Re: [PATCH 2/2] iommu/vt-d: don's issue devTLB flush request when device is disconnected

[Ethan Zhao <haifeng.zhao@linux.intel.com>]

On 12/15/2023 9:34 AM, Baolu Lu wrote:
> On 2023/12/15 9:03, Ethan Zhao wrote:
>>
>> 2. supprise_removal
>>
>>   Users remove the devece directly or bring the device link down/turn 
>> off
>>
>>   device power first by setting pci config space, link-down/not-present/
>>
>>   power-off are all handled by pciehp the same way 
>> "supprise_removal", in
>>
>>   such case, pciehp_ist() will flag the device as "disconnected" 
>> first, then
>>
>>   unconfig the devcie, unload driver, iommu release device(issing 
>> devTLB flush)
>>
>>   delete device. so we checking the device state could work such cases.
>
> If so, then it is fine for the iommu driver. As Robin said, if the
> device needs more cleanup, the iommu core should register a right
> callback to the driver core and handle it before the device goes away.
>
> Disabling PCI features seems to be a reasonable device cleanup. This
> gives us another reason to move ATS enabling/disabling out from the

For supprise_removal, device was already removed, powered-off, iommu

device-release got notification  or cleanup callback is  invoked to disable

ATS to not-present device etc ,

I didn't get the meaning to do so, perhaps I misunderstand ?

Thanks,

Ethan

> iommu subsystem. Once this is done, the device driver will enable ATS
> during its probe and disable it during its release. There will be no
> such workaround in the iommu driver anymore.
>
> Best regards,
> baolu