Re: [PATCH v6 04/10] iommu: Extend domain attach group with handle support

[Jason Gunthorpe]

On Mon, May 27, 2024 at 12:05:11PM +0800, Lu Baolu wrote:
> Unlike the SVA case where each PASID of a device has an SVA domain
> attached to it, the I/O page faults are handled by the fault handler
> of the SVA domain. The I/O page faults for a user page table might
> be handled by the domain attached to RID or the domain attached to
> the PASID, depending on whether the PASID table is managed by user
> space or kernel. As a result, there is a need for the domain attach
> group interfaces to have attach handle support. The attach handle
> will be forwarded to the fault handler of the user domain.
> 
> Add some variants of the domain attaching group interfaces so that they
> could support the attach handle and export them for use in IOMMUFD.
> 
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
>  drivers/iommu/iommu-priv.h |  8 +++
>  drivers/iommu/iommu.c      | 99 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 107 insertions(+)

I don't have an objection to it like this, but I wonder if we could be
smaller to teach iommu_attach_device_pasid to use IOMMU_NO_PASID to
attach the handle to the rid?

It would have an if there to call the  __iommu_attach_group() instead
of the pasid attach ?

Jason