Re: [PATCH v3 02/19] vfio: Move iova_bitmap into iommu core

Jason Gunthorpe
2023-10-13T15:48:30Z

On Sat, Sep 23, 2023 at 02:24:54AM +0100, Joao Martins wrote:
> Both VFIO and IOMMUFD will need iova bitmap for storing dirties and walking
> the user bitmaps, so move to the common dependency into IOMMU core. IOMMUFD
> can't exactly host it given that VFIO dirty tracking can be used without
> IOMMUFD.

Hum, this seems strange. Why not just make those VFIO drivers depends
on iommufd? That seems harmless to me.

However, I think the real issue is that iommu drivers need to use this
API too for their part?

IMHO would I would like to get to is a part of iommufd that used by
iommu drivers (and thus built-in) and the current part that is
modular.

Basically, I think you should put this in the iommufd directory. Make
the vfio side kconfig depend on iommufd at this point

Later when the iommu drivers need it make some
CONFIG_IOMMUFD_DRIVER_SUPPORT to build another module (that will be
built in) and make the drivers that need it select it so it becomes
built in.

Jason