Re: [PATCH 1/2] iommu: Consolidate pasid dma ownership check

From: Baolu Lu
Date: Tue Aug 01 2023 - 03:44:06 EST

On 2023/8/1 15:03, Tian, Kevin wrote:
* iommu_device_use_default_domain() - Device driver wants to handle
* DMA through the kernel DMA API.
@@ -3052,14 +3063,14 @@ int iommu_device_use_default_domain(struct
device *dev)

if (group->owner_cnt) {
- if (group->owner || !iommu_is_default_domain(group) ||
- !xa_empty(&group->pasid_array)) {
+ if (group->owner || !iommu_is_default_domain(group)) {
ret = -EBUSY;
goto unlock_out;

+ assert_pasid_dma_ownership(group);
Old code returns error if pasid_xrrary is not empty.

New code continues to take ownership with a warning.

this is a functional change. Is it intended or not?

If iommu_device_use_default_domain() is called with pasid_array not
empty, there must be a bug somewhere in the device driver. We should
WARN it instead of returning an error. Probably this is a functional
change? If so, I can add this in the commit message.

Best regards,