Hi, Thomas,
On Mon, Jan 24, 2022 at 09:21:24PM +0100, Thomas Gleixner wrote:
> On Fri, Dec 17 2021 at 22:01, Fenghua Yu wrote:
> > diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
> > index bd41405d34e9..ee2294e02716 100644
> > --- a/drivers/iommu/iommu-sva-lib.c
> > +++ b/drivers/iommu/iommu-sva-lib.c
> > @@ -18,8 +18,7 @@ static DECLARE_IOASID_SET(iommu_sva_pasid);
> > *
> > * 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().
> > - * @min must be greater than 0, because 0 indicates an unused mm->pasid.
> > + * available in mm->pasid and will be available for the lifetime of the mm.
> > *
> > * Returns 0 on success and < 0 on error.
> > */
> > @@ -33,38 +32,24 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm,
> > ioasid_t min, ioasid_t max)
> > return -EINVAL;
> >
> > mutex_lock(&iommu_sva_lock);
> > - if (mm->pasid) {
> > - if (mm->pasid >= min && mm->pasid <= max)
> > - ioasid_get(mm->pasid);
> > - else
> > + /* Is a PASID already associated with this mm? */
> > + if (pasid_valid(mm->pasid)) {
> > + if (mm->pasid < min || mm->pasid >= max)
> > ret = -EOVERFLOW;
> > - } else {
> > - pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
> > - if (pasid == INVALID_IOASID)
> > - ret = -ENOMEM;
> > - else
> > - mm->pasid = pasid;
> > + goto out;
> > }
> > +
> > + pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
> > + if (!pasid_valid(pasid))
> > + ret = -ENOMEM;
> > + else
> > + mm_pasid_get(mm, pasid);
>
> Hrm. This is odd.
>
> > +/* Associate a PASID with an mm_struct: */
> > +static inline void mm_pasid_get(struct mm_struct *mm, u32 pasid)
> > +{
> > + mm->pasid = pasid;
> > +}
>
> This does not get anything. It sets the allocated PASID in the mm. The
> refcount on the PASID was already taken by the allocation. So this
> should be mm_pasid_set() or mm_pasid_install(), right?
Ok. Will change mm_pasid_get() to mm_pasid_set().
Thank you very much for your review!
-Fenghua
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