Re: [PATCH v5 6/9] iommufd: Fault-capable hwpt attach/detach/replace

Baolu Lu
2024-05-20T03:57:46Z

On 5/20/24 11:35 AM, Tian, Kevin wrote:
>> From: Baolu Lu <baolu.lu@linux.intel.com>
>> Sent: Monday, May 20, 2024 10:10 AM
>>
>> On 5/15/24 4:43 PM, Tian, Kevin wrote:
>>>> From: Lu Baolu <baolu.lu@linux.intel.com>
>>>> Sent: Tuesday, April 30, 2024 10:57 PM
>>>> +
>>>> +int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
>>>> + struct iommufd_hw_pagetable *hwpt,
>>>> + struct iommufd_hw_pagetable *old)
>>>> +{
>>>> + struct iommu_attach_handle *handle;
>>>> + int ret;
>>>> +
>>>> + if (hwpt->fault)
>>>> + ret = iommufd_fault_iopf_enable(idev);
>>>> + else
>>>> + iommufd_fault_iopf_disable(idev);
>>>> +
>>>> + ret = iommu_group_replace_domain(idev->igroup->group, hwpt-
>>>>> domain);
>>>> + if (ret)
>>>> + goto out_cleanup;
>>>> +
>>>> + iommufd_auto_response_faults(old, idev);
>>>> + handle = iommu_attach_handle_get(idev->igroup->group,
>>>> IOMMU_NO_PASID, 0);
>>>> + handle->idev = idev;
>>>
>>> why is auto response required in replace? new requests can come
>>> after the auto response anyway...
>>>
>>> The user should prepare for faults delivered to the old or new hwpt
>>> in the transition window.
>>
>> The current design of replace allows switching between one that is not
>> IOPF-capable and one that is. This implies that if we switch from an
>> IOPF-capable hwpt to a non-IOPF-capable one, the response queue needs to
>> be auto responded.
>>
>
> then do it only for that scenario?

Yes. Will do this in the new version.

Best regards,
baolu