[Qemu-devel] [PATCH COLO-Frame v9 14/32] COLO: Load VMState into qsb before restore it

[zhanghailiang]

We should not destroy the state of secondary until we receive the whole
state from the primary, in case the primary fails in the middle of sending
the state, so, here we cache the device state in Secondary before restore it.

Besides, we should call qemu_system_reset() before load VM state,
which can ensure the data is intact.

Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Yang Hongyang <address@hidden>
Signed-off-by: Gonglei <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
---
 migration/colo.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 452a77b..cb6a59d 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -313,6 +313,9 @@ static int colo_wait_handle_cmd(QEMUFile *f, int 
*checkpoint_request)
 void *colo_process_incoming_thread(void *opaque)
 {
     MigrationIncomingState *mis = opaque;
+    QEMUFile *fb = NULL;
+    QEMUSizedBuffer *buffer = NULL; /* Cache incoming device state */
+    int  total_size;
     int fd, ret = 0;
 
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
@@ -336,6 +339,12 @@ void *colo_process_incoming_thread(void *opaque)
         goto out;
     }
 
+    buffer = qsb_create(NULL, COLO_BUFFER_BASE_SIZE);
+    if (buffer == NULL) {
+        error_report("Failed to allocate colo buffer!");
+        goto out;
+    }
+
     ret = colo_ctl_put(mis->to_src_file, COLO_CMD_CHECKPOINT_READY, 0);
     if (ret < 0) {
         goto out;
@@ -363,20 +372,50 @@ void *colo_process_incoming_thread(void *opaque)
             goto out;
         }
 
-        /*TODO Load VM state */
+        /* read the VM state total size first */
+        total_size = colo_ctl_get(mis->from_src_file, COLO_CMD_VMSTATE_SIZE);
+        if (total_size <= 0) {
+            goto out;
+        }
+
+        /* read vm device state into colo buffer */
+        ret = qsb_fill_buffer(buffer, mis->from_src_file, total_size);
+        if (ret != total_size) {
+            error_report("can't get all migration data");
+            goto out;
+        }
 
         ret = colo_ctl_put(mis->to_src_file, COLO_CMD_VMSTATE_RECEIVED, 0);
         if (ret < 0) {
             goto out;
         }
 
+        /* open colo buffer for read */
+        fb = qemu_bufopen("r", buffer);
+        if (!fb) {
+            error_report("can't open colo buffer for read");
+            goto out;
+        }
+
+        qemu_mutex_lock_iothread();
+        qemu_system_reset(VMRESET_SILENT);
+        if (qemu_loadvm_state(fb) < 0) {
+            error_report("COLO: loadvm failed");
+            qemu_mutex_unlock_iothread();
+            goto out;
+        }
+        qemu_mutex_unlock_iothread();
+
         /* TODO: flush vm state */
 
         ret = colo_ctl_put(mis->to_src_file, COLO_CMD_VMSTATE_LOADED, 0);
         if (ret < 0) {
             goto out;
         }
-}
+
+        qemu_fclose(fb);
+        fb = NULL;
+    }
 
 out:
     if (ret < 0) {
@@ -384,6 +423,11 @@ out:
                      strerror(-ret));
     }
 
+    if (fb) {
+        qemu_fclose(fb);
+    }
+    qsb_free(buffer);
+
     qemu_mutex_lock_iothread();
     colo_release_ram_cache();
     qemu_mutex_unlock_iothread();
@@ -391,6 +435,7 @@ out:
     if (mis->to_src_file) {
         qemu_fclose(mis->to_src_file);
     }
+
     migration_incoming_exit_colo();
 
     return NULL;
-- 
1.8.3.1