This iova tree function allows it to look for a hole in allocated
regions and return a totally new translation for a given translated
address.
It's usage is mainly to allow devices to access qemu address space,
remapping guest's one into a new iova space where qemu can add chunks of
addresses.
Signed-off-by: Eugenio Pérez <epere...@redhat.com>
---
include/qemu/iova-tree.h | 17 ++++++++
util/iova-tree.c | 86 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 102 insertions(+), 1 deletion(-)
diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h
index 8249edd764..33f9b2e13f 100644
--- a/include/qemu/iova-tree.h
+++ b/include/qemu/iova-tree.h
@@ -29,6 +29,7 @@
#define IOVA_OK (0)
#define IOVA_ERR_INVALID (-1) /* Invalid parameters */
#define IOVA_ERR_OVERLAP (-2) /* IOVA range overlapped */
+#define IOVA_ERR_NOMEM (-3) /* Cannot allocate */
typedef struct IOVATree IOVATree;
typedef struct DMAMap {
@@ -119,6 +120,22 @@ const DMAMap *iova_tree_find_address(const IOVATree *tree,
hwaddr iova);
*/
void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator);
+/**
+ * iova_tree_alloc:
+ *
+ * @tree: the iova tree to allocate from
+ * @map: the new map (as translated addr & size) to allocate in iova region
+ * @iova_begin: the minimum address of the allocation
+ * @iova_end: the maximum addressable direction of the allocation
+ *
+ * Allocates a new region of a given size, between iova_min and iova_max.
+ *
+ * Return: Same as iova_tree_insert, but cannot overlap and can be out of
+ * free contiguous range. Caller can get the assigned iova in map->iova.
+ */
+int iova_tree_alloc(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
+ hwaddr iova_end);
+
/**
* iova_tree_destroy:
*
diff --git a/util/iova-tree.c b/util/iova-tree.c
index 5063a256dd..1439fc9fe2 100644
--- a/util/iova-tree.c
+++ b/util/iova-tree.c
@@ -88,7 +88,7 @@ static DMAMapInternal *iova_tree_find_internal(const IOVATree
*tree,
const DMAMap *iova_tree_find(const IOVATree *tree, const DMAMap *map)
{
const DMAMapInternal *ret = iova_tree_find_internal(tree, map);
- return &ret->map;
+ return ret ? &ret->map : NULL;
}
const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova)
@@ -162,6 +162,90 @@ int iova_tree_remove(IOVATree *tree, const DMAMap *map)
return IOVA_OK;
}
+/**
+ * Check if there is at minimum "size" iova space between the end of "left" and
+ * the start of "right". If some of them is NULL, iova_begin and iova_end will
+ * be used.
+ */
+static bool iova_tree_alloc_map_in_hole(const DMAMapInternal *l,
+ const DMAMapInternal *r,
+ hwaddr iova_begin, hwaddr iova_last,
+ size_t size)
+{
+ const DMAMap *left = l ? &l->map : NULL;
+ const DMAMap *right = r ? &r->map : NULL;
+ uint64_t hole_start, hole_last;
+
+ if (right && right->iova + right->size < iova_begin) {
+ return false;
+ }
+
+ if (left && left->iova > iova_last) {
+ return false;
+ }
+
+ hole_start = MAX(left ? left->iova + left->size + 1 : 0, iova_begin);
+ hole_last = MIN(right ? right->iova : HWADDR_MAX, iova_last);
+
+ if (hole_last - hole_start > size) {
+ /* We found a valid hole. */
+ return true;
+ }
+
+ /* Keep iterating */
+ return false;
+}
+
+/**
+ * Allocates a new entry in the tree
+ *
+ * The caller specifies the size of the new entry with map->size. The new iova
+ * address is returned in map->iova if allocation success. The map ownership is
+ * always of the caller as in iova_tree_insert.
+ *
+ * More contrains can be specified with iova_begin and iova_last.
+ *
+ * Returns the same as iova_tree_insert, but it can return IOVA_ERR_NOMEM if
+ * cannot find a hole in iova range big enough.
+ */
+int iova_tree_alloc(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
+ hwaddr iova_last)
+{
+ const DMAMapInternal *last, *i;
+
+ assert(iova_begin < iova_last);
+
+ /*
+ * Find a valid hole for the mapping
+ *
+ * TODO: Replace all this with g_tree_node_first/next/last when available
+ * (from glib since 2.68). Using a sepparated QTAILQ complicates code.
+ *
+ * Try to allocate first at the end of the list.
+ */
+ last = QTAILQ_LAST(&tree->list);
+ if (iova_tree_alloc_map_in_hole(last, NULL, iova_begin, iova_last,
+ map->size)) {
+ goto alloc;
+ }
+
+ /* Look for inner hole */
+ last = NULL;
+ for (i = QTAILQ_FIRST(&tree->list); i;
+ last = i, i = QTAILQ_NEXT(i, entry)) {
+ if (iova_tree_alloc_map_in_hole(last, i, iova_begin, iova_last,
+ map->size)) {
+ goto alloc;
+ }
+ }
+
+ return IOVA_ERR_NOMEM;
+
+alloc:
+ map->iova = last ? last->map.iova + last->map.size + 1 : iova_begin;
+ return iova_tree_insert(tree, map);
+}
+
void iova_tree_destroy(IOVATree *tree)
{
g_tree_destroy(tree->tree);
--
2.27.0
