> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Thursday, February 2, 2023 3:05 PM
>
> All drivers are already required to support changing between active
> UNMANAGED domains when using their attach_dev ops.
All drivers which don't have *broken* UNMANAGED domain?
>
> +/**
> + * iommu_group_replace_domain - replace the domain that a group is
> attached to
> + * @new_domain: new IOMMU domain to replace with
> + * @group: IOMMU group that will be attached to the new domain
> + *
> + * This API allows the group to switch domains without being forced to go to
> + * the blocking domain in-between.
> + *
> + * If the attached domain is a core domain (e.g. a default_domain), it will act
> + * just like the iommu_attach_group().
I think you meant "the currently-attached domain", which implies a
'detached' state as you replied to Baolu.
> + */
> +int iommu_group_replace_domain(struct iommu_group *group,
> + struct iommu_domain *new_domain)
what actual value does 'replace' give us? It's just a wrapper of
__iommu_group_set_domain() then calling it set_domain is
probably clearer. You can clarify the 'replace' behavior in the
comment.
> +{
> + int ret;
> +
> + if (!new_domain)
> + return -EINVAL;
> +
> + mutex_lock(&group->mutex);
> + ret = __iommu_group_set_domain(group, new_domain);
> + if (ret) {
> + if (__iommu_group_set_domain(group, group->domain))
> + __iommu_group_set_core_domain(group);
> + }
Can you elaborate the error handling here? Ideally if
__iommu_group_set_domain() fails then group->domain shouldn't
be changed. Why do we need further housekeeping here?
