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![Eugenio Pérez](/assets/img/avatar_default.png)
This function does the reverse operation of iova_tree_find: To look for a mapping that match a translated address so we can do the reverse. This have linear complexity instead of logarithmic, but it supports overlapping HVA. Future developments could reduce it. Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
285 lines
7 KiB
C
285 lines
7 KiB
C
/*
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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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#include "qemu/osdep.h"
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#include "qemu/iova-tree.h"
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struct IOVATree {
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GTree *tree;
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};
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/* Args to pass to iova_tree_alloc foreach function. */
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struct IOVATreeAllocArgs {
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/* Size of the desired allocation */
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size_t new_size;
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/* The minimum address allowed in the allocation */
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hwaddr iova_begin;
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/* Map at the left of the hole, can be NULL if "this" is first one */
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const DMAMap *prev;
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/* Map at the right of the hole, can be NULL if "prev" is the last one */
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const DMAMap *this;
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/* If found, we fill in the IOVA here */
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hwaddr iova_result;
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/* Whether have we found a valid IOVA */
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bool iova_found;
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};
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typedef struct IOVATreeFindIOVAArgs {
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const DMAMap *needle;
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const DMAMap *result;
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} IOVATreeFindIOVAArgs;
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/**
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* Iterate args to the next hole
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*
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* @args: The alloc arguments
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* @next: The next mapping in the tree. Can be NULL to signal the last one
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*/
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static void iova_tree_alloc_args_iterate(struct IOVATreeAllocArgs *args,
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const DMAMap *next)
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{
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args->prev = args->this;
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args->this = next;
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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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if (m1->iova > m2->iova + m2->size) {
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return 1;
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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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/* Overlapped */
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return 0;
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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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/* 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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return iova_tree;
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}
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const DMAMap *iova_tree_find(const IOVATree *tree, const 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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static gboolean iova_tree_find_address_iterator(gpointer key, gpointer value,
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gpointer data)
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{
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const DMAMap *map = key;
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IOVATreeFindIOVAArgs *args = data;
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const DMAMap *needle;
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g_assert(key == value);
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needle = args->needle;
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if (map->translated_addr + map->size < needle->translated_addr ||
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needle->translated_addr + needle->size < map->translated_addr) {
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return false;
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}
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args->result = map;
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return true;
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}
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const DMAMap *iova_tree_find_iova(const IOVATree *tree, const DMAMap *map)
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{
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IOVATreeFindIOVAArgs args = {
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.needle = map,
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};
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g_tree_foreach(tree->tree, iova_tree_find_address_iterator, &args);
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return args.result;
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}
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const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova)
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{
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const DMAMap map = { .iova = iova, .size = 0 };
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return iova_tree_find(tree, &map);
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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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int iova_tree_insert(IOVATree *tree, const DMAMap *map)
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{
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DMAMap *new;
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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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/* 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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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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return IOVA_OK;
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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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g_assert(key == value);
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return iterator(map);
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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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int iova_tree_remove(IOVATree *tree, const DMAMap *map)
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{
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const DMAMap *overlap;
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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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return IOVA_OK;
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}
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/**
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* Try to find an unallocated IOVA range between prev and this elements.
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*
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* @args: Arguments to allocation
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*
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* Cases:
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*
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* (1) !prev, !this: No entries allocated, always succeed
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*
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* (2) !prev, this: We're iterating at the 1st element.
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*
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* (3) prev, !this: We're iterating at the last element.
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*
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* (4) prev, this: this is the most common case, we'll try to find a hole
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* between "prev" and "this" mapping.
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*
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* Note that this function assumes the last valid iova is HWADDR_MAX, but it
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* searches linearly so it's easy to discard the result if it's not the case.
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*/
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static void iova_tree_alloc_map_in_hole(struct IOVATreeAllocArgs *args)
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{
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const DMAMap *prev = args->prev, *this = args->this;
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uint64_t hole_start, hole_last;
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if (this && this->iova + this->size < args->iova_begin) {
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return;
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}
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hole_start = MAX(prev ? prev->iova + prev->size + 1 : 0, args->iova_begin);
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hole_last = this ? this->iova : HWADDR_MAX;
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if (hole_last - hole_start > args->new_size) {
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args->iova_result = hole_start;
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args->iova_found = true;
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}
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}
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/**
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* Foreach dma node in the tree, compare if there is a hole with its previous
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* node (or minimum iova address allowed) and the node.
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*
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* @key: Node iterating
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* @value: Node iterating
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* @pargs: Struct to communicate with the outside world
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*
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* Return: false to keep iterating, true if needs break.
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*/
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static gboolean iova_tree_alloc_traverse(gpointer key, gpointer value,
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gpointer pargs)
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{
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struct IOVATreeAllocArgs *args = pargs;
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DMAMap *node = value;
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assert(key == value);
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iova_tree_alloc_args_iterate(args, node);
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iova_tree_alloc_map_in_hole(args);
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return args->iova_found;
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}
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int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
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hwaddr iova_last)
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{
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struct IOVATreeAllocArgs args = {
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.new_size = map->size,
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.iova_begin = iova_begin,
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};
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if (unlikely(iova_last < iova_begin)) {
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return IOVA_ERR_INVALID;
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}
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/*
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* Find a valid hole for the mapping
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*
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* Assuming low iova_begin, so no need to do a binary search to
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* locate the first node.
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*
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* TODO: Replace all this with g_tree_node_first/next/last when available
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* (from glib since 2.68). To do it with g_tree_foreach complicates the
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* code a lot.
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*
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*/
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g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
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if (!args.iova_found) {
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/*
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* Either tree is empty or the last hole is still not checked.
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* g_tree_foreach does not compare (last, iova_last] range, so we check
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* it here.
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*/
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iova_tree_alloc_args_iterate(&args, NULL);
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iova_tree_alloc_map_in_hole(&args);
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}
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if (!args.iova_found || args.iova_result + map->size > iova_last) {
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return IOVA_ERR_NOMEM;
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}
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map->iova = args.iova_result;
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return iova_tree_insert(tree, map);
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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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