From: Baolu Lu <baolu.lu@linux•intel.com>
To: Pranjal Shrivastava <praan@google•com>,
iommu@lists•linux.dev, linux-pci@vger•kernel.org,
linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org
Cc: Joerg Roedel <joro@8bytes•org>, Will Deacon <will@kernel•org>,
Bjorn Helgaas <bhelgaas@google•com>,
David Woodhouse <dwmw2@infradead•org>,
Robin Murphy <robin.murphy@arm•com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd•com>,
Jason Gunthorpe <jgg@ziepe•ca>,
Nicolin Chen <nicolinc@nvidia•com>,
David Matlack <dmatlack@google•com>,
Samiullah Khawaja <skhawaja@google•com>,
Daniel Mentz <danielmentz@google•com>,
Pasha Tatashin <pasha.tatashin@soleen•com>,
Mostafa Saleh <smostafa@google•com>,
Jason Gunthorpe <jgg@nvidia•com>
Subject: Re: [PATCH v5 2/7] PCI/ATS: Validate STU for VFs in pci_prepare_ats()
Date: Fri, 29 May 2026 14:05:45 +0800 [thread overview]
Message-ID: <691d3688-df39-40f6-88b5-2f62d9a94bc1@linux.intel.com> (raw)
In-Reply-To: <20260528202353.3422206-3-praan@google.com>
On 5/29/26 04:23, Pranjal Shrivastava wrote:
> While every PCI Function that implements ATS has an independent ATS
> Extended Capability structure with a Read/Write Smallest Translation
> Unit (STU) field, the kernel manages SR-IOV ATS by requiring the IOMMU
> driver to configure the STU on the Physical Function (PF) before any
> any Virtual Functions (VFs) are created.
>
> Currently, pci_prepare_ats() bails out early for VFs, assuming that the
> PF has already been correctly prepared. However, this creates a potential
> mismatch if a VF is subsequently prepared with a different page shift.
>
> Update pci_prepare_ats() to validate that the requested page shift (ps)
> matches the STU already configured in the associated PF. This ensures
> early detection of incompatible configurations and maintains the kernel's
> policy of consistent STU sizing across all functions associated with a
> given SMMU.
>
> Reviewed-by: Jason Gunthorpe<jgg@nvidia•com>
> Reviewed-by: Samiullah Khawaja<skhawaja@google•com>
> Reviewed-by: Nicolin Chen<nicolinc@nvidia•com>
> Signed-off-by: Pranjal Shrivastava<praan@google•com>
> ---
> drivers/pci/ats.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
Reviewed-by: Lu Baolu <baolu.lu@linux•intel.com>
next prev parent reply other threads:[~2026-05-29 6:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-28 20:23 [PATCH v5 0/7] iommu: Standardize ATS robustness and state tracking Pranjal Shrivastava
2026-05-28 20:23 ` [PATCH v5 1/7] PCI/ATS: Ensure pci_ats_supported() is PF-aware for VFs Pranjal Shrivastava
2026-05-29 6:02 ` Baolu Lu
2026-05-28 20:23 ` [PATCH v5 2/7] PCI/ATS: Validate STU for VFs in pci_prepare_ats() Pranjal Shrivastava
2026-05-29 6:05 ` Baolu Lu [this message]
2026-05-28 20:23 ` [PATCH v5 3/7] PCI/ATS: Decouple pci_ats_supported() from pci_prepare_ats() Pranjal Shrivastava
2026-05-29 6:29 ` Baolu Lu
2026-05-29 7:08 ` Pranjal Shrivastava
2026-05-28 20:23 ` [PATCH v5 4/7] iommu/arm-smmu-v3: Standardize ATS enablement failure reporting Pranjal Shrivastava
2026-05-28 20:23 ` [PATCH v5 5/7] iommu/vt-d: Fix RB-tree corruption and Use-After-Free in probe Pranjal Shrivastava
2026-05-29 3:20 ` Baolu Lu
2026-05-29 7:04 ` Pranjal Shrivastava
2026-05-28 20:23 ` [PATCH v5 6/7] iommu/vt-d: Fail probe on ATS configuration failure Pranjal Shrivastava
2026-05-29 6:39 ` Baolu Lu
2026-05-29 7:03 ` Pranjal Shrivastava
2026-05-28 20:23 ` [PATCH v5 7/7] iommu/amd: " Pranjal Shrivastava
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