From 9376bde894e444ebe2d2ec236569b6e55faa4765 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= Date: Mon, 14 Mar 2022 18:34:48 +0100 Subject: [PATCH] util: Add iova_tree_alloc_map MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Pérez Reviewed-by: Peter Xu Acked-by: Michael S. Tsirkin Signed-off-by: Jason Wang --- include/qemu/iova-tree.h | 18 ++++++ util/iova-tree.c | 136 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 154 insertions(+) diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h index 8249edd764..d066400f09 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 */ typedef struct IOVATree IOVATree; typedef struct DMAMap { @@ -119,6 +120,23 @@ const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova); */ void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator); +/** + * iova_tree_alloc_map: + * + * @tree: the iova tree to allocate from + * @map: the new map (as translated addr & size) to allocate in the 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 return error if + * iova tree is out of free contiguous range. The caller gets the assigned iova + * in map->iova. + */ +int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin, + hwaddr iova_end); + /** * iova_tree_destroy: * diff --git a/util/iova-tree.c b/util/iova-tree.c index 23ea35b7a4..139626b46f 100644 --- a/util/iova-tree.c +++ b/util/iova-tree.c @@ -16,6 +16,40 @@ 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; +}; + +/** + * 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; @@ -107,6 +141,108 @@ int iova_tree_remove(IOVATree *tree, const DMAMap *map) return IOVA_OK; } +/** + * 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);