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Mon, 25 May 2026 11:44:02 -0700 (PDT) Date: Mon, 25 May 2026 18:43:47 +0000 In-Reply-To: <20260525184347.4059549-1-praan@google.com> Mime-Version: 1.0 References: <20260525184347.4059549-1-praan@google.com> X-Mailer: git-send-email 2.54.0.746.g67dd491aae-goog Message-ID: <20260525184347.4059549-6-praan@google.com> Subject: [PATCH v4 5/5] iommu/amd: Fail probe on ATS configuration failure From: Pranjal Shrivastava To: iommu@lists.linux.dev, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Joerg Roedel , Will Deacon , Bjorn Helgaas , David Woodhouse , Lu Baolu , Robin Murphy , Suravee Suthikulpanit , Jason Gunthorpe , Nicolin Chen , David Matlack , Samiullah Khawaja , Daniel Mentz , Pasha Tatashin , Mostafa Saleh , Pranjal Shrivastava Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260525_114403_783070_5FC8F53A X-CRM114-Status: GOOD ( 15.84 ) 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 Update the AMD IOMMU driver to handle ATS configuration and enablement more strictly. Specifically, update the device probe to fail if pci_prepare_ats() returns an error. This ensures that any ATS-capable master reaching the attach phase is guaranteed to have a valid config. Additionally, update pdev_enable_cap_ats() to WARN_ON() if pci_enable_ats fails. Since earlier checks in the probe phase preclude config-related failures, any failure during hardware enablement is considered a kernel bug. Signed-off-by: Pranjal Shrivastava --- drivers/iommu/amd/iommu.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index 84cad43dc188..1dddb08e7b22 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -570,10 +570,16 @@ static inline int pdev_enable_cap_ats(struct pci_dev *pdev) if (amd_iommu_iotlb_sup && (dev_data->flags & AMD_IOMMU_DEVICE_FLAG_ATS_SUP)) { ret = pci_enable_ats(pdev, PAGE_SHIFT); - if (!ret) { - dev_data->ats_enabled = 1; - dev_data->ats_qdep = pci_ats_queue_depth(pdev); - } + /* + * pci_enable_ats() should not fail here because earlier checks + * have already verified support and configuration. + */ + if (WARN_ON(ret)) + return ret; + + dev_data->ats_enabled = 1; + dev_data->ats_qdep = pci_ats_queue_depth(pdev); + ret = 0; } return ret; @@ -2502,8 +2508,17 @@ static struct iommu_device *amd_iommu_probe_device(struct device *dev) else dev_data->max_irqs = MAX_IRQS_PER_TABLE_512; - if (dev_is_pci(dev)) - pci_prepare_ats(to_pci_dev(dev), PAGE_SHIFT); + if (dev_is_pci(dev)) { + struct pci_dev *pdev = to_pci_dev(dev); + + if (pci_ats_supported(pdev)) { + ret = pci_prepare_ats(pdev, PAGE_SHIFT); + if (ret) { + iommu_dev = ERR_PTR(ret); + goto out_err; + } + } + } out_err: return iommu_dev; -- 2.54.0.746.g67dd491aae-goog