Re: [PATCH v4 12/18] iommu/vt-d: Handle reattach of the restored domain

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

On 8/28/26 01:52, Samiullah Khawaja wrote:
>>> +
>>> +static int domain_reattach_iommu(struct dmar_domain *domain,
>>> +                 struct intel_iommu *iommu,
>>> +                 struct iommu_device_ser *device_ser)
>>> +{
>>> +    struct iommu_domain_info *info, *curr;
>>> +    int restored_did;
>>> +    int ret;
>>> +
>>> +    if (!iommu_domain_restored_state(&domain->domain))
>>> +        return -EINVAL;
>>> +
>>> +    restored_did = device_ser->domain_iommu_ser.attachment_id;
>>> +    if (!ida_exists(&iommu->domain_ida, restored_did))
>>> +        return -EINVAL;
>>
>> It seems that checking only whether the domain ID is reserved on this
>> IOMMU may not be sufficient. It would be safer to also verify that:
>>
>> - device_ser->domain_iommu_ser.iommu_phys matches iommu->reg_phys, and
>> - device_ser->domain_iommu_ser.domain_phys matches @domain.
>>
>> ?
> 
> Interesting.. The caller of this attach from core fetches the correct
> domain based on the checks you mentioned. But you are right, adding a
> check here makes sense to prevent anyone else calling attach with a
> mismatch.

If the iommu core has already verified the domain-device relationship,
then we probably don’t need to duplicate that check in the iommu driver.
Maybe just add a short comment above this function stating that
validation is done by the iommu core?

Thanks,
baolu