linux-kernel - Re: [PATCH 1/1] iommu/arm-smmu: Add SID information to context fault log

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Date:   Mon, 15 Apr 2019 17:35:27 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     Robin Murphy <robin.murphy@....com>, joro@...tes.org,
        will.deacon@....com, iommu@...ts.linux-foundation.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 1/1] iommu/arm-smmu: Add SID information to context fault
 log


On 4/15/2019 3:11 PM, Robin Murphy wrote:
> On 15/04/2019 09:07, Vivek Gautam wrote:
>> Extract the SID and add the information to context fault log.
>> This is specially useful in a distributed smmu architecture
>> where multiple masters are connected to smmu. SID information
>> helps to quickly identify the faulting master device.
>
> Hmm, given how it's UNKNOWN for translation faults, which are arguably 
> the most likely context fault, I reckon it probably makes more sense 
> to just dump the raw register value for the user to interpret, as we 
> do for fsr/fsynr.


Thanks Robin. Sure will update it to dump the raw register value.

Regards
Vivek

>
> Robin.
>
>> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
>> ---
>>   drivers/iommu/arm-smmu-regs.h |  4 ++++
>>   drivers/iommu/arm-smmu.c      | 14 ++++++++++++--
>>   2 files changed, 16 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-regs.h 
>> b/drivers/iommu/arm-smmu-regs.h
>> index a1226e4ab5f8..e5be0344b610 100644
>> --- a/drivers/iommu/arm-smmu-regs.h
>> +++ b/drivers/iommu/arm-smmu-regs.h
>> @@ -147,6 +147,10 @@ enum arm_smmu_s2cr_privcfg {
>>   #define CBAR_IRPTNDX_SHIFT        24
>>   #define CBAR_IRPTNDX_MASK        0xff
>>   +#define ARM_SMMU_GR1_CBFRSYNRA(n)    (0x400 + ((n) << 2))
>> +#define CBFRSYNRA_V2_SID_MASK        0xffff
>> +#define CBFRSYNRA_V1_SID_MASK        0x7fff
>> +
>>   #define ARM_SMMU_GR1_CBA2R(n)        (0x800 + ((n) << 2))
>>   #define CBA2R_RW64_32BIT        (0 << 0)
>>   #define CBA2R_RW64_64BIT        (1 << 0)
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index 045d93884164..aa3426dc68d0 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -575,7 +575,10 @@ static irqreturn_t arm_smmu_context_fault(int 
>> irq, void *dev)
>>       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>>       struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
>>       struct arm_smmu_device *smmu = smmu_domain->smmu;
>> +    void __iomem *gr1_base = ARM_SMMU_GR1(smmu);
>>       void __iomem *cb_base;
>> +    u32 cbfrsynra;
>> +    u16 sid;
>>         cb_base = ARM_SMMU_CB(smmu, cfg->cbndx);
>>       fsr = readl_relaxed(cb_base + ARM_SMMU_CB_FSR);
>> @@ -586,9 +589,16 @@ static irqreturn_t arm_smmu_context_fault(int 
>> irq, void *dev)
>>       fsynr = readl_relaxed(cb_base + ARM_SMMU_CB_FSYNR0);
>>       iova = readq_relaxed(cb_base + ARM_SMMU_CB_FAR);
>>   +    cbfrsynra = readl_relaxed(gr1_base +
>> +                  ARM_SMMU_GR1_CBFRSYNRA(cfg->cbndx));
>> +    if (smmu->version > ARM_SMMU_V1)
>> +        sid = cbfrsynra & CBFRSYNRA_V2_SID_MASK;
>> +    else
>> +        sid = cbfrsynra & CBFRSYNRA_V1_SID_MASK;
>> +
>>       dev_err_ratelimited(smmu->dev,
>> -    "Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, 
>> cb=%d\n",
>> -                fsr, iova, fsynr, cfg->cbndx);
>> +    "Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, 
>> cb=%d sid = %u\n",
>> +                fsr, iova, fsynr, cfg->cbndx, sid);
>>         writel(fsr, cb_base + ARM_SMMU_CB_FSR);
>>       return IRQ_HANDLED;
>>