On 2022/6/2 14:29, Tian, Kevin wrote:
From: Baolu Lu <baolu...@linux.intel.com>
Sent: Wednesday, June 1, 2022 7:02 PM
On 2022/6/1 17:28, Tian, Kevin wrote:
From: Lu Baolu <baolu...@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...
I have ever thought the same thing. :-)
Blocking DMA from attached device should be done when setting blocking
domain to the device. It should not be part of freeing a domain.
yes but here we are talking about some bug scenario.
Here, the caller asks the driver to free the domain, but the driver
finds that something is wrong. Therefore, it warns and returns directly.
The domain will still be there in use until the next set_domain().
at least it'd look safer if we always try to unmap the entire domain i.e.:
static void domain_exit(struct dmar_domain *domain)
{
-
- /* Remove associated devices and clear attached or cached domains */
- domain_remove_dev_info(domain);
if (domain->pgd) {
LIST_HEAD(freelist);
domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw), &freelist);
put_pages_list(&freelist);
}
+ if (WARN_ON(!list_empty(&domain->devices)))
+ return;
kfree(domain);
}
Fair enough. Removing all mappings is safer.
Best regards,
baolu
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