RE: [PATCH v5 2/7] iommu/sva: Explicitly exclude RID_PASID from SVA

Tian, Kevin
2023-04-28T09:40:21Z

> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Sent: Friday, April 28, 2023 1:50 AM
>
> 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.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> drivers/iommu/iommu-sva.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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);
>
> /* Allocate mm->pasid if necessary. */
> - ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
> + ret = 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?