Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs

[Jacob Pan]

Hi Jean,

Slightly off the title. As we are moving to use cgroup to limit PASID
allocations, it would be much simpler if we enforce on the current task.

However, iommu_sva_alloc_pasid() takes an mm_struct pointer as argument
which implies it can be something other the the current task mm. So far all
kernel callers use current task mm. Is there a use case for doing PASID
allocation on behalf of another mm? If not, can we remove the mm argument?

Thanks,

Jacob

>  /**
>   * iommu_sva_alloc_pasid - Allocate a PASID for the mm
> @@ -35,11 +44,11 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm,
> ioasid_t min, ioasid_t max) mutex_lock(&iommu_sva_lock);
>  	if (mm->pasid) {
>  		if (mm->pasid >= min && mm->pasid <= max)
> -			ioasid_get(mm->pasid);
> +			ioasid_get(iommu_sva_pasid, mm->pasid);
>  		else
>  			ret = -EOVERFLOW;
>  	} else {
> -		pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
> +		pasid = ioasid_alloc(iommu_sva_pasid, min, max, mm);
>  		if (pasid == INVALID_IOASID)
>  			ret = -ENOMEM;

Thanks,

Jacob