[PATCH 03/11] migration: Make migration json writer part of MigrationState struct

[Nikolay Borisov]

This is required so that migration stream configuration is written
to the migration stream. This would allow analyze-migration to
parse enabled capabilities for the migration and adjust its behavior
accordingly. This is in preparation for analyze-migration.py to support
'fixed-ram' capability format changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 migration/migration.c |  5 +++++
 migration/migration.h |  3 +++
 migration/savevm.c    | 38 ++++++++++++++++++++++----------------
 3 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 140b0f1a54bd..d0779bbaf862 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1896,6 +1896,8 @@ static void migrate_fd_cleanup(MigrationState *s)
     g_free(s->hostname);
     s->hostname = NULL;
 
+    json_writer_free(s->vmdesc);
+
     qemu_savevm_state_cleanup();
 
     if (s->to_dst_file) {
@@ -2154,6 +2156,7 @@ void migrate_init(MigrationState *s)
     error_free(s->error);
     s->error = NULL;
     s->hostname = NULL;
+    s->vmdesc = NULL;
 
     migrate_set_state(&s->state, MIGRATION_STATUS_NONE, 
MIGRATION_STATUS_SETUP);
 
@@ -4269,6 +4272,8 @@ void migrate_fd_connect(MigrationState *s, Error 
*error_in)
         return;
     }
 
+    s->vmdesc = json_writer_new(false);
+
     if (multifd_save_setup(&local_err) != 0) {
         error_report_err(local_err);
         migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
diff --git a/migration/migration.h b/migration/migration.h
index cdad8aceaaab..96f27aba2210 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -17,6 +17,7 @@
 #include "exec/cpu-common.h"
 #include "hw/qdev-core.h"
 #include "qapi/qapi-types-migration.h"
+#include "qapi/qmp/json-writer.h"
 #include "qemu/thread.h"
 #include "qemu/coroutine_int.h"
 #include "io/channel.h"
@@ -261,6 +262,8 @@ struct MigrationState {
 
     int state;
 
+    JSONWriter *vmdesc;
+
     /* State related to return path */
     struct {
         /* Protected by qemu_file_lock */
diff --git a/migration/savevm.c b/migration/savevm.c
index 48e85c052c2c..174cdbefc29d 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1137,13 +1137,18 @@ void qemu_savevm_non_migratable_list(strList **reasons)
 
 void qemu_savevm_state_header(QEMUFile *f)
 {
+    MigrationState *s = migrate_get_current();
     trace_savevm_state_header();
     qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
     qemu_put_be32(f, QEMU_VM_FILE_VERSION);
 
-    if (migrate_get_current()->send_configuration) {
+    if (s->send_configuration) {
         qemu_put_byte(f, QEMU_VM_CONFIGURATION);
-        vmstate_save_state(f, &vmstate_configuration, &savevm_state, 0);
+       json_writer_start_object(s->vmdesc, NULL);
+       json_writer_start_object(s->vmdesc, "configuration");
+        vmstate_save_state(f, &vmstate_configuration, &savevm_state, 
s->vmdesc);
+       json_writer_end_object(s->vmdesc);
+
     }
 }
 
@@ -1364,15 +1369,16 @@ int 
qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
                                                     bool in_postcopy,
                                                     bool inactivate_disks)
 {
-    g_autoptr(JSONWriter) vmdesc = NULL;
+    MigrationState *s = migrate_get_current();
     int vmdesc_len;
     SaveStateEntry *se;
     int ret;
 
-    vmdesc = json_writer_new(false);
-    json_writer_start_object(vmdesc, NULL);
-    json_writer_int64(vmdesc, "page_size", qemu_target_page_size());
-    json_writer_start_array(vmdesc, "devices");
+    if (!s->send_configuration) {
+           json_writer_start_object(s->vmdesc, NULL);
+    }
+    json_writer_int64(s->vmdesc, "page_size", qemu_target_page_size());
+    json_writer_start_array(s->vmdesc, "devices");
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
 
         if ((!se->ops || !se->ops->save_state) && !se->vmsd) {
@@ -1385,12 +1391,12 @@ int 
qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
 
         trace_savevm_section_start(se->idstr, se->section_id);
 
-        json_writer_start_object(vmdesc, NULL);
-        json_writer_str(vmdesc, "name", se->idstr);
-        json_writer_int64(vmdesc, "instance_id", se->instance_id);
+        json_writer_start_object(s->vmdesc, NULL);
+        json_writer_str(s->vmdesc, "name", se->idstr);
+        json_writer_int64(s->vmdesc, "instance_id", se->instance_id);
 
         save_section_header(f, se, QEMU_VM_SECTION_FULL);
-        ret = vmstate_save(f, se, vmdesc);
+        ret = vmstate_save(f, se, s->vmdesc);
         if (ret) {
             qemu_file_set_error(f, ret);
             return ret;
@@ -1398,7 +1404,7 @@ int 
qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
         trace_savevm_section_end(se->idstr, se->section_id, 0);
         save_section_footer(f, se);
 
-        json_writer_end_object(vmdesc);
+        json_writer_end_object(s->vmdesc);
     }
 
     if (inactivate_disks) {
@@ -1417,14 +1423,14 @@ int 
qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
         qemu_put_byte(f, QEMU_VM_EOF);
     }
 
-    json_writer_end_array(vmdesc);
-    json_writer_end_object(vmdesc);
-    vmdesc_len = strlen(json_writer_get(vmdesc));
+    json_writer_end_array(s->vmdesc);
+    json_writer_end_object(s->vmdesc);
+    vmdesc_len = strlen(json_writer_get(s->vmdesc));
 
     if (should_send_vmdesc()) {
         qemu_put_byte(f, QEMU_VM_VMDESCRIPTION);
         qemu_put_be32(f, vmdesc_len);
-        qemu_put_buffer(f, (uint8_t *)json_writer_get(vmdesc), vmdesc_len);
+        qemu_put_buffer(f, (uint8_t *)json_writer_get(s->vmdesc), vmdesc_len);
     }
 
     return 0;
-- 
2.34.1