Re: [PATCH 0/6] Make set_dev_pasid op supportting domain replacement

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

On 8/16/24 9:19 AM, Yi Liu wrote:
> On 2024/8/16 01:49, Vasant Hegde wrote:
>> Hi All,
>>
>> On 6/28/2024 2:25 PM, Yi Liu wrote:
>>> This splits the preparation works of the iommu and the Intel iommu 
>>> driver
>>> out from the iommufd pasid attach/replace series. [1]
>>>
>>> To support domain replacement, the definition of the set_dev_pasid op
>>> needs to be enhanced. Meanwhile, the existing set_dev_pasid callbacks
>>> should be extended as well to suit the new definition.
>>
>> IIUC this will remove PASID from old SVA domain and attaches to new 
>> SVA domain.
>> (basically attaching same dev/PASID to different process). Is that the 
>> correct?
> 
> In brief, yes. But it's not only for SVA domain. Remember that SIOVr1
> extends the usage of PASID. At least on Intel side, a PASID may be
> attached to paging domains.

You are correct.

The idxd driver attaches a paging domain to a non-zero PASID for kernel
DMA with PASID. From an architectural perspective, other architectures,
like ARM, AMD, and RISC-V, also support this. Therefore, attaching a
paging domain to a PASID is not Intel-specific but a generic feature.

Thanks,
baolu