Re: [PATCH v3 2/8] iommu/sva: Use iopf domain attach/detach interface

[Baolu Lu]

On 3/23/24 12:59 AM, Jason Gunthorpe wrote:
> On Thu, Mar 14, 2024 at 03:41:23PM +0800, Baolu Lu wrote:
>
> > The whole cookie mechanism aims to address two things:
> >
> > - Extend the domain lifetime until all pending page faults are
> > resolved.
> Like you answered, I think the flush is a simpler scheme..

Yeah! Let me head this direction.

> > - Associate information about the iommu device with each attachment of
> >    the domain so that the iommufd device object ID could be quickly
> >    retrieved in the fault delivering path.
>   
> > > I see we also need to stick a pointer in the domain for iommufd to get
> > > back to the hwpt, but that doesn't seem to need such a big system to
> > > accomplish - just add a void *. It would make sense for the domain to
> > > have some optional pointer to a struct for all the fault related data
> > > that becomes allocated when a PRI domain is created..
> > It's not getting back hwpt from domain, just getting the iommufd_device
> > in the fault delivering path. The iommufd_device is not per-domain, but
> > per-domain-attachment.
> It does make sense you'd need that, but I think something like this is
> a more direct way to get it. Caller allocates the handle struct. The
> iopf will provide the handle from the XA to the
> callback. container_of() not void * is used to in the caller's API.

Your code looks attractive to me. It's much simpler. Thank you!

Best regards,
baolu