migration: disallow migrate_add_blocker during migration

If a migration is already in progress and somebody attempts
to add a migration blocker, this should rightly fail.

Add an errp parameter and a retcode return value to migrate_add_blocker.

Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Ashijeet Acharya <ashijeetacharya@gmail.com>
Message-Id: <1484566314-3987-5-git-send-email-ashijeetacharya@gmail.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  Merged with recent 'Allow invtsc migration' change

1 files changed, 11 insertions, 6 deletions

diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
index 11729ee902..ec952ece93 100644
--- a/hw/intc/arm_gic_kvm.c
+++ b/hw/intc/arm_gic_kvm.c
@@ -510,6 +510,17 @@ static void kvm_arm_gic_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (!kvm_arm_gic_can_save_restore(s)) {
+        error_setg(&s->migration_blocker, "This operating system kernel does "
+                                          "not support vGICv2 migration");
+        migrate_add_blocker(s->migration_blocker, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            error_free(s->migration_blocker);
+            return;
+        }
+    }
+
     gic_init_irqs_and_mmio(s, kvm_arm_gicv2_set_irq, NULL);
 
     for (i = 0; i < s->num_irq - GIC_INTERNAL; i++) {
@@ -558,12 +569,6 @@ static void kvm_arm_gic_realize(DeviceState *dev, Error **errp)
                             KVM_VGIC_V2_ADDR_TYPE_CPU,
                             s->dev_fd);
 
-    if (!kvm_arm_gic_can_save_restore(s)) {
-        error_setg(&s->migration_blocker, "This operating system kernel does "
-                                          "not support vGICv2 migration");
-        migrate_add_blocker(s->migration_blocker);
-    }
-
     if (kvm_has_gsi_routing()) {
         /* set up irq routing */
         kvm_init_irq_routing(kvm_state);