Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs

From: Jason Gunthorpe
Date: Fri May 07 2021 - 13:10:57 EST

On Fri, May 07, 2021 at 11:06:14AM -0600, Alex Williamson wrote:

> We had tossed around an idea of a super-container with vfio, it's maybe
> something we'd want to incorporate into this design. For instance, if
> memory could be pre-registered with a super container, which would
> handle the locked memory accounting for that memory, then
> sub-containers could all handle the IOMMU context of their sets of
> devices relative to that common memory pool.

This is where I suggested to David to use nesting of IOASIDs.

Without HW support for nesting a SW nest is really just re-using the
memory registration information stored in the parent when constructing
the children