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

[Vasant Hegde <vasant.hegde@amd.com>]

Baolu,


On 8/16/2024 8:19 AM, Baolu Lu wrote:
> 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.

Thanks.

> 
> 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.

Right. We can enhance AMD driver to support attaching PASID to paging/UNMANAGED
domains. It needs some more rework/cleanup before we do that.

-Vasant