iommu/arm-smmu: Add a way for implementations to influence SCTLR

For the Adreno GPU's SMMU, we want SCTLR.HUPCF set to ensure that
pending translations are not terminated on iova fault.  Otherwise
a terminated CP read could hang the GPU by returning invalid
command-stream data. Add a hook to for the implementation to modify
the sctlr value if it wishes.
Co-developed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Link: https://lore.kernel.org/r/20201109184728.2463097-3-jcrouse@codeaurora.orgSigned-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c

@@ -20,6 +20,18 @@ static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
 	return container_of(smmu, struct qcom_smmu, smmu);
 }
 
+static void qcom_adreno_smmu_write_sctlr(struct arm_smmu_device *smmu, int idx,
+		u32 reg)
+{
+	/*
+	 * On the GPU device we want to process subsequent transactions after a
+	 * fault to keep the GPU from hanging
+	 */
+	reg |= ARM_SMMU_SCTLR_HUPCF;
+
+	arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_SCTLR, reg);
+}
+
 #define QCOM_ADRENO_SMMU_GPU_SID 0
 
 static bool qcom_adreno_smmu_is_gpu_device(struct device *dev)
@@ -289,6 +301,7 @@ static const struct arm_smmu_impl qcom_adreno_smmu_impl = {
 	.def_domain_type = qcom_smmu_def_domain_type,
 	.reset = qcom_smmu500_reset,
 	.alloc_context_bank = qcom_adreno_smmu_alloc_context_bank,
+	.write_sctlr = qcom_adreno_smmu_write_sctlr,
 };
 
 static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,

drivers/iommu/arm/arm-smmu/arm-smmu.c

@@ -617,7 +617,10 @@ void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx)
 	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
 		reg |= ARM_SMMU_SCTLR_E;
 
-	arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_SCTLR, reg);
+	if (smmu->impl && smmu->impl->write_sctlr)
+		smmu->impl->write_sctlr(smmu, idx, reg);
+	else
+		arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_SCTLR, reg);
 }
 
 static int arm_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_domain,

drivers/iommu/arm/arm-smmu/arm-smmu.h

@@ -144,6 +144,7 @@ enum arm_smmu_cbar_type {
 #define ARM_SMMU_CB_SCTLR		0x0
 #define ARM_SMMU_SCTLR_S1_ASIDPNE	BIT(12)
 #define ARM_SMMU_SCTLR_CFCFG		BIT(7)
+#define ARM_SMMU_SCTLR_HUPCF		BIT(8)
 #define ARM_SMMU_SCTLR_CFIE		BIT(6)
 #define ARM_SMMU_SCTLR_CFRE		BIT(5)
 #define ARM_SMMU_SCTLR_E		BIT(4)
@@ -437,6 +438,7 @@ struct arm_smmu_impl {
 				  struct arm_smmu_device *smmu,
 				  struct device *dev, int start);
 	void (*write_s2cr)(struct arm_smmu_device *smmu, int idx);
+	void (*write_sctlr)(struct arm_smmu_device *smmu, int idx, u32 reg);
 };
 
 #define INVALID_SMENDX			-1