qemu

iova-tree.c (7185B)

---

 /*
  * 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, 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);
 }