[Qemu-devel] [PATCH COLO-Frame v14 13/40] COLO: Load VMState into qsb before restore it

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

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 <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
v13:
- Fix the define of colo_get_cmd_value() to use 'Error **errp' instead of
  return value.
v12:
- Use the new helper colo_get_cmd_value() instead of colo_ctl_get()
---
 migration/colo.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 72 insertions(+), 2 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 57a1132..b9f60c7 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -114,6 +114,28 @@ static void colo_get_check_cmd(QEMUFile *f, COLOMessage expect_cmd,
     }
 }
 
+static uint64_t colo_get_cmd_value(QEMUFile *f, uint32_t expect_cmd,
+                                   Error **errp)
+{
+    Error *local_err = NULL;
+    uint64_t value;
+    int ret;
+
+    colo_get_check_cmd(f, expect_cmd, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return 0;
+    }
+
+    value = qemu_get_be64(f);
+    ret = qemu_file_get_error(f);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Failed to get value for COLO commnd: %s",
+                         COLOMessage_lookup[expect_cmd]);
+    }
+    return value;
+}
+
 static int colo_do_checkpoint_transaction(MigrationState *s,
                                           QEMUSizedBuffer *buffer)
 {
@@ -297,6 +319,10 @@ static void 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;
+    uint64_t value;
     Error *local_err = NULL;
     int ret;
 
@@ -320,6 +346,12 @@ 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;
+    }
+
     colo_put_cmd(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
                  &local_err);
     if (local_err) {
@@ -347,7 +379,21 @@ void *colo_process_incoming_thread(void *opaque)
             goto out;
         }
 
-        /* TODO: read migration data into colo buffer */
+        /* read the VM state total size first */
+        value = colo_get_cmd_value(mis->from_src_file,
+                                 COLO_MESSAGE_VMSTATE_SIZE, &local_err);
+        if (local_err) {
+            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;
+        }
 
         colo_put_cmd(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
                      &local_err);
@@ -355,13 +401,32 @@ void *colo_process_incoming_thread(void *opaque)
             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 */
 
         colo_put_cmd(mis->to_src_file, COLO_MESSAGE_VMSTATE_LOADED,
                      &local_err);
         if (local_err) {
             goto out;
         }
+
+        qemu_fclose(fb);
+        fb = NULL;
     }
 
 out:
@@ -370,6 +435,11 @@ out:
         error_report_err(local_err);
     }
 
+    if (fb) {
+        qemu_fclose(fb);
+    }
+    qsb_free(buffer);
+
     qemu_mutex_lock_iothread();
     colo_release_ram_cache();
     qemu_mutex_unlock_iothread();
-- 
1.8.3.1