Re: [PATCH v3 11/13] vfio/migration: Block migration with vIOMMU

[Joao Martins]

On 06/03/2023 17:00, Cédric Le Goater wrote:
> On 3/4/23 02:43, Joao Martins wrote:
>> Migrating with vIOMMU will require either tracking maximum
>> IOMMU supported address space (e.g. 39/48 address width on Intel)
>> or range-track current mappings and dirty track the new ones
>> post starting dirty tracking. This will be done as a separate
>> series, so add a live migration blocker until that is fixed.
>>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> ---
>>   hw/vfio/common.c              | 51 +++++++++++++++++++++++++++++++++++
>>   hw/vfio/migration.c           |  6 +++++
>>   include/hw/vfio/vfio-common.h |  2 ++
>>   3 files changed, 59 insertions(+)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 5b8456975e97..9b909f856722 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -365,6 +365,7 @@ bool vfio_mig_active(void)
>>   }
>>     static Error *multiple_devices_migration_blocker;
>> +static Error *giommu_migration_blocker;
>>     static unsigned int vfio_migratable_device_num(void)
>>   {
>> @@ -416,6 +417,56 @@ void vfio_unblock_multiple_devices_migration(void)
>>       multiple_devices_migration_blocker = NULL;
>>   }
>>   +static unsigned int vfio_use_iommu_device_num(void)
>> +{
>> +    VFIOGroup *group;
>> +    VFIODevice *vbasedev;
>> +    unsigned int device_num = 0;
>> +
>> +    QLIST_FOREACH(group, &vfio_group_list, next) {
>> +        QLIST_FOREACH(vbasedev, &group->device_list, next) {
>> +            if (vbasedev->group->container->space->as !=
>> +                                    &address_space_memory) {
> 
> Can't we avoid the second loop and test directly :
> 
>   group->container->space->as
> 
> ?
>
Ah yes

> 
> The rest looks good. So,
> 
> Reviewed-by: Cédric Le Goater <clg@redhat.com>
> 
Thanks!

> Thanks,
> 
> C.
> 
>> +                device_num++;
>> +            }
>> +        }
>> +    }
>> +
>> +    return device_num;
>> +}
>> +
>> +int vfio_block_giommu_migration(Error **errp)
>> +{
>> +    int ret;
>> +
>> +    if (giommu_migration_blocker ||
>> +        !vfio_use_iommu_device_num()) {
>> +        return 0;
>> +    }
>> +
>> +    error_setg(&giommu_migration_blocker,
>> +               "Migration is currently not supported with vIOMMU enabled");
>> +    ret = migrate_add_blocker(giommu_migration_blocker, errp);
>> +    if (ret < 0) {
>> +        error_free(giommu_migration_blocker);
>> +        giommu_migration_blocker = NULL;
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +void vfio_unblock_giommu_migration(void)
>> +{
>> +    if (!giommu_migration_blocker ||
>> +        vfio_use_iommu_device_num()) {
>> +        return;
>> +    }
>> +
>> +    migrate_del_blocker(giommu_migration_blocker);
>> +    error_free(giommu_migration_blocker);
>> +    giommu_migration_blocker = NULL;
>> +}
>> +
>>   static void vfio_set_migration_error(int err)
>>   {
>>       MigrationState *ms = migrate_get_current();
>> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
>> index a2c3d9bade7f..3e75868ae7a9 100644
>> --- a/hw/vfio/migration.c
>> +++ b/hw/vfio/migration.c
>> @@ -634,6 +634,11 @@ int vfio_migration_probe(VFIODevice *vbasedev, Error 
>> **errp)
>>           return ret;
>>       }
>>   +    ret = vfio_block_giommu_migration(errp);
>> +    if (ret) {
>> +        return ret;
>> +    }
>> +
>>       trace_vfio_migration_probe(vbasedev->name);
>>       return 0;
>>   @@ -659,6 +664,7 @@ void vfio_migration_finalize(VFIODevice *vbasedev)
>>           unregister_savevm(VMSTATE_IF(vbasedev->dev), "vfio", vbasedev);
>>           vfio_migration_exit(vbasedev);
>>           vfio_unblock_multiple_devices_migration();
>> +        vfio_unblock_giommu_migration();
>>       }
>>         if (vbasedev->migration_blocker) {
>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
>> index 1cbbccd91e11..38e44258925b 100644
>> --- a/include/hw/vfio/vfio-common.h
>> +++ b/include/hw/vfio/vfio-common.h
>> @@ -233,6 +233,8 @@ extern VFIOGroupList vfio_group_list;
>>   bool vfio_mig_active(void);
>>   int vfio_block_multiple_devices_migration(Error **errp);
>>   void vfio_unblock_multiple_devices_migration(void);
>> +int vfio_block_giommu_migration(Error **errp);
>> +void vfio_unblock_giommu_migration(void);
>>   int64_t vfio_mig_bytes_transferred(void);
>>     #ifdef CONFIG_LINUX
>