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From 8a24ceae4f758b12ac0cda2559b9cbda41487027 Mon Sep 17 00:00:00 2001
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From: Peter Xu <peterx@redhat.com>
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Date: Fri, 12 Oct 2018 07:58:45 +0100
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Subject: [PATCH 15/17] util: implement simple iova tree
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RH-Author: Peter Xu <peterx@redhat.com>
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Message-id: <20181012075846.25449-9-peterx@redhat.com>
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Patchwork-id: 82681
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O-Subject: [RHEL-8 qemu-kvm PATCH 8/9] util: implement simple iova tree
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Bugzilla: 1450712
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RH-Acked-by: Auger Eric <eric.auger@redhat.com>
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RH-Acked-by: Xiao Wang <jasowang@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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Introduce a simplest iova tree implementation based on GTree.
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CC: QEMU Stable <qemu-stable@nongnu.org>
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Signed-off-by: Peter Xu <peterx@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit eecf5eedbdc0fc04f39abcf3afeedfbf21b25ca4)
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Signed-off-by: Peter Xu <peterx@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 MAINTAINERS              |   6 +++
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 include/qemu/iova-tree.h | 134 +++++++++++++++++++++++++++++++++++++++++++++++
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 util/Makefile.objs       |   1 +
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 util/iova-tree.c         | 114 ++++++++++++++++++++++++++++++++++++++++
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 4 files changed, 255 insertions(+)
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 create mode 100644 include/qemu/iova-tree.h
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 create mode 100644 util/iova-tree.c
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diff --git a/MAINTAINERS b/MAINTAINERS
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index 53d5216..1e32116 100644
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--- a/MAINTAINERS
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+++ b/MAINTAINERS
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@@ -1787,6 +1787,12 @@ F: include/sysemu/replay.h
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 F: docs/replay.txt
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 F: stubs/replay.c
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+IOVA Tree
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+M: Peter Xu <peterx@redhat.com>
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+S: Maintained
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+F: include/qemu/iova-tree.h
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+F: util/iova-tree.c
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+
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 Usermode Emulation
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 ------------------
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 Overall
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diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h
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new file mode 100644
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index 0000000..b061932
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--- /dev/null
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+++ b/include/qemu/iova-tree.h
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@@ -0,0 +1,134 @@
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+/*
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+ * An very simplified iova tree implementation based on GTree.
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+ *
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+ * Copyright 2018 Red Hat, Inc.
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+ *
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+ * Authors:
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+ *  Peter Xu <peterx@redhat.com>
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+ *
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+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
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+ */
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+#ifndef IOVA_TREE_H
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+#define IOVA_TREE_H
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+
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+/*
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+ * Currently the iova tree will only allow to keep ranges
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+ * information, and no extra user data is allowed for each element.  A
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+ * benefit is that we can merge adjacent ranges internally within the
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+ * tree.  It can save a lot of memory when the ranges are splitted but
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+ * mostly continuous.
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+ *
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+ * Note that current implementation does not provide any thread
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+ * protections.  Callers of the iova tree should be responsible
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+ * for the thread safety issue.
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+ */
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+
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+#include "qemu/osdep.h"
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+#include "exec/memory.h"
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+#include "exec/hwaddr.h"
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+
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+#define  IOVA_OK           (0)
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+#define  IOVA_ERR_INVALID  (-1) /* Invalid parameters */
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+#define  IOVA_ERR_OVERLAP  (-2) /* IOVA range overlapped */
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+
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+typedef struct IOVATree IOVATree;
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+typedef struct DMAMap {
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+    hwaddr iova;
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+    hwaddr translated_addr;
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+    hwaddr size;                /* Inclusive */
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+    IOMMUAccessFlags perm;
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+} QEMU_PACKED DMAMap;
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+typedef gboolean (*iova_tree_iterator)(DMAMap *map);
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+
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+/**
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+ * iova_tree_new:
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+ *
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+ * Create a new iova tree.
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+ *
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+ * Returns: the tree pointer when succeeded, or NULL if error.
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+ */
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+IOVATree *iova_tree_new(void);
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+
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+/**
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+ * iova_tree_insert:
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+ *
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+ * @tree: the iova tree to insert
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+ * @map: the mapping to insert
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+ *
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+ * Insert an iova range to the tree.  If there is overlapped
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+ * ranges, IOVA_ERR_OVERLAP will be returned.
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+ *
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+ * Return: 0 if succeeded, or <0 if error.
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+ */
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+int iova_tree_insert(IOVATree *tree, DMAMap *map);
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+
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+/**
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+ * iova_tree_remove:
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+ *
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+ * @tree: the iova tree to remove range from
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+ * @map: the map range to remove
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+ *
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+ * Remove mappings from the tree that are covered by the map range
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+ * provided.  The range does not need to be exactly what has inserted,
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+ * all the mappings that are included in the provided range will be
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+ * removed from the tree.  Here map->translated_addr is meaningless.
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+ *
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+ * Return: 0 if succeeded, or <0 if error.
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+ */
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+int iova_tree_remove(IOVATree *tree, DMAMap *map);
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+
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+/**
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+ * iova_tree_find:
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+ *
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+ * @tree: the iova tree to search from
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+ * @map: the mapping to search
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+ *
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+ * Search for a mapping in the iova tree that overlaps with the
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+ * mapping range specified.  Only the first found mapping will be
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+ * returned.
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+ *
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+ * Return: DMAMap pointer if found, or NULL if not found.  Note that
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+ * the returned DMAMap pointer is maintained internally.  User should
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+ * only read the content but never modify or free the content.  Also,
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+ * user is responsible to make sure the pointer is valid (say, no
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+ * concurrent deletion in progress).
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+ */
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+DMAMap *iova_tree_find(IOVATree *tree, DMAMap *map);
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+
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+/**
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+ * iova_tree_find_address:
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+ *
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+ * @tree: the iova tree to search from
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+ * @iova: the iova address to find
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+ *
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+ * Similar to iova_tree_find(), but it tries to find mapping with
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+ * range iova=iova & size=0.
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+ *
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+ * Return: same as iova_tree_find().
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+ */
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+DMAMap *iova_tree_find_address(IOVATree *tree, hwaddr iova);
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+
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+/**
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+ * iova_tree_foreach:
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+ *
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+ * @tree: the iova tree to iterate on
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+ * @iterator: the interator for the mappings, return true to stop
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+ *
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+ * Iterate over the iova tree.
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+ *
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+ * Return: 1 if found any overlap, 0 if not, <0 if error.
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+ */
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+void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator);
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+
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+/**
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+ * iova_tree_destroy:
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+ *
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+ * @tree: the iova tree to destroy
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+ *
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+ * Destroy an existing iova tree.
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+ *
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+ * Return: None.
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+ */
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+void iova_tree_destroy(IOVATree *tree);
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+
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+#endif
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diff --git a/util/Makefile.objs b/util/Makefile.objs
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index 728c354..e1c3fed 100644
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--- a/util/Makefile.objs
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+++ b/util/Makefile.objs
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@@ -47,4 +47,5 @@ util-obj-y += qht.o
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 util-obj-y += range.o
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 util-obj-y += stats64.o
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 util-obj-y += systemd.o
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+util-obj-y += iova-tree.o
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 util-obj-$(CONFIG_LINUX) += vfio-helpers.o
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diff --git a/util/iova-tree.c b/util/iova-tree.c
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new file mode 100644
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index 0000000..2d9cebf
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--- /dev/null
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+++ b/util/iova-tree.c
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@@ -0,0 +1,114 @@
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+/*
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+ * IOVA tree implementation based on GTree.
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+ *
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+ * Copyright 2018 Red Hat, Inc.
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+ *
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+ * Authors:
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+ *  Peter Xu <peterx@redhat.com>
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+ *
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+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
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+ */
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+
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+#include <glib.h>
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+#include "qemu/iova-tree.h"
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+
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+struct IOVATree {
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+    GTree *tree;
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+};
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+
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+static int iova_tree_compare(gconstpointer a, gconstpointer b, gpointer data)
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+{
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+    const DMAMap *m1 = a, *m2 = b;
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+
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+    if (m1->iova > m2->iova + m2->size) {
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+        return 1;
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+    }
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+
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+    if (m1->iova + m1->size < m2->iova) {
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+        return -1;
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+    }
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+
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+    /* Overlapped */
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+    return 0;
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+}
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+
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+IOVATree *iova_tree_new(void)
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+{
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+    IOVATree *iova_tree = g_new0(IOVATree, 1);
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+
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+    /* We don't have values actually, no need to free */
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+    iova_tree->tree = g_tree_new_full(iova_tree_compare, NULL, g_free, NULL);
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+
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+    return iova_tree;
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+}
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+
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+DMAMap *iova_tree_find(IOVATree *tree, DMAMap *map)
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+{
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+    return g_tree_lookup(tree->tree, map);
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+}
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+
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+DMAMap *iova_tree_find_address(IOVATree *tree, hwaddr iova)
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+{
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+    DMAMap map = { .iova = iova, .size = 0 };
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+
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+    return iova_tree_find(tree, &map);
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+}
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+
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+static inline void iova_tree_insert_internal(GTree *gtree, DMAMap *range)
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+{
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+    /* Key and value are sharing the same range data */
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+    g_tree_insert(gtree, range, range);
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+}
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+
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+int iova_tree_insert(IOVATree *tree, DMAMap *map)
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+{
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+    DMAMap *new;
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+
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+    if (map->iova + map->size < map->iova || map->perm == IOMMU_NONE) {
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+        return IOVA_ERR_INVALID;
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+    }
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+
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+    /* We don't allow to insert range that overlaps with existings */
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+    if (iova_tree_find(tree, map)) {
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+        return IOVA_ERR_OVERLAP;
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+    }
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+
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+    new = g_new0(DMAMap, 1);
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+    memcpy(new, map, sizeof(*new));
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+    iova_tree_insert_internal(tree->tree, new);
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+
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+    return IOVA_OK;
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+}
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+
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+static gboolean iova_tree_traverse(gpointer key, gpointer value,
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+                                gpointer data)
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+{
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+    iova_tree_iterator iterator = data;
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+    DMAMap *map = key;
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+
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+    g_assert(key == value);
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+
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+    return iterator(map);
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+}
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+
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+void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator)
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+{
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+    g_tree_foreach(tree->tree, iova_tree_traverse, iterator);
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+}
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+
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+int iova_tree_remove(IOVATree *tree, DMAMap *map)
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+{
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+    DMAMap *overlap;
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+
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+    while ((overlap = iova_tree_find(tree, map))) {
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+        g_tree_remove(tree->tree, overlap);
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+    }
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+
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+    return IOVA_OK;
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+}
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+
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+void iova_tree_destroy(IOVATree *tree)
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+{
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+    g_tree_destroy(tree->tree);
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+    g_free(tree);
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+}
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-- 
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1.8.3.1
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