RE: [PATCH v3 2/6] vfio/type1: Check reserve region conflict and update iova list

[Shameerali Kolothum Thodi]

> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx]
> Sent: Friday, February 16, 2018 9:18 PM
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>
> Cc: eric.auger@xxxxxxxxxx; pmorel@xxxxxxxxxxxxxxxxxx;
> kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Linuxarm
> <linuxarm@xxxxxxxxxx>; John Garry <john.garry@xxxxxxxxxx>; xuwei (O)
> <xuwei5@xxxxxxxxxx>
> Subject: Re: [PATCH v3 2/6] vfio/type1: Check reserve region conflict and
> update iova list
> 
> On Thu, 15 Feb 2018 09:45:00 +0000
> Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> wrote:
> 
> > This retrieves the reserved regions associated with dev group and
> > checks for conflicts with any existing dma mappings. Also update
> > the iova list excluding the reserved regions.
> >
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> > ---
> >  drivers/vfio/vfio_iommu_type1.c | 86
> ++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 85 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/vfio/vfio_iommu_type1.c
> b/drivers/vfio/vfio_iommu_type1.c
> > index 4726f55..4db87a9 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -1303,6 +1303,72 @@ static int vfio_iommu_aper_resize(struct
> list_head *iova,
> >  	return 0;
> >  }
> >
> > +/*
> > + * Check reserved region conflicts with existing dma mappings
> > + */
> > +static bool vfio_iommu_resv_conflict(struct vfio_iommu *iommu,
> > +				struct list_head *resv_regions)
> > +{
> > +	struct iommu_resv_region *region;
> > +
> > +	/* Check for conflict with existing dma mappings */
> > +	list_for_each_entry(region, resv_regions, list) {
> > +		if (vfio_find_dma(iommu, region->start, region->length))
> > +			return true;
> > +	}
> > +
> > +	return false;
> > +}
> > +
> > +/*
> > + * Check iova region overlap with  reserved regions and
> > + * exclude them from the iommu iova range
> > + */
> > +static int vfio_iommu_resv_exclude(struct list_head *iova,
> > +					struct list_head *resv_regions)
> > +{
> > +	struct iommu_resv_region *resv;
> > +	struct vfio_iova *n, *next;
> > +
> > +	list_for_each_entry(resv, resv_regions, list) {
> > +		phys_addr_t start, end;
> > +
> > +		start = resv->start;
> > +		end = resv->start + resv->length - 1;
> > +
> > +		list_for_each_entry_safe(n, next, iova, list) {
> > +			int ret = 0;
> > +
> > +			/* No overlap */
> > +			if ((start > n->end) || (end < n->start))
> > +				continue;
> > +			/*
> > +			 * Insert a new node if current node overlaps with the
> > +			 * reserve region to exlude that from valid iova range.
> > +			 * Note that, new node is inserted before the current
> > +			 * node and finally the current node is deleted keeping
> > +			 * the list updated and sorted.
> > +			 */
> > +			if (start > n->start)
> > +				ret = vfio_insert_iova(n->start, start - 1,
> > +								 &n->list);
> > +			if (!ret && end < n->end)
> > +				ret = vfio_insert_iova(end + 1, n->end,
> > +							     &n->list);
> > +			if (ret)
> > +				return ret;
> > +
> > +			list_del(&n->list);
> > +			kfree(n);
> > +		}
> > +	}
> > +
> > +	if (list_empty(iova))
> > +		return -EINVAL;
> > +
> > +	return 0;
> > +}
> > +
> >  static int vfio_iommu_get_iova_copy(struct vfio_iommu *iommu,
> >  				struct list_head *iova_copy)
> >  {
> > @@ -1346,7 +1412,8 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  	bool resv_msi, msi_remap;
> >  	phys_addr_t resv_msi_base;
> >  	struct iommu_domain_geometry geo;
> > -	struct list_head iova_copy;
> > +	struct list_head iova_copy, group_resv_regions;
> > +	struct iommu_resv_region *resv, *resv_next;
> >  	struct vfio_iova *iova, *iova_next;
> >
> >  	mutex_lock(&iommu->lock);
> > @@ -1426,6 +1493,14 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  		goto out_detach;
> >  	}
> >
> > +	INIT_LIST_HEAD(&group_resv_regions);
> 
> LIST_HEAD()

Ok.

> > +	iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
> > +
> > +	if (vfio_iommu_resv_conflict(iommu, &group_resv_regions)) {
> > +		ret = -EINVAL;
> > +		goto out_detach;
> > +	}
> > +
> >  	/* Get a copy of the current iova list and work on it */
> >  	INIT_LIST_HEAD(&iova_copy);
> >  	ret = vfio_iommu_get_iova_copy(iommu, &iova_copy);
> > @@ -1437,6 +1512,10 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  	if (ret)
> >  		goto out_detach;
> >
> > +	ret = vfio_iommu_resv_exclude(&iova_copy, &group_resv_regions);
> > +	if (ret)
> > +		goto out_detach;
> > +
> >  	resv_msi = vfio_iommu_has_sw_msi(iommu_group, &resv_msi_base);
> >
> >  	INIT_LIST_HEAD(&domain->group_list);
> > @@ -1497,6 +1576,9 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  	/* Delete the old one and insert new iova list */
> >  	vfio_iommu_insert_iova_copy(iommu, &iova_copy);
> >
> > +	list_for_each_entry_safe(resv, resv_next, &group_resv_regions, list)
> > +		kfree(resv);
> 
> list_del() here and below, also this can be done after the mutex unlock.

Ok. I thought that as the reserved regions are local to this function, list_del() is
not required.  Same for the iova_copy in the first patch as well(which I missed to
comment there).

Thanks,
Shameer 

> > +
> >  	mutex_unlock(&iommu->lock);
> >
> >  	return 0;
> > @@ -1507,6 +1589,8 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> >  	iommu_domain_free(domain->domain);
> >  	list_for_each_entry_safe(iova, iova_next, &iova_copy, list)
> >  		kfree(iova);
> > +	list_for_each_entry_safe(resv, resv_next, &group_resv_regions, list)
> > +		kfree(resv);
> >  out_free:
> >  	kfree(domain);
> >  	kfree(group);