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SubjectRe: [PATCH v8 1/6] vfio/type1: Introduce iova list and add iommu aperture validity check
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Hi Shameer,

On 7/23/19 6:06 PM, Shameer Kolothum wrote:
> This introduces an iova list that is valid for dma mappings. Make
> sure the new iommu aperture window doesn't conflict with the current
> one or with any existing dma mappings during attach.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric
> ---
> v7-->v8
> -Addressed suggestions by Eric to update comments.
> ---
> drivers/vfio/vfio_iommu_type1.c | 184 +++++++++++++++++++++++++++++++-
> 1 file changed, 181 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 054391f30fa8..6a69652b406b 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -62,6 +62,7 @@ MODULE_PARM_DESC(dma_entry_limit,
>
> struct vfio_iommu {
> struct list_head domain_list;
> + struct list_head iova_list;
> struct vfio_domain *external_domain; /* domain for external user */
> struct mutex lock;
> struct rb_root dma_list;
> @@ -97,6 +98,12 @@ struct vfio_group {
> bool mdev_group; /* An mdev group */
> };
>
> +struct vfio_iova {
> + struct list_head list;
> + dma_addr_t start;
> + dma_addr_t end;
> +};
> +
> /*
> * Guest RAM pinning working set or DMA target
> */
> @@ -1388,6 +1395,146 @@ static int vfio_mdev_iommu_device(struct device *dev, void *data)
> return 0;
> }
>
> +/*
> + * This is a helper function to insert an address range to iova list.
> + * The list is initially created with a single entry corresponding to
> + * the IOMMU domain geometry to which the device group is attached.
> + * The list aperture gets modified when a new domain is added to the
> + * container if the new aperture doesn't conflict with the current one
> + * or with any existing dma mappings. The list is also modified to
> + * exclude any reserved regions associated with the device group.
> + */
> +static int vfio_iommu_iova_insert(struct list_head *head,
> + dma_addr_t start, dma_addr_t end)
> +{
> + struct vfio_iova *region;
> +
> + region = kmalloc(sizeof(*region), GFP_KERNEL);
> + if (!region)
> + return -ENOMEM;
> +
> + INIT_LIST_HEAD(&region->list);
> + region->start = start;
> + region->end = end;
> +
> + list_add_tail(&region->list, head);
> + return 0;
> +}
> +
> +/*
> + * Check the new iommu aperture conflicts with existing aper or with any
> + * existing dma mappings.
> + */
> +static bool vfio_iommu_aper_conflict(struct vfio_iommu *iommu,
> + dma_addr_t start, dma_addr_t end)
> +{
> + struct vfio_iova *first, *last;
> + struct list_head *iova = &iommu->iova_list;
> +
> + if (list_empty(iova))
> + return false;
> +
> + /* Disjoint sets, return conflict */
> + first = list_first_entry(iova, struct vfio_iova, list);
> + last = list_last_entry(iova, struct vfio_iova, list);
> + if (start > last->end || end < first->start)
> + return true;
> +
> + /* Check for any existing dma mappings below the new start */
> + if (start > first->start) {
> + if (vfio_find_dma(iommu, first->start, start - first->start))
> + return true;
> + }
> +
> + /* Check for any existing dma mappings beyond the new end */
> + if (end < last->end) {
> + if (vfio_find_dma(iommu, end + 1, last->end - end))
> + return true;
> + }
> +
> + return false;
> +}
> +
> +/*
> + * Resize iommu iova aperture window. This is called only if the new
> + * aperture has no conflict with existing aperture and dma mappings.
> + */
> +static int vfio_iommu_aper_resize(struct list_head *iova,
> + dma_addr_t start, dma_addr_t end)
> +{
> + struct vfio_iova *node, *next;
> +
> + if (list_empty(iova))
> + return vfio_iommu_iova_insert(iova, start, end);
> +
> + /* Adjust iova list start */
> + list_for_each_entry_safe(node, next, iova, list) {
> + if (start < node->start)
> + break;
> + if (start >= node->start && start < node->end) {
> + node->start = start;
> + break;
> + }
> + /* Delete nodes before new start */
> + list_del(&node->list);
> + kfree(node);
> + }
> +
> + /* Adjust iova list end */
> + list_for_each_entry_safe(node, next, iova, list) {
> + if (end > node->end)
> + continue;
> + if (end > node->start && end <= node->end) {
> + node->end = end;
> + continue;
> + }
> + /* Delete nodes after new end */
> + list_del(&node->list);
> + kfree(node);
> + }
> +
> + return 0;
> +}
> +
> +static void vfio_iommu_iova_free(struct list_head *iova)
> +{
> + struct vfio_iova *n, *next;
> +
> + list_for_each_entry_safe(n, next, iova, list) {
> + list_del(&n->list);
> + kfree(n);
> + }
> +}
> +
> +static int vfio_iommu_iova_get_copy(struct vfio_iommu *iommu,
> + struct list_head *iova_copy)
> +{
> + struct list_head *iova = &iommu->iova_list;
> + struct vfio_iova *n;
> + int ret;
> +
> + list_for_each_entry(n, iova, list) {
> + ret = vfio_iommu_iova_insert(iova_copy, n->start, n->end);
> + if (ret)
> + goto out_free;
> + }
> +
> + return 0;
> +
> +out_free:
> + vfio_iommu_iova_free(iova_copy);
> + return ret;
> +}
> +
> +static void vfio_iommu_iova_insert_copy(struct vfio_iommu *iommu,
> + struct list_head *iova_copy)
> +{
> + struct list_head *iova = &iommu->iova_list;
> +
> + vfio_iommu_iova_free(iova);
> +
> + list_splice_tail(iova_copy, iova);
> +}
> static int vfio_iommu_type1_attach_group(void *iommu_data,
> struct iommu_group *iommu_group)
> {
> @@ -1398,6 +1545,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> int ret;
> bool resv_msi, msi_remap;
> phys_addr_t resv_msi_base;
> + struct iommu_domain_geometry geo;
> + LIST_HEAD(iova_copy);
>
> mutex_lock(&iommu->lock);
>
> @@ -1474,6 +1623,29 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> if (ret)
> goto out_domain;
>
> + /* Get aperture info */
> + iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, &geo);
> +
> + if (vfio_iommu_aper_conflict(iommu, geo.aperture_start,
> + geo.aperture_end)) {
> + ret = -EINVAL;
> + goto out_detach;
> + }
> +
> + /*
> + * We don't want to work on the original iova list as the list
> + * gets modified and in case of failure we have to retain the
> + * original list. Get a copy here.
> + */
> + ret = vfio_iommu_iova_get_copy(iommu, &iova_copy);
> + if (ret)
> + goto out_detach;
> +
> + ret = vfio_iommu_aper_resize(&iova_copy, geo.aperture_start,
> + geo.aperture_end);
> + if (ret)
> + goto out_detach;
> +
> resv_msi = vfio_iommu_has_sw_msi(iommu_group, &resv_msi_base);
>
> INIT_LIST_HEAD(&domain->group_list);
> @@ -1507,8 +1679,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> list_add(&group->next, &d->group_list);
> iommu_domain_free(domain->domain);
> kfree(domain);
> - mutex_unlock(&iommu->lock);
> - return 0;
> + goto done;
> }
>
> ret = vfio_iommu_attach_group(domain, group);
> @@ -1531,7 +1702,9 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> }
>
> list_add(&domain->next, &iommu->domain_list);
> -
> +done:
> + /* Delete the old one and insert new iova list */
> + vfio_iommu_iova_insert_copy(iommu, &iova_copy);
> mutex_unlock(&iommu->lock);
>
> return 0;
> @@ -1540,6 +1713,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> vfio_iommu_detach_group(domain, group);
> out_domain:
> iommu_domain_free(domain->domain);
> + vfio_iommu_iova_free(&iova_copy);
> out_free:
> kfree(domain);
> kfree(group);
> @@ -1679,6 +1853,7 @@ static void *vfio_iommu_type1_open(unsigned long arg)
> }
>
> INIT_LIST_HEAD(&iommu->domain_list);
> + INIT_LIST_HEAD(&iommu->iova_list);
> iommu->dma_list = RB_ROOT;
> iommu->dma_avail = dma_entry_limit;
> mutex_init(&iommu->lock);
> @@ -1722,6 +1897,9 @@ static void vfio_iommu_type1_release(void *iommu_data)
> list_del(&domain->next);
> kfree(domain);
> }
> +
> + vfio_iommu_iova_free(&iommu->iova_list);
> +
> kfree(iommu);
> }
>
>

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