1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (C) 2020 Red Hat, Inc.
3 * Author: Jason Wang <jasowang@redhat.com>
4 *
5 * IOTLB implementation for vhost.
6 */
7#include <linux/slab.h>
8#include <linux/vhost_iotlb.h>
9#include <linux/module.h>
10
11#define MOD_VERSION  "0.1"
12#define MOD_DESC     "VHOST IOTLB"
13#define MOD_AUTHOR   "Jason Wang <jasowang@redhat.com>"
14#define MOD_LICENSE  "GPL v2"
15
16#define START(map) ((map)->start)
17#define LAST(map) ((map)->last)
18
19INTERVAL_TREE_DEFINE(struct vhost_iotlb_map,
20		     rb, __u64, __subtree_last,
21		     START, LAST, static inline, vhost_iotlb_itree);
22
23/**
24 * vhost_iotlb_map_free - remove a map node and free it
25 * @iotlb: the IOTLB
26 * @map: the map that want to be remove and freed
27 */
28void vhost_iotlb_map_free(struct vhost_iotlb *iotlb,
29			  struct vhost_iotlb_map *map)
30{
31	vhost_iotlb_itree_remove(map, &iotlb->root);
32	list_del(&map->link);
33	kfree(map);
34	iotlb->nmaps--;
35}
36EXPORT_SYMBOL_GPL(vhost_iotlb_map_free);
37
38/**
39 * vhost_iotlb_add_range_ctx - add a new range to vhost IOTLB
40 * @iotlb: the IOTLB
41 * @start: start of the IOVA range
42 * @last: last of IOVA range
43 * @addr: the address that is mapped to @start
44 * @perm: access permission of this range
45 * @opaque: the opaque pointer for the new mapping
46 *
47 * Returns an error last is smaller than start or memory allocation
48 * fails
49 */
50int vhost_iotlb_add_range_ctx(struct vhost_iotlb *iotlb,
51			      u64 start, u64 last,
52			      u64 addr, unsigned int perm,
53			      void *opaque)
54{
55	struct vhost_iotlb_map *map;
56
57	if (last < start)
58		return -EFAULT;
59
60	/* If the range being mapped is [0, ULONG_MAX], split it into two entries
61	 * otherwise its size would overflow u64.
62	 */
63	if (start == 0 && last == ULONG_MAX) {
64		u64 mid = last / 2;
65		int err = vhost_iotlb_add_range_ctx(iotlb, start, mid, addr,
66				perm, opaque);
67
68		if (err)
69			return err;
70
71		addr += mid + 1;
72		start = mid + 1;
73	}
74
75	if (iotlb->limit &&
76	    iotlb->nmaps == iotlb->limit &&
77	    iotlb->flags & VHOST_IOTLB_FLAG_RETIRE) {
78		map = list_first_entry(&iotlb->list, typeof(*map), link);
79		vhost_iotlb_map_free(iotlb, map);
80	}
81
82	map = kmalloc(sizeof(*map), GFP_ATOMIC);
83	if (!map)
84		return -ENOMEM;
85
86	map->start = start;
87	map->size = last - start + 1;
88	map->last = last;
89	map->addr = addr;
90	map->perm = perm;
91	map->opaque = opaque;
92
93	iotlb->nmaps++;
94	vhost_iotlb_itree_insert(map, &iotlb->root);
95
96	INIT_LIST_HEAD(&map->link);
97	list_add_tail(&map->link, &iotlb->list);
98
99	return 0;
100}
101EXPORT_SYMBOL_GPL(vhost_iotlb_add_range_ctx);
102
103int vhost_iotlb_add_range(struct vhost_iotlb *iotlb,
104			  u64 start, u64 last,
105			  u64 addr, unsigned int perm)
106{
107	return vhost_iotlb_add_range_ctx(iotlb, start, last,
108					 addr, perm, NULL);
109}
110EXPORT_SYMBOL_GPL(vhost_iotlb_add_range);
111
112/**
113 * vhost_iotlb_del_range - delete overlapped ranges from vhost IOTLB
114 * @iotlb: the IOTLB
115 * @start: start of the IOVA range
116 * @last: last of IOVA range
117 */
118void vhost_iotlb_del_range(struct vhost_iotlb *iotlb, u64 start, u64 last)
119{
120	struct vhost_iotlb_map *map;
121
122	while ((map = vhost_iotlb_itree_iter_first(&iotlb->root,
123						   start, last)))
124		vhost_iotlb_map_free(iotlb, map);
125}
126EXPORT_SYMBOL_GPL(vhost_iotlb_del_range);
127
128/**
129 * vhost_iotlb_init - initialize a vhost IOTLB
130 * @iotlb: the IOTLB that needs to be initialized
131 * @limit: maximum number of IOTLB entries
132 * @flags: VHOST_IOTLB_FLAG_XXX
133 */
134void vhost_iotlb_init(struct vhost_iotlb *iotlb, unsigned int limit,
135		      unsigned int flags)
136{
137	iotlb->root = RB_ROOT_CACHED;
138	iotlb->limit = limit;
139	iotlb->nmaps = 0;
140	iotlb->flags = flags;
141	INIT_LIST_HEAD(&iotlb->list);
142}
143EXPORT_SYMBOL_GPL(vhost_iotlb_init);
144
145/**
146 * vhost_iotlb_alloc - add a new vhost IOTLB
147 * @limit: maximum number of IOTLB entries
148 * @flags: VHOST_IOTLB_FLAG_XXX
149 *
150 * Returns an error is memory allocation fails
151 */
152struct vhost_iotlb *vhost_iotlb_alloc(unsigned int limit, unsigned int flags)
153{
154	struct vhost_iotlb *iotlb = kzalloc(sizeof(*iotlb), GFP_KERNEL);
155
156	if (!iotlb)
157		return NULL;
158
159	vhost_iotlb_init(iotlb, limit, flags);
160
161	return iotlb;
162}
163EXPORT_SYMBOL_GPL(vhost_iotlb_alloc);
164
165/**
166 * vhost_iotlb_reset - reset vhost IOTLB (free all IOTLB entries)
167 * @iotlb: the IOTLB to be reset
168 */
169void vhost_iotlb_reset(struct vhost_iotlb *iotlb)
170{
171	vhost_iotlb_del_range(iotlb, 0ULL, 0ULL - 1);
172}
173EXPORT_SYMBOL_GPL(vhost_iotlb_reset);
174
175/**
176 * vhost_iotlb_free - reset and free vhost IOTLB
177 * @iotlb: the IOTLB to be freed
178 */
179void vhost_iotlb_free(struct vhost_iotlb *iotlb)
180{
181	if (iotlb) {
182		vhost_iotlb_reset(iotlb);
183		kfree(iotlb);
184	}
185}
186EXPORT_SYMBOL_GPL(vhost_iotlb_free);
187
188/**
189 * vhost_iotlb_itree_first - return the first overlapped range
190 * @iotlb: the IOTLB
191 * @start: start of IOVA range
192 * @last: last byte in IOVA range
193 */
194struct vhost_iotlb_map *
195vhost_iotlb_itree_first(struct vhost_iotlb *iotlb, u64 start, u64 last)
196{
197	return vhost_iotlb_itree_iter_first(&iotlb->root, start, last);
198}
199EXPORT_SYMBOL_GPL(vhost_iotlb_itree_first);
200
201/**
202 * vhost_iotlb_itree_next - return the next overlapped range
203 * @map: the starting map node
204 * @start: start of IOVA range
205 * @last: last byte IOVA range
206 */
207struct vhost_iotlb_map *
208vhost_iotlb_itree_next(struct vhost_iotlb_map *map, u64 start, u64 last)
209{
210	return vhost_iotlb_itree_iter_next(map, start, last);
211}
212EXPORT_SYMBOL_GPL(vhost_iotlb_itree_next);
213
214MODULE_VERSION(MOD_VERSION);
215MODULE_DESCRIPTION(MOD_DESC);
216MODULE_AUTHOR(MOD_AUTHOR);
217MODULE_LICENSE(MOD_LICENSE);
218