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To:     Jacob Pan <jacob.jun.pan@linux.intel.com>,
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Subject: RE: [PATCH v5 2/7] iommu/sva: Explicitly exclude RID_PASID from SVA
Thread-Topic: [PATCH v5 2/7] iommu/sva: Explicitly exclude RID_PASID from SVA
Thread-Index: AQHZeTAT/rkavmSXnkuwelIyLgcV1K9AeBIw
Date:   Fri, 28 Apr 2023 09:40:12 +0000
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References: <20230427174937.471668-1-jacob.jun.pan@linux.intel.com>
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> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Sent: Friday, April 28, 2023 1:50 AM
>=20
> SVA PASID allocation is hardcoded to start from 1 because 0 is used for
> RID_PASID, let's make it explicit to avoid the potential conflicts.
>=20
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>  drivers/iommu/iommu-sva.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index c434b95dc8eb..ac7c93bacb5c 100644
> --- a/drivers/iommu/iommu-sva.c
> +++ b/drivers/iommu/iommu-sva.c
> @@ -66,7 +66,7 @@ struct iommu_sva *iommu_sva_bind_device(struct
> device *dev, struct mm_struct *mm
>  		return ERR_PTR(-EOPNOTSUPP);
>=20
>  	/* Allocate mm->pasid if necessary. */
> -	ret =3D iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
> +	ret =3D iommu_sva_alloc_pasid(mm, IOMMU_DEF_RID_PASID + 1,
> max_pasids - 1);

To be future proof it's probably cleaner to define a
IOMMU_MAX_RSVD_PASID in case there may be more reserved
pasids in future usages?