? 2021/10/30 ??2:35, Eugenio P?rez ??:> 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 P?rez <eperezma at redhat.com>
> ---
> include/qemu/iova-tree.h | 17 +++++
> util/iova-tree.c | 139 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 156 insertions(+)
>
> 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 */
I think we need a better name other than "NOMEM", since it's
actually
means there's no sufficient hole for the range?
>
> 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_alloc_map" seems better.
> /**
> * iova_tree_destroy:
> *
> diff --git a/util/iova-tree.c b/util/iova-tree.c
> index 23ea35b7a4..27c921c4e2 100644
> --- a/util/iova-tree.c
> +++ b/util/iova-tree.c
> @@ -16,6 +16,36 @@ 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;
> +
> + /* The last addressable allowed in the allocation */
> + hwaddr iova_last;
> +
> + /* Previously-to-last iterated map, can be NULL in the first node */
> + const DMAMap *hole_left;
> +
> + /* Last iterated map */
> + const DMAMap *hole_right;
Any reason we can move those to IOVATree structure, it can simplify a
lot of things.
> +};
> +
> +/**
> + * Iterate args to tne 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->hole_left = args->hole_right;
> + args->hole_right = next;
> +}
> +
> static int iova_tree_compare(gconstpointer a, gconstpointer b, gpointer
data)
> {
> const DMAMap *m1 = a, *m2 = b;
> @@ -107,6 +137,115 @@ int iova_tree_remove(IOVATree *tree, const DMAMap
*map)
> return IOVA_OK;
> }
>
> +/**
> + * Try to accomodate a map of size ret->size in a hole between
> + * max(end(hole_left), iova_start).
> + *
> + * @args Arguments to allocation
> + */
> +static bool iova_tree_alloc_map_in_hole(const struct IOVATreeAllocArgs
*args)
> +{
> + const DMAMap *left = args->hole_left, *right = args->hole_right;
> + uint64_t hole_start, hole_last;
> +
> + if (right && right->iova + right->size <
args->iova_begin) {
> + return false;
> + }
> +
> + if (left && left->iova > args->iova_last) {
> + return false;
> + }
> +
> + hole_start = MAX(left ? left->iova + left->size + 1 : 0,
args->iova_begin);
> + hole_last = MIN(right ? right->iova : HWADDR_MAX,
args->iova_last);
> +
> + if (hole_last - hole_start > args->new_size) {
> + /* We found a valid hole. */
> + return true;
> + }
> +
> + /* Keep iterating */
> + return false;
> +}
> +
> +/**
> + * Foreach dma node in the tree, compare if there is a hole wit 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);
> + if (args->hole_left && args->hole_left->iova >
args->iova_last) {
> + return true;
> + }
> +
> + if (iova_tree_alloc_map_in_hole(args)) {
> + return true;
> + }
> +
> + return false;
> +}
> +
> +int iova_tree_alloc(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
> + hwaddr iova_last)
> +{
> + struct IOVATreeAllocArgs args = {
> + .new_size = map->size,
> + .iova_begin = iova_begin,
> + .iova_last = iova_last,
> + };
> +
> + if (iova_begin == 0) {
> + /* Some devices does not like addr 0 */
> + iova_begin += qemu_real_host_page_size;
> + }
> +
> + assert(iova_begin < iova_last);
> +
> + /*
> + * 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: We can improve the search speed if we save the beginning and
the
> + * end of holes, so we don't iterate over the previous saved ones.
> + *
> + * 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.
To say the truth, the codes in iova_tree_alloc_traverse() is hard to be
reviewed. I think it would be easy to use first/next/last. What we
really need is to calculate the hole between two ranges with handmade
first, last.
Thanks
> + *
> + */
> + g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
> + if (!iova_tree_alloc_map_in_hole(&args)) {
> + /*
> + * 2nd try: Last iteration left args->right as the last DMAMap.
But
> + * (right, end) hole needs to be checked too
> + */
> + iova_tree_alloc_args_iterate(&args, NULL);
> + if (!iova_tree_alloc_map_in_hole(&args)) {
> + return IOVA_ERR_NOMEM;
> + }
> + }
> +
> + map->iova = MAX(iova_begin,
> + args.hole_left ?
> + args.hole_left->iova + args.hole_left->size + 1
: 0);
> + return iova_tree_insert(tree, map);
> +}
> +
> void iova_tree_destroy(IOVATree *tree)
> {
> g_tree_destroy(tree->tree);