From: Nicolin Chen nicolinc@nvidia.com 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?