Re: [PATCH v9 10/11] iommu: Per-domain I/O page fault handling

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2022/6/28 16:39, Tian, Kevin wrote:
>>   static void iopf_handle_group(struct work_struct *work)
>>   {
>>   	struct iopf_group *group;
>> +	struct iommu_domain *domain;
>>   	struct iopf_fault *iopf, *next;
>>   	enum iommu_page_response_code status =
>> IOMMU_PAGE_RESP_SUCCESS;
>>
>>   	group = container_of(work, struct iopf_group, work);
>> +	domain = iommu_get_domain_for_dev_pasid(group->dev,
>> +				group->last_fault.fault.prm.pasid);
>> +	if (!domain || !domain->iopf_handler)
>> +		status = IOMMU_PAGE_RESP_INVALID;
> Miss a comment on why no refcnt is required on domain as explained
> in the commit msg.

I had some comments around iommu_queue_iopf() in the previous patch. The
iommu_queue_iopf() is the generic page fault handler exposed by iommu
core, hence that's the right place to document this.

Post it below as well:

diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
index 1df8c1dcae77..aee9e033012f 100644
--- a/drivers/iommu/io-pgfault.c
+++ b/drivers/iommu/io-pgfault.c
@@ -181,6 +181,13 @@ static void iopf_handle_group(struct work_struct *work)
   * request completes, outstanding faults will have been dealt with by 
the time
   * the PASID is freed.
   *
+ * Any valid page fault will be eventually routed to an iommu domain 
and the
+ * page fault handler installed there will get called. The users of this
+ * handling framework should guarantee that the iommu domain could only be
+ * freed after the device has stopped generating page faults (or the iommu
+ * hardware has been set to block the page faults) and the pending page 
faults
+ * have been flushed.
+ *
   * Return: 0 on success and <0 on error.
   */
  int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)

Best regards,
baolu