Re: [PATCH v11 04/13] PCI: Allow PASID only when ACS enforced on upstreaming path

[Bjorn Helgaas]

On Tue, Aug 23, 2022 at 03:05:53PM +0800, Baolu Lu wrote:
> On 2022/8/19 07:00, Bjorn Helgaas wrote:

> > PCI: Enable PASID only when ACS RR & UF enabled on upstream path
> > 
> > The Requester ID/Process Address Space ID (PASID) combination
> > identifies an address space distinct from the PCI bus address space,
> > e.g., an address space defined by an IOMMU.
> > 
> > But the PCIe fabric routes Memory Requests based on the TLP address,
> > ignoring any PASID (PCIe r6.0, sec 2.2.10.4), so a TLP with PASID that
> > *should*  go upstream to the IOMMU may instead be routed as a P2P
> > Request if its address falls in a bridge window.
> > 
> > To ensure that all Memory Requests with PASID are routed upstream,
> > only enable PASID if ACS P2P Request Redirect and Upstream Forwarding
> > are enabled for the path leading to the device.
> 
> Yours is clear and straight-forward. I will update the patch with above.
> Thank you and very appreciated!

With the update to only require RR and UF and the commit log update,

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

Thanks!