Message-ID: <1c18d68c-a20d-0f6d-4bf7-56f40557d151@redhat.com>
Date:   Fri, 10 Mar 2023 17:39:22 +0100
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Reply-To: eric.auger@redhat.com
Subject: Re: [PATCH v1 05/14] iommu/arm-smmu-v3: Remove ARM_SMMU_DOMAIN_NESTED
Content-Language: en-US
To:     Nicolin Chen <nicolinc@nvidia.com>, jgg@nvidia.com,
        robin.murphy@arm.com, will@kernel.org
Cc:     kevin.tian@intel.com, baolu.lu@linux.intel.com, joro@8bytes.org,
        shameerali.kolothum.thodi@huawei.com, jean-philippe@linaro.org,
        linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
        linux-kernel@vger.kernel.org
References: <cover.1678348754.git.nicolinc@nvidia.com>
 <c62c9405ff31ab3c97a9165ff710dce68217fe22.1678348754.git.nicolinc@nvidia.com>
From:   Eric Auger <eric.auger@redhat.com>
In-Reply-To: <c62c9405ff31ab3c97a9165ff710dce68217fe22.1678348754.git.nicolinc@nvidia.com>
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Precedence: bulk

Hi Nicolin,

On 3/9/23 11:53, Nicolin Chen wrote:
> IOMMUFD designs two iommu_domain pointers to represent two stages. The S1
s/designs/uses?
> iommu_domain (IOMMU_DOMAIN_NESTED type) represents the Context Descriptor
> table in the user space. The S2 iommu_domain (IOMMU_DOMAIN_UNMANAGED type)
> represents the translation table in the kernel, owned by a hypervisor.
>
> So there comes to no use case of the ARM_SMMU_DOMAIN_NESTED. Drop it, and
> use the type IOMMU_DOMAIN_NESTED instead.
last sentence may be rephrased as this patch does not use
IOMMU_DOMAIN_NESTED anywhere:
Generic IOMMU_DOMAIN_NESTED type will be used in nested SMMU
implementation instead.
>
> Also drop the unused arm_smmu_enable_nesting(). One following patche will
> configure the correct smmu_domain->stage.
>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 18 ------------------
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  1 -
If you go this way you may also remove it from arm/arm-smmu/arm-smmu.c.
Then if I am not wrong no other driver does implement enable_nesting cb.
Shouldn't we also remove it and fellow iommu_enable_nesting()?

Thanks

Eric
>  2 files changed, 19 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index c1aac695ae0d..c5616145e2a3 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1279,7 +1279,6 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>  			s1_cfg = &smmu_domain->s1_cfg;
>  			break;
>  		case ARM_SMMU_DOMAIN_S2:
> -		case ARM_SMMU_DOMAIN_NESTED:
>  			s2_cfg = &smmu_domain->s2_cfg;
>  			break;
>  		default:
> @@ -2220,7 +2219,6 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain,
>  		fmt = ARM_64_LPAE_S1;
>  		finalise_stage_fn = arm_smmu_domain_finalise_s1;
>  		break;
> -	case ARM_SMMU_DOMAIN_NESTED:
>  	case ARM_SMMU_DOMAIN_S2:
>  		ias = smmu->ias;
>  		oas = smmu->oas;
> @@ -2747,21 +2745,6 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
>  	return group;
>  }
>  
> -static int arm_smmu_enable_nesting(struct iommu_domain *domain)
> -{
> -	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> -	int ret = 0;
> -
> -	mutex_lock(&smmu_domain->init_mutex);
> -	if (smmu_domain->smmu)
> -		ret = -EPERM;
> -	else
> -		smmu_domain->stage = ARM_SMMU_DOMAIN_NESTED;
> -	mutex_unlock(&smmu_domain->init_mutex);
> -
> -	return ret;
> -}
> -
>  static int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args *args)
>  {
>  	return iommu_fwspec_add_ids(dev, args->args, 1);
> @@ -2890,7 +2873,6 @@ static struct iommu_ops arm_smmu_ops = {
>  		.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
>  		.iotlb_sync		= arm_smmu_iotlb_sync,
>  		.iova_to_phys		= arm_smmu_iova_to_phys,
> -		.enable_nesting		= arm_smmu_enable_nesting,
>  		.free			= arm_smmu_domain_free,
>  	}
>  };
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index ba2b4562f4b2..233bfc377267 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -704,7 +704,6 @@ struct arm_smmu_master {
>  enum arm_smmu_domain_stage {
>  	ARM_SMMU_DOMAIN_S1 = 0,
>  	ARM_SMMU_DOMAIN_S2,
> -	ARM_SMMU_DOMAIN_NESTED,
>  	ARM_SMMU_DOMAIN_BYPASS,
>  };
>