Re: [PATCH 09/11] iommu/vt-d: Reuse intel_iommu_set_dev_pasid function

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

On 2/19/24 9:01 AM, Zhang, Tina wrote:
>>> +		if (ret)
>>> +			goto out_free;
>>> +
>>> +		ret = domain_attach_iommu(dmar_domain, iommu);
>> The same here.
>>
>> The domain_attach_iommu() is called to setup the relationship between a
>> domain and an iommu. You should make it compatible with sva domain as
>> well.
> The problem is whether we need struct iommu_domain_info for sva domain. I didn't see any necessary to allocate struct iommu_domain_info instance for sva domain, as all the fields of struct iommu_domain_info can be gotten from dev_pasids.
> 
> Since we want to make the domain_attach_iommu() generic (i.e., all domains, no matter what type they are, need to call this function), I think we can check the domain type within the function and add comments there to tell that we didn't see any necessary to let sva domain have a struct iommu_domain_info and therefore the function returns immediately if it meets a sva domain. What do you think?

The SVA domain is nothing special compared to other types of domains.
The ultimate goal is that we should have a common attach-detach
implementation for all.

The iommu_domain_info structure stores the relationship between a domain
and IOMMU, mainly for the cache tag information, also known as the
domain ID. It's a bit outdated if we consider SVA and nested domains. As
I told in another thread, I am working on a solution to address
this. Let's sync our efforts to avoid duplication of efforts.

Best regards,
baolu