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);