[Qemu-devel] [PATCH COLO-Frame v12 17/38] COLO: Load VMState into qsb before restore it

[zhanghailiang]

We should not destroy the state of SVM (Secondary VM) until we receive the whole
state from the PVM (Primary VM), 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: Li Zhijian <address@hidden>
Signed-off-by: Gonglei <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
Cc: Dr. David Alan Gilbert <address@hidden>

---
v12:
- Use the new helper colo_get_cmd_value() instead of colo_ctl_get()

Signed-off-by: zhanghailiang <address@hidden>
---
 migration/colo.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 5ff4946..a4d49ff 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -107,6 +107,21 @@ static int colo_get_check_cmd(QEMUFile *f, uint32_t 
expect_cmd)
     return 0;
 }
 
+static int colo_get_cmd_value(QEMUFile *f, uint32_t expect_cmd, uint64_t 
*value)
+{
+    int ret;
+
+    ret = colo_get_check_cmd(f, expect_cmd);
+    if (ret < 0) {
+        return ret;
+    }
+
+    *value = qemu_get_be64(f);
+    ret = qemu_file_get_error(f);
+
+    return ret;
+}
+
 static int colo_do_checkpoint_transaction(MigrationState *s,
                                           QEMUSizedBuffer *buffer)
 {
@@ -287,7 +302,11 @@ 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 */
+    uint64_t  total_size;
     int ret = 0;
+    uint64_t value;
 
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                       MIGRATION_STATUS_COLO);
@@ -310,6 +329,12 @@ 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_put_cmd(mis->to_src_file, COLO_COMMAND_CHECKPOINT_READY);
     if (ret < 0) {
         goto out;
@@ -338,19 +363,53 @@ void *colo_process_incoming_thread(void *opaque)
             goto out;
         }
 
-        /* TODO: read migration data into colo buffer */
+        /* read the VM state total size first */
+        ret = colo_get_cmd_value(mis->from_src_file,
+                                 COLO_COMMAND_VMSTATE_SIZE, &value);
+        if (ret < 0) {
+            error_report("%s: Failed to get vmstate size", __func__);
+            goto out;
+        }
+
+        /* read vm device state into colo buffer */
+        total_size = qsb_fill_buffer(buffer, mis->from_src_file, value);
+        if (total_size != value) {
+            error_report("Got %lu VMState data, less than expected %lu",
+                         total_size, value);
+            ret = -EINVAL;
+            goto out;
+        }
 
         ret = colo_put_cmd(mis->to_src_file, COLO_COMMAND_VMSTATE_RECEIVED);
         if (ret < 0) {
             goto out;
         }
 
-        /* TODO: load vm state */
+        /* 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_put_cmd(mis->to_src_file, COLO_COMMAND_VMSTATE_LOADED);
         if (ret < 0) {
             goto out;
         }
+
+        qemu_fclose(fb);
+        fb = NULL;
     }
 
 out:
@@ -359,6 +418,11 @@ out:
                      strerror(-ret));
     }
 
+    if (fb) {
+        qemu_fclose(fb);
+    }
+    qsb_free(buffer);
+
     qemu_mutex_lock_iothread();
     colo_release_ram_cache();
     qemu_mutex_unlock_iothread();
-- 
1.8.3.1