RE: [PATCH 09/12] iommu/vt-d: Check device list of domain in domain free path

Tian, Kevin
2022-06-01T09:28:12Z

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Friday, May 27, 2022 2:30 PM
>
> When the IOMMU domain is about to be freed, it should not be set on any
> device. Instead of silently dealing with some bug cases, it's better to
> trigger a warning to report and fix any potential bugs at the first time.
>

> static void domain_exit(struct dmar_domain *domain)
> {
> -
> - /* Remove associated devices and clear attached or cached domains
> */
> - domain_remove_dev_info(domain);
> + if (WARN_ON(!list_empty(&domain->devices)))
> + return;
>

warning is good but it doesn't mean the driver shouldn't deal with
that situation to make it safer e.g. blocking DMA from all attached
device...