linux-kernel - Re: [PATCH RFC v1 04/15] iommu/arm-smmu-v3: Update CD base address info for user-space

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Date:   Wed, 3 Mar 2021 18:14:28 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Vivek Gautam <vivek.gautam@....com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org,
        virtualization@...ts.linux-foundation.org, joro@...tes.org,
        will.deacon@....com, mst@...hat.com, robin.murphy@....com,
        eric.auger@...hat.com, alex.williamson@...hat.com,
        kevin.tian@...el.com, jacob.jun.pan@...ux.intel.com,
        yi.l.liu@...el.com, lorenzo.pieralisi@....com,
        shameerali.kolothum.thodi@...wei.com
Subject: Re: [PATCH RFC v1 04/15] iommu/arm-smmu-v3: Update CD base address
 info for user-space

On Fri, Jan 15, 2021 at 05:43:31PM +0530, Vivek Gautam wrote:
> Update base address information in vendor pasid table info to pass that
> to user-space for stage1 table management.
> 
> Signed-off-by: Vivek Gautam <vivek.gautam@....com>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Robin Murphy <robin.murphy@....com>
> Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Cc: Eric Auger <eric.auger@...hat.com>
> Cc: Alex Williamson <alex.williamson@...hat.com>
> Cc: Kevin Tian <kevin.tian@...el.com>
> Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Cc: Liu Yi L <yi.l.liu@...el.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-cd-lib.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> 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 8a7187534706..ec37476c8d09 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
> @@ -55,6 +55,9 @@ static __le64 *arm_smmu_get_cd_ptr(struct iommu_vendor_psdtable_cfg *pst_cfg,
>  		if (arm_smmu_alloc_cd_leaf_table(dev, l1_desc))
>  			return NULL;
>  
> +		if (s1cfg->s1fmt == STRTAB_STE_0_S1FMT_LINEAR)
> +			pst_cfg->base = l1_desc->l2ptr_dma;
> +

This isn't the right place, because this path allocates second-level
tables for two-level tables. I don't think we need pst_cfg->base at all,
because for both linear and two-level tables, the base pointer is in
cdcfg->cdtab_dma, which can be read directly.

Thanks,
Jean

>  		l1ptr = cdcfg->cdtab + idx * CTXDESC_L1_DESC_DWORDS;
>  		arm_smmu_write_cd_l1_desc(l1ptr, l1_desc);
>  		/* An invalid L1CD can be cached */
> @@ -211,6 +214,9 @@ static int arm_smmu_alloc_cd_tables(struct iommu_vendor_psdtable_cfg *pst_cfg)
>  		goto err_free_l1;
>  	}
>  
> +	if (s1cfg->s1fmt == STRTAB_STE_0_S1FMT_64K_L2)
> +		pst_cfg->base = cdcfg->cdtab_dma;
> +
>  	return 0;
>  
>  err_free_l1:
> -- 
> 2.17.1
>