RE: [PATCH v5 1/9] iommu: Introduce domain attachment handle

Tian, Kevin
2024-05-15T07:17:32Z

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Tuesday, April 30, 2024 10:57 PM
>
> +/* Add an attach handle to the group's pasid array. */
> +static struct iommu_attach_handle *
> +iommu_attach_handle_set(struct iommu_domain *domain,
> + struct iommu_group *group, ioasid_t pasid)
> +{
> + struct iommu_attach_handle *handle;
> + void *curr;
> +
> + handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> + if (!handle)
> + return ERR_PTR(-ENOMEM);
> +
> + handle->domain = domain;
> + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, handle,
> GFP_KERNEL);

this could be just xa_insert() which returns -EBUSY if the entry isn't NULL.

> + if (curr) {
> + kfree(handle);
> + return xa_err(curr) ? curr : ERR_PTR(-EBUSY);

'curr' is not an error pointer. You need ERR_PTR(xa_err(curr)).

> int iommu_attach_group(struct iommu_domain *domain, struct
> iommu_group *group)
> {
> + struct iommu_attach_handle *handle;
> int ret;
>
> mutex_lock(&group->mutex);
> + handle = iommu_attach_handle_set(domain, group,
> IOMMU_NO_PASID);
> + if (IS_ERR(handle)) {
> + ret = PTR_ERR(handle);
> + goto out_unlock;
> + }
> ret = __iommu_attach_group(domain, group);
> + if (ret)
> + goto out_remove_handle;
> mutex_unlock(&group->mutex);

It's slightly better to set the handler after __iommu_attach_group().

doing so is aligned to the sequence in iommu_group_replace_domain().

> @@ -2211,13 +2307,33 @@ EXPORT_SYMBOL_GPL(iommu_attach_group);
> int iommu_group_replace_domain(struct iommu_group *group,
> struct iommu_domain *new_domain)
> {
> + struct iommu_domain *old_domain = group->domain;
> + struct iommu_attach_handle *handle;
> int ret;
>
> if (!new_domain)
> return -EINVAL;
>
> + if (new_domain == old_domain)
> + return 0;
> +

__iommu_group_set_domain() already does the check.