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Date:   Wed, 24 Aug 2022 11:23:21 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Baolu Lu <baolu.lu@linux.intel.com>
Cc:     Joerg Roedel <joro@8bytes.org>, Jason Gunthorpe <jgg@nvidia.com>,
        Christoph Hellwig <hch@infradead.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Vinod Koul <vkoul@kernel.org>,
        Eric Auger <eric.auger@redhat.com>,
        Liu Yi L <yi.l.liu@intel.com>,
        Jacob jun Pan <jacob.jun.pan@intel.com>,
        Zhangfei Gao <zhangfei.gao@linaro.org>,
        Zhu Tony <tony.zhu@intel.com>, iommu@lists.linux.dev,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 04/13] PCI: Allow PASID only when ACS enforced on
 upstreaming path
Message-ID: <20220824162321.GA2783649@bhelgaas>
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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!