Re: [PATCH v7 10/28] iommufd/access: Bypass access->ops->unmap for internal use

Nicolin Chen
2025-07-02T20:14:57Z

On Wed, Jul 02, 2025 at 09:45:26AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > Sent: Friday, June 27, 2025 3:35 AM
> >
> > +int iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long
> > iova,
> > + unsigned long length)
> > {
> > struct iommufd_ioas *ioas =
> > container_of(iopt, struct iommufd_ioas, iopt);
> > struct iommufd_access *access;
> > unsigned long index;
> > + int ret = 0;
> >
> > xa_lock(&ioas->iopt.access_list);
> > + /* Bypass any unmap if there is an internal access */
> > + xa_for_each(&ioas->iopt.access_list, index, access) {
> > + if (iommufd_access_is_internal(access)) {
> > + ret = -EBUSY;
> > + goto unlock;
> > + }
> > + }
> > +
>
> hmm all those checks are per iopt. Could do one-off check in
> iopt_unmap_iova_range() and store the result in a local flag.
>
> Then use that flag to decide whether to return -EBUSY if
> area->num_accesses is true in the loop.

I don't quite follow this...

Do you suggest to move this xa_for_each to iopt_unmap_iova_range?

What's that local flag used for?

Thanks
Nicolin