From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Donald Dutile <ddutile@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 03/11] iommu: Compute iommu_groups properly for PCIe switches
Date: Mon, 22 Sep 2025 20:15:41 -0300 [thread overview]
Message-ID: <20250922231541.GF1391379@nvidia.com> (raw)
In-Reply-To: <20250922163200.14025a41.alex.williamson@redhat.com>
On Mon, Sep 22, 2025 at 04:32:00PM -0600, Alex Williamson wrote:
> The ACS capability was only introduced in PCIe 2.0 and vendors have
> only become more diligent about implementing it as it's become
> important for device isolation and assignment.
IDK about this, I have very new systems and they still not have ACS
flags according to this interpretation.
> IMO, we can't assume anything at all about a multifunction device
> that does not implement ACS.
Yeah this is all true.
But we are already assuming. Today we assume MFDs without caps must
have internal loopback in some cases, and then in other cases we
assume they don't.
I've sent and people have tested various different rules - please tell
me what you can live with.
Assuming the MFD does not have internal loopback, while not entirely
satisfactory, is the one that gives the least practical breakage.
I think it most accurately reflects the majority of real hardware out
there.
We can quirk to fix the remainder.
This is the best plan I've got..
Jason
next prev parent reply other threads:[~2025-09-22 23:15 UTC|newest]
Thread overview: 45+ 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
2025-09-22 22:32 ` Alex Williamson
2025-09-22 23:15 ` Jason Gunthorpe [this message]
2025-09-23 0:51 ` Donald Dutile
2025-09-23 1:17 ` Alex Williamson
2025-09-23 1:10 ` Alex Williamson
2025-09-23 2:26 ` Donald Dutile
2025-09-23 2:50 ` Alex Williamson
2025-09-23 12:32 ` Jason Gunthorpe
2025-09-23 12:58 ` Alex Williamson
2025-09-23 13:03 ` Jason Gunthorpe
2025-09-23 21:29 ` Alex Williamson
2025-09-25 12:20 ` 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
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