    case FAILOVER_STATUS_NONE:
+        qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
+                                  COLO_EXIT_REASON_ERROR);
+        break;
+    case FAILOVER_STATUS_REQUIRE:
+        qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
+                                  COLO_EXIT_REASON_REQUEST);
+        break;
+    default:
+        abort();
+    }
 
     /* Hope this not to be too long to wait here */
     qemu_sem_wait(&s->colo_exit_sem);
     qemu_sem_destroy(&s->colo_exit_sem);
+
+    /*
+     * It is safe to unregister notifier after failover finished.
+     * Besides, colo_delay_timer and colo_checkpoint_sem can't be
+     * released befor unregister notifier, or there will be use-after-free
+     * error.
+     */
+    colo_compare_unregister_notifier(&packets_compare_notifier);
+    timer_del(s->colo_delay_timer);
+    timer_free(s->colo_delay_timer);
+    qemu_sem_destroy(&s->colo_checkpoint_sem);
+
     /*
      * Must be called after failover BH is completed,
      * Or the failover BH may shutdown the wrong fd that
@@ -533,6 +662,7 @@ void *colo_process_incoming_thread(void *opaque)
     uint64_t total_size;
     uint64_t value;
     Error *local_err = NULL;
+    int ret;
 
     rcu_register_thread();
     qemu_sem_init(&mis->colo_incoming_sem, 0);
@@ -559,6 +689,16 @@ void *colo_process_incoming_thread(void *opaque)
     fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
     object_unref(OBJECT(bioc));
 
+    qemu_mutex_lock_iothread();
+    replication_start_all(REPLICATION_MODE_SECONDARY, &local_err);
+    if (local_err) {
+        qemu_mutex_unlock_iothread();
+        goto out;
+    }
+    vm_start();
+    trace_colo_vm_state_change("stop", "run");
+    qemu_mutex_unlock_iothread();
+
     colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
                       &local_err);
     if (local_err) {
@@ -578,6 +718,11 @@ void *colo_process_incoming_thread(void *opaque)
             goto out;
         }
 
+        qemu_mutex_lock_iothread();
+        vm_stop_force_state(RUN_STATE_COLO);
+        trace_colo_vm_state_change("run", "stop");
+        qemu_mutex_unlock_iothread();
+
         /* FIXME: This is unnecessary for periodic checkpoint mode */
         colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
                      &local_err);
@@ -591,6 +736,16 @@ void *colo_process_incoming_thread(void *opaque)
             goto out;
         }
 
+        qemu_mutex_lock_iothread();
+        cpu_synchronize_all_pre_loadvm();
+        ret = qemu_loadvm_state_main(mis->from_src_file, mis);
+        qemu_mutex_unlock_iothread();
+
+        if (ret < 0) {
+            error_report("Load VM's live state (ram) error");
+            goto out;
+        }
+
         value = colo_receive_message_value(mis->from_src_file,
                                  COLO_MESSAGE_VMSTATE_SIZE, &local_err);
         if (local_err) {
@@ -622,15 +777,37 @@ void *colo_process_incoming_thread(void *opaque)
         }
 
         qemu_mutex_lock_iothread();
-        qemu_system_reset(SHUTDOWN_CAUSE_NONE);
         vmstate_loading = true;
-        if (qemu_loadvm_state(fb) < 0) {
-            error_report("COLO: loadvm failed");
+        ret = qemu_load_device_state(fb);
+        if (ret < 0) {
+            error_report("COLO: load device state failed");
+            qemu_mutex_unlock_iothread();
+            goto out;
+        }
+
+        replication_get_error_all(&local_err);
+        if (local_err) {
+            qemu_mutex_unlock_iothread();
+            goto out;
+        }
+        /* discard colo disk buffer */
+        replication_do_checkpoint_all(&local_err);
+        if (local_err) {
+            qemu_mutex_unlock_iothread();
+            goto out;
+        }
+
+        /* Notify all filters of all NIC to do checkpoint */
+        colo_notify_filters_event(COLO_EVENT_CHECKPOINT, &local_err);
+
+        if (local_err) {
             qemu_mutex_unlock_iothread();
             goto out;
         }
 
         vmstate_loading = false;
+        vm_start();
+        trace_colo_vm_state_change("stop", "run");
         qemu_mutex_unlock_iothread();
 
         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
@@ -654,6 +831,19 @@ out:
         error_report_err(local_err);
     }
 
+    switch (failover_get_state()) {
+    case FAILOVER_STATUS_NONE:
+        qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
+                                  COLO_EXIT_REASON_ERROR);
+        break;
+    case FAILOVER_STATUS_REQUIRE:
+        qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
+                                  COLO_EXIT_REASON_REQUEST);
+        break;
+    default:
+        abort();
+    }
+
     if (fb) {
         qemu_fclose(fb);
     }
@@ -665,7 +855,7 @@ out:
     if (mis->to_src_file) {
         qemu_fclose(mis->to_src_file);
     }
-    migration_incoming_exit_colo();
+    migration_incoming_disable_colo();
 
     rcu_unregister_thread();
     return NULL;
diff --git a/migration/migration.c b/migration/migration.c
index d6ae879dc8..7696729340 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -76,10 +76,8 @@
 /* Migration XBZRLE default cache size */
 #define DEFAULT_MIGRATE_XBZRLE_CACHE_SIZE (64 * 1024 * 1024)
 
-/* The delay time (in ms) between two COLO checkpoints
- * Note: Please change this default value to 10000 when we support hybrid mode.
- */
-#define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY 200
+/* The delay time (in ms) between two COLO checkpoints */
+#define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY (200 * 100)
 #define DEFAULT_MIGRATE_MULTIFD_CHANNELS 2
 #define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 16
 
@@ -298,6 +296,22 @@ int migrate_send_rp_req_pages(MigrationIncomingState *mis, const char *rbname,
     return migrate_send_rp_message(mis, msg_type, msglen, bufc);
 }
 
+static bool migration_colo_enabled;
+bool migration_incoming_colo_enabled(void)
+{
+    return migration_colo_enabled;
+}
+
+void migration_incoming_disable_colo(void)
+{
+    migration_colo_enabled = false;
+}
+
+void migration_incoming_enable_colo(void)
+{
+    migration_colo_enabled = true;
+}
+
 void qemu_start_incoming_migration(const char *uri, Error **errp)
 {
     const char *p;
@@ -388,6 +402,7 @@ static void process_incoming_migration_co(void *opaque)
     MigrationIncomingState *mis = migration_incoming_get_current();
     PostcopyState ps;
     int ret;
+    Error *local_err = NULL;
 
     assert(mis->from_src_file);
     mis->migration_incoming_co = qemu_coroutine_self();
@@ -419,7 +434,21 @@ static void process_incoming_migration_co(void *opaque)
     }
 
     /* we get COLO info, and know if we are in COLO mode */
-    if (!ret && migration_incoming_enable_colo()) {
+    if (!ret && migration_incoming_colo_enabled()) {
+        /* Make sure all file formats flush their mutable metadata */
+        bdrv_invalidate_cache_all(&local_err);
+        if (local_err) {
+            migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
+                    MIGRATION_STATUS_FAILED);
+            error_report_err(local_err);
+            exit(EXIT_FAILURE);
+        }
+
+        if (colo_init_ram_cache() < 0) {
+            error_report("Init ram cache failed");
+            exit(EXIT_FAILURE);
+        }
+
         qemu_thread_create(&mis->colo_incoming_thread, "COLO incoming",
              colo_process_incoming_thread, mis, QEMU_THREAD_JOINABLE);
         mis->have_colo_incoming_thread = true;
@@ -427,6 +456,8 @@ static void process_incoming_migration_co(void *opaque)
 
         /* Wait checkpoint incoming thread exit before free resource */
         qemu_thread_join(&mis->colo_incoming_thread);
+        /* We hold the global iothread lock, so it is safe here */
+        colo_release_ram_cache();
     }
 
     if (ret < 0) {
@@ -3017,6 +3048,11 @@ static void *migration_thread(void *opaque)
         qemu_savevm_send_postcopy_advise(s->to_dst_file);
     }
 
+    if (migrate_colo_enabled()) {
+        /* Notify migration destination that we enable COLO */
+        qemu_savevm_send_colo_enable(s->to_dst_file);
+    }
+
     qemu_savevm_state_setup(s->to_dst_file);
 
     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
diff --git a/migration/ram.c b/migration/ram.c
index bc38d98cc3..7e7deec4d8 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3447,6 +3447,29 @@ static inline void *host_from_ram_block_offset(RAMBlock *block,
     return block->host + offset;
 }
 
+static inline void *colo_cache_from_block_offset(RAMBlock *block,
+                                                 ram_addr_t offset)
+{
+    if (!offset_in_ramblock(block, offset)) {
+        return NULL;
+    }
+    if (!block->colo_cache) {
+        error_report("%s: colo_cache is NULL in block :%s",
+                     __func__, block->idstr);
+        return NULL;
+    }
+
+    /*
+    * During colo checkpoint, we need bitmap of these migrated pages.
+    * It help us to decide which pages in ram cache should be flushed
+    * into VM's RAM later.
+    */
+    if (!test_and_set_bit(offset >> TARGET_PAGE_BITS, block->bmap)) {
+        ram_state->migration_dirty_pages++;
+    }
+    return block->colo_cache + offset;
+}
+
 /**
  * ram_handle_compressed: handle the zero page case
  *
@@ -3651,6 +3674,88 @@ static void decompress_data_with_multi_threads(QEMUFile *f,
     qemu_mutex_unlock(&decomp_done_lock);
 }
 
+/*
+ * colo cache: this is for secondary VM, we cache the whole
+ * memory of the secondary VM, it is need to hold the global lock
+ * to call this helper.
+ */
+int colo_init_ram_cache(void)
+{
+    RAMBlock *block;
+
+    rcu_read_lock();
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        block->colo_cache = qemu_anon_ram_alloc(block->used_length,
+                                                NULL,
+                                                false);
+        if (!block->colo_cache) {
+            error_report("%s: Can't alloc memory for COLO cache of block %s,"
+                         "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
+                         block->used_length);
+            goto out_locked;
+        }
+        memcpy(block->colo_cache, block->host, block->used_length);
+    }
+    rcu_read_unlock();
+    /*
+    * Record the dirty pages that sent by PVM, we use this dirty bitmap together
+    * with to decide which page in cache should be flushed into SVM's RAM. Here
+    * we use the same name 'ram_bitmap' as for migration.
+    */
+    if (ram_bytes_total()) {
+        RAMBlock *block;
+
+        RAMBLOCK_FOREACH_MIGRATABLE(block) {
+            unsigned long pages = block->max_length >> TARGET_PAGE_BITS;
+
+            block->bmap = bitmap_new(pages);
+            bitmap_set(block->bmap, 0, pages);
+        }
+    }
+    ram_state = g_new0(RAMState, 1);
+    ram_state->migration_dirty_pages = 0;
+    memory_global_dirty_log_start();
+
+    return 0;
+
+out_locked:
+
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (block->colo_cache) {
+            qemu_anon_ram_free(block->colo_cache, block->used_length);
+            block->colo_cache = NULL;
+        }
+    }
+
+    rcu_read_unlock();
+    return -errno;
+}
+
+/* It is need to hold the global lock to call this helper */
+void colo_release_ram_cache(void)
+{
+    RAMBlock *block;
+
+    memory_global_dirty_log_stop();
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        g_free(block->bmap);
+        block->bmap = NULL;
+    }
+
+    rcu_read_lock();
+
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (block->colo_cache) {
+            qemu_anon_ram_free(block->colo_cache, block->used_length);
+            block->colo_cache = NULL;
+        }
+    }
+
+    rcu_read_unlock();
+    g_free(ram_state);
+    ram_state = NULL;
+}
+
 /**
  * ram_load_setup: Setup RAM for migration incoming side
  *
@@ -3667,6 +3772,7 @@ static int ram_load_setup(QEMUFile *f, void *opaque)
 
     xbzrle_load_setup();
     ramblock_recv_map_init();
+
     return 0;
 }
 
@@ -3687,6 +3793,7 @@ static int ram_load_cleanup(void *opaque)
         g_free(rb->receivedmap);
         rb->receivedmap = NULL;
     }
+
     return 0;
 }
 
@@ -3869,6 +3976,46 @@ static bool postcopy_is_running(void)
     return ps >= POSTCOPY_INCOMING_LISTENING && ps < POSTCOPY_INCOMING_END;
 }
 
+/*
+ * Flush content of RAM cache into SVM's memory.
+ * Only flush the pages that be dirtied by PVM or SVM or both.
+ */
+static void colo_flush_ram_cache(void)
+{
+    RAMBlock *block = NULL;
+    void *dst_host;
+    void *src_host;
+    unsigned long offset = 0;
+
+    memory_global_dirty_log_sync();
+    rcu_read_lock();
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        migration_bitmap_sync_range(ram_state, block, 0, block->used_length);
+    }
+    rcu_read_unlock();
+
+    trace_colo_flush_ram_cache_begin(ram_state->migration_dirty_pages);
+    rcu_read_lock();
+    block = QLIST_FIRST_RCU(&ram_list.blocks);
+
+    while (block) {
+        offset = migration_bitmap_find_dirty(ram_state, block, offset);
+
+        if (offset << TARGET_PAGE_BITS >= block->used_length) {
+            offset = 0;
+            block = QLIST_NEXT_RCU(block, next);
+        } else {
+            migration_bitmap_clear_dirty(ram_state, block, offset);
+            dst_host = block->host + (offset << TARGET_PAGE_BITS);
+            src_host = block->colo_cache + (offset << TARGET_PAGE_BITS);
+            memcpy(dst_host, src_host, TARGET_PAGE_SIZE);
+        }
+    }
+
+    rcu_read_unlock();
+    trace_colo_flush_ram_cache_end();
+}
+
 static int ram_load(QEMUFile *f, void *opaque, int version_id)
 {
     int flags = 0, ret = 0, invalid_flags = 0;
@@ -3924,13 +4071,24 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
                      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);
+            /*
+             * After going into COLO, we should load the Page into colo_cache.
+             */
+            if (migration_incoming_in_colo_state()) {
+                host = colo_cache_from_block_offset(block, addr);
+            } else {
+                host = host_from_ram_block_offset(block, addr);
+            }
             if (!host) {
                 error_report("Illegal RAM offset " RAM_ADDR_FMT, addr);
                 ret = -EINVAL;
                 break;
             }
-            ramblock_recv_bitmap_set(block, host);
+
+            if (!migration_incoming_in_colo_state()) {
+                ramblock_recv_bitmap_set(block, host);
+            }
+
             trace_ram_load_loop(block->idstr, (uint64_t)addr, flags, host);
         }
 
@@ -4034,6 +4192,10 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
     ret |= wait_for_decompress_done();
     rcu_read_unlock();
     trace_ram_load_complete(ret, seq_iter);
+
+    if (!ret  && migration_incoming_in_colo_state()) {
+        colo_flush_ram_cache();
+    }
     return ret;
 }
 
diff --git a/migration/ram.h b/migration/ram.h
index a139066846..83ff1bc11a 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -71,4 +71,8 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file,
                                   const char *block_name);
 int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb);
 
+/* ram cache */
+int colo_init_ram_cache(void);
+void colo_release_ram_cache(void);
+
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 2d10e45582..e4caff9a6a 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -56,6 +56,7 @@
 #include "io/channel-file.h"
 #include "sysemu/replay.h"
 #include "qjson.h"
+#include "migration/colo.h"
 
 #ifndef ETH_P_RARP
 #define ETH_P_RARP 0x8035
@@ -82,6 +83,7 @@ enum qemu_vm_cmd {
                                       were previously sent during
                                       precopy but are dirty. */
     MIG_CMD_PACKAGED,          /* Send a wrapped stream within this stream */
+    MIG_CMD_ENABLE_COLO,       /* Enable COLO */
     MIG_CMD_POSTCOPY_RESUME,   /* resume postcopy on dest */
     MIG_CMD_RECV_BITMAP,       /* Request for recved bitmap on dst */
     MIG_CMD_MAX
@@ -841,6 +843,12 @@ static void qemu_savevm_command_send(QEMUFile *f,
     qemu_fflush(f);
 }
 
+void qemu_savevm_send_colo_enable(QEMUFile *f)
+{
+    trace_savevm_send_colo_enable();
+    qemu_savevm_command_send(f, MIG_CMD_ENABLE_COLO, 0, NULL);
+}
+
 void qemu_savevm_send_ping(QEMUFile *f, uint32_t value)
 {
     uint32_t buf;
@@ -1370,13 +1378,21 @@ done:
     return ret;
 }
 
-static int qemu_save_device_state(QEMUFile *f)
+void qemu_savevm_live_state(QEMUFile *f)
 {
-    SaveStateEntry *se;
+    /* save QEMU_VM_SECTION_END section */
+    qemu_savevm_state_complete_precopy(f, true, false);
+    qemu_put_byte(f, QEMU_VM_EOF);
+}
 
-    qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
-    qemu_put_be32(f, QEMU_VM_FILE_VERSION);
+int qemu_save_device_state(QEMUFile *f)
+{
+    SaveStateEntry *se;
 
+    if (!migration_in_colo_state()) {
+        qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
+        qemu_put_be32(f, QEMU_VM_FILE_VERSION);
+    }
     cpu_synchronize_all_states();
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
@@ -1432,8 +1448,6 @@ enum LoadVMExitCodes {
     LOADVM_QUIT     =  1,
 };
 
-static int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
-
 /* ------ incoming postcopy messages ------ */
 /* 'advise' arrives before any transfers just to tell us that a postcopy
  * *might* happen - it might be skipped if precopy transferred everything
@@ -1922,6 +1936,12 @@ static int loadvm_handle_recv_bitmap(MigrationIncomingState *mis,
     return 0;
 }
 
+static int loadvm_process_enable_colo(MigrationIncomingState *mis)
+{
+    migration_incoming_enable_colo();
+    return colo_init_ram_cache();
+}
+
 /*
  * Process an incoming 'QEMU_VM_COMMAND'
  * 0           just a normal return
@@ -2001,6 +2021,9 @@ static int loadvm_process_command(QEMUFile *f)
 
     case MIG_CMD_RECV_BITMAP:
         return loadvm_handle_recv_bitmap(mis, len);
+
+    case MIG_CMD_ENABLE_COLO:
+        return loadvm_process_enable_colo(mis);
     }
 
     return 0;
@@ -2230,7 +2253,7 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
     return true;
 }
 
-static int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis)
+int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis)
 {
     uint8_t section_type;
     int ret = 0;
@@ -2401,6 +2424,22 @@ int qemu_loadvm_state(QEMUFile *f)
     return ret;
 }
 
+int qemu_load_device_state(QEMUFile *f)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+    int ret;
+
+    /* Load QEMU_VM_SECTION_FULL section */
+    ret = qemu_loadvm_state_main(f, mis);
+    if (ret < 0) {
+        error_report("Failed to load device state: %d", ret);
+        return ret;
+    }
+
+    cpu_synchronize_all_post_init();
+    return 0;
+}
+
 int save_snapshot(const char *name, Error **errp)
 {
     BlockDriverState *bs, *bs1;
diff --git a/migration/savevm.h b/migration/savevm.h
index a5e65b8ae3..51a4b9caa8 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -55,8 +55,13 @@ void qemu_savevm_send_postcopy_ram_discard(QEMUFile *f, const char *name,
                                            uint16_t len,
                                            uint64_t *start_list,
                                            uint64_t *length_list);
+void qemu_savevm_send_colo_enable(QEMUFile *f);
+void qemu_savevm_live_state(QEMUFile *f);
+int qemu_save_device_state(QEMUFile *f);
 
 int qemu_loadvm_state(QEMUFile *f);
 void qemu_loadvm_state_cleanup(void);
+int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
+int qemu_load_device_state(QEMUFile *f);
 
 #endif
diff --git a/migration/trace-events b/migration/trace-events
index 9430f3cbe0..bd2d0cd25a 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -37,6 +37,7 @@ savevm_send_ping(uint32_t val) "0x%x"
 savevm_send_postcopy_listen(void) ""
 savevm_send_postcopy_run(void) ""
 savevm_send_postcopy_resume(void) ""
+savevm_send_colo_enable(void) ""
 savevm_send_recv_bitmap(char *name) "%s"
 savevm_state_setup(void) ""
 savevm_state_resume_prepare(void) ""
@@ -101,6 +102,8 @@ ram_dirty_bitmap_sync_start(void) ""
 ram_dirty_bitmap_sync_wait(void) ""
 ram_dirty_bitmap_sync_complete(void) ""
 ram_state_resume_prepare(uint64_t v) "%" PRId64
+colo_flush_ram_cache_begin(uint64_t dirty_pages) "dirty_pages %" PRIu64
+colo_flush_ram_cache_end(void) ""
 
 # migration/migration.c
 await_return_path_close_on_source_close(void) ""
diff --git a/net/colo-compare.c b/net/colo-compare.c
index dd745a491b..a39191d522 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -27,11 +27,20 @@
 #include "qemu/sockets.h"
 #include "colo.h"
 #include "sysemu/iothread.h"
+#include "net/colo-compare.h"
+#include "migration/colo.h"
+#include "migration/migration.h"
 
 #define TYPE_COLO_COMPARE "colo-compare"
 #define COLO_COMPARE(obj) \
     OBJECT_CHECK(CompareState, (obj), TYPE_COLO_COMPARE)
 
+static QTAILQ_HEAD(, CompareState) net_compares =
+       QTAILQ_HEAD_INITIALIZER(net_compares);
+
+static NotifierList colo_compare_notifiers =
+    NOTIFIER_LIST_INITIALIZER(colo_compare_notifiers);
+
 #define COMPARE_READ_LEN_MAX NET_BUFSIZE
 #define MAX_QUEUE_SIZE 1024
 
@@ -41,6 +50,10 @@
 /* TODO: Should be configurable */
 #define REGULAR_PACKET_CHECK_MS 3000
 
+static QemuMutex event_mtx;
+static QemuCond event_complete_cond;
+static int event_unhandled_count;
+
 /*
  *  + CompareState ++
  *  |               |
@@ -87,6 +100,11 @@ typedef struct CompareState {
     IOThread *iothread;
     GMainContext *worker_context;
     QEMUTimer *packet_check_timer;
+
+    QEMUBH *event_bh;
+    enum colo_event event;
+
+    QTAILQ_ENTRY(CompareState) next;
 } CompareState;
 
 typedef struct CompareClass {
@@ -98,6 +116,12 @@ enum {
     SECONDARY_IN,
 };
 
+static void colo_compare_inconsistency_notify(void)
+{
+    notifier_list_notify(&colo_compare_notifiers,
+                migrate_get_current());
+}
+
 static int compare_chr_send(CompareState *s,
                             const uint8_t *buf,
                             uint32_t size,
@@ -413,10 +437,7 @@ sec:
         qemu_hexdump((char *)spkt->data, stderr,
                      "colo-compare spkt", spkt->size);
 
-        /*
-         * colo_compare_inconsistent_notify();
-         * TODO: notice to checkpoint();
-         */
+        colo_compare_inconsistency_notify();
     }
 }
 
@@ -547,8 +568,18 @@ static int colo_old_packet_check_one(Packet *pkt, int64_t *check_time)
     }
 }
 
+void colo_compare_register_notifier(Notifier *notify)
+{
+    notifier_list_add(&colo_compare_notifiers, notify);
+}
+
+void colo_compare_unregister_notifier(Notifier *notify)
+{
+    notifier_remove(notify);
+}
+
 static int colo_old_packet_check_one_conn(Connection *conn,
-                                          void *user_data)
+                                           void *user_data)
 {
     GList *result = NULL;
     int64_t check_time = REGULAR_PACKET_CHECK_MS;
@@ -559,10 +590,7 @@ static int colo_old_packet_check_one_conn(Connection *conn,
 
     if (result) {
         /* Do checkpoint will flush old packet */
-        /*
-         * TODO: Notify colo frame to do checkpoint.
-         * colo_compare_inconsistent_notify();
-         */
+        colo_compare_inconsistency_notify();
         return 0;
     }
 
@@ -606,11 +634,12 @@ static void colo_compare_packet(CompareState *s, Connection *conn,
             /*
              * If one packet arrive late, the secondary_list or
              * primary_list will be empty, so we can't compare it
-             * until next comparison.
+             * until next comparison. If the packets in the list are
+             * timeout, it will trigger a checkpoint request.
              */
             trace_colo_compare_main("packet different");
             g_queue_push_head(&conn->primary_list, pkt);
-            /* TODO: colo_notify_checkpoint();*/
+            colo_compare_inconsistency_notify();
             break;
         }
     }
@@ -736,6 +765,25 @@ static void check_old_packet_regular(void *opaque)
                 REGULAR_PACKET_CHECK_MS);
 }
 
+/* Public API, Used for COLO frame to notify compare event */
+void colo_notify_compares_event(void *opaque, int event, Error **errp)
+{
+    CompareState *s;
+
+    qemu_mutex_lock(&event_mtx);
+    QTAILQ_FOREACH(s, &net_compares, next) {
+        s->event = event;
+        qemu_bh_schedule(s->event_bh);
+        event_unhandled_count++;
+    }
+    /* Wait all compare threads to finish handling this event */
+    while (event_unhandled_count > 0) {
+        qemu_cond_wait(&event_complete_cond, &event_mtx);
+    }
+
+    qemu_mutex_unlock(&event_mtx);
+}
+
 static void colo_compare_timer_init(CompareState *s)
 {
     AioContext *ctx = iothread_get_aio_context(s->iothread);
@@ -756,6 +804,30 @@ static void colo_compare_timer_del(CompareState *s)
     }
  }
 
+static void colo_flush_packets(void *opaque, void *user_data);
+
+static void colo_compare_handle_event(void *opaque)
+{
+    CompareState *s = opaque;
+
+    switch (s->event) {
+    case COLO_EVENT_CHECKPOINT:
+        g_queue_foreach(&s->conn_list, colo_flush_packets, s);
+        break;
+    case COLO_EVENT_FAILOVER:
+        break;
+    default:
+        break;
+    }
+
+    assert(event_unhandled_count > 0);
+
+    qemu_mutex_lock(&event_mtx);
+    event_unhandled_count--;
+    qemu_cond_broadcast(&event_complete_cond);
+    qemu_mutex_unlock(&event_mtx);
+}
+
 static void colo_compare_iothread(CompareState *s)
 {
     object_ref(OBJECT(s->iothread));
@@ -769,6 +841,7 @@ static void colo_compare_iothread(CompareState *s)
                              s, s->worker_context, true);
 
     colo_compare_timer_init(s);
+    s->event_bh = qemu_bh_new(colo_compare_handle_event, s);
 }
 
 static char *compare_get_pri_indev(Object *obj, Error **errp)
@@ -926,8 +999,13 @@ static void colo_compare_complete(UserCreatable *uc, Error **errp)
     net_socket_rs_init(&s->pri_rs, compare_pri_rs_finalize, s->vnet_hdr);
     net_socket_rs_init(&s->sec_rs, compare_sec_rs_finalize, s->vnet_hdr);
 
+    QTAILQ_INSERT_TAIL(&net_compares, s, next);
+
     g_queue_init(&s->conn_list);
 
+    qemu_mutex_init(&event_mtx);
+    qemu_cond_init(&event_complete_cond);
+
     s->connection_track_table = g_hash_table_new_full(connection_key_hash,
                                                       connection_key_equal,
                                                       g_free,
@@ -990,6 +1068,7 @@ static void colo_compare_init(Object *obj)
 static void colo_compare_finalize(Object *obj)
 {
     CompareState *s = COLO_COMPARE(obj);
+    CompareState *tmp = NULL;
 
     qemu_chr_fe_deinit(&s->chr_pri_in, false);
     qemu_chr_fe_deinit(&s->chr_sec_in, false);
@@ -997,6 +1076,16 @@ static void colo_compare_finalize(Object *obj)
     if (s->iothread) {
         colo_compare_timer_del(s);
     }
+
+    qemu_bh_delete(s->event_bh);
+
+    QTAILQ_FOREACH(tmp, &net_compares, next) {
+        if (tmp == s) {
+            QTAILQ_REMOVE(&net_compares, s, next);
+            break;
+        }
+    }
+
     /* Release all unhandled packets after compare thead exited */
     g_queue_foreach(&s->conn_list, colo_flush_packets, s);
 
@@ -1009,6 +1098,10 @@ static void colo_compare_finalize(Object *obj)
     if (s->iothread) {
         object_unref(OBJECT(s->iothread));
     }
+
+    qemu_mutex_destroy(&event_mtx);
+    qemu_cond_destroy(&event_complete_cond);
+
     g_free(s->pri_indev);
     g_free(s->sec_indev);
     g_free(s->outdev);
diff --git a/net/colo-compare.h b/net/colo-compare.h
new file mode 100644
index 0000000000..22ddd512e2
--- /dev/null
+++ b/net/colo-compare.h
@@ -0,0 +1,24 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2017 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2017 FUJITSU LIMITED
+ * Copyright (c) 2017 Intel Corporation
+ *
+ * Authors:
+ *    zhanghailiang <zhang.zhanghailiang@huawei.com>
+ *    Zhang Chen <zhangckid@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_COLO_COMPARE_H
+#define QEMU_COLO_COMPARE_H
+
+void colo_notify_compares_event(void *opaque, int event, Error **errp);
+void colo_compare_register_notifier(Notifier *notify);
+void colo_compare_unregister_notifier(Notifier *notify);
+
+#endif /* QEMU_COLO_COMPARE_H */
diff --git a/net/colo.c b/net/colo.c
index 6dda4ed66e..49176bf07b 100644
--- a/net/colo.c
+++ b/net/colo.c
@@ -137,7 +137,7 @@ Connection *connection_new(ConnectionKey *key)
     conn->ip_proto = key->ip_proto;
     conn->processing = false;
     conn->offset = 0;
-    conn->syn_flag = 0;
+    conn->tcp_state = TCPS_CLOSED;
     conn->pack = 0;
     conn->sack = 0;
     g_queue_init(&conn->primary_list);
@@ -221,3 +221,11 @@ Connection *connection_get(GHashTable *connection_track_table,
 
     return conn;
 }
+
+bool connection_has_tracked(GHashTable *connection_track_table,
+                            ConnectionKey *key)
+{
+    Connection *conn = g_hash_table_lookup(connection_track_table, key);
+
+    return conn ? true : false;
+}
diff --git a/net/colo.h b/net/colo.h
index da6c36dcf7..11c5226488 100644
--- a/net/colo.h
+++ b/net/colo.h
@@ -18,6 +18,7 @@
 #include "slirp/slirp.h"
 #include "qemu/jhash.h"
 #include "qemu/timer.h"
+#include "slirp/tcp.h"
 
 #define HASHTABLE_MAX_SIZE 16384
 
@@ -81,11 +82,9 @@ typedef struct Connection {
     uint32_t sack;
     /* offset = secondary_seq - primary_seq */
     tcp_seq  offset;
-    /*
-     * we use this flag update offset func
-     * run once in independent tcp connection
-     */
-    int syn_flag;
+
+    int tcp_state; /* TCP FSM state */
+    tcp_seq fin_ack_seq; /* the seq of 'fin=1,ack=1' */
 } Connection;
 
 uint32_t connection_key_hash(const void *opaque);
@@ -99,6 +98,8 @@ void connection_destroy(void *opaque);
 Connection *connection_get(GHashTable *connection_track_table,
                            ConnectionKey *key,
                            GQueue *conn_list);
+bool connection_has_tracked(GHashTable *connection_track_table,
+                            ConnectionKey *key);
 void connection_hashtable_reset(GHashTable *connection_track_table);
 Packet *packet_new(const void *data, int size, int vnet_hdr_len);
 void packet_destroy(void *opaque, void *user_data);
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index f584e4eba4..bb8f4d93b1 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -20,11 +20,15 @@
 #include "qemu/main-loop.h"
 #include "qemu/iov.h"
 #include "net/checksum.h"
+#include "net/colo.h"
+#include "migration/colo.h"
 
 #define FILTER_COLO_REWRITER(obj) \
     OBJECT_CHECK(RewriterState, (obj), TYPE_FILTER_REWRITER)
 
 #define TYPE_FILTER_REWRITER "filter-rewriter"
+#define FAILOVER_MODE_ON  true
+#define FAILOVER_MODE_OFF false
 
 typedef struct RewriterState {
     NetFilterState parent_obj;
@@ -32,8 +36,14 @@ typedef struct RewriterState {
     /* hashtable to save connection */
     GHashTable *connection_track_table;
     bool vnet_hdr;
+    bool failover_mode;
 } RewriterState;
 
+static void filter_rewriter_failover_mode(RewriterState *s)
+{
+    s->failover_mode = FAILOVER_MODE_ON;
+}
+
 static void filter_rewriter_flush(NetFilterState *nf)
 {
     RewriterState *s = FILTER_COLO_REWRITER(nf);
@@ -59,9 +69,9 @@ static int is_tcp_packet(Packet *pkt)
 }
 
 /* handle tcp packet from primary guest */
-static int handle_primary_tcp_pkt(NetFilterState *nf,
+static int handle_primary_tcp_pkt(RewriterState *rf,
                                   Connection *conn,
-                                  Packet *pkt)
+                                  Packet *pkt, ConnectionKey *key)
 {
     struct tcphdr *tcp_pkt;
 
@@ -74,23 +84,28 @@ static int handle_primary_tcp_pkt(NetFilterState *nf,
         trace_colo_filter_rewriter_conn_offset(conn->offset);
     }
 
+    if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN)) &&
+        conn->tcp_state == TCPS_SYN_SENT) {
+        conn->tcp_state = TCPS_ESTABLISHED;
+    }
+
     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
         /*
          * we use this flag update offset func
          * run once in independent tcp connection
          */
-        conn->syn_flag = 1;
+        conn->tcp_state = TCPS_SYN_RECEIVED;
     }
 
     if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
-        if (conn->syn_flag) {
+        if (conn->tcp_state == TCPS_SYN_RECEIVED) {
             /*
              * offset = secondary_seq - primary seq
              * ack packet sent by guest from primary node,
              * so we use th_ack - 1 get primary_seq
              */
             conn->offset -= (ntohl(tcp_pkt->th_ack) - 1);
-            conn->syn_flag = 0;
+            conn->tcp_state = TCPS_ESTABLISHED;
         }
         if (conn->offset) {
             /* handle packets to the secondary from the primary */
@@ -99,15 +114,66 @@ static int handle_primary_tcp_pkt(NetFilterState *nf,
             net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
                                    pkt->size - pkt->vnet_hdr_len);
         }
+
+        /*
+         * Passive close step 3
+         */
+        if ((conn->tcp_state == TCPS_LAST_ACK) &&
+            (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
+            conn->tcp_state = TCPS_CLOSED;
+            g_hash_table_remove(rf->connection_track_table, key);
+        }
+    }
+
+    if ((tcp_pkt->th_flags & TH_FIN) == TH_FIN) {
+        /*
+         * Passive close.
+         * Step 1:
+         * The *server* side of this connect is VM, *client* tries to close
+         * the connection. We will into CLOSE_WAIT status.
+         *
+         * Step 2:
+         * In this step we will into LAST_ACK status.
+         *
+         * We got 'fin=1, ack=1' packet from server side, we need to
+         * record the seq of 'fin=1, ack=1' packet.
+         *
+         * Step 3:
+         * We got 'ack=1' packets from client side, it acks 'fin=1, ack=1'
+         * packet from server side. From this point, we can ensure that there
+         * will be no packets in the connection, except that, some errors
+         * happen between the path of 'filter object' and vNIC, if this rare
+         * case really happen, we can still create a new connection,
+         * So it is safe to remove the connection from connection_track_table.
+         *
+         */
+        if (conn->tcp_state == TCPS_ESTABLISHED) {
+            conn->tcp_state = TCPS_CLOSE_WAIT;
+        }
+
+        /*
+         * Active close step 2.
+         */
+        if (conn->tcp_state == TCPS_FIN_WAIT_1) {
+            conn->tcp_state = TCPS_TIME_WAIT;
+            /*
+             * For simplify implementation, we needn't wait 2MSL time
+             * in filter rewriter. Because guest kernel will track the
+             * TCP status and wait 2MSL time, if client resend the FIN
+             * packet, guest will apply the last ACK too.
+             */
+            conn->tcp_state = TCPS_CLOSED;
+            g_hash_table_remove(rf->connection_track_table, key);
+        }
     }
 
     return 0;
 }
 
 /* handle tcp packet from secondary guest */
-static int handle_secondary_tcp_pkt(NetFilterState *nf,
+static int handle_secondary_tcp_pkt(RewriterState *rf,
                                     Connection *conn,
-                                    Packet *pkt)
+                                    Packet *pkt, ConnectionKey *key)
 {
     struct tcphdr *tcp_pkt;
 
@@ -121,7 +187,8 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
         trace_colo_filter_rewriter_conn_offset(conn->offset);
     }
 
-    if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
+    if (conn->tcp_state == TCPS_SYN_RECEIVED &&
+        ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
         /*
          * save offset = secondary_seq and then
          * in handle_primary_tcp_pkt make offset
@@ -130,6 +197,12 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
         conn->offset = ntohl(tcp_pkt->th_seq);
     }
 
+    /* VM active connect */
+    if (conn->tcp_state == TCPS_CLOSED &&
+        ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
+        conn->tcp_state = TCPS_SYN_SENT;
+    }
+
     if ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK) {
         /* Only need to adjust seq while offset is Non-zero */
         if (conn->offset) {
@@ -141,6 +214,32 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
         }
     }
 
+    /*
+     * Passive close step 2:
+     */
+    if (conn->tcp_state == TCPS_CLOSE_WAIT &&
+        (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
+        conn->fin_ack_seq = ntohl(tcp_pkt->th_seq);
+        conn->tcp_state = TCPS_LAST_ACK;
+    }
+
+    /*
+     * Active close
+     *
+     * Step 1:
+     * The *server* side of this connect is VM, *server* tries to close
+     * the connection.
+     *
+     * Step 2:
+     * We will into CLOSE_WAIT status.
+     * We simplify the TCPS_FIN_WAIT_2, TCPS_TIME_WAIT and
+     * CLOSING status.
+     */
+    if (conn->tcp_state == TCPS_ESTABLISHED &&
+        (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == TH_FIN) {
+        conn->tcp_state = TCPS_FIN_WAIT_1;
+    }
+
     return 0;
 }
 
@@ -184,13 +283,20 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
              */
             reverse_connection_key(&key);
         }
+
+        /* After failover we needn't change new TCP packet */
+        if (s->failover_mode &&
+            !connection_has_tracked(s->connection_track_table, &key)) {
+            goto out;
+        }
+
         conn = connection_get(s->connection_track_table,
                               &key,
                               NULL);
 
         if (sender == nf->netdev) {
             /* NET_FILTER_DIRECTION_TX */
-            if (!handle_primary_tcp_pkt(nf, conn, pkt)) {
+            if (!handle_primary_tcp_pkt(s, conn, pkt, &key)) {
                 qemu_net_queue_send(s->incoming_queue, sender, 0,
                 (const uint8_t *)pkt->data, pkt->size, NULL);
                 packet_destroy(pkt, NULL);
@@ -203,7 +309,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
             }
         } else {
             /* NET_FILTER_DIRECTION_RX */
-            if (!handle_secondary_tcp_pkt(nf, conn, pkt)) {
+            if (!handle_secondary_tcp_pkt(s, conn, pkt, &key)) {
                 qemu_net_queue_send(s->incoming_queue, sender, 0,
                 (const uint8_t *)pkt->data, pkt->size, NULL);
                 packet_destroy(pkt, NULL);
@@ -217,11 +323,49 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
         }
     }
 
+out:
     packet_destroy(pkt, NULL);
     pkt = NULL;
     return 0;
 }
 
+static void reset_seq_offset(gpointer key, gpointer value, gpointer user_data)
+{
+    Connection *conn = (Connection *)value;
+
+    conn->offset = 0;
+}
+
+static gboolean offset_is_nonzero(gpointer key,
+                                  gpointer value,
+                                  gpointer user_data)
+{
+    Connection *conn = (Connection *)value;
+
+    return conn->offset ? true : false;
+}
+
+static void colo_rewriter_handle_event(NetFilterState *nf, int event,
+                                       Error **errp)
+{
+    RewriterState *rs = FILTER_COLO_REWRITER(nf);
+
+    switch (event) {
+    case COLO_EVENT_CHECKPOINT:
+        g_hash_table_foreach(rs->connection_track_table,
+                            reset_seq_offset, NULL);
+        break;
+    case COLO_EVENT_FAILOVER:
+        if (!g_hash_table_find(rs->connection_track_table,
+                              offset_is_nonzero, NULL)) {
+            filter_rewriter_failover_mode(rs);
+        }
+        break;
+    default:
+        break;
+    }
+}
+
 static void colo_rewriter_cleanup(NetFilterState *nf)
 {
     RewriterState *s = FILTER_COLO_REWRITER(nf);
@@ -265,6 +409,7 @@ static void filter_rewriter_init(Object *obj)
     RewriterState *s = FILTER_COLO_REWRITER(obj);
 
     s->vnet_hdr = false;
+    s->failover_mode = FAILOVER_MODE_OFF;
     object_property_add_bool(obj, "vnet_hdr_support",
                              filter_rewriter_get_vnet_hdr,
                              filter_rewriter_set_vnet_hdr, NULL);
@@ -277,6 +422,7 @@ static void colo_rewriter_class_init(ObjectClass *oc, void *data)
     nfc->setup = colo_rewriter_setup;
     nfc->cleanup = colo_rewriter_cleanup;
     nfc->receive_iov = colo_rewriter_receive_iov;
+    nfc->handle_event = colo_rewriter_handle_event;
 }
 
 static const TypeInfo colo_rewriter_info = {
diff --git a/net/filter.c b/net/filter.c
index 2fd7d7d663..c9f9e5fa08 100644
--- a/net/filter.c
+++ b/net/filter.c
@@ -17,6 +17,8 @@
 #include "net/vhost_net.h"
 #include "qom/object_interfaces.h"
 #include "qemu/iov.h"
+#include "net/colo.h"
+#include "migration/colo.h"
 
 static inline bool qemu_can_skip_netfilter(NetFilterState *nf)
 {
@@ -245,11 +247,26 @@ static void netfilter_finalize(Object *obj)
     g_free(nf->netdev_id);
 }
 
+static void default_handle_event(NetFilterState *nf, int event, Error **errp)
+{
+    switch (event) {
+    case COLO_EVENT_CHECKPOINT:
+        break;
+    case COLO_EVENT_FAILOVER:
+        object_property_set_str(OBJECT(nf), "off", "status", errp);
+        break;
+    default:
+        break;
+    }
+}
+
 static void netfilter_class_init(ObjectClass *oc, void *data)
 {
     UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
+    NetFilterClass *nfc = NETFILTER_CLASS(oc);
 
     ucc->complete = netfilter_complete;
+    nfc->handle_event = default_handle_event;
 }
 
 static const TypeInfo netfilter_info = {
diff --git a/net/net.c b/net/net.c
index cdcd5cf634..07c194a8f6 100644
--- a/net/net.c
+++ b/net/net.c
@@ -712,10 +712,15 @@ ssize_t qemu_deliver_packet_iov(NetClientState *sender,
                                 void *opaque)
 {
     NetClientState *nc = opaque;
+    size_t size = iov_size(iov, iovcnt);
     int ret;
 
+    if (size > INT_MAX) {
+        return size;
+    }
+
     if (nc->link_down) {
-        return iov_size(iov, iovcnt);
+        return size;
     }
 
     if (nc->receive_disabled) {
@@ -1335,6 +1340,25 @@ void hmp_info_network(Monitor *mon, const QDict *qdict)
     }
 }
 
+void colo_notify_filters_event(int event, Error **errp)
+{
+    NetClientState *nc;
+    NetFilterState *nf;
+    NetFilterClass *nfc = NULL;
+    Error *local_err = NULL;
+
+    QTAILQ_FOREACH(nc, &net_clients, next) {
+        QTAILQ_FOREACH(nf, &nc->filters, next) {
+            nfc = NETFILTER_GET_CLASS(OBJECT(nf));
+            nfc->handle_event(nf, event, &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                return;
+            }
+        }
+    }
+}
+
 void qmp_set_link(const char *name, bool up, Error **errp)
 {
     NetClientState *ncs[MAX_QUEUE_NUM];
diff --git a/qapi/migration.json b/qapi/migration.json
index 6e8c21258a..0928f4b727 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -923,18 +923,18 @@
 ##
 # @COLOMode:
 #
-# The colo mode
+# The COLO current mode.
 #
-# @unknown: unknown mode
+# @none: COLO is disabled.
 #
-# @primary: master side
+# @primary: COLO node in primary side.
 #
-# @secondary: slave side
+# @secondary: COLO node in slave side.
 #
 # Since: 2.8
 ##
 { 'enum': 'COLOMode',
-  'data': [ 'unknown', 'primary', 'secondary'] }
+  'data': [ 'none', 'primary', 'secondary'] }
 
 ##
 # @FailoverStatus:
@@ -957,6 +957,44 @@
   'data': [ 'none', 'require', 'active', 'completed', 'relaunch' ] }
 
 ##
+# @COLO_EXIT:
+#
+# Emitted when VM finishes COLO mode due to some errors happening or
+# at the request of users.
+#
+# @mode: report COLO mode when COLO exited.
+#
+# @reason: describes the reason for the COLO exit.
+#
+# Since: 3.1
+#
+# Example:
+#
+# <- { "timestamp": {"seconds": 2032141960, "microseconds": 417172},
+#      "event": "COLO_EXIT", "data": {"mode": "primary", "reason": "request" } }
+#
+##
+{ 'event': 'COLO_EXIT',
+  'data': {'mode': 'COLOMode', 'reason': 'COLOExitReason' } }
+
+##
+# @COLOExitReason:
+#
+# The reason for a COLO exit
+#
+# @none: no failover has ever happened. This can't occur in the
+# COLO_EXIT event, only in the result of query-colo-status.
+#
+# @request: COLO exit is due to an external request
+#
+# @error: COLO exit is due to an internal error
+#
+# Since: 3.1
+##
+{ 'enum': 'COLOExitReason',
+  'data': [ 'none', 'request', 'error' ] }
+
+##
 # @x-colo-lost-heartbeat:
 #
 # Tell qemu that heartbeat is lost, request it to do takeover procedures.
@@ -1270,6 +1308,38 @@
 { 'command': 'xen-colo-do-checkpoint' }
 
 ##
+# @COLOStatus:
+#
+# The result format for 'query-colo-status'.
+#
+# @mode: COLO running mode. If COLO is running, this field will return
+#        'primary' or 'secondary'.
+#
+# @reason: describes the reason for the COLO exit.
+#
+# Since: 3.0
+##
+{ 'struct': 'COLOStatus',
+  'data': { 'mode': 'COLOMode', 'reason': 'COLOExitReason' } }
+
+##
+# @query-colo-status:
+#
+# Query COLO status while the vm is running.
+#
+# Returns: A @COLOStatus object showing the status.
+#
+# Example:
+#
+# -> { "execute": "query-colo-status" }
+# <- { "return": { "mode": "primary", "active": true, "reason": "request" } }
+#
+# Since: 3.0
+##
+{ 'command': 'query-colo-status',
+  'returns': 'COLOStatus' }
+
+##
 # @migrate-recover:
 #
 # Provide a recovery migration stream URI.
diff --git a/qemu-options.hx b/qemu-options.hx
index f139459e80..0f2f65ee40 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2256,7 +2256,7 @@ qemu-system-i386 linux.img \
                  -netdev socket,id=n2,mcast=230.0.0.1:1234
 # launch yet another QEMU instance on same "bus"
 qemu-system-i386 linux.img \
-                 -device e1000,netdev=n3,macaddr=52:54:00:12:34:58 \
+                 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \
                  -netdev socket,id=n3,mcast=230.0.0.1:1234
 @end example
 
diff --git a/vl.c b/vl.c
index 4e25c78bff..ac3ed17de4 100644
--- a/vl.c
+++ b/vl.c
@@ -4365,8 +4365,6 @@ int main(int argc, char **argv, char **envp)
 #endif
     }
 
-    colo_info_init();
-
     if (net_init_clients(&err) < 0) {
         error_report_err(err);
         exit(1);