1/*-
2 * SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0
3 *
4 * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
5 *
6 * This software is available to you under a choice of one of two
7 * licenses.  You may choose to be licensed under the terms of the GNU
8 * General Public License (GPL) Version 2, available from the file
9 * COPYING in the main directory of this source tree, or the
10 * OpenIB.org BSD license below:
11 *
12 *     Redistribution and use in source and binary forms, with or
13 *     without modification, are permitted provided that the following
14 *     conditions are met:
15 *
16 *      - Redistributions of source code must retain the above
17 *        copyright notice, this list of conditions and the following
18 *        disclaimer.
19 *
20 *      - Redistributions in binary form must reproduce the above
21 *        copyright notice, this list of conditions and the following
22 *        disclaimer in the documentation and/or other materials
23 *        provided with the distribution.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
26 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
27 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
28 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
29 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
30 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
31 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
32 * SOFTWARE.
33 */
34
35#ifndef IB_UMEM_ODP_H
36#define IB_UMEM_ODP_H
37
38#include <linux/rbtree.h>
39
40#include <rdma/ib_umem.h>
41#include <rdma/ib_verbs.h>
42
43struct umem_odp_node {
44	u64 __subtree_last;
45	struct rb_node rb;
46};
47
48struct ib_umem_odp {
49	/*
50	 * An array of the pages included in the on-demand paging umem.
51	 * Indices of pages that are currently not mapped into the device will
52	 * contain NULL.
53	 */
54	struct page		**page_list;
55	/*
56	 * An array of the same size as page_list, with DMA addresses mapped
57	 * for pages the pages in page_list. The lower two bits designate
58	 * access permissions. See ODP_READ_ALLOWED_BIT and
59	 * ODP_WRITE_ALLOWED_BIT.
60	 */
61	dma_addr_t		*dma_list;
62	/*
63	 * The umem_mutex protects the page_list and dma_list fields of an ODP
64	 * umem, allowing only a single thread to map/unmap pages. The mutex
65	 * also protects access to the mmu notifier counters.
66	 */
67	struct mutex		umem_mutex;
68	void			*private; /* for the HW driver to use. */
69
70	/* When false, use the notifier counter in the ucontext struct. */
71	bool mn_counters_active;
72	int notifiers_seq;
73	int notifiers_count;
74
75	/* A linked list of umems that don't have private mmu notifier
76	 * counters yet. */
77	struct list_head no_private_counters;
78	struct ib_umem		*umem;
79
80	/* Tree tracking */
81	struct umem_odp_node	interval_tree;
82
83	struct completion	notifier_completion;
84	int			dying;
85};
86
87#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
88
89int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem);
90
91void ib_umem_odp_release(struct ib_umem *umem);
92
93/*
94 * The lower 2 bits of the DMA address signal the R/W permissions for
95 * the entry. To upgrade the permissions, provide the appropriate
96 * bitmask to the map_dma_pages function.
97 *
98 * Be aware that upgrading a mapped address might result in change of
99 * the DMA address for the page.
100 */
101#define ODP_READ_ALLOWED_BIT  (1<<0ULL)
102#define ODP_WRITE_ALLOWED_BIT (1<<1ULL)
103
104#define ODP_DMA_ADDR_MASK (~(ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT))
105
106int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 start_offset, u64 bcnt,
107			      u64 access_mask, unsigned long current_seq);
108
109void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 start_offset,
110				 u64 bound);
111
112void rbt_ib_umem_insert(struct umem_odp_node *node, struct rb_root *root);
113void rbt_ib_umem_remove(struct umem_odp_node *node, struct rb_root *root);
114typedef int (*umem_call_back)(struct ib_umem *item, u64 start, u64 end,
115			      void *cookie);
116/*
117 * Call the callback on each ib_umem in the range. Returns the logical or of
118 * the return values of the functions called.
119 */
120int rbt_ib_umem_for_each_in_range(struct rb_root *root, u64 start, u64 end,
121				  umem_call_back cb, void *cookie);
122
123struct umem_odp_node *rbt_ib_umem_iter_first(struct rb_root *root,
124					     u64 start, u64 last);
125struct umem_odp_node *rbt_ib_umem_iter_next(struct umem_odp_node *node,
126					    u64 start, u64 last);
127
128static inline int ib_umem_mmu_notifier_retry(struct ib_umem *item,
129					     unsigned long mmu_seq)
130{
131	/*
132	 * This code is strongly based on the KVM code from
133	 * mmu_notifier_retry. Should be called with
134	 * the relevant locks taken (item->odp_data->umem_mutex
135	 * and the ucontext umem_mutex semaphore locked for read).
136	 */
137
138	/* Do not allow page faults while the new ib_umem hasn't seen a state
139	 * with zero notifiers yet, and doesn't have its own valid set of
140	 * private counters. */
141	if (!item->odp_data->mn_counters_active)
142		return 1;
143
144	if (unlikely(item->odp_data->notifiers_count))
145		return 1;
146	if (item->odp_data->notifiers_seq != mmu_seq)
147		return 1;
148	return 0;
149}
150
151#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
152
153static inline int ib_umem_odp_get(struct ib_ucontext *context,
154				  struct ib_umem *umem)
155{
156	return -EINVAL;
157}
158
159static inline void ib_umem_odp_release(struct ib_umem *umem) {}
160
161#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
162
163#endif /* IB_UMEM_ODP_H */
164