[RFC v4 04/14] dma-reserved-iommu: reserved binding rb-tree and helpers

[Eric Auger <eric.auger@linaro.org>]

we will need to track which host physical addresses are mapped to
reserved IOVA. In that prospect we introduce a new RB tree indexed
by physical address. This RB tree only is used for reserved IOVA
bindings.

It is expected this RB tree will contain very few bindings. Those
generally correspond to single page mapping one MSI frame (GICv2m
frame or ITS GITS_TRANSLATER frame).

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---

v3 -> v4:
- that code was formerly in "iommu/arm-smmu: add a reserved binding RB tree"
---
 drivers/iommu/dma-reserved-iommu.c | 60 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/drivers/iommu/dma-reserved-iommu.c b/drivers/iommu/dma-reserved-iommu.c
index 41a1add..30d54d0 100644
--- a/drivers/iommu/dma-reserved-iommu.c
+++ b/drivers/iommu/dma-reserved-iommu.c
@@ -20,6 +20,66 @@
 #include <linux/iommu.h>
 #include <linux/iova.h>
 
+struct iommu_reserved_binding {
+	struct kref		kref;
+	struct rb_node		node;
+	struct iommu_domain	*domain;
+	phys_addr_t		addr;
+	dma_addr_t		iova;
+	size_t			size;
+};
+
+/* Reserved binding RB-tree manipulation */
+
+static struct iommu_reserved_binding *find_reserved_binding(
+				    struct iommu_domain *d,
+				    phys_addr_t start, size_t size)
+{
+	struct rb_node *node = d->reserved_binding_list.rb_node;
+
+	while (node) {
+		struct iommu_reserved_binding *binding =
+			rb_entry(node, struct iommu_reserved_binding, node);
+
+		if (start + size <= binding->addr)
+			node = node->rb_left;
+		else if (start >= binding->addr + binding->size)
+			node = node->rb_right;
+		else
+			return binding;
+	}
+
+	return NULL;
+}
+
+static void link_reserved_binding(struct iommu_domain *d,
+				  struct iommu_reserved_binding *new)
+{
+	struct rb_node **link = &d->reserved_binding_list.rb_node;
+	struct rb_node *parent = NULL;
+	struct iommu_reserved_binding *binding;
+
+	while (*link) {
+		parent = *link;
+		binding = rb_entry(parent, struct iommu_reserved_binding,
+				   node);
+
+		if (new->addr + new->size <= binding->addr)
+			link = &(*link)->rb_left;
+		else
+			link = &(*link)->rb_right;
+	}
+
+	rb_link_node(&new->node, parent, link);
+	rb_insert_color(&new->node, &d->reserved_binding_list);
+}
+
+static void unlink_reserved_binding(struct iommu_domain *d,
+				    struct iommu_reserved_binding *old)
+{
+	rb_erase(&old->node, &d->reserved_binding_list);
+}
+
 int iommu_alloc_reserved_iova_domain(struct iommu_domain *domain,
 				     dma_addr_t iova, size_t size,
 				     unsigned long order)
-- 
1.9.1