[RFC v4 06/16] iommu: iommu_get_group_resv_regions

[Eric Auger <eric.auger@redhat.com>]

Introduce iommu_get_group_resv_regions whose role consists in
enumerating all devices from the group and collecting their
reserved regions. The list is sorted and overlaps are checked.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v3 -> v4:
- take the iommu_group lock in iommu_get_group_resv_regions
- the list now is sorted and overlaps are checked

NOTE:
- we do not move list elements from device to group list since
  the iommu_put_resv_regions() could not be called.
- at the moment I did not introduce any iommu_put_group_resv_regions
  since it simply consists in voiding/freeing the list
---
 drivers/iommu/iommu.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/iommu.h |  8 ++++++
 2 files changed, 86 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ae3d97b..1565df4 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -133,6 +133,84 @@ static ssize_t iommu_group_show_name(struct iommu_group *group, char *buf)
 	return sprintf(buf, "%s\n", group->name);
 }
 
+static int iommu_insert_resv_region(struct iommu_resv_region *new,
+				    struct list_head *regions)
+{
+	struct iommu_resv_region *region;
+	phys_addr_t start = new->start;
+	phys_addr_t end = new->start + new->length - 1;
+	struct list_head *pos = regions->next;
+
+	while (pos != regions) {
+		struct iommu_resv_region *entry =
+			list_entry(pos, struct iommu_resv_region, list);
+		phys_addr_t a = entry->start;
+		phys_addr_t b = entry->start + entry->length - 1;
+
+		if (end < a) {
+			goto insert;
+		} else if (start > b) {
+			pos = pos->next;
+		} else if ((start >= a) && (end <= b)) {
+			goto done;
+		} else {
+			phys_addr_t new_start = min(a, start);
+			phys_addr_t new_end = max(b, end);
+
+			list_del(&entry->list);
+			entry->start = new_start;
+			entry->length = new_end - new_start + 1;
+			iommu_insert_resv_region(entry, regions);
+		}
+	}
+insert:
+	region = iommu_alloc_resv_region(new->start, new->length,
+					 new->prot, new->type);
+	if (!region)
+		return -ENOMEM;
+
+	list_add_tail(&region->list, pos);
+done:
+	return 0;
+}
+
+static int
+iommu_insert_device_resv_regions(struct list_head *dev_resv_regions,
+				 struct list_head *group_resv_regions)
+{
+	struct iommu_resv_region *entry;
+	int ret;
+
+	list_for_each_entry(entry, dev_resv_regions, list) {
+		ret = iommu_insert_resv_region(entry, group_resv_regions);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+int iommu_get_group_resv_regions(struct iommu_group *group,
+				 struct list_head *head)
+{
+	struct iommu_device *device;
+	int ret = 0;
+
+	mutex_lock(&group->mutex);
+	list_for_each_entry(device, &group->devices, list) {
+		struct list_head dev_resv_regions;
+
+		INIT_LIST_HEAD(&dev_resv_regions);
+		iommu_get_resv_regions(device->dev, &dev_resv_regions);
+		ret = iommu_insert_device_resv_regions(&dev_resv_regions, head);
+		iommu_put_resv_regions(device->dev, &dev_resv_regions);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&group->mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_get_group_resv_regions);
+
 static IOMMU_GROUP_ATTR(name, S_IRUGO, iommu_group_show_name, NULL);
 
 static void iommu_group_release(struct kobject *kobj)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 66b0c1c..f7c0606 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -246,6 +246,8 @@ extern void iommu_set_fault_handler(struct iommu_domain *domain,
 extern int iommu_request_dm_for_dev(struct device *dev);
 extern struct iommu_resv_region *
 iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot, int type);
+extern int iommu_get_group_resv_regions(struct iommu_group *group,
+					struct list_head *head);
 
 extern int iommu_attach_group(struct iommu_domain *domain,
 			      struct iommu_group *group);
@@ -459,6 +461,12 @@ static inline void iommu_put_resv_regions(struct device *dev,
 {
 }
 
+static inline int iommu_get_group_resv_regions(struct iommu_group *group,
+					       struct list_head *head)
+{
+	return -ENODEV;
+}
+
 static inline int iommu_request_dm_for_dev(struct device *dev)
 {
 	return -ENODEV;
-- 
1.9.1