On 2017/12/1 22:39, Michael S. Tsirkin wrote:
> On Fri, Dec 01, 2017 at 01:58:32PM +0800, fangying wrote:
>> QEMU will abort when vhost-user process is restarted during migration
>> when vhost_log_global_start/stop is called. The reason is clear that
>> vhost_dev_set_log returns -1 because network connection is lost.
>>
>> To handle this situation, let's cancel migration by setting migrate
>> state to failure and report it to user.
>
> In fact I don't see this as the right way to fix it. Backend is dead so why
> not just proceed with migration? We just need to make sure we re-send
> migration data on re-connect.
> This is where vhost start/stop migration dirty log. The original code aborts
qemu here beacuse vhost data stream may break down if we fail to start/stop
vhost dirty log during migration. Backend may be active after
vhost_log_global_start.
dirty log start ----------------- dirty log stop
^ ^
| |
----- backend dead ----- backend active
Currently we don't re-send migration data on re-connect in this situation.
May we should work it out.
>> ---
>> hw/virtio/vhost.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
>> index ddc42f0..92725f7 100644
>> --- a/hw/virtio/vhost.c
>> +++ b/hw/virtio/vhost.c
>> @@ -26,6 +26,8 @@
>> #include "hw/virtio/virtio-bus.h"
>> #include "hw/virtio/virtio-access.h"
>> #include "migration/blocker.h"
>> +#include "migration/migration.h"
>> +#include "migration/qemu-file.h"
>> #include "sysemu/dma.h"
>>
>> /* enabled until disconnected backend stabilizes */
>> @@ -885,7 +887,10 @@ static void vhost_log_global_start(MemoryListener
>> *listener)
>>
>> r = vhost_migration_log(listener, true);
>> if (r < 0) {
>> - abort();
>> + error_report("Failed to start vhost dirty log");
>> + if (migrate_get_current()->migration_thread_running) {
>> + qemu_file_set_error(migrate_get_current()->to_dst_file,
>> -ECHILD);
>> + }
>> }
>> }
>>
>> @@ -895,7 +900,10 @@ static void vhost_log_global_stop(MemoryListener
>> *listener)
>>
>> r = vhost_migration_log(listener, false);
>> if (r < 0) {
>> - abort();
>> + error_report("Failed to stop vhost dirty log");
>> + if (migrate_get_current()->migration_thread_running) {
>> + qemu_file_set_error(migrate_get_current()->to_dst_file,
>> -ECHILD);
>> + }
>> }
>> }
>>
>> --
>> 1.8.3.1
>>
>
> .
>
