RE: [PATCH v4 04/10] iommufd: Always pass iommu_attach_handle to iommu core

From: Liu, Yi L yi.l.liu@intel.com Sent: Thursday, September 12, 2024 9:13 PM

The iommu_attach_handle is optional in the RID attach/replace API and the PASID attach APIs. But it is a mandatory argument for the PASID replace API. Without it, the PASID replace path cannot get the old domain. Hence, the PASID path (attach/replace) requires the attach handle. As iommufd is the major user of the RID attach/replace with iommu_attach_handle, this also makes the iommufd always pass the attach handle for the RID path as well. This keeps the RID and PASID path much aligned.

hmm this looks more like a design choice instead of mandatory requirement, e.g. as Baolu commented you can also pass in the old domain. though I'm OK with what this patch does...