Re: [PATCH v5 2/5] iommu/arm-smmu-qcom: Add an adreno-smmu-priv callback to get pagefault info

[Bjorn Andersson]

On Thu 10 Jun 16:44 CDT 2021, Rob Clark wrote:

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

I presume this implies that more generic options has been discussed.
Regardless, if further conclusions are made in that regard I expect that
this could serve as a base for such efforts.

Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

Regards,
Bjorn

> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 17 ++++++++++++
>  drivers/iommu/arm/arm-smmu/arm-smmu.h      |  2 ++
>  include/linux/adreno-smmu-priv.h           | 31 +++++++++++++++++++++-
>  3 files changed, 49 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 98b3a1c2a181..b2e31ea84128 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -32,6 +32,22 @@ 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);
> +	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 +172,7 @@ 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 c31a59d35c64..84c21c4b0691 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..53fe32fb9214 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: Called by the GPU fault handler to get information about
> + *                  the fault
>   *
>   * 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 */
> -- 
> 2.31.1
>