From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: 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 00/11] Fix incorrect iommu_groups with PCIe switches
Date: Fri, 11 Jul 2025 13:14:10 -0300 [thread overview]
Message-ID: <20250711161410.GD1951027@nvidia.com> (raw)
In-Reply-To: <20250711094020.697678fc.alex.williamson@redhat.com>
On Fri, Jul 11, 2025 at 09:40:20AM -0600, Alex Williamson wrote:
> Yeah, that might work since it does report itself as a host bridge.
> Probably noteworthy that you'd end up catching the Intel host bridge
> with this too.
Yes, I think the argument holds for Intel too. A device with no way to
initiate DMA and no MMIO to target P2P can always be its own group,
regardless of type.
> Again, it should be perfectly safe to assign things downstream of the
> ACS isolated root ports in the MFD to userspace drivers, their egress
> DMA is isolated. It would only be ingress from an endpoint that seems
> like it cannot exist that would be troublesome. I don't have a good
> solution.
I don't know what the kernel can do with this, IMHO the PCIE
capabilities are simply out of spec.
If we want to do my relaxed idea then we could also say that root
ports without ACS are assumed to have no possible P2P as well.
Jason
prev parent reply other threads:[~2025-07-11 16:14 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-30 22:28 [PATCH 00/11] Fix incorrect iommu_groups with PCIe switches Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 01/11] PCI: Move REQ_ACS_FLAGS into pci_regs.h as PCI_ACS_ISOLATED Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 02/11] PCI: Add pci_bus_isolation() Jason Gunthorpe
2025-07-01 19:28 ` Alex Williamson
2025-07-02 1:00 ` Jason Gunthorpe
2025-07-03 15:30 ` Jason Gunthorpe
2025-07-03 22:17 ` Alex Williamson
2025-07-03 23:08 ` Alex Williamson
2025-07-03 23:21 ` Jason Gunthorpe
2025-07-03 23:15 ` Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 03/11] iommu: Compute iommu_groups properly for PCIe switches Jason Gunthorpe
2025-07-01 19:29 ` Alex Williamson
2025-07-02 1:04 ` Jason Gunthorpe
2025-07-17 19:25 ` Donald Dutile
2025-07-17 20:27 ` Jason Gunthorpe
2025-07-18 2:31 ` Donald Dutile
2025-07-18 13:32 ` Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 04/11] iommu: Organize iommu_group by member size Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 05/11] PCI: Add pci_reachable_set() Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 06/11] iommu: Use pci_reachable_set() in pci_device_group() Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 07/11] iommu: Validate that pci_for_each_dma_alias() matches the groups Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 08/11] PCI: Add the ACS Enhanced Capability definitions Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 09/11] PCI: Enable ACS Enhanced bits for enable_acs and config_acs Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 10/11] PCI: Check ACS DSP/USP redirect bits in pci_enable_pasid() Jason Gunthorpe
2025-06-30 22:28 ` [PATCH 11/11] PCI: Check ACS Extended flags for pci_bus_isolated() Jason Gunthorpe
2025-07-01 21:48 ` [PATCH 00/11] Fix incorrect iommu_groups with PCIe switches Alex Williamson
2025-07-02 1:47 ` Jason Gunthorpe
2025-07-04 0:37 ` Jason Gunthorpe
2025-07-11 14:55 ` Alex Williamson
2025-07-11 16:08 ` Jason Gunthorpe
2025-07-08 20:47 ` Jason Gunthorpe
2025-07-11 15:40 ` Alex Williamson
2025-07-11 16:14 ` Jason Gunthorpe [this message]
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