Re: [PATCH v4 09/10] iommu: Make iommu_queue_iopf() more generic

Baolu Lu
2023-08-26T08:11:31Z

On 8/25/23 4:17 PM, Tian, Kevin wrote:
>> +
>> + list_for_each_entry(iopf, &iopf_param->faults, list) {
>> + if (WARN_ON(iopf->fault.prm.pasid == pasid))
>> + break;
>> + }
>> + mutex_unlock(&iopf_param->lock);
>> +}
>> +
>> void iommu_detach_device(struct iommu_domain *domain, struct device
>> *dev)
>> {
>> struct iommu_group *group;
>> @@ -1959,6 +1980,7 @@ void iommu_detach_device(struct iommu_domain
>> *domain, struct device *dev)
>> if (!group)
>> return;
>>
>> + assert_no_pending_iopf(dev, IOMMU_NO_PASID);
>> mutex_lock(&group->mutex);
>> if (WARN_ON(domain != group->domain) ||
>> WARN_ON(list_count_nodes(&group->devices) != 1))
>> @@ -3269,6 +3291,7 @@ void iommu_detach_device_pasid(struct
>> iommu_domain *domain, struct device *dev,
>> {
>> struct iommu_group *group = iommu_group_get(dev);
>>
>> + assert_no_pending_iopf(dev, pasid);
> this doesn't look correct. A sane driver will stop triggering new
> page request before calling detach but there are still pending ones
> not drained until iopf_queue_flush_dev() called by
> ops->remove_dev_pasid().
>
> then this check will cause false warning.
>

You are right. It is not only incorrect but also pointless. The iommu
driver should flush the iopf queues in the path of detaching domains. I
will remove it if no objection.

Best regards,
baolu