Re: [PATCH] PCI: revert "Enable PASID only when ACS RR & UF enabled on upstream path"

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Jan 11, 2023 at 09:54:03PM +0800, Baolu Lu wrote:
> On 2023/1/11 21:44, Jason Gunthorpe wrote:
> > > iommu_enable_pci_caps() in the Intel IOMMU driver. This also does some
> > > handling for ATS, so here we could check the info->ats_supported flag if ACS
> > > needs to be checked or not.
> > *groan*  this is seems wrong 🙁 Lu why are we doing this inside iommu
> > drivers instead of in the device drivers to declare they want to use
> > PASID?
> 
> Currently it's common to enable pasid in the IOMMU drivers, but device
> driver has more knowledge of the device, hence it makes more sense to
> move pci_enable_pasid() to the device driver.

So, lets fix it that way.

Add the flag to the pci_enable_pasid(), set the flag in the AMD
IOMMU's special AMD GPU only path assuming the device will always use
ATS

Do not set the flag in the other iommu drivers

Baolu will send a series to move the pasid enabling from the common
path to the drivers

Jason