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X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The primary motivation for this series is an ATS state mismatch observed under heavy load (via iova_stress). A failure in pci_enable_ats() leaves IOMMU drivers like arm-smmu-v3 with inconsistent state leading to PCI core warnings during device detach. While David's recent work [1] addressed a discovery race for specific quirked devices by moving them to the HEADER phase, gaps remained regarding how Virtual Functions (VFs) inherit state from their Physical Functions (PFs). Specifically, pci_ats_supported() did not account for PF-level quirked status, and pci_prepare_ats() lacked STU validation for VFs. Based on discussion with Jason in v3 it was decided that IOMMU drivers should explicitly check pci_ats_supported before calling pci_prepare_ats and the device probe should fail if pci_prepare_ats fails. Since these early gates preclude software configuration errors, any remaining failure during pci_enable_ats() is treated as a kernel bug & reported via WARN(). This series standardizes this pattern across ARM SMMUv3, Intel VT-d, & AMD IOMMU drivers. [1] https://lore.kernel.org/linux-pci/20260403222750.1215002-1-dmatlack@google.com/ [v4] - Standardized the pattern across Intel VT-d and AMD IOMMU drivers. - Replaced the SMMUv3 ats_prepared gate with a fatal probe-fail logic. - Utilized WARN() macros for runtime enablement failures in all drivers. - Collected R-b tags from Jason and Sami. [v3] https://lore.kernel.org/all/20260519135323.1558777-1-praan@google.com/ [v2] https://lore.kernel.org/all/20260504163842.2692314-1-praan@google.com/ Pranjal Shrivastava (5): PCI/ATS: Ensure pci_ats_supported() is PF-aware for VFs PCI/ATS: Validate STU for VFs in pci_prepare_ats() iommu/arm-smmu-v3: Fix ATS state tracking iommu/vt-d: Fail probe on ATS configuration failure iommu/amd: Fail probe on ATS configuration failure drivers/iommu/amd/iommu.c | 27 ++++++++++++++++----- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 21 +++++++++++++--- drivers/iommu/intel/iommu.c | 15 +++++++++--- drivers/pci/ats.c | 14 ++++++++--- 4 files changed, 61 insertions(+), 16 deletions(-) -- 2.54.0.746.g67dd491aae-goog