Hi Jason,
On 2022/5/4 08:11, Jason Gunthorpe wrote:
+static int __iommu_group_attach_domain(struct iommu_group *group,
+ struct iommu_domain *new_domain)
{
int ret;
+ if (group->domain == new_domain)
+ return 0;
+
/*
- * If the group has been claimed already, do not re-attach the default
- * domain.
+ * A NULL domain means to call the detach_dev() op. New drivers should
+ * use a IOMMU_DOMAIN_IDENTITY domain instead of a NULL default_domain
+ * and detatch_dev().
*/
- if (!group->default_domain || group->owner) {
- __iommu_group_for_each_dev(group, domain,
+ if (!new_domain) {
+ WARN_ON(!group->domain->ops->detach_dev);
+ __iommu_group_for_each_dev(group, group->domain,
iommu_group_do_detach_device);
group->domain = NULL;
- return;
+ return 0;
}
- if (group->domain == group->default_domain)
- return;
-
- /* Detach by re-attaching to the default domain */
+ /*
+ * New drivers do not implement detach_dev, so changing the domain is
+ * done by calling attach on the new domain. Drivers should implement
+ * this so that DMA is always translated by either the new, old, or a
+ * blocking domain. DMA should never become untranslated.
+ *
+ * Note that this is called in error unwind paths, attaching to a
+ * domain that has already been attached cannot fail.
+ */
ret = __iommu_group_for_each_dev(group, group->default_domain,
^^^^^^^^^^^^^^^^^^^^^^
I suppose this should be @new_domain, right?
iommu_group_do_attach_device);
- if (ret != 0)
- WARN_ON(1);
+ if (ret)
+ return ret;
+ group->domain = new_domain;
+ return 0;
+}
Best regards,
baolu
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