[PATCH V2 2/9] vfio/type1: find first dma

[Steve Sistare <steven.sistare@oracle.com>]

Add a variant of vfio_find_dma that returns the entry with the lowest iova
in the search range.  This is needed later for visiting all entries without
requiring one to delete each visited entry as in vfio_dma_do_unmap.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 drivers/vfio/vfio_iommu_type1.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5fbf0c1..a2c2b96 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -173,6 +173,29 @@ static struct vfio_dma *vfio_find_dma(struct vfio_iommu *iommu,
 	return NULL;
 }
 
+static struct vfio_dma *vfio_find_dma_first(struct vfio_iommu *iommu,
+					    dma_addr_t start, size_t size)
+{
+	struct vfio_dma *res = NULL;
+	struct rb_node *node = iommu->dma_list.rb_node;
+
+	while (node) {
+		struct vfio_dma *dma = rb_entry(node, struct vfio_dma, node);
+
+		if (start < dma->iova + dma->size) {
+			res = dma;
+			if (start >= dma->iova)
+				break;
+			node = node->rb_left;
+		} else {
+			node = node->rb_right;
+		}
+	}
+	if (res && size && res->iova >= start + size)
+		res = NULL;
+	return res;
+}
+
 static void vfio_link_dma(struct vfio_iommu *iommu, struct vfio_dma *new)
 {
 	struct rb_node **link = &iommu->dma_list.rb_node, *parent = NULL;
-- 
1.8.3.1