linux-kernel - [RFC PATCH v1 2/3] drm/msm: Add an adreno-smmu-priv callback to get pagefault info

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Message-Id: <20201109222319.2630557-3-jcrouse@codeaurora.org>
Date:   Mon,  9 Nov 2020 15:23:18 -0700
From:   Jordan Crouse <jcrouse@...eaurora.org>
To:     linux-arm-msm@...r.kernel.org
Cc:     Robin Murphy <robin.murphy@....com>, Will Deacon <will@...nel.org>,
        iommu@...ts.linux-foundation.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Joerg Roedel <joro@...tes.org>,
        Krishna Reddy <vdumpa@...dia.com>,
        Rob Clark <robdclark@...omium.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v1 2/3] drm/msm: Add an adreno-smmu-priv callback to get pagefault info

Add a callback in adreno-smmu-priv to read interesting SMMU
registers to provide an opportunity for a richer debug experience
in the GPU driver.

Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
---

 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 19 +++++++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu.h      |  2 ++
 include/linux/adreno-smmu-priv.h           | 31 +++++++++++++++++++++-
 3 files changed, 51 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 d0636c803a36..367a267324a2 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -32,6 +32,24 @@ static void qcom_adreno_smmu_write_sctlr(struct arm_smmu_device *smmu, int idx,
 	arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_SCTLR, reg);
 }
 
+static void qcom_adreno_smmu_get_fault_info(const void *cookie,
+		struct adreno_smmu_fault_info *info)
+{
+	struct arm_smmu_domain *smmu_domain = (void *)cookie;
+	struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
+	struct arm_smmu_device *smmu = smmu_domain->smmu;
+
+	info->fsr = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_FSR);
+	/* FIXME: return error here if we aren't really in a fault? */
+
+	info->fsynr0 = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_FSYNR0);
+	info->fsynr1 = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_FSYNR1);
+	info->far = arm_smmu_cb_readq(smmu, cfg->cbndx, ARM_SMMU_CB_FAR);
+	info->cbfrsynra = arm_smmu_gr1_read(smmu, ARM_SMMU_GR1_CBFRSYNRA(cfg->cbndx));
+	info->ttbr0 = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_TTBR0);
+	info->contextidr = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_CONTEXTIDR);
+}
+
 #define QCOM_ADRENO_SMMU_GPU_SID 0
 
 static bool qcom_adreno_smmu_is_gpu_device(struct device *dev)
@@ -156,6 +174,7 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
 	priv->cookie = smmu_domain;
 	priv->get_ttbr1_cfg = qcom_adreno_smmu_get_ttbr1_cfg;
 	priv->set_ttbr0_cfg = qcom_adreno_smmu_set_ttbr0_cfg;
+	priv->get_fault_info = qcom_adreno_smmu_get_fault_info;
 
 	return 0;
 }
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
index 04288b6fc619..fe511540a6bf 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
@@ -224,6 +224,8 @@ enum arm_smmu_cbar_type {
 #define ARM_SMMU_CB_FSYNR0		0x68
 #define ARM_SMMU_FSYNR0_WNR		BIT(4)
 
+#define ARM_SMMU_CB_FSYNR1		0x6c
+
 #define ARM_SMMU_CB_S1_TLBIVA		0x600
 #define ARM_SMMU_CB_S1_TLBIASID		0x610
 #define ARM_SMMU_CB_S1_TLBIVAL		0x620
diff --git a/include/linux/adreno-smmu-priv.h b/include/linux/adreno-smmu-priv.h
index a889f28afb42..fc2592ebb9ba 100644
--- a/include/linux/adreno-smmu-priv.h
+++ b/include/linux/adreno-smmu-priv.h
@@ -8,6 +8,32 @@
 
 #include <linux/io-pgtable.h>
 
+/**
+ * struct adreno_smmu_fault_info - container for key fault information
+ *
+ * @far: The faulting IOVA from ARM_SMMU_CB_FAR
+ * @ttbr0: The current TTBR0 pagetable from ARM_SMMU_CB_TTBR0
+ * @contextidr: The value of ARM_SMMU_CB_CONTEXTIDR
+ * @fsr: The fault status from ARM_SMMU_CB_FSR
+ * @fsynr0: The value of FSYNR0 from ARM_SMMU_CB_FSYNR0
+ * @fsynr1: The value of FSYNR1 from ARM_SMMU_CB_FSYNR0
+ * @cbfrsynra: The value of CBFRSYNRA from ARM_SMMU_GR1_CBFRSYNRA(idx)
+ *
+ * This struct passes back key page fault information to the GPU driver
+ * through the get_fault_info function pointer.
+ * The GPU driver can use this information to print informative
+ * log messages and provide deeper GPU specific insight into the fault.
+ */
+struct adreno_smmu_fault_info {
+	u64 far;
+	u64 ttbr0;
+	u32 contextidr;
+	u32 fsr;
+	u32 fsynr0;
+	u32 fsynr1;
+	u32 cbfrsynra;
+};
+
 /**
  * struct adreno_smmu_priv - private interface between adreno-smmu and GPU
  *
@@ -17,6 +43,8 @@
  * @set_ttbr0_cfg: Set the TTBR0 config for the GPUs context bank.  A
  *                 NULL config disables TTBR0 translation, otherwise
  *                 TTBR0 translation is enabled with the specified cfg
+ * @get_fault_info: Call a helper function in the GPU driver to process a
+ *                 pagefault
  *
  * The GPU driver (drm/msm) and adreno-smmu work together for controlling
  * the GPU's SMMU instance.  This is by necessity, as the GPU is directly
@@ -31,6 +59,7 @@ struct adreno_smmu_priv {
     const void *cookie;
     const struct io_pgtable_cfg *(*get_ttbr1_cfg)(const void *cookie);
     int (*set_ttbr0_cfg)(const void *cookie, const struct io_pgtable_cfg *cfg);
+    void (*get_fault_info)(const void *cookie, struct adreno_smmu_fault_info *info);
 };
 
-#endif /* __ADRENO_SMMU_PRIV_H */
\ No newline at end of file
+#endif /* __ADRENO_SMMU_PRIV_H */
-- 
2.25.1