[PATCH 1/2] iommu/arm-smmu-v3: Detect Tegra264 erratum
From: Ashish Mhetre <hidden>
Date: 2026-05-28 10:16:58
Also in:
linux-iommu, linux-tegra, lkml
Subsystem:
arm smmu drivers, iommu subsystem, the rest · Maintainers:
Will Deacon, Joerg Roedel, Linus Torvalds
Tegra264 SMMU is affected by erratum where a TLB entry can survive an invalidation that races with concurrent traffic targeting the same entry. The hardware-recommended software workaround is to issue every CFGI/TLBI command (each followed by CMD_SYNC) twice. The second issue is guaranteed to evict the entry. ATC_INV is not affected and must not be doubled. Add the ARM_SMMU_OPT_TLBI_TWICE option and set it on instances matching the existing "nvidia,tegra264-smmu" compatible. No callers consume the option yet, next patch wires the workaround into the CMDQ issue paths. Signed-off-by: Ashish Mhetre <redacted> --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 +++- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 8 ++++++++ 2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 9be589d14a3b..88296c0a5337 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -5229,8 +5229,10 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev, if (of_dma_is_coherent(dev->of_node)) smmu->features |= ARM_SMMU_FEAT_COHERENCY; - if (of_device_is_compatible(dev->of_node, "nvidia,tegra264-smmu")) + if (of_device_is_compatible(dev->of_node, "nvidia,tegra264-smmu")) { tegra_cmdqv_dt_probe(dev->of_node, smmu); + smmu->options |= ARM_SMMU_OPT_TLBI_TWICE; + } return ret; }
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 16353596e08a..08d1abaf31ae 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h@@ -928,6 +928,14 @@ struct arm_smmu_device { #define ARM_SMMU_OPT_MSIPOLL (1 << 2) #define ARM_SMMU_OPT_CMDQ_FORCE_SYNC (1 << 3) #define ARM_SMMU_OPT_TEGRA241_CMDQV (1 << 4) +/* + * Tegra264 erratum: a TLB entry can survive an invalidation that races + * with concurrent traffic targeting the same entry. The software + * workaround is to issue every CFGI/TLBI command twice, each followed + * by CMD_SYNC. The second issue is guaranteed to evict the entry. + * ATC_INV commands are not affected and must not be doubled. + */ +#define ARM_SMMU_OPT_TLBI_TWICE (1 << 5) u32 options; struct arm_smmu_cmdq cmdq;
--
2.50.1