Re: [PATCH v3 01/17] iommu: Add new iommu op to create domains owned by userspace

[Jason Gunthorpe]

On Fri, Jul 28, 2023 at 09:37:21AM +0000, Tian, Kevin wrote:
> > From: Yi Liu <yi.l.liu@xxxxxxxxx>
> > Sent: Monday, July 24, 2023 7:04 PM
> >
> > + * @domain_alloc_user: allocate a user iommu domain corresponding to
> > the input
> > + *                     @hwpt_type that is defined as enum iommu_hwpt_type in the
> > + *                     include/uapi/linux/iommufd.h. A returning domain will be
> > + *                     set to an IOMMU_DOMAIN_NESTED type, upon valid
> > @user_data
> > + *                     and @parent that is a kernel-managed domain. Otherwise,
> > + *                     it will be set to an IOMMU_DOMAIN_UNMANAGED type.
> > Return
> > + *                     ERR_PTR on allocation failure.
> 
> "If @user_data is valid and @parent points to a kernel-managed domain,
> the returning domain is set to IOMMU_DOMAIN_NESTED type. Otherwise
> it is set to IOMMU_DOMAIN_UNMANAGED type."

 "If @user_data is valid and @parent points to a kernel-managed domain,
 then the returned domain must be the IOMMU_DOMAIN_NESTED type. Otherwise
 the returned domain is IOMMU_DOMAIN_UNMANAGED."

Notice the detail that this API expects the driver to set the type and
fully initialize the domain, including the generic iommu_domain
struct, which is different than alloc_domain.

When we implement this in drivers we should tidy this so all the alloc
flows fully initialize the domain internally.

Jason