qemu_snapshot: correctly load the saved memory state file

Original code assumed that the memory state file is only migration
stream but it has additional metadata stored by libvirt. To correctly
load the memory state file we need to reuse code that is used when
restoring domain from saved image.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

src/qemu/qemu_snapshot.c

@@ -2000,6 +2000,21 @@ qemuSnapshotRevertWriteMetadata(virDomainObj *vm,
 }
 
 
+typedef struct _qemuSnapshotRevertMemoryData {
+    int fd;
+    char *path;
+    virQEMUSaveData *data;
+} qemuSnapshotRevertMemoryData;
+
+static void
+qemuSnapshotClearRevertMemoryData(qemuSnapshotRevertMemoryData *memdata)
+{
+    VIR_FORCE_CLOSE(memdata->fd);
+    virQEMUSaveDataFree(memdata->data);
+}
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(qemuSnapshotRevertMemoryData, qemuSnapshotClearRevertMemoryData);
+
+
 /**
  * qemuSnapshotRevertExternalPrepare:
  * @vm: domain object
@@ -2007,15 +2022,13 @@ qemuSnapshotRevertWriteMetadata(virDomainObj *vm,
  * @snap: snapshot object we are reverting to
  * @config: live domain definition
  * @inactiveConfig: offline domain definition
- * memsnapFD: pointer to store memory state file FD or NULL
+ * @memdata: struct with data to load memory state
- * memsnapPath: pointer to store memory state file path or NULL
  *
  * Prepare new temporary snapshot definition @tmpsnapdef that will
  * be used while creating new overlay files after reverting to snapshot
  * @snap. In case we are reverting to snapshot with memory state it will
- * open it and pass FD via @memsnapFD and path to the file via
+ * open it and store necessary data in @memdata. Caller is responsible
- * @memsnapPath, caller is responsible for freeing both @memsnapFD and
+ * to clear the data by using qemuSnapshotClearRevertMemoryData().
- * memsnapPath.
  *
  * Returns 0 in success, -1 on error.
  */
@@ -2025,8 +2038,7 @@ qemuSnapshotRevertExternalPrepare(virDomainObj *vm,
                                   virDomainMomentObj *snap,
                                   virDomainDef *config,
                                   virDomainDef *inactiveConfig,
-                                  int *memsnapFD,
+                                  qemuSnapshotRevertMemoryData *memdata)
-                                  char **memsnapPath)
 {
     size_t i;
     bool active = virDomainObjIsActive(vm);
@@ -2061,12 +2073,21 @@ qemuSnapshotRevertExternalPrepare(virDomainObj *vm,
             return -1;
     }
 
-    if (memsnapFD && memsnapPath && snapdef->memorysnapshotfile) {
+    if (memdata && snapdef->memorysnapshotfile) {
         virQEMUDriver *driver = ((qemuDomainObjPrivate *) vm->privateData)->driver;
-        g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+        g_autoptr(virDomainDef) savedef = NULL;
 
-        *memsnapPath = snapdef->memorysnapshotfile;
+        memdata->path = snapdef->memorysnapshotfile;
-        *memsnapFD = qemuDomainOpenFile(cfg, NULL, *memsnapPath, O_RDONLY, NULL);
+        memdata->fd = qemuSaveImageOpen(driver, NULL, memdata->path,
+                                        &savedef, &memdata->data,
+                                        false, NULL,
+                                        false, false);
+
+        if (memdata->fd < 0)
+            return -1;
+
+        if (!virDomainDefCheckABIStability(savedef, domdef, driver->xmlopt))
+            return -1;
     }
 
     return 0;
@@ -2250,13 +2271,12 @@ qemuSnapshotRevertActive(virDomainObj *vm,
     virObjectEvent *event = NULL;
     virObjectEvent *event2 = NULL;
     virDomainMomentObj *loadSnap = NULL;
-    VIR_AUTOCLOSE memsnapFD = -1;
-    char *memsnapPath = NULL;
     int detail;
     bool defined = false;
-    qemuDomainSaveCookie *cookie = (qemuDomainSaveCookie *) snapdef->cookie;
     int rc;
     g_autoptr(virDomainSnapshotDef) tmpsnapdef = NULL;
+    g_auto(qemuSnapshotRevertMemoryData) memdata = { -1, NULL, NULL };
+    bool started = false;
 
     start_flags |= VIR_QEMU_PROCESS_START_PAUSED;
 
@@ -2280,7 +2300,7 @@ qemuSnapshotRevertActive(virDomainObj *vm,
 
         if (qemuSnapshotRevertExternalPrepare(vm, tmpsnapdef, snap,
                                               *config, *inactiveConfig,
-                                              &memsnapFD, &memsnapPath) < 0) {
+                                              &memdata) < 0) {
             return -1;
         }
     } else {
@@ -2294,28 +2314,24 @@ qemuSnapshotRevertActive(virDomainObj *vm,
 
     virDomainObjAssignDef(vm, config, true, NULL);
 
-    /* No cookie means libvirt which saved the domain was too old to
+    if (qemuProcessStartWithMemoryState(snapshot->domain->conn, driver, vm,
-     * mess up the CPU definitions.
+                                        &memdata.fd, memdata.path, loadSnap,
-     */
+                                        memdata.data, VIR_ASYNC_JOB_SNAPSHOT,
-    if (cookie &&
+                                        start_flags, "from-snapshot",
-        qemuDomainFixupCPUs(vm, &cookie->cpu) < 0)
+                                        &started) < 0) {
+        if (started) {
+            qemuProcessStop(driver, vm, VIR_DOMAIN_SHUTOFF_FAILED,
+                            VIR_ASYNC_JOB_SNAPSHOT,
+                            VIR_QEMU_PROCESS_STOP_MIGRATED);
+        }
         return -1;
+    }
 
-    rc = qemuProcessStart(snapshot->domain->conn, driver, vm,
-                          cookie ? cookie->cpu : NULL,
-                          VIR_ASYNC_JOB_SNAPSHOT, NULL, memsnapFD,
-                          memsnapPath, loadSnap,
-                          VIR_NETDEV_VPORT_PROFILE_OP_CREATE,
-                          start_flags);
-    virDomainAuditStart(vm, "from-snapshot", rc >= 0);
     detail = VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT;
     event = virDomainEventLifecycleNewFromObj(vm,
                                      VIR_DOMAIN_EVENT_STARTED,
                                      detail);
     virObjectEventStateQueue(driver->domainEventState, event);
-    if (rc < 0)
-        return -1;
-
 
     if (virDomainSnapshotIsExternal(snap)) {
         if (qemuSnapshotRevertExternalActive(vm, tmpsnapdef) < 0)
@@ -2423,8 +2439,7 @@ qemuSnapshotRevertInactive(virDomainObj *vm,
             return -1;
 
         if (qemuSnapshotRevertExternalPrepare(vm, tmpsnapdef, snap,
-                                              NULL, *inactiveConfig,
+                                              NULL, *inactiveConfig, NULL) < 0) {
-                                              NULL, NULL) < 0) {
             return -1;
         }