Re: [PATCH v2 1/1] PCI: Add translated request only flag for pci_enable_pasid()

[Baolu Lu]

On 2023/1/13 10:24, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Friday, January 13, 2023 9:44 AM
> >
> > One alternative is ATS which lets the device resolve the PASID+addr pair
> > before a memory request is made into a routeable TLB address through the
> > TA. Those resolved addresses are then cached on the device instead of
> > in the IOMMU TLB and the device always sets the translated bit for PASID.
> > One example of those devices are AMD graphic devices that always have ACS
> > or ATS enabled together with PASID.
>
> this should be made clear that ATS alone doesn't imply that translated
> bit is always set. It's just an optimization so the device may cache
> translation for selective requests. Only combining with PRI to
> support SVA has such implication.
>
> > + * @flags: device-specific flags
> > + *   - PCI_PASID_XLATED_REQ_ONLY: The PCI device only issues PASID
> > + *                                memory requests of translated type.
>
> this reads like the device even doesn't issue non-PASID requests.
>
> It is clearer to be "The PCI device always use translated type for all
> PASID memory requests".
>
> Otherwise looks good to me:
>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>

Both make sense to me. It's updated. Thanks a lot!

--
Best regards,
baolu