From: Peter Xu <peterx@redhat.com>
Date: Tue, 27 Jan 2026 18:52:45 +0000 (-0500)
Subject: migration: Provide helper for save vm description
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=56294bcd25572c47fdfc43504f1d9e7640a59a05;p=thirdparty%2Fqemu.git

migration: Provide helper for save vm description

Provide two smaller helpers to dump the vm desc.  Preparing to move it out
and generalize device state dump.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Tested-by: Lukas Straub <lukasstraub2@web.de>
Link: https://lore.kernel.org/qemu-devel/20260127185254.3954634-16-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
---

diff --git a/migration/savevm.c b/migration/savevm.c
index a787691352..41560b97a4 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1669,13 +1669,34 @@ ret_fail_abort_threads:
     return -1;
 }
 
+static void qemu_savevm_state_vm_desc(MigrationState *s, QEMUFile *f)
+{
+    JSONWriter *vmdesc = s->vmdesc;
+    int vmdesc_len;
+
+    if (vmdesc) {
+        json_writer_end_array(vmdesc);
+        json_writer_end_object(vmdesc);
+        vmdesc_len = strlen(json_writer_get(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);
+    }
+}
+
+void qemu_savevm_state_end_precopy(MigrationState *s, QEMUFile *f)
+{
+    qemu_savevm_state_end(f);
+    qemu_savevm_state_vm_desc(s, f);
+}
+
 int qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
                                                     bool in_postcopy)
 {
     MigrationState *ms = migrate_get_current();
     int64_t start_ts_each, end_ts_each;
     JSONWriter *vmdesc = ms->vmdesc;
-    int vmdesc_len;
     SaveStateEntry *se;
     Error *local_err = NULL;
     int ret;
@@ -1705,17 +1726,7 @@ int qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
 
     if (!in_postcopy) {
         /* Postcopy stream will still be going */
-        qemu_savevm_state_end(f);
-
-        if (vmdesc) {
-            json_writer_end_array(vmdesc);
-            json_writer_end_object(vmdesc);
-            vmdesc_len = strlen(json_writer_get(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_savevm_state_end_precopy(ms, f);
     }
 
     trace_vmstate_downtime_checkpoint("src-non-iterable-saved");
diff --git a/migration/savevm.h b/migration/savevm.h
index d0596d1d62..f957f851ef 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -50,6 +50,7 @@ void qemu_savevm_state_pending_estimate(uint64_t *must_precopy,
 int qemu_savevm_state_complete_precopy_iterable(QEMUFile *f, bool in_postcopy);
 bool qemu_savevm_state_postcopy_prepare(QEMUFile *f, Error **errp);
 void qemu_savevm_state_end(QEMUFile *f);
+void qemu_savevm_state_end_precopy(MigrationState *s, QEMUFile *f);
 void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
 void qemu_savevm_send_open_return_path(QEMUFile *f);
 int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);