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SubjectRe: [PATCH 1/2] iommu: Consolidate pasid dma ownership check
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On 2023/8/1 15:03, Tian, Kevin wrote:
>> /**
>> * iommu_device_use_default_domain() - Device driver wants to handle
>> device
>> * DMA through the kernel DMA API.
>> @@ -3052,14 +3063,14 @@ int iommu_device_use_default_domain(struct
>> device *dev)
>>
>> mutex_lock(&group->mutex);
>> 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;
>> }
>> }
>>
>> group->owner_cnt++;
>> + 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,
baolu

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