Re: [PATCH v4 3/7] iommu: Support allocation of global PASIDs outside SVA

[Baolu Lu]

On 4/11/23 4:02 PM, Tian, Kevin wrote:
> > From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Sent: Saturday, April 8, 2023 2:06 AM
> > @@ -28,8 +26,8 @@ static int iommu_sva_alloc_pasid(struct mm_struct
> > *mm, ioasid_t min, ioasid_t ma
> >   		goto out;
> >   	}
> >
> > -	ret = ida_alloc_range(&iommu_global_pasid_ida, min, max,
> > GFP_KERNEL);
> > -	if (ret < min)
> > +	ret = iommu_alloc_global_pasid(min, max);
>
> I wonder whether this can take a device pointer so dev->iommu->max_pasids
> is enforced inside the alloc function.

Agreed. Instead of using the open code, it looks better to have a helper
like dev_iommu_max_pasids().

> and do we even need the min/max parameters? With special pasids reserved
> then what driver needs is just to get a free pasid from the global space within
> dev->iommu->max_pasids constraint...
>
> iommu_sva_alloc_pasid() can be reworked to avoid min/max by taking a
> device pointer too.

Best regards,
baolu