/*
* IOVA tree implementation based on GTree.
*
* Copyright 2018 Red Hat, Inc.
*
* Authors:
* Peter Xu <peterx@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
*/
#include "qemu/osdep.h"
#include "qemu/iova-tree.h"
struct IOVATree {
GTree *tree;
};
/* Args to pass to iova_tree_alloc foreach function. */
struct IOVATreeAllocArgs {
/* Size of the desired allocation */
size_t new_size;
/* The minimum address allowed in the allocation */
hwaddr iova_begin;
/* Map at the left of the hole, can be NULL if "this" is first one */
const DMAMap *prev;
/* Map at the right of the hole, can be NULL if "prev" is the last one */
const DMAMap *this;
/* If found, we fill in the IOVA here */
hwaddr iova_result;
/* Whether have we found a valid IOVA */
bool iova_found;
};
typedef struct IOVATreeFindIOVAArgs {
const DMAMap *needle;
const DMAMap *result;
} IOVATreeFindIOVAArgs;
/**
* Iterate args to the next hole
*
* @args: The alloc arguments
* @next: The next mapping in the tree. Can be NULL to signal the last one
*/
static void iova_tree_alloc_args_iterate(struct IOVATreeAllocArgs *args,
const DMAMap *next)
{
args->prev = args->this;
args->this = next;
}
static int iova_tree_compare(gconstpointer a, gconstpointer b, gpointer data)
{
const DMAMap *m1 = a, *m2 = b;
if (m1->iova > m2->iova + m2->size) {
return 1;
}
if (m1->iova + m1->size < m2->iova) {
return -1;
}
/* Overlapped */
return 0;
}
IOVATree *iova_tree_new(void)
{
IOVATree *iova_tree = g_new0(IOVATree, 1);
/* We don't have values actually, no need to free */
iova_tree->tree = g_tree_new_full(iova_tree_compare, NULL, g_free, NULL);
return iova_tree;
}
const DMAMap *iova_tree_find(const IOVATree *tree, const DMAMap *map)
{
return g_tree_lookup(tree->tree, map);
}
static gboolean iova_tree_find_address_iterator(gpointer key, gpointer value,
gpointer data)
{
const DMAMap *map = key;
IOVATreeFindIOVAArgs *args = data;
const DMAMap *needle;
g_assert(key == value);
needle = args->needle;
if (map->translated_addr + map->size < needle->translated_addr ||
needle->translated_addr + needle->size < map->translated_addr) {
return false;
}
args->result = map;
return true;
}
const DMAMap *iova_tree_find_iova(const IOVATree *tree, const DMAMap *map)
{
IOVATreeFindIOVAArgs args = {
.needle = map,
};
g_tree_foreach(tree->tree, iova_tree_find_address_iterator, &args);
return args.result;
}
const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova)
{
const DMAMap map = { .iova = iova, .size = 0 };
return iova_tree_find(tree, &map);
}
static inline void iova_tree_insert_internal(GTree *gtree, DMAMap *range)
{
/* Key and value are sharing the same range data */
g_tree_insert(gtree, range, range);
}
int iova_tree_insert(IOVATree *tree, const DMAMap *map)
{
DMAMap *new;
if (map->iova + map->size < map->iova || map->perm == IOMMU_NONE) {
return IOVA_ERR_INVALID;
}
/* We don't allow to insert range that overlaps with existings */
if (iova_tree_find(tree, map)) {
return IOVA_ERR_OVERLAP;
}
new = g_new0(DMAMap, 1);
memcpy(new, map, sizeof(*new));
iova_tree_insert_internal(tree->tree, new);
return IOVA_OK;
}
static gboolean iova_tree_traverse(gpointer key, gpointer value,
gpointer data)
{
iova_tree_iterator iterator = data;
DMAMap *map = key;
g_assert(key == value);
return iterator(map);
}
void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator)
{
g_tree_foreach(tree->tree, iova_tree_traverse, iterator);
}
void iova_tree_remove(IOVATree *tree, const DMAMap *map)
{
const DMAMap *overlap;
while ((overlap = iova_tree_find(tree, map))) {
g_tree_remove(tree->tree, overlap);
}
}
/**
* Try to find an unallocated IOVA range between prev and this elements.
*
* @args: Arguments to allocation
*
* Cases:
*
* (1) !prev, !this: No entries allocated, always succeed
*
* (2) !prev, this: We're iterating at the 1st element.
*
* (3) prev, !this: We're iterating at the last element.
*
* (4) prev, this: this is the most common case, we'll try to find a hole
* between "prev" and "this" mapping.
*
* Note that this function assumes the last valid iova is HWADDR_MAX, but it
* searches linearly so it's easy to discard the result if it's not the case.
*/
static void iova_tree_alloc_map_in_hole(struct IOVATreeAllocArgs *args)
{
const DMAMap *prev = args->prev, *this = args->this;
uint64_t hole_start, hole_last;
if (this && this->iova + this->size < args->iova_begin) {
return;
}
hole_start = MAX(prev ? prev->iova + prev->size + 1 : 0, args->iova_begin);
hole_last = this ? this->iova : HWADDR_MAX;
if (hole_last - hole_start > args->new_size) {
args->iova_result = hole_start;
args->iova_found = true;
}
}
/**
* Foreach dma node in the tree, compare if there is a hole with its previous
* node (or minimum iova address allowed) and the node.
*
* @key: Node iterating
* @value: Node iterating
* @pargs: Struct to communicate with the outside world
*
* Return: false to keep iterating, true if needs break.
*/
static gboolean iova_tree_alloc_traverse(gpointer key, gpointer value,
gpointer pargs)
{
struct IOVATreeAllocArgs *args = pargs;
DMAMap *node = value;
assert(key == value);
iova_tree_alloc_args_iterate(args, node);
iova_tree_alloc_map_in_hole(args);
return args->iova_found;
}
int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
hwaddr iova_last)
{
struct IOVATreeAllocArgs args = {
.new_size = map->size,
.iova_begin = iova_begin,
};
if (unlikely(iova_last < iova_begin)) {
return IOVA_ERR_INVALID;
}
/*
* Find a valid hole for the mapping
*
* Assuming low iova_begin, so no need to do a binary search to
* locate the first node.
*
* TODO: Replace all this with g_tree_node_first/next/last when available
* (from glib since 2.68). To do it with g_tree_foreach complicates the
* code a lot.
*
*/
g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
if (!args.iova_found) {
/*
* Either tree is empty or the last hole is still not checked.
* g_tree_foreach does not compare (last, iova_last] range, so we check
* it here.
*/
iova_tree_alloc_args_iterate(&args, NULL);
iova_tree_alloc_map_in_hole(&args);
}
if (!args.iova_found || args.iova_result + map->size > iova_last) {
return IOVA_ERR_NOMEM;
}
map->iova = args.iova_result;
return iova_tree_insert(tree, map);
}
void iova_tree_destroy(IOVATree *tree)
{
g_tree_destroy(tree->tree);
g_free(tree);
}
