[PATCH rc v4 5/5] iommu/arm-smmu-v3: Detect ARM_SMMU_OPT_KDUMP_ADOPT in probe()

Nicolin Chen
2026-04-29T07:22:14Z

arm_smmu_device_hw_probe() runs before arm_smmu_init_structures(), so it's
natural to decide whether the kdump kernel must adopt the crashed kernel's
stream table.

Given that memremap is used to adopt the old stream table, set this option
only on a coherent SMMU.

And make sure SMMU isn't in Service Failure Mode.

Fixes: b63b3439b856 ("iommu/arm-smmu-v3: Abort all transactions if SMMU is enabled in kdump kernel")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 34 +++++++++++++++++++++
1 file changed, 34 insertions(+)

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 f9332cf0b28a6..18e0d97cec401 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -5402,6 +5402,36 @@ static void arm_smmu_get_httu(struct arm_smmu_device *smmu, u32 reg)
hw_features, fw_features);
}

+static void arm_smmu_device_hw_probe_kdump(struct arm_smmu_device *smmu)
+{
+ u32 gerror, gerrorn, active;
+
+ /*
+ * If SMMU is already active in kdump case, there could be in-flight DMA
+ * from devices initiated by the crashed kernel.
+ */
+ if (!(readl_relaxed(smmu->base + ARM_SMMU_CR0) & CR0_SMMUEN))
+ return;
+
+ /* For now, only support a coherent SMMU that works with MEMREMAP_WB */
+ if (!(smmu->features & ARM_SMMU_FEAT_COHERENCY)) {
+ dev_warn(smmu->dev,
+ "kdump: non-coherent SMMU can't adopt stream table\n");
+ return;
+ }
+
+ gerror = readl_relaxed(smmu->base + ARM_SMMU_GERROR);
+ gerrorn = readl_relaxed(smmu->base + ARM_SMMU_GERRORN);
+ active = gerror ^ gerrorn;
+ if (active & GERROR_SFM_ERR) {
+ dev_warn(smmu->dev,
+ "kdump: SMMU in Service Failure Mode, must reset\n");
+ return;
+ }
+
+ smmu->options |= ARM_SMMU_OPT_KDUMP_ADOPT;
+}
+
static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
{
u32 reg;
@@ -5616,6 +5646,10 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)

dev_info(smmu->dev, "oas %lu-bit (features 0x%08x)\n",
smmu->oas, smmu->features);
+
+ if (is_kdump_kernel())
+ arm_smmu_device_hw_probe_kdump(smmu);
+
return 0;
}

--
2.43.0