Re: [PATCH v3 3/3] iommu/arm-smmu: Pretty-print context fault related regs

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Jul 01, 2024 at 09:20:12AM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> Parse out the bitfields for easier-to-read fault messages.
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  .../iommu/arm/arm-smmu/arm-smmu-qcom-debug.c  | 52 +++++---------
>  drivers/iommu/arm/arm-smmu/arm-smmu.c         | 70 +++++++++++++++----
>  drivers/iommu/arm/arm-smmu/arm-smmu.h         | 21 ++++++
>  3 files changed, 92 insertions(+), 51 deletions(-)
> 

[...]

> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index 23cf91ac409b..79ec911ae151 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -405,32 +405,72 @@ static const struct iommu_flush_ops arm_smmu_s2_tlb_ops_v1 = {
>  	.tlb_add_page	= arm_smmu_tlb_add_page_s2_v1,
>  };
>  
> +
> +void arm_smmu_read_context_fault_info(struct arm_smmu_device *smmu, int idx,
> +				      struct arm_smmu_context_fault_info *cfi)
> +{
> +	cfi->iova = arm_smmu_cb_readq(smmu, idx, ARM_SMMU_CB_FAR);
> +	cfi->fsr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSR);
> +	cfi->fsynr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSYNR0);
> +	cfi->cbfrsynra = arm_smmu_gr1_read(smmu, ARM_SMMU_GR1_CBFRSYNRA(idx));
> +}
> +
> +void arm_smmu_print_context_fault_info(struct arm_smmu_device *smmu, int idx,
> +				       const struct arm_smmu_context_fault_info *cfi)
> +{
> +	dev_dbg(smmu->dev,
> +		"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cbfrsynra=0x%x, cb=%d\n",
> +		cfi->fsr, cfi->iova, cfi->fsynr, cfi->cbfrsynra, idx);
> +

I just happen to hit an IOMMU fault in 6.11-rc4 and I did not see the 'Unhandled
context fault' log, but just the register dump in dmesg. Tracking that lead me
to this patch.

May I know the reasoning behind making the actual error message _dbg()? It is
intentional first place?

- Mani

> +	dev_err(smmu->dev, "FSR    = %08x [%s%sFormat=%u%s%s%s%s%s%s%s%s], SID=0x%x\n",
> +		cfi->fsr,
> +		(cfi->fsr & ARM_SMMU_CB_FSR_MULTI)  ? "MULTI " : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_SS)     ? "SS " : "",
> +		(u32)FIELD_GET(ARM_SMMU_CB_FSR_FORMAT, cfi->fsr),
> +		(cfi->fsr & ARM_SMMU_CB_FSR_UUT)    ? " UUT" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_ASF)    ? " ASF" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_TLBLKF) ? " TLBLKF" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_TLBMCF) ? " TLBMCF" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_EF)     ? " EF" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_PF)     ? " PF" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_AFF)    ? " AFF" : "",
> +		(cfi->fsr & ARM_SMMU_CB_FSR_TF)     ? " TF" : "",
> +		cfi->cbfrsynra);
> +
> +	dev_err(smmu->dev, "FSYNR0 = %08x [S1CBNDX=%u%s%s%s%s%s%s PLVL=%u]\n",
> +		cfi->fsynr,
> +		(u32)FIELD_GET(ARM_SMMU_CB_FSYNR0_S1CBNDX, cfi->fsynr),
> +		(cfi->fsynr & ARM_SMMU_CB_FSYNR0_AFR) ? " AFR" : "",
> +		(cfi->fsynr & ARM_SMMU_CB_FSYNR0_PTWF) ? " PTWF" : "",
> +		(cfi->fsynr & ARM_SMMU_CB_FSYNR0_NSATTR) ? " NSATTR" : "",
> +		(cfi->fsynr & ARM_SMMU_CB_FSYNR0_IND) ? " IND" : "",
> +		(cfi->fsynr & ARM_SMMU_CB_FSYNR0_PNU) ? " PNU" : "",
> +		(cfi->fsynr & ARM_SMMU_CB_FSYNR0_WNR) ? " WNR" : "",
> +		(u32)FIELD_GET(ARM_SMMU_CB_FSYNR0_PLVL, cfi->fsynr));
> +}
> +
>  static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
>  {
> -	u32 fsr, fsynr, cbfrsynra;
> -	unsigned long iova;
> +	struct arm_smmu_context_fault_info cfi;
>  	struct arm_smmu_domain *smmu_domain = dev;
>  	struct arm_smmu_device *smmu = smmu_domain->smmu;
> +	static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
> +				      DEFAULT_RATELIMIT_BURST);
>  	int idx = smmu_domain->cfg.cbndx;
>  	int ret;
>  
> -	fsr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSR);
> -	if (!(fsr & ARM_SMMU_CB_FSR_FAULT))
> -		return IRQ_NONE;
> +	arm_smmu_read_context_fault_info(smmu, idx, &cfi);
>  
> -	fsynr = arm_smmu_cb_read(smmu, idx, ARM_SMMU_CB_FSYNR0);
> -	iova = arm_smmu_cb_readq(smmu, idx, ARM_SMMU_CB_FAR);
> -	cbfrsynra = arm_smmu_gr1_read(smmu, ARM_SMMU_GR1_CBFRSYNRA(idx));
> +	if (!(cfi.fsr & ARM_SMMU_CB_FSR_FAULT))
> +		return IRQ_NONE;
>  
> -	ret = report_iommu_fault(&smmu_domain->domain, NULL, iova,
> -		fsynr & ARM_SMMU_CB_FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ);
> +	ret = report_iommu_fault(&smmu_domain->domain, NULL, cfi.iova,
> +		cfi.fsynr & ARM_SMMU_CB_FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ);
>  
> -	if (ret == -ENOSYS)
> -		dev_err_ratelimited(smmu->dev,
> -		"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cbfrsynra=0x%x, cb=%d\n",
> -			    fsr, iova, fsynr, cbfrsynra, idx);
> +	if (ret == -ENOSYS && __ratelimit(&rs))
> +		arm_smmu_print_context_fault_info(smmu, idx, &cfi);
>  
> -	arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_FSR, fsr);
> +	arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_FSR, cfi.fsr);
>  	return IRQ_HANDLED;
>  }
>  
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index b04a00126a12..e2aeb511ae90 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -198,6 +198,7 @@ enum arm_smmu_cbar_type {
>  #define ARM_SMMU_CB_FSR			0x58
>  #define ARM_SMMU_CB_FSR_MULTI		BIT(31)
>  #define ARM_SMMU_CB_FSR_SS		BIT(30)
> +#define ARM_SMMU_CB_FSR_FORMAT		GENMASK(10, 9)
>  #define ARM_SMMU_CB_FSR_UUT		BIT(8)
>  #define ARM_SMMU_CB_FSR_ASF		BIT(7)
>  #define ARM_SMMU_CB_FSR_TLBLKF		BIT(6)
> @@ -223,7 +224,14 @@ enum arm_smmu_cbar_type {
>  #define ARM_SMMU_CB_FAR			0x60
>  
>  #define ARM_SMMU_CB_FSYNR0		0x68
> +#define ARM_SMMU_CB_FSYNR0_PLVL		GENMASK(1, 0)
>  #define ARM_SMMU_CB_FSYNR0_WNR		BIT(4)
> +#define ARM_SMMU_CB_FSYNR0_PNU		BIT(5)
> +#define ARM_SMMU_CB_FSYNR0_IND		BIT(6)
> +#define ARM_SMMU_CB_FSYNR0_NSATTR	BIT(8)
> +#define ARM_SMMU_CB_FSYNR0_PTWF		BIT(10)
> +#define ARM_SMMU_CB_FSYNR0_AFR		BIT(11)
> +#define ARM_SMMU_CB_FSYNR0_S1CBNDX	GENMASK(23, 16)
>  
>  #define ARM_SMMU_CB_FSYNR1		0x6c
>  
> @@ -533,4 +541,17 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu);
>  void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx);
>  int arm_mmu500_reset(struct arm_smmu_device *smmu);
>  
> +struct arm_smmu_context_fault_info {
> +	unsigned long iova;
> +	u32 fsr;
> +	u32 fsynr;
> +	u32 cbfrsynra;
> +};
> +
> +void arm_smmu_read_context_fault_info(struct arm_smmu_device *smmu, int idx,
> +				      struct arm_smmu_context_fault_info *cfi);
> +
> +void arm_smmu_print_context_fault_info(struct arm_smmu_device *smmu, int idx,
> +				       const struct arm_smmu_context_fault_info *cfi);
> +
>  #endif /* _ARM_SMMU_H */
> -- 
> 2.45.2
> 
> 

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