RE: [PATCH v5 2/7] vfio/type1: Check reserve region conflict and update iova list

Tian, Kevin
2018-03-19T07:51:58Z

> From: Shameer Kolothum
> Sent: Friday, March 16, 2018 12:35 AM
>
> 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-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> ---
> drivers/vfio/vfio_iommu_type1.c | 90
> +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 90 insertions(+)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c
> b/drivers/vfio/vfio_iommu_type1.c
> index 1123c74..cfe2bb2 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1313,6 +1313,82 @@ 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_iommu_iova_insert(&n->list,
> + n->start, start - 1);
> + if (!ret && end < n->end)
> + ret = vfio_iommu_iova_insert(&n->list,
> + end + 1, n->end);
> + if (ret)
> + return ret;

Is it safer to delete the 1st node here in case of failure of the 2nd node?
There is no problem with current logic since upon error iova_copy will
be released anyway. However this function alone doesn't assume the
fact of a temporary list, thus it's better to keep the list clean w/o garbage
left from any error handling.

> +
> + list_del(&n->list);
> + kfree(n);
> + }
> + }
> +
> + if (list_empty(iova))
> + return -EINVAL;

if list_empty should BUG_ON here? or do we really need this check?

> +
> + return 0;
> +}
> +
> +static void vfio_iommu_resv_free(struct list_head *resv_regions)
> +{
> + struct iommu_resv_region *n, *next;
> +
> + list_for_each_entry_safe(n, next, resv_regions, list) {
> + list_del(&n->list);
> + kfree(n);
> + }
> +}
> +
> static void vfio_iommu_iova_free(struct list_head *iova)
> {
> struct vfio_iova *n, *next;
> @@ -1366,6 +1442,7 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> phys_addr_t resv_msi_base;
> struct iommu_domain_geometry geo;
> LIST_HEAD(iova_copy);
> + LIST_HEAD(group_resv_regions);
>
> mutex_lock(&iommu->lock);
>
> @@ -1444,6 +1521,13 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> goto out_detach;
> }
>
> + 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 */
> ret = vfio_iommu_iova_get_copy(iommu, &iova_copy);
> if (ret)
> @@ -1454,6 +1538,10 @@ 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);
> @@ -1514,6 +1602,7 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> /* Delete the old one and insert new iova list */
> vfio_iommu_iova_insert_copy(iommu, &iova_copy);
> mutex_unlock(&iommu->lock);
> + vfio_iommu_resv_free(&group_resv_regions);
>
> return 0;
>
> @@ -1522,6 +1611,7 @@ static int vfio_iommu_type1_attach_group(void
> *iommu_data,
> out_domain:
> iommu_domain_free(domain->domain);
> vfio_iommu_iova_free(&iova_copy);
> + vfio_iommu_resv_free(&group_resv_regions);
> out_free:
> kfree(domain);
> kfree(group);
> --
> 2.7.4
>
>
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