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    SubjectRe: [PATCH v11 04/13] PCI: Allow PASID only when ACS enforced on upstreaming path
    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@google.com>

    Thanks!

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