Re: [PATCH v4 15/15] vfio/common: Block migration with vIOMMUs without address width limits

[Joao Martins <joao.m.martins@oracle.com>]

On 08/09/2023 07:28, Duan, Zhenzhong wrote:
> 
> On 6/23/2023 5:48 AM, Joao Martins wrote:
>> Only block the case when the underlying vIOMMU model does not report any
>> address space limits, in addition to DMA translation being off or no
>> vIOMMU present. The limits are needed such that can define the IOVA limits
>> that arm the device dirty tracker.
>>
>> Additionally, reword the migration blocker error message to clarify that
>> we the configured vIOMMU does not support migration, as opposed to
>> implying that just being there blocks migration.
>>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> ---
>>   hw/vfio/common.c | 7 +++++--
>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 62f91e8e102d..c3cc0dd47044 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -449,15 +449,18 @@ static int vfio_viommu_get_max_iova(hwaddr *max_iova)
>>     int vfio_block_giommu_migration(Error **errp)
>>   {
>> +    hwaddr max;
>>       int ret;
>>         if (giommu_migration_blocker ||
>> -        !vfio_viommu_preset()) {
>> +        !vfio_viommu_preset() ||
>> +        (vfio_viommu_preset() && !vfio_viommu_get_max_iova(&max))) {
> 
> Could be simplified as below:
> 
> +        !vfio_viommu_preset() || !vfio_viommu_get_max_iova(&max))) {
> 

True.