From: Jason Gunthorpe <jgg@nvidia.com>
To: Donald Dutile <ddutile@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
Bjorn Helgaas <bhelgaas@google.com>,
iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
linux-pci@vger.kernel.org, Robin Murphy <robin.murphy@arm.com>,
Will Deacon <will@kernel.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
galshalom@nvidia.com, Joerg Roedel <jroedel@suse.de>,
Kevin Tian <kevin.tian@intel.com>,
kvm@vger.kernel.org, maorg@nvidia.com, patches@lists.linux.dev,
tdave@nvidia.com, Tony Zhu <tony.zhu@intel.com>
Subject: Re: [PATCH v3 00/11] Fix incorrect iommu_groups with PCIe ACS
Date: Tue, 30 Sep 2025 13:21:40 -0300 [thread overview]
Message-ID: <20250930162140.GJ2942991@nvidia.com> (raw)
In-Reply-To: <8e679dad-b16d-45e3-b844-fa30b5a574ee@redhat.com>
On Tue, Sep 30, 2025 at 11:23:06AM -0400, Donald Dutile wrote:
> This is boiling down to an interpretation of the spec.
I think we all agree a reasonable intepretation of the spec is that no
ACS means *undefined*
But Linux cannot work on undefined. It needs to assume a definition
because it needs to make security decisions.
So I think this entirely a Linux discussion about how we should
respond to this undefined behavior in the spec.
Every heuristic option should be consider even if not directly
supported by the spec. Our current behavior isn't strongly spec
supported either :\
> I believe a definitive answer from the PCI-SIG would be best, especially wrt
> backward compatibility.
IMHO they will say it is undefined. Device are allowed to implement
both internal loopback and block internal loopback.
This position is useless for the OS, but it is how PCI SIG has acted
historically. They don't retroactively make existing devices
non-compliant.
Jason
prev parent reply other threads:[~2025-09-30 16:21 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-05 18:06 [PATCH v3 00/11] Fix incorrect iommu_groups with PCIe ACS Jason Gunthorpe
2025-09-05 18:06 ` [PATCH v3 01/11] PCI: Move REQ_ACS_FLAGS into pci_regs.h as PCI_ACS_ISOLATED Jason Gunthorpe
2025-09-09 4:08 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 02/11] PCI: Add pci_bus_isolated() Jason Gunthorpe
2025-09-09 4:09 ` Donald Dutile
2025-09-09 19:54 ` Bjorn Helgaas
2025-09-09 21:21 ` Jason Gunthorpe
2025-09-05 18:06 ` [PATCH v3 03/11] iommu: Compute iommu_groups properly for PCIe switches Jason Gunthorpe
2025-09-09 4:14 ` Donald Dutile
2025-09-09 12:18 ` Jason Gunthorpe
2025-09-09 19:33 ` Donald Dutile
2025-09-09 20:27 ` Bjorn Helgaas
2025-09-09 21:21 ` Jason Gunthorpe
2025-09-05 18:06 ` [PATCH v3 04/11] iommu: Organize iommu_group by member size Jason Gunthorpe
2025-09-09 4:16 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 05/11] PCI: Add pci_reachable_set() Jason Gunthorpe
2025-09-09 21:03 ` Bjorn Helgaas
2025-09-10 16:13 ` Jason Gunthorpe
2025-09-11 19:56 ` Donald Dutile
2025-09-15 13:38 ` Jason Gunthorpe
2025-09-15 14:32 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 06/11] iommu: Compute iommu_groups properly for PCIe MFDs Jason Gunthorpe
2025-09-09 4:57 ` Donald Dutile
2025-09-09 13:31 ` Jason Gunthorpe
2025-09-09 19:55 ` Donald Dutile
2025-09-09 21:24 ` Bjorn Helgaas
2025-09-09 23:20 ` Jason Gunthorpe
2025-09-10 1:59 ` Donald Dutile
2025-09-10 17:43 ` Jason Gunthorpe
2025-09-05 18:06 ` [PATCH v3 07/11] iommu: Validate that pci_for_each_dma_alias() matches the groups Jason Gunthorpe
2025-09-09 5:00 ` Donald Dutile
2025-09-09 15:35 ` Jason Gunthorpe
2025-09-09 19:58 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 08/11] PCI: Add the ACS Enhanced Capability definitions Jason Gunthorpe
2025-09-09 5:01 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 09/11] PCI: Enable ACS Enhanced bits for enable_acs and config_acs Jason Gunthorpe
2025-09-09 5:01 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 10/11] PCI: Check ACS DSP/USP redirect bits in pci_enable_pasid() Jason Gunthorpe
2025-09-09 5:02 ` Donald Dutile
2025-09-09 21:43 ` Bjorn Helgaas
2025-09-10 17:34 ` Jason Gunthorpe
2025-09-11 19:50 ` Donald Dutile
2025-09-05 18:06 ` [PATCH v3 11/11] PCI: Check ACS Extended flags for pci_bus_isolated() Jason Gunthorpe
2025-09-09 5:04 ` Donald Dutile
2025-09-15 9:41 ` [PATCH v3 00/11] Fix incorrect iommu_groups with PCIe ACS Cédric Le Goater
2025-09-22 22:39 ` Alex Williamson
2025-09-23 1:44 ` Donald Dutile
2025-09-23 2:06 ` Alex Williamson
2025-09-23 2:42 ` Donald Dutile
2025-09-23 22:23 ` Alex Williamson
2025-09-30 15:23 ` Donald Dutile
2025-09-30 16:21 ` Jason Gunthorpe [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250930162140.GJ2942991@nvidia.com \
--to=jgg@nvidia.com \
--cc=alex.williamson@redhat.com \
--cc=baolu.lu@linux.intel.com \
--cc=bhelgaas@google.com \
--cc=ddutile@redhat.com \
--cc=galshalom@nvidia.com \
--cc=iommu@lists.linux.dev \
--cc=joro@8bytes.org \
--cc=jroedel@suse.de \
--cc=kevin.tian@intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=maorg@nvidia.com \
--cc=patches@lists.linux.dev \
--cc=robin.murphy@arm.com \
--cc=tdave@nvidia.com \
--cc=tony.zhu@intel.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).