With colo we load device vmstate during each checkpoint, on top of
a vm that was already running. Some devices expect a reset before
loading vmstate on such a previously running vm.

This fixes a crash when using COLO with Q35 machine.

The reset adds 10-20ms overhead to the checkpointing proces in my
testing.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
---
 migration/colo.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/migration/colo.c b/migration/colo.c
index 96102c9d0fb3b60e063c81ce07b730011bc4919f..dc7cfa81ef7db78e3ee372642de48567c5bc06eb 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -729,6 +729,12 @@ static void colo_incoming_process_checkpoint(MigrationIncomingState *mis,
 
     bql_lock();
     vmstate_loading = true;
+    /*
+     * With colo we load device vmstate during each checkpoint, on top of
+     * a vm that was already running. Some devices expect a reset before
+     * loading vmstate on such a previously running vm.
+     */
+    qemu_system_reset(SHUTDOWN_CAUSE_SNAPSHOT_LOAD);
     colo_flush_ram_cache();
     ret = qemu_load_device_state(fb, errp);
     if (ret < 0) {

-- 
2.39.5