[Qemu-devel] [PATCH COLO-Frame v10 08/38] COLO/migration: establish a new communication path from destination to source

[zhanghailiang]

Add a new member 'to_src_file' to MigrationIncomingState and a
new member 'from_dst_file' to MigrationState.
They will be used for returning messages from destination to source.
It will also be used by post-copy migration.

Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Cc: Dr. David Alan Gilbert <address@hidden>
---
v10: fix the the error log (Dave's suggestion).
---
 include/migration/migration.h |  3 ++-
 migration/colo.c              | 44 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index a874da1..0c0309d 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -50,7 +50,7 @@ typedef QLIST_HEAD(, LoadStateEntry) LoadStateEntry_Head;
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
-
+    QEMUFile *to_src_file;
     int state;
 
     bool have_colo_incoming_thread;
@@ -74,6 +74,7 @@ struct MigrationState
     QemuThread thread;
     QEMUBH *cleanup_bh;
     QEMUFile *to_dst_file;
+    QEMUFile  *from_dst_file;
     int parameters[MIGRATION_PARAMETER_MAX];
 
     int state;
diff --git a/migration/colo.c b/migration/colo.c
index 6880aa0..4fdf3a9 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -36,6 +36,21 @@ bool migration_incoming_in_colo_state(void)
 
 static void colo_process_checkpoint(MigrationState *s)
 {
+    int fd, ret = 0;
+
+    /* Dup the fd of to_dst_file */
+    fd = dup(qemu_get_fd(s->to_dst_file));
+    if (fd == -1) {
+        ret = -errno;
+        goto out;
+    }
+    s->from_dst_file = qemu_fopen_socket(fd, "rb");
+    if (!s->from_dst_file) {
+        ret = -EINVAL;
+        error_report("Open QEMUFile from_dst_file failed");
+        goto out;
+    }
+
     qemu_mutex_lock_iothread();
     vm_start();
     qemu_mutex_unlock_iothread();
@@ -43,8 +58,16 @@ static void colo_process_checkpoint(MigrationState *s)
 
     /*TODO: COLO checkpoint savevm loop*/
 
+out:
+    if (ret < 0) {
+        error_report("%s: %s", __func__, strerror(-ret));
+    }
     migrate_set_state(&s->state, MIGRATION_STATUS_COLO,
                       MIGRATION_STATUS_COMPLETED);
+
+    if (s->from_dst_file) {
+        qemu_fclose(s->from_dst_file);
+    }
 }
 
 void migrate_start_colo_process(MigrationState *s)
@@ -59,12 +82,33 @@ void migrate_start_colo_process(MigrationState *s)
 void *colo_process_incoming_thread(void *opaque)
 {
     MigrationIncomingState *mis = opaque;
+    int fd, ret = 0;
 
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                       MIGRATION_STATUS_COLO);
 
+    fd = dup(qemu_get_fd(mis->from_src_file));
+    if (fd < 0) {
+        ret = -errno;
+        goto out;
+    }
+    mis->to_src_file = qemu_fopen_socket(fd, "wb");
+    if (!mis->to_src_file) {
+        ret = -EINVAL;
+        error_report("colo incoming thread: Open QEMUFile to_src_file failed");
+        goto out;
+    }
     /* TODO: COLO checkpoint restore loop */
 
+out:
+    if (ret < 0) {
+        error_report("colo incoming thread will exit, detect error: %s",
+                     strerror(-ret));
+    }
+
+    if (mis->to_src_file) {
+        qemu_fclose(mis->to_src_file);
+    }
     migration_incoming_exit_colo();
 
     return NULL;
-- 
1.8.3.1