Re: [PATCH v2 2/4] iommu: Add new iommu op to get iommu hardware information

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2023/3/16 16:16, Tian, Kevin wrote:
>> + *           allocated in the IOMMU driver and the caller should free it
>> + *           after use. Return the data buffer if success, or ERR_PTR on
>> + *           failure.
>>    * @domain_alloc: allocate iommu domain
>>    * @probe_device: Add device to iommu driver handling
>>    * @release_device: Remove device from iommu driver handling
>> @@ -246,11 +252,17 @@ struct iommu_iotlb_gather {
>>    * @remove_dev_pasid: Remove any translation configurations of a specific
>>    *                    pasid, so that any DMA transactions with this pasid
>>    *                    will be blocked by the hardware.
>> + * @driver_type: One of enum iommu_hw_info_type. This is used in the
>> hw_info
>> + *               reporting path. For the drivers that supports it, a unique
>> + *               type should be defined. For the driver that does not support
>> + *               it, this field is the IOMMU_HW_INFO_TYPE_DEFAULT that is 0.
>> + *               Hence, such drivers do not need to care this field.
> The meaning of "driver_type" is much broader than reporting hw_info.
> 
> let's be accurate to call it as "hw_info_type". and while we have two
> separate fields for one feature where is the check enforced on whether
> both are provided?
> 
> Is it simpler to return the type directly in @hw_info?

If I remember correctly, the vendor iommu type and hardware info are
reported to user space separately.

Best regards,
baolu