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Date:   Wed, 3 Mar 2021 18:15:57 +0100
From:   Jean-Philippe Brucker <jean-philippe@linaro.org>
To:     Vivek Gautam <vivek.gautam@arm.com>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org,
        virtualization@lists.linux-foundation.org, joro@8bytes.org,
        will.deacon@arm.com, mst@redhat.com, robin.murphy@arm.com,
        eric.auger@redhat.com, alex.williamson@redhat.com,
        kevin.tian@intel.com, jacob.jun.pan@linux.intel.com,
        yi.l.liu@intel.com, lorenzo.pieralisi@arm.com,
        shameerali.kolothum.thodi@huawei.com
Subject: Re: [PATCH RFC v1 05/15] iommu/arm-smmu-v3: Set sync op from
 consumer driver of cd-lib
Message-ID: <YD/ETcVwWATG4M6e@myrica>
References: <20210115121342.15093-1-vivek.gautam@arm.com>
 <20210115121342.15093-6-vivek.gautam@arm.com>
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In-Reply-To: <20210115121342.15093-6-vivek.gautam@arm.com>
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On Fri, Jan 15, 2021 at 05:43:32PM +0530, Vivek Gautam wrote:
> Te change allows different consumers of arm-smmu-v3-cd-lib to set
> their respective sync op for pasid entries.
> 
> Signed-off-by: Vivek Gautam <vivek.gautam@arm.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Liu Yi L <yi.l.liu@intel.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c | 1 -
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c        | 7 +++++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c
> index ec37476c8d09..acaa09acecdd 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c
> @@ -265,7 +265,6 @@ struct iommu_vendor_psdtable_ops arm_cd_table_ops = {
>  	.free	 = arm_smmu_free_cd_tables,
>  	.prepare = arm_smmu_prepare_cd,
>  	.write	 = arm_smmu_write_ctx_desc,
> -	.sync	 = arm_smmu_sync_cd,
>  };
>  
>  struct iommu_pasid_table *arm_smmu_register_cd_table(struct device *dev,
> 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 2f86c6ac42b6..0c644be22b4b 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1869,6 +1869,13 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
>  	if (ret)
>  		goto out_free_cd_tables;
>  
> +	/*
> +	 * Strange to setup an op here?
> +	 * cd-lib is the actual user of sync op, and therefore the platform
> +	 * drivers should assign this sync/maintenance ops as per need.
> +	 */
> +	tbl->ops->sync = arm_smmu_sync_cd;
> +

Modifying a static struct from here doesn't feel right. I think the
interface should be roughly similar to io-pgtable since the principle is
the same. So the sync() op should be separate from arm_cd_table_ops since
it's a callback into the driver. Maybe pass it to
iommu_register_pasid_table().

Thanks,
Jean