[Qemu-devel] [PATCH V6 00/17] COLO: integrate colo frame with block replication and COLO proxy

[Qemu-devel] [PATCH V6 00/17] COLO: integrate colo frame with block replication and COLO proxy

[Zhang Chen]

Hi~ All~

COLO Frame, block replication and COLO proxy(colo-compare,filter-mirror,
filter-redirector,filter-rewriter) have been exist in qemu
for long time, it's time to integrate these three parts to make COLO really works.

In this series, we have some optimizations for COLO frame, including separating the
process of saving ram and device state, using an COLO_EXIT event to notify users that
VM exits COLO, for these parts, most of them have been reviewed long time ago in old version,
but since this series have just rebased on upstream which had merged a new series of migration,
parts of pathes in this series deserve review again.

We use notifier/callback method for COLO compare to notify COLO frame about
net packets inconsistent event, and add a handle_event method for NetFilterClass to
help COLO frame to notify filters and colo-compare about checkpoint/failover event, 
it is flexible.

For the neweset version, please refer to:
https://github.com/zhangckid/qemu/tree/qemu-colo-18mar11

Please review, thanks.

V6:
 - Addressed Eric Blake's comments, use the enum to feedback in patch 11/17.
 - Fixed QAPI command separator problem in patch 11/17.

V5:
 - Addressed Markus's comments add new command to
   query COLO status(patch 11/17).
 - Rebased on upstream codes.
 - Fixed qapi header problem in patch 10/17.
 - Fixed the conflict of "qemu_anon_ram_alloc()" in patch 07/17. 

V4:
 - Address Eric's comments in patch 10/16.
 - Rebase on upstream codes.
 - Fix mingw compile error in patch 02/16.
 - Fix some comments.
 - Fix conflect with the patch "migration: remove "enable_colo" var" in patch 06/16.

V3:
 - Address community comments from V2.
 - Rebase on upstream codes.
 - Fix several bugs.
 - Splite shared disk part to indepentent patch set.
 - Optimize codes.


Zhang Chen (10):
  filter-rewriter: fix memory leak for connection in
    connection_track_table
  colo-compare: implement the process of checkpoint
  colo-compare: use notifier to notify packets comparing result
  COLO: integrate colo compare with colo frame
  COLO: Add block replication into colo process
  COLO: Remove colo_state migration struct
  ram/COLO: Record the dirty pages that SVM received
  qapi: Add new command to query colo status
  filter: Add handle_event method for NetFilterClass
  filter-rewriter: handle checkpoint and failover event

zhanghailiang (7):
  COLO: Load dirty pages into SVM's RAM cache firstly
  COLO: Flush memory data from ram cache
  qmp event: Add COLO_EXIT event to notify users while exited COLO
  savevm: split the process of different stages for loadvm/savevm
  COLO: flush host dirty ram from cache
  COLO: notify net filters about checkpoint/failover event
  COLO: quick failover process by kick COLO thread

 include/exec/ram_addr.h  |   1 +
 include/migration/colo.h |  11 ++-
 include/net/filter.h     |   5 ++
 migration/Makefile.objs  |   2 +-
 migration/colo-comm.c    |  76 -----------------
 migration/colo.c         | 216 ++++++++++++++++++++++++++++++++++++++++++++---
 migration/migration.c    |  38 ++++++++-
 migration/ram.c          | 183 ++++++++++++++++++++++++++++++++++++++-
 migration/ram.h          |   4 +
 migration/savevm.c       |  54 ++++++++++--
 migration/savevm.h       |   5 ++
 migration/trace-events   |   3 +
 net/colo-compare.c       | 108 ++++++++++++++++++++++--
 net/colo-compare.h       |  24 ++++++
 net/colo.h               |   4 +
 net/filter-rewriter.c    | 109 ++++++++++++++++++++++--
 net/filter.c             |  17 ++++
 net/net.c                |  28 ++++++
 qapi/migration.json      |  68 +++++++++++++++
 vl.c                     |   2 -
 20 files changed, 840 insertions(+), 118 deletions(-)
 delete mode 100644 migration/colo-comm.c
 create mode 100644 net/colo-compare.h

-- 
2.7.4

[Qemu-devel] [PATCH V6 00/17] COLO: integrate colo frame with block replication and COLO proxy

[Zhang Chen]

Hi~

COLO Frame, block replication and COLO proxy(colo-compare,filter-mirror,
filter-redirector,filter-rewriter) have been exist in qemu
for long time, it's time to integrate these three parts to make COLO really works.

In this series, we have some optimizations for COLO frame, including separating the
process of saving ram and device state, using an COLO_EXIT event to notify users that
VM exits COLO, for these parts, most of them have been reviewed long time ago in old version,
but since this series have just rebased on upstream which had merged a new series of migration,
parts of pathes in this series deserve review again.

We use notifier/callback method for COLO compare to notify COLO frame about
net packets inconsistent event, and add a handle_event method for NetFilterClass to
help COLO frame to notify filters and colo-compare about checkpoint/failover event, 
it is flexible.

For the neweset version, please refer to:
https://github.com/zhangckid/qemu/tree/qemu-colo-18mar10

Please review, thanks.

V6:
 - Addressed Eric Blake's comments, use the enum to feedback in patch 11/17.
 - Fixed QAPI command separator problem in patch 11/17.

V5:
 - Addressed Markus's comments add new command to
   query COLO status(patch 11/17).
 - Rebased on upstream codes.
 - Fixed qapi header problem in patch 10/17.
 - Fixed the conflict of "qemu_anon_ram_alloc()" in patch 07/17. 

V4:
 - Address Eric's comments in patch 10/16.
 - Rebase on upstream codes.
 - Fix mingw compile error in patch 02/16.
 - Fix some comments.
 - Fix conflect with the patch "migration: remove "enable_colo" var" in patch 06/16.

V3:
 - Address community comments from V2.
 - Rebase on upstream codes.
 - Fix several bugs.
 - Splite shared disk part to indepentent patch set.
 - Optimize codes.


Zhang Chen (10):
  filter-rewriter: fix memory leak for connection in
    connection_track_table
  colo-compare: implement the process of checkpoint
  colo-compare: use notifier to notify packets comparing result
  COLO: integrate colo compare with colo frame
  COLO: Add block replication into colo process
  COLO: Remove colo_state migration struct
  ram/COLO: Record the dirty pages that SVM received
  qapi: Add new command to query colo status
  filter: Add handle_event method for NetFilterClass
  filter-rewriter: handle checkpoint and failover event

zhanghailiang (7):
  COLO: Load dirty pages into SVM's RAM cache firstly
  COLO: Flush memory data from ram cache
  qmp event: Add COLO_EXIT event to notify users while exited COLO
  savevm: split the process of different stages for loadvm/savevm
  COLO: flush host dirty ram from cache
  COLO: notify net filters about checkpoint/failover event
  COLO: quick failover process by kick COLO thread

 include/exec/ram_addr.h  |   1 +
 include/migration/colo.h |  11 ++-
 include/net/filter.h     |   5 ++
 migration/Makefile.objs  |   2 +-
 migration/colo-comm.c    |  76 -----------------
 migration/colo.c         | 216 ++++++++++++++++++++++++++++++++++++++++++++---
 migration/migration.c    |  38 ++++++++-
 migration/ram.c          | 183 ++++++++++++++++++++++++++++++++++++++-
 migration/ram.h          |   4 +
 migration/savevm.c       |  54 ++++++++++--
 migration/savevm.h       |   5 ++
 migration/trace-events   |   3 +
 net/colo-compare.c       | 108 ++++++++++++++++++++++--
 net/colo-compare.h       |  24 ++++++
 net/colo.h               |   4 +
 net/filter-rewriter.c    | 109 ++++++++++++++++++++++--
 net/filter.c             |  17 ++++
 net/net.c                |  28 ++++++
 qapi/migration.json      |  68 +++++++++++++++
 vl.c                     |   2 -
 20 files changed, 840 insertions(+), 118 deletions(-)
 delete mode 100644 migration/colo-comm.c
 create mode 100644 net/colo-compare.h

-- 
2.7.4

[Qemu-devel] [PATCH V6 01/17] filter-rewriter: fix memory leak for connection in connection_track_table

[Zhang Chen]

After a net connection is closed, we didn't clear its releated resources
in connection_track_table, which will lead to memory leak.

Let't track the state of net connection, if it is closed, its related
resources will be cleared up.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 net/colo.h            |  4 +++
 net/filter-rewriter.c | 69 +++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 66 insertions(+), 7 deletions(-)

diff --git a/net/colo.h b/net/colo.h
index da6c36d..cd11851 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
 
@@ -86,6 +87,9 @@ typedef struct Connection {
      * 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);
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index 62dad2d..0909a9a 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -59,9 +59,9 @@ 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;
 
@@ -99,15 +99,44 @@ 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);
         }
+        /*
+         * Case 1:
+         * The *server* side of this connect is VM, *client* tries to close
+         * the connection.
+         *
+         * 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_LAST_ACK) &&
+            (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
+            g_hash_table_remove(rf->connection_track_table, key);
+        }
+    }
+    /*
+     * Case 2:
+     * The *server* side of this connect is VM, *server* tries to close
+     * the connection.
+     *
+     * We got 'fin=1, ack=1' packet from client side, we need to
+     * record the seq of 'fin=1, ack=1' packet.
+     */
+    if ((tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
+        conn->fin_ack_seq = htonl(tcp_pkt->th_seq);
+        conn->tcp_state = TCPS_LAST_ACK;
     }
 
     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;
 
@@ -139,8 +168,34 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
             net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
                                    pkt->size - pkt->vnet_hdr_len);
         }
+        /*
+         * Case 2:
+         * The *server* side of this connect is VM, *server* tries to close
+         * the connection.
+         *
+         * We got 'ack=1' packets from server side, it acks 'fin=1, ack=1'
+         * packet from client side. Like Case 1, there should be no packets
+         * in the connection from now know, But the difference here is
+         * if the packet is lost, We will get the resent 'fin=1,ack=1' packet.
+         * TODO: Fix above case.
+         */
+        if ((conn->tcp_state == TCPS_LAST_ACK) &&
+            (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
+            g_hash_table_remove(rf->connection_track_table, key);
+        }
+    }
+    /*
+     * Case 1:
+     * The *server* side of this connect is VM, *client* tries to close
+     * the connection.
+     *
+     * We got 'fin=1, ack=1' packet from server side, we need to
+     * record the seq of 'fin=1, ack=1' packet.
+     */
+    if ((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;
     }
-
     return 0;
 }
 
@@ -190,7 +245,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
 
         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 +258,7 @@ 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);
-- 
2.7.4

[Qemu-devel] [PATCH V6 02/17] colo-compare: implement the process of checkpoint

[Zhang Chen]

While do checkpoint, we need to flush all the unhandled packets,
By using the filter notifier mechanism, we can easily to notify
every compare object to do this process, which runs inside
of compare threads as a coroutine.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 include/migration/colo.h |  6 ++++
 net/colo-compare.c       | 76 ++++++++++++++++++++++++++++++++++++++++++++++++
 net/colo-compare.h       | 22 ++++++++++++++
 3 files changed, 104 insertions(+)
 create mode 100644 net/colo-compare.h

diff --git a/include/migration/colo.h b/include/migration/colo.h
index 2fe48ad..fefb2fc 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -16,6 +16,12 @@
 #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);
diff --git a/net/colo-compare.c b/net/colo-compare.c
index 23b2d2c..7ff3ae8 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -27,11 +27,16 @@
 #include "qemu/sockets.h"
 #include "net/colo.h"
 #include "sysemu/iothread.h"
+#include "net/colo-compare.h"
+#include "migration/colo.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);
+
 #define COMPARE_READ_LEN_MAX NET_BUFSIZE
 #define MAX_QUEUE_SIZE 1024
 
@@ -41,6 +46,10 @@
 /* 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 +96,11 @@ 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 {
@@ -736,6 +750,25 @@ 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 +789,28 @@ 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;
+    }
+    qemu_mutex_lock(&event_mtx);
+    assert(event_unhandled_count > 0);
+    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 +824,7 @@ 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 +982,13 @@ 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 +1051,7 @@ 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 +1059,16 @@ 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 (!strcmp(tmp->outdev, s->outdev)) {
+            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 +1081,10 @@ 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 0000000..1b1ce76
--- /dev/null
+++ b/net/colo-compare.h
@@ -0,0 +1,22 @@
+/*
+ * 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);
+
+#endif /* QEMU_COLO_COMPARE_H */
-- 
2.7.4

[Qemu-devel] [PATCH V6 03/17] colo-compare: use notifier to notify packets comparing result

[Zhang Chen]

It's a good idea to use notifier to notify COLO frame of
inconsistent packets comparing.

Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 net/colo-compare.c | 32 +++++++++++++++++++++++++-------
 net/colo-compare.h |  2 ++
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/net/colo-compare.c b/net/colo-compare.c
index 7ff3ae8..05061cd 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -29,6 +29,7 @@
 #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) \
@@ -37,6 +38,9 @@
 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
 
@@ -561,8 +565,24 @@ static int colo_old_packet_check_one(Packet *pkt, int64_t *check_time)
     }
 }
 
+static void colo_compare_inconsistent_notify(void)
+{
+    notifier_list_notify(&colo_compare_notifiers,
+                migrate_get_current());
+}
+
+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;
@@ -573,10 +593,7 @@ 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_inconsistent_notify();
         return 0;
     }
 
@@ -620,11 +637,12 @@ 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_inconsistent_notify();
             break;
         }
     }
diff --git a/net/colo-compare.h b/net/colo-compare.h
index 1b1ce76..22ddd51 100644
--- a/net/colo-compare.h
+++ b/net/colo-compare.h
@@ -18,5 +18,7 @@
 #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 */
-- 
2.7.4

[Qemu-devel] [PATCH V6 04/17] COLO: integrate colo compare with colo frame

[Zhang Chen]

For COLO FT, both the PVM and SVM run at the same time,
only sync the state while it needs.

So here, let SVM runs while not doing checkpoint, change
DEFAULT_MIGRATE_X_CHECKPOINT_DELAY to 200*100.

Besides, we forgot to release colo_checkpoint_semd and
colo_delay_timer, fix them here.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/colo.c      | 42 ++++++++++++++++++++++++++++++++++++++++--
 migration/migration.c |  4 ++--
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 4381067..081df18 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -25,8 +25,11 @@
 #include "qemu/error-report.h"
 #include "migration/failover.h"
 #include "replication.h"
+#include "net/colo-compare.h"
+#include "net/colo.h"
 
 static bool vmstate_loading;
+static Notifier packets_compare_notifier;
 
 #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024)
 
@@ -343,6 +346,11 @@ 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);
@@ -400,6 +408,11 @@ 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 +429,9 @@ 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.
@@ -461,11 +477,21 @@ out:
         qemu_fclose(fb);
     }
 
-    timer_del(s->colo_delay_timer);
-
     /* 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
@@ -558,6 +584,11 @@ void *colo_process_incoming_thread(void *opaque)
     fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
     object_unref(OBJECT(bioc));
 
+    qemu_mutex_lock_iothread();
+    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) {
@@ -577,6 +608,11 @@ 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);
@@ -630,6 +666,8 @@ void *colo_process_incoming_thread(void *opaque)
         }
 
         vmstate_loading = false;
+        vm_start();
+        trace_colo_vm_state_change("stop", "run");
         qemu_mutex_unlock_iothread();
 
         if (failover_get_state() == FAILOVER_STATUS_RELAUNCH) {
diff --git a/migration/migration.c b/migration/migration.c
index e345d0c..7f72f78 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -76,9 +76,9 @@
 #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.
+ * Note: Please change this default value to 20000 when we support hybrid mode.
  */
-#define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY 200
+#define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY (200 * 100)
 #define DEFAULT_MIGRATE_MULTIFD_CHANNELS 2
 #define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 16
 
-- 
2.7.4

[Qemu-devel] [PATCH V6 05/17] COLO: Add block replication into colo process

[Zhang Chen]

Make sure master start block replication after slave's block
replication started.

Besides, we need to activate VM's blocks before goes into
COLO state.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 migration/colo.c      | 43 +++++++++++++++++++++++++++++++++++++++++++
 migration/migration.c |  9 +++++++++
 2 files changed, 52 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index 081df18..e06640c 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -27,6 +27,7 @@
 #include "replication.h"
 #include "net/colo-compare.h"
 #include "net/colo.h"
+#include "block/block.h"
 
 static bool vmstate_loading;
 static Notifier packets_compare_notifier;
@@ -56,6 +57,7 @@ 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.
@@ -73,6 +75,11 @@ 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);
+    }
+
     if (!autostart) {
         error_report("\"-S\" qemu option will be ignored in secondary side");
         /* recover runstate to normal migration finish state */
@@ -110,6 +117,7 @@ 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);
@@ -133,6 +141,13 @@ 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);
 }
@@ -356,6 +371,11 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
     qemu_savevm_state_header(fb);
     qemu_savevm_state_setup(fb);
     qemu_mutex_lock_iothread();
+    replication_do_checkpoint_all(&local_err);
+    if (local_err) {
+        qemu_mutex_unlock_iothread();
+        goto out;
+    }
     qemu_savevm_state_complete_precopy(fb, false, false);
     qemu_mutex_unlock_iothread();
 
@@ -446,6 +466,12 @@ 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");
@@ -585,6 +611,11 @@ void *colo_process_incoming_thread(void *opaque)
     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();
@@ -665,6 +696,18 @@ void *colo_process_incoming_thread(void *opaque)
             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;
+        }
+
         vmstate_loading = false;
         vm_start();
         trace_colo_vm_state_change("stop", "run");
diff --git a/migration/migration.c b/migration/migration.c
index 7f72f78..128daaa 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -346,6 +346,7 @@ 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->largest_page_size = qemu_ram_pagesize_largest();
@@ -377,6 +378,14 @@ 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()) {
+        /* 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);
+        }
         mis->migration_incoming_co = qemu_coroutine_self();
         qemu_thread_create(&mis->colo_incoming_thread, "COLO incoming",
              colo_process_incoming_thread, mis, QEMU_THREAD_JOINABLE);
-- 
2.7.4

[Qemu-devel] [PATCH V6 06/17] COLO: Remove colo_state migration struct

[Zhang Chen]

We need to know if migration is going into COLO state for
incoming side before start normal migration.

Instead by using the VMStateDescription to send colo_state
from source side to destination side, we use MIG_CMD_ENABLE_COLO
to indicate whether COLO is enabled or not.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 include/migration/colo.h |  5 ++--
 migration/Makefile.objs  |  2 +-
 migration/colo-comm.c    | 76 ------------------------------------------------
 migration/colo.c         | 13 ++++++++-
 migration/migration.c    | 23 ++++++++++++++-
 migration/savevm.c       | 19 ++++++++++++
 migration/savevm.h       |  1 +
 migration/trace-events   |  1 +
 vl.c                     |  2 --
 9 files changed, 59 insertions(+), 83 deletions(-)
 delete mode 100644 migration/colo-comm.c

diff --git a/include/migration/colo.h b/include/migration/colo.h
index fefb2fc..99ce17a 100644
--- a/include/migration/colo.h
+++ b/include/migration/colo.h
@@ -28,8 +28,9 @@ 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/migration/Makefile.objs b/migration/Makefile.objs
index 99e0380..3099eec 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 df26e4d..0000000
--- 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.c b/migration/colo.c
index e06640c..c083d36 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -152,6 +152,17 @@ static void primary_vm_do_failover(void)
     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_UNKNOWN;
+    }
+}
+
 void colo_do_failover(MigrationState *s)
 {
     /* Make sure VM stopped while failover happened. */
@@ -745,7 +756,7 @@ out:
     if (mis->to_src_file) {
         qemu_fclose(mis->to_src_file);
     }
-    migration_incoming_exit_colo();
+    migration_incoming_disable_colo();
 
     return NULL;
 }
diff --git a/migration/migration.c b/migration/migration.c
index 128daaa..47328df 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -268,6 +268,22 @@ 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;
@@ -377,7 +393,7 @@ 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) {
@@ -2365,6 +2381,11 @@ 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/savevm.c b/migration/savevm.c
index 358c5b5..10a6676 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -54,6 +54,7 @@
 #include "qemu/cutils.h"
 #include "io/channel-buffer.h"
 #include "io/channel-file.h"
+#include "migration/colo.h"
 
 #ifndef ETH_P_RARP
 #define ETH_P_RARP 0x8035
@@ -80,6 +81,9 @@ 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_MAX
 };
 
@@ -835,6 +839,12 @@ 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;
@@ -1769,6 +1779,12 @@ static int loadvm_handle_cmd_packaged(MigrationIncomingState *mis)
     return ret;
 }
 
+static int loadvm_process_enable_colo(MigrationIncomingState *mis)
+{
+    migration_incoming_enable_colo();
+    return 0;
+}
+
 /*
  * Process an incoming 'QEMU_VM_COMMAND'
  * 0           just a normal return
@@ -1842,6 +1858,9 @@ static int loadvm_process_command(QEMUFile *f)
 
     case MIG_CMD_POSTCOPY_RAM_DISCARD:
         return loadvm_postcopy_ram_handle_discard(mis, len);
+
+    case MIG_CMD_ENABLE_COLO:
+        return loadvm_process_enable_colo(mis);
     }
 
     return 0;
diff --git a/migration/savevm.h b/migration/savevm.h
index 295c4a1..041d23c 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -51,6 +51,7 @@ 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);
 
 int qemu_loadvm_state(QEMUFile *f);
 void qemu_loadvm_state_cleanup(void);
diff --git a/migration/trace-events b/migration/trace-events
index 93961de..b27a3a0 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -34,6 +34,7 @@ savevm_send_open_return_path(void) ""
 savevm_send_ping(uint32_t val) "0x%x"
 savevm_send_postcopy_listen(void) ""
 savevm_send_postcopy_run(void) ""
+savevm_send_colo_enable(void) ""
 savevm_state_setup(void) ""
 savevm_state_header(void) ""
 savevm_state_iterate(void) ""
diff --git a/vl.c b/vl.c
index dae986b..e67750d 100644
--- a/vl.c
+++ b/vl.c
@@ -4471,8 +4471,6 @@ int main(int argc, char **argv, char **envp)
 #endif
     }
 
-    colo_info_init();
-
     if (net_init_clients(&err) < 0) {
         error_report_err(err);
         exit(1);
-- 
2.7.4

[Qemu-devel] [PATCH V6 07/17] COLO: Load dirty pages into SVM's RAM cache firstly

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

We should not load PVM's state directly into SVM, because there maybe some
errors happen when SVM is receving data, which will break SVM.

We need to ensure receving all data before load the state into SVM. We use
an extra memory to cache these data (PVM's ram). The ram cache in secondary side
is initially the same as SVM/PVM's memory. And in the process of checkpoint,
we cache the dirty pages of PVM into this ram cache firstly, so this ram cache
always the same as PVM's memory at every checkpoint, then we flush this cached ram
to SVM after we receive all PVM's state.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 include/exec/ram_addr.h |  1 +
 migration/migration.c   |  2 +
 migration/ram.c         | 99 +++++++++++++++++++++++++++++++++++++++++++++++--
 migration/ram.h         |  4 ++
 migration/savevm.c      |  2 +-
 5 files changed, 104 insertions(+), 4 deletions(-)

diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index cf2446a..51ec153 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/migration/migration.c b/migration/migration.c
index 47328df..4d5e188 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -410,6 +410,8 @@ 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) {
diff --git a/migration/ram.c b/migration/ram.c
index 3b6c077..86f5c3c 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2470,6 +2470,20 @@ 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;
+    }
+    return block->colo_cache + offset;
+}
+
 /**
  * ram_handle_compressed: handle the zero page case
  *
@@ -2623,6 +2637,57 @@ 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();
+    QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+        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;
+        }
+    }
+    rcu_read_unlock();
+    return 0;
+
+out_locked:
+    QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+        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;
+
+    rcu_read_lock();
+    QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+        if (block->colo_cache) {
+            qemu_anon_ram_free(block->colo_cache, block->used_length);
+            block->colo_cache = NULL;
+        }
+    }
+    rcu_read_unlock();
+}
+
 /**
  * ram_load_setup: Setup RAM for migration incoming side
  *
@@ -2636,6 +2701,7 @@ static int ram_load_setup(QEMUFile *f, void *opaque)
     xbzrle_load_setup();
     compress_threads_load_setup();
     ramblock_recv_map_init();
+
     return 0;
 }
 
@@ -2649,6 +2715,7 @@ static int ram_load_cleanup(void *opaque)
         g_free(rb->receivedmap);
         rb->receivedmap = NULL;
     }
+
     return 0;
 }
 
@@ -2862,7 +2929,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
 
     while (!postcopy_running && !ret && !(flags & RAM_SAVE_FLAG_EOS)) {
         ram_addr_t addr, total_ram_bytes;
-        void *host = NULL;
+        void *host = NULL, *host_bak = NULL;
         uint8_t ch;
 
         addr = qemu_get_be64(f);
@@ -2882,13 +2949,36 @@ 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
+             * NOTE: We need to keep a copy of SVM's ram in colo_cache.
+             * Privously, we copied all these memory in preparing stage of COLO
+             * while we need to stop VM, which is a time-consuming process.
+             * Here we optimize it by a trick, back-up every page while in
+             * migration process while COLO is enabled, though it affects the
+             * speed of the migration, but it obviously reduce the downtime of
+             * back-up all SVM'S memory in COLO preparing stage.
+             */
+            if (migration_incoming_in_colo_state()) {
+                host = colo_cache_from_block_offset(block, addr);
+                /* After goes into COLO state, don't backup it any more */
+                if (!migration_incoming_in_colo_state()) {
+                    host_bak = host;
+                }
+            }
+            if (!migration_incoming_in_colo_state()) {
+                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);
         }
 
@@ -2983,6 +3073,9 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
         if (!ret) {
             ret = qemu_file_get_error(f);
         }
+        if (!ret && host_bak && host) {
+            memcpy(host_bak, host, TARGET_PAGE_SIZE);
+        }
     }
 
     wait_for_decompress_done();
diff --git a/migration/ram.h b/migration/ram.h
index 53f0021..3a8e5a6 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -63,4 +63,8 @@ int ramblock_recv_bitmap_test(RAMBlock *rb, void *host_addr);
 void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr);
 void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr, size_t nr);
 
+/* 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 10a6676..0d1f593 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1782,7 +1782,7 @@ static int loadvm_handle_cmd_packaged(MigrationIncomingState *mis)
 static int loadvm_process_enable_colo(MigrationIncomingState *mis)
 {
     migration_incoming_enable_colo();
-    return 0;
+    return colo_init_ram_cache();
 }
 
 /*
-- 
2.7.4

[Qemu-devel] [PATCH V6 08/17] ram/COLO: Record the dirty pages that SVM received

[Zhang Chen]

We record the address of the dirty pages that received,
it will help flushing pages that cached into SVM.

Here, it is a trick, we record dirty pages by re-using migration
dirty bitmap. In the later patch, we will start the dirty log
for SVM, just like migration, in this way, we can record both
the dirty pages caused by PVM and SVM, we only flush those dirty
pages from RAM cache while do checkpoint.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/ram.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/migration/ram.c b/migration/ram.c
index 86f5c3c..4534c7a 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2481,6 +2481,15 @@ static inline void *colo_cache_from_block_offset(RAMBlock *block,
                      __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;
 }
 
@@ -2659,6 +2668,24 @@ int colo_init_ram_cache(void)
         }
     }
     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;
+
+        QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+            unsigned long pages = block->max_length >> TARGET_PAGE_BITS;
+
+            block->bmap = bitmap_new(pages);
+            bitmap_set(block->bmap, 0, pages);
+         }
+    }
+    ram_state = g_new0(RAMState, 1);
+    ram_state->migration_dirty_pages = 0;
+
     return 0;
 
 out_locked:
@@ -2678,6 +2705,10 @@ void colo_release_ram_cache(void)
 {
     RAMBlock *block;
 
+    QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+        g_free(block->bmap);
+        block->bmap = NULL;
+    }
     rcu_read_lock();
     QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
         if (block->colo_cache) {
@@ -2686,6 +2717,8 @@ void colo_release_ram_cache(void)
         }
     }
     rcu_read_unlock();
+    g_free(ram_state);
+    ram_state = NULL;
 }
 
 /**
-- 
2.7.4

[Qemu-devel] [PATCH V6 09/17] COLO: Flush memory data from ram cache

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

During the time of VM's running, PVM may dirty some pages, we will transfer
PVM's dirty pages to SVM and store them into SVM's RAM cache at next checkpoint
time. So, the content of SVM's RAM cache will always be same with PVM's memory
after checkpoint.

Instead of flushing all content of PVM's RAM cache into SVM's MEMORY,
we do this in a more efficient way:
Only flush any page that dirtied by PVM since last checkpoint.
In this way, we can ensure SVM's memory same with PVM's.

Besides, we must ensure flush RAM cache before load device state.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/ram.c        | 39 +++++++++++++++++++++++++++++++++++++++
 migration/trace-events |  2 ++
 2 files changed, 41 insertions(+)

diff --git a/migration/ram.c b/migration/ram.c
index 4534c7a..ff7265e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2927,6 +2927,40 @@ 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;
+
+    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);
+        migration_bitmap_clear_dirty(ram_state, block, offset);
+
+        if (offset << TARGET_PAGE_BITS >= block->used_length) {
+            offset = 0;
+            block = QLIST_NEXT_RCU(block, next);
+        } else {
+            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();
+    assert(ram_state->migration_dirty_pages == 0);
+}
+
 static int ram_load(QEMUFile *f, void *opaque, int version_id)
 {
     int flags = 0, ret = 0, invalid_flags = 0;
@@ -2939,6 +2973,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
     bool postcopy_running = postcopy_is_running();
     /* ADVISE is earlier, it shows the source has the postcopy capability on */
     bool postcopy_advised = postcopy_is_advised();
+    bool need_flush = false;
 
     seq_iter++;
 
@@ -3114,6 +3149,10 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
     wait_for_decompress_done();
     rcu_read_unlock();
     trace_ram_load_complete(ret, seq_iter);
+
+    if (!ret  && migration_incoming_in_colo_state() && need_flush) {
+        colo_flush_ram_cache();
+    }
     return ret;
 }
 
diff --git a/migration/trace-events b/migration/trace-events
index b27a3a0..a3a124b 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -78,6 +78,8 @@ ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64 " %x"
 ram_postcopy_send_discard_bitmap(void) ""
 ram_save_page(const char *rbname, uint64_t offset, void *host) "%s: offset: 0x%" PRIx64 " host: %p"
 ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start: 0x%zx len: 0x%zx"
+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) ""
-- 
2.7.4

[Qemu-devel] [PATCH V6 10/17] qmp event: Add COLO_EXIT event to notify users while exited COLO

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

If some errors happen during VM's COLO FT stage, it's important to
notify the users of this event. Together with 'x-colo-lost-heartbeat',
Users can intervene in COLO's failover work immediately.
If users don't want to get involved in COLO's failover verdict,
it is still necessary to notify users that we exited COLO mode.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 migration/colo.c    | 20 ++++++++++++++++++++
 qapi/migration.json | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index c083d36..8ca6381 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -28,6 +28,7 @@
 #include "net/colo-compare.h"
 #include "net/colo.h"
 #include "block/block.h"
+#include "qapi/qapi-events-migration.h"
 
 static bool vmstate_loading;
 static Notifier packets_compare_notifier;
@@ -514,6 +515,18 @@ out:
         qemu_fclose(fb);
     }
 
+    /*
+     * There are only two reasons we can go here, some error happened.
+     * Or the user triggered failover.
+     */
+    if (failover_get_state() == FAILOVER_STATUS_NONE) {
+        qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
+                                  COLO_EXIT_REASON_ERROR, NULL);
+    } else {
+        qapi_event_send_colo_exit(COLO_MODE_PRIMARY,
+                                  COLO_EXIT_REASON_REQUEST, NULL);
+    }
+
     /* Hope this not to be too long to wait here */
     qemu_sem_wait(&s->colo_exit_sem);
     qemu_sem_destroy(&s->colo_exit_sem);
@@ -744,6 +757,13 @@ out:
     if (local_err) {
         error_report_err(local_err);
     }
+    if (failover_get_state() == FAILOVER_STATUS_NONE) {
+        qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
+                                  COLO_EXIT_REASON_ERROR, NULL);
+    } else {
+        qapi_event_send_colo_exit(COLO_MODE_SECONDARY,
+                                  COLO_EXIT_REASON_REQUEST, NULL);
+    }
 
     if (fb) {
         qemu_fclose(fb);
diff --git a/qapi/migration.json b/qapi/migration.json
index 7f465a1..6c6c50e 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -858,6 +858,41 @@
   '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: which COLO mode the VM was in when it exited.
+#
+# @reason: describes the reason for the COLO exit.
+#
+# Since: 2.12
+#
+# 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
+#
+# @request: COLO exit is due to an external request
+#
+# @error: COLO exit is due to an internal error
+#
+# Since: 2.12
+##
+{ 'enum': 'COLOExitReason',
+  'data': [ 'request', 'error' ] }
+
+##
 # @x-colo-lost-heartbeat:
 #
 # Tell qemu that heartbeat is lost, request it to do takeover procedures.
-- 
2.7.4

[Qemu-devel] [PATCH V6 11/17] qapi: Add new command to query colo status

[Zhang Chen]

Libvirt or other high level software can use this command query colo status.
You can test this command like that:
{'execute':'query-colo-status'}

Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 migration/colo.c    | 31 +++++++++++++++++++++++++++++++
 qapi/migration.json | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index 8ca6381..127db3c 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -237,6 +237,37 @@ void qmp_xen_colo_do_checkpoint(Error **errp)
 #endif
 }
 
+COLOStatus *qmp_query_colo_status(Error **errp)
+{
+    MigrationState *m;
+    MigrationIncomingState *mis;
+    COLOStatus *s = g_new0(COLOStatus, 1);
+
+    if (get_colo_mode() == COLO_MODE_PRIMARY) {
+        m = migrate_get_current();
+
+        if (m->state == MIGRATION_STATUS_COLO) {
+            s->colo_running = true;
+        } else {
+            s->colo_running = false;
+        }
+        s->mode = COLO_MODE_PRIMARY;
+    } else {
+        mis = migration_incoming_get_current();
+
+        if (mis->state == MIGRATION_STATUS_COLO) {
+            s->colo_running = true;
+        } else {
+            s->colo_running = false;
+        }
+        s->mode = COLO_MODE_SECONDARY;
+    }
+
+    s->reason = failover_get_state();
+
+    return s;
+}
+
 static void colo_send_message(QEMUFile *f, COLOMessage msg,
                               Error **errp)
 {
diff --git a/qapi/migration.json b/qapi/migration.json
index 6c6c50e..8ccdd21 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1201,3 +1201,36 @@
 # Since: 2.9
 ##
 { 'command': 'xen-colo-do-checkpoint' }
+
+##
+# @COLOStatus:
+#
+# The result format for 'query-colo-status'.
+#
+# @mode: which COLO mode the VM was in when it exited.
+#
+# @colo-running: if true means COLO running well, otherwise COLO have done.
+#
+# @reason: describes the reason for the COLO exit.
+#
+# Since: 2.12
+##
+{ 'struct': 'COLOStatus',
+  'data': { 'mode': 'COLOMode', 'colo-running': 'bool', '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", "colo-running": true, "reason": "request" } }
+#
+# Since: 2.12
+##
+{ 'command': 'query-colo-status',
+  'returns': 'COLOStatus' }
-- 
2.7.4

[Qemu-devel] [PATCH V6 12/17] savevm: split the process of different stages for loadvm/savevm

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

There are several stages during loadvm/savevm process. In different stage,
migration incoming processes different types of sections.
We want to control these stages more accuracy, it will benefit COLO
performance, we don't have to save type of QEMU_VM_SECTION_START
sections everytime while do checkpoint, besides, we want to separate
the process of saving/loading memory and devices state.

So we add three new helper functions: qemu_load_device_state() and
qemu_savevm_live_state() to achieve different process during migration.

Besides, we make qemu_loadvm_state_main() and qemu_save_device_state()
public, and simplify the codes of qemu_save_device_state() by calling the
wrapper qemu_savevm_state_header().

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/colo.c   | 36 ++++++++++++++++++++++++++++--------
 migration/savevm.c | 35 ++++++++++++++++++++++++++++-------
 migration/savevm.h |  4 ++++
 3 files changed, 60 insertions(+), 15 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 127db3c..f514492 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -29,6 +29,7 @@
 #include "net/colo.h"
 #include "block/block.h"
 #include "qapi/qapi-events-migration.h"
+#include "sysemu/cpus.h"
 
 static bool vmstate_loading;
 static Notifier packets_compare_notifier;
@@ -411,24 +412,31 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
 
     /* Disable block migration */
     migrate_set_block_enabled(false, &local_err);
-    qemu_savevm_state_header(fb);
-    qemu_savevm_state_setup(fb);
     qemu_mutex_lock_iothread();
     replication_do_checkpoint_all(&local_err);
     if (local_err) {
         qemu_mutex_unlock_iothread();
         goto out;
     }
-    qemu_savevm_state_complete_precopy(fb, false, false);
-    qemu_mutex_unlock_iothread();
-
-    qemu_fflush(fb);
 
     colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
     if (local_err) {
         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);
+    /* Note: device state is saved into buffer */
+    ret = qemu_save_device_state(fb);
+
+    qemu_mutex_unlock_iothread();
+
+    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.
      */
@@ -640,6 +648,7 @@ void *colo_process_incoming_thread(void *opaque)
     uint64_t total_size;
     uint64_t value;
     Error *local_err = NULL;
+    int ret;
 
     qemu_sem_init(&mis->colo_incoming_sem, 0);
 
@@ -712,6 +721,16 @@ 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) {
@@ -745,8 +764,9 @@ 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;
         }
diff --git a/migration/savevm.c b/migration/savevm.c
index 0d1f593..e347f73 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1322,13 +1322,20 @@ 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_savevm_state_header(f);
+    }
     cpu_synchronize_all_states();
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
@@ -1384,8 +1391,6 @@ 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
@@ -2050,7 +2055,7 @@ void qemu_loadvm_state_cleanup(void)
     }
 }
 
-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;
@@ -2204,6 +2209,22 @@ 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 041d23c..8d463fd 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -52,8 +52,12 @@ void qemu_savevm_send_postcopy_ram_discard(QEMUFile *f, const char *name,
                                            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
-- 
2.7.4

[Qemu-devel] [PATCH V6 13/17] COLO: flush host dirty ram from cache

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

Don't need to flush all VM's ram from cache, only
flush the dirty pages since last checkpoint

Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 migration/ram.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/migration/ram.c b/migration/ram.c
index ff7265e..003617e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2685,6 +2685,7 @@ int colo_init_ram_cache(void)
     }
     ram_state = g_new0(RAMState, 1);
     ram_state->migration_dirty_pages = 0;
+    memory_global_dirty_log_start();
 
     return 0;
 
@@ -2705,10 +2706,12 @@ void colo_release_ram_cache(void)
 {
     RAMBlock *block;
 
+    memory_global_dirty_log_stop();
     QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
         g_free(block->bmap);
         block->bmap = NULL;
     }
+
     rcu_read_lock();
     QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
         if (block->colo_cache) {
@@ -2938,6 +2941,15 @@ static void colo_flush_ram_cache(void)
     void *src_host;
     unsigned long offset = 0;
 
+    memory_global_dirty_log_sync();
+    qemu_mutex_lock(&ram_state->bitmap_mutex);
+    rcu_read_lock();
+    RAMBLOCK_FOREACH(block) {
+        migration_bitmap_sync_range(ram_state, block, 0, block->used_length);
+    }
+    rcu_read_unlock();
+    qemu_mutex_unlock(&ram_state->bitmap_mutex);
+
     trace_colo_flush_ram_cache_begin(ram_state->migration_dirty_pages);
     rcu_read_lock();
     block = QLIST_FIRST_RCU(&ram_list.blocks);
-- 
2.7.4

[Qemu-devel] [PATCH V6 14/17] filter: Add handle_event method for NetFilterClass

[Zhang Chen]

Filter needs to process the event of checkpoint/failover or
other event passed by COLO frame.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 include/net/filter.h |  5 +++++
 net/filter.c         | 17 +++++++++++++++++
 net/net.c            | 28 ++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/include/net/filter.h b/include/net/filter.h
index 435acd6..49da666 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/net/filter.c b/net/filter.c
index 2fd7d7d..0f17eba 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 dummy_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 = dummy_handle_event;
 }
 
 static const TypeInfo netfilter_info = {
diff --git a/net/net.c b/net/net.c
index 5222e45..5bdbd6a 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1336,6 +1336,34 @@ void hmp_info_network(Monitor *mon, const QDict *qdict)
     }
 }
 
+void colo_notify_filters_event(int event, Error **errp)
+{
+    NetClientState *nc, *peer;
+    NetClientDriver type;
+    NetFilterState *nf;
+    NetFilterClass *nfc = NULL;
+    Error *local_err = NULL;
+
+    QTAILQ_FOREACH(nc, &net_clients, next) {
+        peer = nc->peer;
+        type = nc->info->type;
+        if (!peer || type != NET_CLIENT_DRIVER_TAP) {
+            continue;
+        }
+        QTAILQ_FOREACH(nf, &nc->filters, next) {
+            nfc =  NETFILTER_GET_CLASS(OBJECT(nf));
+            if (!nfc->handle_event) {
+                continue;
+            }
+            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];
-- 
2.7.4

[Qemu-devel] [PATCH V6 15/17] filter-rewriter: handle checkpoint and failover event

[Zhang Chen]

After one round of checkpoint, the states between PVM and SVM
become consistent, so it is unnecessary to adjust the sequence
of net packets for old connections, besides, while failover
happens, filter-rewriter needs to check if it still needs to
adjust sequence of net packets.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Zhang Chen <zhangckid@gmail.com>
---
 migration/colo.c      | 13 +++++++++++++
 net/filter-rewriter.c | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index f514492..f3d588e 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -30,6 +30,7 @@
 #include "block/block.h"
 #include "qapi/qapi-events-migration.h"
 #include "sysemu/cpus.h"
+#include "net/filter.h"
 
 static bool vmstate_loading;
 static Notifier packets_compare_notifier;
@@ -81,6 +82,11 @@ static void secondary_vm_do_failover(void)
     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");
@@ -783,6 +789,13 @@ void *colo_process_incoming_thread(void *opaque)
             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");
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index 0909a9a..f3c306c 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -20,6 +20,8 @@
 #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)
@@ -277,6 +279,43 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
     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)) {
+            object_property_set_str(OBJECT(nf), "off", "status", errp);
+        }
+        break;
+    default:
+        break;
+    }
+}
+
 static void colo_rewriter_cleanup(NetFilterState *nf)
 {
     RewriterState *s = FILTER_COLO_REWRITER(nf);
@@ -332,6 +371,7 @@ 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 = {
-- 
2.7.4

[Qemu-devel] [PATCH V6 16/17] COLO: notify net filters about checkpoint/failover event

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

Notify all net filters about the checkpoint and failover event.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 migration/colo.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index f3d588e..1a59baa 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -87,6 +87,11 @@ static void secondary_vm_do_failover(void)
     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");
@@ -796,6 +801,13 @@ void *colo_process_incoming_thread(void *opaque)
             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");
-- 
2.7.4

[Qemu-devel] [PATCH V6 17/17] COLO: quick failover process by kick COLO thread

[Zhang Chen]

From: zhanghailiang <zhang.zhanghailiang@huawei.com>

COLO thread may sleep at qemu_sem_wait(&s->colo_checkpoint_sem),
while failover works begin, It's better to wakeup it to quick
the process.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
 migration/colo.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index 1a59baa..1bc5f02 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -134,6 +134,11 @@ static void primary_vm_do_failover(void)
 
     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(),
@@ -549,6 +554,9 @@ 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;
-- 
2.7.4

Re: [Qemu-devel] [PATCH V6 11/17] qapi: Add new command to query colo status

[Markus Armbruster]

Zhang Chen <zhangckid@gmail.com> writes:

> Libvirt or other high level software can use this command query colo status.
> You can test this command like that:
> {'execute':'query-colo-status'}
>
> Signed-off-by: Zhang Chen <zhangckid@gmail.com>
> ---
>  migration/colo.c    | 31 +++++++++++++++++++++++++++++++
>  qapi/migration.json | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 64 insertions(+)
>
> diff --git a/migration/colo.c b/migration/colo.c
> index 8ca6381..127db3c 100644
> --- a/migration/colo.c
> +++ b/migration/colo.c
> @@ -237,6 +237,37 @@ void qmp_xen_colo_do_checkpoint(Error **errp)
>  #endif
>  }
>  
> +COLOStatus *qmp_query_colo_status(Error **errp)
> +{
> +    MigrationState *m;
> +    MigrationIncomingState *mis;
> +    COLOStatus *s = g_new0(COLOStatus, 1);
> +
> +    if (get_colo_mode() == COLO_MODE_PRIMARY) {
> +        m = migrate_get_current();
> +
> +        if (m->state == MIGRATION_STATUS_COLO) {
> +            s->colo_running = true;
> +        } else {
> +            s->colo_running = false;
> +        }
> +        s->mode = COLO_MODE_PRIMARY;
> +    } else {

Can get_colo_mode() == COLO_MODE_UNKNOWN happen here?  If not, why not?

> +        mis = migration_incoming_get_current();
> +
> +        if (mis->state == MIGRATION_STATUS_COLO) {
> +            s->colo_running = true;
> +        } else {
> +            s->colo_running = false;
> +        }
> +        s->mode = COLO_MODE_SECONDARY;
> +    }

Simpler:

       if (get_colo_mode() == COLO_MODE_PRIMARY) {
           state = migrate_get_current()->state;
       } else {
           state = migration_incoming_get_current()->state;
       }
       s->colo_running = state == MIGRATION_STATUS_COLO;
       s->mode = get_colo_mode();

> +
> +    s->reason = failover_get_state();

COLOStatus member @reason is COLOExitReason, but failover_get_state()
returns FailoverStatus, a different enum.  Am I confused?

> +
> +    return s;
> +}
> +
>  static void colo_send_message(QEMUFile *f, COLOMessage msg,
>                                Error **errp)
>  {
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 6c6c50e..8ccdd21 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1201,3 +1201,36 @@
>  # Since: 2.9
>  ##
>  { 'command': 'xen-colo-do-checkpoint' }
> +
> +##
> +# @COLOStatus:
> +#
> +# The result format for 'query-colo-status'.
> +#
> +# @mode: which COLO mode the VM was in when it exited.

This documents the meaning of @mode "when it exited".  Two questions:

1. What's "it"?  The VM?  COLO?

2. What's the meaning of @mode when "it" hasn't exited, yet?

> +#
> +# @colo-running: if true means COLO running well, otherwise COLO have done.

Suggest

   # @colo-running: true if COLO is running

> +#
> +# @reason: describes the reason for the COLO exit.

If there has been no COLO exit, there can't be a reason for one.  What's
the value of @reason then?  Hmm, peeking at FailoverStatus makes me
guess its @none.  Correct?

> +#
> +# Since: 2.12
> +##
> +{ 'struct': 'COLOStatus',
> +  'data': { 'mode': 'COLOMode', 'colo-running': 'bool', '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", "colo-running": true, "reason": "request" } }
> +#
> +# Since: 2.12
> +##
> +{ 'command': 'query-colo-status',
> +  'returns': 'COLOStatus' }

Re: [Qemu-devel] [PATCH V6 11/17] qapi: Add new command to query colo status

[Zhang Chen]

On Tue, Apr 17, 2018 at 8:46 PM, Markus Armbruster <armbru@redhat.com>
wrote:

> Zhang Chen <zhangckid@gmail.com> writes:
>
> > Libvirt or other high level software can use this command query colo
> status.
> > You can test this command like that:
> > {'execute':'query-colo-status'}
> >
> > Signed-off-by: Zhang Chen <zhangckid@gmail.com>
> > ---
> >  migration/colo.c    | 31 +++++++++++++++++++++++++++++++
> >  qapi/migration.json | 33 +++++++++++++++++++++++++++++++++
> >  2 files changed, 64 insertions(+)
> >
> > diff --git a/migration/colo.c b/migration/colo.c
> > index 8ca6381..127db3c 100644
> > --- a/migration/colo.c
> > +++ b/migration/colo.c
> > @@ -237,6 +237,37 @@ void qmp_xen_colo_do_checkpoint(Error **errp)
> >  #endif
> >  }
> >
> > +COLOStatus *qmp_query_colo_status(Error **errp)
> > +{
> > +    MigrationState *m;
> > +    MigrationIncomingState *mis;
> > +    COLOStatus *s = g_new0(COLOStatus, 1);
> > +
> > +    if (get_colo_mode() == COLO_MODE_PRIMARY) {
> > +        m = migrate_get_current();
> > +
> > +        if (m->state == MIGRATION_STATUS_COLO) {
> > +            s->colo_running = true;
> > +        } else {
> > +            s->colo_running = false;
> > +        }
> > +        s->mode = COLO_MODE_PRIMARY;
> > +    } else {
>
> Can get_colo_mode() == COLO_MODE_UNKNOWN happen here?  If not, why not?
>

Good catch, I will check it in next version.


>
> > +        mis = migration_incoming_get_current();
> > +
> > +        if (mis->state == MIGRATION_STATUS_COLO) {
> > +            s->colo_running = true;
> > +        } else {
> > +            s->colo_running = false;
> > +        }
> > +        s->mode = COLO_MODE_SECONDARY;
> > +    }
>
> Simpler:
>
>        if (get_colo_mode() == COLO_MODE_PRIMARY) {
>            state = migrate_get_current()->state;
>        } else {
>            state = migration_incoming_get_current()->state;
>        }
>        s->colo_running = state == MIGRATION_STATUS_COLO;
>        s->mode = get_colo_mode();
>

Good idea. I will use this codes in next version.
By the way, do I need add your SOB?


>
> > +
> > +    s->reason = failover_get_state();
>
> COLOStatus member @reason is COLOExitReason, but failover_get_state()
> returns FailoverStatus, a different enum.  Am I confused?
>

No, here I want to reused the FailoverStatus, but missed something in
rebase progress.
I will make FailoverStatus's @none = COLOExitReason's @none,
                  FailoverStatus's @requre = COLOExitReason's @request
                  FailoverStatus's other status = COLOExitReason's @error.
in next version.



>
> > +
> > +    return s;
> > +}
> > +
> >  static void colo_send_message(QEMUFile *f, COLOMessage msg,
> >                                Error **errp)
> >  {
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index 6c6c50e..8ccdd21 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -1201,3 +1201,36 @@
> >  # Since: 2.9
> >  ##
> >  { 'command': 'xen-colo-do-checkpoint' }
> > +
> > +##
> > +# @COLOStatus:
> > +#
> > +# The result format for 'query-colo-status'.
> > +#
> > +# @mode: which COLO mode the VM was in when it exited.
>
> This documents the meaning of @mode "when it exited".  Two questions:
>
> 1. What's "it"?  The VM?  COLO?
>

COLO.


>
> 2. What's the meaning of @mode when "it" hasn't exited, yet?
>

Just return the COLO running mode(primary, secondary or unknown) when COLO
hasn't exited.


>
> > +#
> > +# @colo-running: if true means COLO running well, otherwise COLO have
> done.
>
> Suggest
>
>    # @colo-running: true if COLO is running
>
> > +#
> > +# @reason: describes the reason for the COLO exit.
>
> If there has been no COLO exit, there can't be a reason for one.  What's
> the value of @reason then?  Hmm, peeking at FailoverStatus makes me
> guess its @none.  Correct?
>

Yes, you are right. I will fix it in next version.

Thanks your comments.
Zhang Chen



>
> > +#
> > +# Since: 2.12
> > +##
> > +{ 'struct': 'COLOStatus',
> > +  'data': { 'mode': 'COLOMode', 'colo-running': 'bool', '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", "colo-running": true, "reason":
> "request" } }
> > +#
> > +# Since: 2.12
> > +##
> > +{ 'command': 'query-colo-status',
> > +  'returns': 'COLOStatus' }
>