[PATCH v19 2/4] iommu/arm-smmu: Add a way for implementations to influence SCTLR

From: Jordan Crouse
Date: Mon Nov 09 2020 - 13:47:50 EST


From: Rob Clark <robdclark@xxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
---

drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 13 +++++++++++++
drivers/iommu/arm/arm-smmu/arm-smmu.c | 5 ++++-
drivers/iommu/arm/arm-smmu/arm-smmu.h | 2 ++
3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index b5384c4d92c8..d0636c803a36 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/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,
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index bcbacf22331d..0f28a8614da3 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/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,
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
index 9a5eb6782918..04288b6fc619 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
+++ b/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
--
2.25.1