Re: [PATCH 2/2] iommu/sva: Remove mm parameter from SVA bind API

Lu Baolu
2021-04-09T12:45:34Z

Hi,

On 2021/4/9 1:08, Jacob Pan wrote:
> /**
> * iommu_sva_alloc_pasid - Allocate a PASID for the mm
> - * @mm: the mm
> * @min: minimum PASID value (inclusive)
> * @max: maximum PASID value (inclusive)
> *
> - * Try to allocate a PASID for this mm, or take a reference to the existing one
> - * provided it fits within the [@min, @max] range. On success the PASID is
> - * available in mm->pasid, and must be released with iommu_sva_free_pasid().
> + * Try to allocate a PASID for the current mm, or take a reference to the
> + * existing one provided it fits within the [@min, @max] range. On success
> + * the PASID is available in the current mm->pasid, and must be released with
> + * iommu_sva_free_pasid().
> * @min must be greater than 0, because 0 indicates an unused mm->pasid.
> *
> * Returns 0 on success and < 0 on error.
> */
> -int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
> +int iommu_sva_alloc_pasid(ioasid_t min, ioasid_t max)
> {
> int ret = 0;
> ioasid_t pasid;
> + struct mm_struct *mm;
>
> if (min == INVALID_IOASID || max == INVALID_IOASID ||
> min == 0 || max < min)
> return -EINVAL;
>
> mutex_lock(&iommu_sva_lock);
> + mm = get_task_mm(current);

How could we allocate a supervisor PASID through iommu_sva_alloc_pasid()
if we always use current->mm here?

> + if (!mm) {
> + ret = -EINVAL;
> + goto out_unlock;
> + }
> if (mm->pasid) {
> if (mm->pasid >= min && mm->pasid <= max)
> ioasid_get(mm->pasid);
> @@ -45,22 +51,32 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
> else
> mm->pasid = pasid;
> }
> + mmput(mm);
> +out_unlock:
> mutex_unlock(&iommu_sva_lock);
> return ret;
> }
> EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);

Best regards,
baolu