[PATCH rc v6 7/7] iommu/arm-smmu-v3: Detect ARM_SMMU_OPT_KDUMP_ADOPT in probe()

[Nicolin Chen]

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 at vger.kernel.org # v6.12+
Reviewed-by: Kevin Tian <kevin.tian at intel.com>
Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 31 +++++++++++++++++++++
 1 file changed, 31 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 851bcebfdb3d4..fb34c3ffee9fe 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -5353,6 +5353,33 @@ 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;
+
+	/* No adoption if SMMU is disabled (i.e., there is no in-flight DMA) */
+	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 unsupported; reset to block all DMAs\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;
@@ -5567,6 +5594,10 @@ 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