RE: [PATCH v2] vfio/migration: Refactor and fix print of "Migration disabled"

[Duan, Zhenzhong]

>-----Original Message-----
>From: Avihai Horon <avihaih@nvidia.com>
>Sent: Monday, June 19, 2023 7:14 PM
...
>> a/hw/vfio/migration.c b/hw/vfio/migration.c index
>> 6b58dddb8859..bc51aa765cb8 100644
>> --- a/hw/vfio/migration.c
>> +++ b/hw/vfio/migration.c
>> @@ -632,42 +632,41 @@ int64_t vfio_mig_bytes_transferred(void)
>>       return bytes_transferred;
>>   }
>>
>> -int vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
>> +bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
>>   {
>> -    int ret = -ENOTSUP;
>> +    int ret;
>>
>> -    if (!vbasedev->enable_migration) {
>> +    if (!vbasedev->enable_migration || vfio_migration_init(vbasedev)) {
>> +        error_setg(&vbasedev->migration_blocker,
>> +                   "VFIO device doesn't support migration");
>>           goto add_blocker;
>>       }
>>
>> -    ret = vfio_migration_init(vbasedev);
>> -    if (ret) {
>> +    if (vfio_block_multiple_devices_migration(errp)) {
>> +        error_setg(&vbasedev->migration_blocker,
>> +                   "Migration is currently not supported with multiple "
>> +                   "VFIO devices");
>>           goto add_blocker;
>>       }
>
>Here you are tying the multiple devices blocker to a specific device.
>This could be problematic:
>If you add vfio device #1 and then device #2 then the blocker will be added to
>device #2. If you then remove device #1, migration will still be blocked
>although it shouldn't.
>
>I think we should keep it as a global blocker and not a per-device blocker.

Thanks for point out, you are right, seems I need to restore the multiple 
devices part code.

Regards
Zhenzhong