RE: [RFC 4/7] iommufd: Support attach/replace for SIOV virtual device {dev, pasid}

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Monday, October 9, 2023 4:51 PM
> 
> From: Kevin Tian <kevin.tian@xxxxxxxxx>
> 
> SIOV devices allows driver to tag different PASIDs for the virtual devices
> within it. Such driver should call iommufd_device_bind_pasid() to connect
> the pasid of the device to iommufd, and then driver is able to attach the
> virtual device to IOAS/HWPT with the iommufd_device_attach() API.
> 
> Unlike physical devices, for SIOV virtual devices, iommufd_device_attach()
> eventually uses the idev->default_pasid when the virtual device is attached

s/default_pasid/rid_pasid/? or just call it idev->pasid. 'default' adds slight
confusion instead...

> to an IOAS/HWPT. Also, there is no need to do immediate_attach per iommu
> domain allocation in the attach/replace path if any iommu domain allocation
> happens since the attach/replace is eventually pasid attach/replace.

immediate_attach rationale belongs to earlier pasid attach series when
iommufd_device_pasid_attach() was introduced. Not here.