Re: [PATCH v4 11/13] iommu/vt-d: Add set_dev_pasid callback for nested domain

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

On 2024/11/6 17:14, Yi Liu wrote:
> On 2024/11/6 16:41, Baolu Lu wrote:
>> On 2024/11/6 16:17, Tian, Kevin wrote:
>>>> From: Liu, Yi L <yi.l.liu@intel.com>
>>>> Sent: Monday, November 4, 2024 9:19 PM
>>>>
>>>> +
>>>> +    dev_pasid = domain_add_dev_pasid(domain, dev, pasid);
>>>> +    if (IS_ERR(dev_pasid))
>>>> +        return PTR_ERR(dev_pasid);
>>>> +
>>>> +    ret = domain_setup_nested(iommu, dmar_domain, dev, pasid, old);
>>>> +    if (ret)
>>>> +        goto out_remove_dev_pasid;
>>>> +
>>>> +    domain_remove_dev_pasid(old, dev, pasid);
>>>> +
>>>
>>> forgot one thing. Why not required to create a debugfs entry for
>>> nested dev_pasid?
>>
>> This debugfs node is only created for paging domain.
> 
> I think Kevin got one point. The debugfs is added when paging domain
> is attached. How about the paging domains that is only used as nested
> parent domain. We seem to lack a debugfs node for such paging domains.

Are you talking about the nested parent domain? It's also a paging
domain, hence a debugfs node will be created.