qemu: migration: Skip few checks while doing offline migration

qemuMigrationIsAllowed would disallow offline migration if the VM
contained host devices or memory modules. Since during offline migration
we don't transfer any state we can safely migrate VMs with such
configuration.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1265049

src/qemu/qemu_migration.c

@@ -2208,12 +2208,6 @@ qemuMigrationIsAllowed(virQEMUDriverPtr driver,
     int pauseReason;
     size_t i;
 
-    if (qemuProcessAutoDestroyActive(driver, vm)) {
-        virReportError(VIR_ERR_OPERATION_INVALID,
-                       "%s", _("domain is marked for auto destroy"));
-        return false;
-    }
-
     /* perform these checks only when migrating to remote hosts */
     if (remote) {
         nsnapshots = virDomainSnapshotObjListNum(vm->snapshots, NULL, 0);
@@ -2229,6 +2223,7 @@ qemuMigrationIsAllowed(virQEMUDriverPtr driver,
 
         /* cancel migration if disk I/O error is emitted while migrating */
         if (flags & VIR_MIGRATE_ABORT_ON_ERROR &&
+            !(flags & VIR_MIGRATE_OFFLINE) &&
             virDomainObjGetState(vm, &pauseReason) == VIR_DOMAIN_PAUSED &&
             pauseReason == VIR_DOMAIN_PAUSED_IOERROR) {
             virReportError(VIR_ERR_OPERATION_INVALID, "%s",
@@ -2238,43 +2233,53 @@ qemuMigrationIsAllowed(virQEMUDriverPtr driver,
 
     }
 
-    if (qemuDomainHasBlockjob(vm, false)) {
-        virReportError(VIR_ERR_OPERATION_INVALID, "%s",
-                       _("domain has an active block job"));
-        return false;
-    }
+    /* following checks don't make sense for offline migration */
+    if (!(flags & VIR_MIGRATE_OFFLINE)) {
+        if (qemuProcessAutoDestroyActive(driver, vm)) {
+            virReportError(VIR_ERR_OPERATION_INVALID,
+                           "%s", _("domain is marked for auto destroy"));
+            return false;
+        }
 
-    if (!qemuMigrationIsAllowedHostdev(vm->def))
-        return false;
 
-    if (vm->def->cpu && vm->def->cpu->mode != VIR_CPU_MODE_HOST_PASSTHROUGH) {
-        for (i = 0; i < vm->def->cpu->nfeatures; i++) {
-            virCPUFeatureDefPtr feature = &vm->def->cpu->features[i];
+        if (qemuDomainHasBlockjob(vm, false)) {
+            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+                           _("domain has an active block job"));
+            return false;
+        }
+
+        if (!qemuMigrationIsAllowedHostdev(vm->def))
+            return false;
 
-            if (feature->policy != VIR_CPU_FEATURE_REQUIRE)
-                continue;
+        if (vm->def->cpu && vm->def->cpu->mode != VIR_CPU_MODE_HOST_PASSTHROUGH) {
+            for (i = 0; i < vm->def->cpu->nfeatures; i++) {
+                virCPUFeatureDefPtr feature = &vm->def->cpu->features[i];
 
-            /* QEMU blocks migration and save with invariant TSC enabled */
-            if (STREQ(feature->name, "invtsc")) {
-                virReportError(VIR_ERR_OPERATION_INVALID,
-                               _("domain has CPU feature: %s"),
-                               feature->name);
-                return false;
+                if (feature->policy != VIR_CPU_FEATURE_REQUIRE)
+                    continue;
+
+                /* QEMU blocks migration and save with invariant TSC enabled */
+                if (STREQ(feature->name, "invtsc")) {
+                    virReportError(VIR_ERR_OPERATION_INVALID,
+                                   _("domain has CPU feature: %s"),
+                                   feature->name);
+                    return false;
+                }
             }
         }
-    }
 
-    /* Verify that memory device config can be transferred reliably */
-    for (i = 0; i < vm->def->nmems; i++) {
-        virDomainMemoryDefPtr mem = vm->def->mems[i];
+        /* Verify that memory device config can be transferred reliably */
+        for (i = 0; i < vm->def->nmems; i++) {
+            virDomainMemoryDefPtr mem = vm->def->mems[i];
 
-        if (mem->model == VIR_DOMAIN_MEMORY_MODEL_DIMM &&
-            mem->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_DIMM) {
-            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
-                           _("domain's dimm info lacks slot ID "
-                             "or base address"));
+            if (mem->model == VIR_DOMAIN_MEMORY_MODEL_DIMM &&
+                mem->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_DIMM) {
+                virReportError(VIR_ERR_OPERATION_INVALID, "%s",
+                               _("domain's dimm info lacks slot ID "
+                                 "or base address"));
 
-            return false;
+                return false;
+            }
         }
     }