linux-kernel - Re: [PATCH v3 1/8] iommu/arm-smmu: Refactor context bank allocation

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Message-ID: <010101746f066e2c-c8c73cb8-a6ca-4a64-922f-16064f24a55b-000000@us-west-2.amazonses.com>
Date:   Tue, 8 Sep 2020 18:42:06 +0000
From:   Jordan Crouse <jcrouse@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Rob Clark <robdclark@...omium.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v3 1/8] iommu/arm-smmu: Refactor context bank allocation

On Fri, Sep 04, 2020 at 03:55:06PM +0000, Bjorn Andersson wrote:
> Extract the conditional invocation of the platform defined
> alloc_context_bank() to a separate function to keep
> arm_smmu_init_domain_context() cleaner.
> 
> Instead pass a reference to the arm_smmu_device as parameter to the
> call. Also remove the count parameter, as this can be read from the
> newly passed object.
> 
> This allows us to not assign smmu_domain->smmu before attempting to
> allocate the context bank and as such we don't need to roll back this
> assignment on failure.

Much nicer.

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

> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> 
> Note that this series applies ontop of:
> https://lore.kernel.org/linux-arm-msm/20200901164707.2645413-1-robdclark@gmail.com/
> 
> This could either go on its own, or be squashed with "[PATCH v16 14/20]
> iommu/arm-smmu: Prepare for the adreno-smmu implementation" from Rob's series.
> 
> Changes since v2:
> - New patch
> 
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c |  6 ++++--
>  drivers/iommu/arm/arm-smmu/arm-smmu.c      | 23 ++++++++++++----------
>  drivers/iommu/arm/arm-smmu/arm-smmu.h      |  3 ++-
>  3 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 2aa6249050ff..0663d7d26908 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -91,9 +91,10 @@ static int qcom_adreno_smmu_set_ttbr0_cfg(const void *cookie,
>  }
>  
>  static int qcom_adreno_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_domain,
> -		struct device *dev, int start, int count)
> +					       struct arm_smmu_device *smmu,
> +					       struct device *dev, int start)
>  {
> -	struct arm_smmu_device *smmu = smmu_domain->smmu;
> +	int count;
>  
>  	/*
>  	 * Assign context bank 0 to the GPU device so the GPU hardware can
> @@ -104,6 +105,7 @@ static int qcom_adreno_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_doma
>  		count = 1;
>  	} else {
>  		start = 1;
> +		count = smmu->num_context_banks;
>  	}
>  
>  	return __arm_smmu_alloc_bitmap(smmu->context_map, start, count);
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index bbec5793faf8..e19d7bdc7674 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -623,6 +623,16 @@ void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx)
>  	arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_SCTLR, reg);
>  }
>  
> +static int arm_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_domain,
> +				       struct arm_smmu_device *smmu,
> +				       struct device *dev, unsigned int start)
> +{
> +	if (smmu->impl && smmu->impl->alloc_context_bank)
> +		return smmu->impl->alloc_context_bank(smmu_domain, smmu, dev, start);
> +
> +	return __arm_smmu_alloc_bitmap(smmu->context_map, start, smmu->num_context_banks);
> +}
> +
>  static int arm_smmu_init_domain_context(struct iommu_domain *domain,
>  					struct arm_smmu_device *smmu,
>  					struct device *dev)
> @@ -741,20 +751,13 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
>  		goto out_unlock;
>  	}
>  
> -	smmu_domain->smmu = smmu;
> -
> -	if (smmu->impl && smmu->impl->alloc_context_bank)
> -		ret = smmu->impl->alloc_context_bank(smmu_domain, dev,
> -				start, smmu->num_context_banks);
> -	else
> -		ret = __arm_smmu_alloc_bitmap(smmu->context_map, start,
> -				      smmu->num_context_banks);
> -
> +	ret = arm_smmu_alloc_context_bank(smmu_domain, smmu, dev, start);
>  	if (ret < 0) {
> -		smmu_domain->smmu = NULL;
>  		goto out_unlock;
>  	}
>  
> +	smmu_domain->smmu = smmu;
> +
>  	cfg->cbndx = ret;
>  	if (smmu->version < ARM_SMMU_V2) {
>  		cfg->irptndx = atomic_inc_return(&smmu->irptndx);
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index 2df3a70a8a41..ddf2ca4c923d 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -437,7 +437,8 @@ struct arm_smmu_impl {
>  	irqreturn_t (*global_fault)(int irq, void *dev);
>  	irqreturn_t (*context_fault)(int irq, void *dev);
>  	int (*alloc_context_bank)(struct arm_smmu_domain *smmu_domain,
> -			struct device *dev, int start, int max);
> +				  struct arm_smmu_device *smmu,
> +				  struct device *dev, int start);
>  };
>  
>  #define INVALID_SMENDX			-1
> -- 
> 2.28.0
> 

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