1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * Device memory TCP support
4 *
5 * Authors: Mina Almasry <almasrymina@google.com>
6 * Willem de Bruijn <willemb@google.com>
7 * Kaiyuan Zhang <kaiyuanz@google.com>
8 *
9 */
10 #ifndef _NET_DEVMEM_H
11 #define _NET_DEVMEM_H
12
13 struct netlink_ext_ack;
14
15 struct net_devmem_dmabuf_binding {
16 struct dma_buf *dmabuf;
17 struct dma_buf_attachment *attachment;
18 struct sg_table *sgt;
19 struct net_device *dev;
20 struct gen_pool *chunk_pool;
21
22 /* The user holds a ref (via the netlink API) for as long as they want
23 * the binding to remain alive. Each page pool using this binding holds
24 * a ref to keep the binding alive. Each allocated net_iov holds a
25 * ref.
26 *
27 * The binding undos itself and unmaps the underlying dmabuf once all
28 * those refs are dropped and the binding is no longer desired or in
29 * use.
30 */
31 refcount_t ref;
32
33 /* The list of bindings currently active. Used for netlink to notify us
34 * of the user dropping the bind.
35 */
36 struct list_head list;
37
38 /* rxq's this binding is active on. */
39 struct xarray bound_rxqs;
40
41 /* ID of this binding. Globally unique to all bindings currently
42 * active.
43 */
44 u32 id;
45 };
46
47 #if defined(CONFIG_NET_DEVMEM)
48 /* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist
49 * entry from the dmabuf is inserted into the genpool as a chunk, and needs
50 * this owner struct to keep track of some metadata necessary to create
51 * allocations from this chunk.
52 */
53 struct dmabuf_genpool_chunk_owner {
54 /* Offset into the dma-buf where this chunk starts. */
55 unsigned long base_virtual;
56
57 /* dma_addr of the start of the chunk. */
58 dma_addr_t base_dma_addr;
59
60 /* Array of net_iovs for this chunk. */
61 struct net_iov *niovs;
62 size_t num_niovs;
63
64 struct net_devmem_dmabuf_binding *binding;
65 };
66
67 void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding);
68 struct net_devmem_dmabuf_binding *
69 net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
70 struct netlink_ext_ack *extack);
71 void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
72 int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
73 struct net_devmem_dmabuf_binding *binding,
74 struct netlink_ext_ack *extack);
75 void dev_dmabuf_uninstall(struct net_device *dev);
76
77 static inline struct dmabuf_genpool_chunk_owner *
78 net_iov_owner(const struct net_iov *niov)
79 {
80 return niov->owner;
81 }
82
83 static inline unsigned int net_iov_idx(const struct net_iov *niov)
84 {
85 return niov - net_iov_owner(niov)->niovs;
86 }
87
88 static inline struct net_devmem_dmabuf_binding *
89 net_iov_binding(const struct net_iov *niov)
90 {
91 return net_iov_owner(niov)->binding;
92 }
93
94 static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
95 {
96 struct dmabuf_genpool_chunk_owner *owner = net_iov_owner(niov);
97
98 return owner->base_virtual +
99 ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
100 }
101
102 static inline u32 net_iov_binding_id(const struct net_iov *niov)
103 {
104 return net_iov_owner(niov)->binding->id;
105 }
106
107 static inline void
108 net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
109 {
110 refcount_inc(&binding->ref);
111 }
112
113 static inline void
114 net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
115 {
116 if (!refcount_dec_and_test(&binding->ref))
117 return;
118
119 __net_devmem_dmabuf_binding_free(binding);
120 }
121
122 struct net_iov *
123 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
124 void net_devmem_free_dmabuf(struct net_iov *ppiov);
125
126 #else
127 struct net_devmem_dmabuf_binding;
128
129 static inline void
130 __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
131 {
132 }
133
134 static inline struct net_devmem_dmabuf_binding *
135 net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
136 struct netlink_ext_ack *extack)
137 {
138 return ERR_PTR(-EOPNOTSUPP);
139 }
140
141 static inline void
142 net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
143 {
144 }
145
146 static inline int
147 net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
148 struct net_devmem_dmabuf_binding *binding,
149 struct netlink_ext_ack *extack)
150
151 {
152 return -EOPNOTSUPP;
153 }
154
155 static inline void dev_dmabuf_uninstall(struct net_device *dev)
156 {
157 }
158
159 static inline struct net_iov *
160 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
161 {
162 return NULL;
163 }
164
165 static inline void net_devmem_free_dmabuf(struct net_iov *ppiov)
166 {
167 }
168
169 static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
170 {
171 return 0;
172 }
173
174 static inline u32 net_iov_binding_id(const struct net_iov *niov)
175 {
176 return 0;
177 }
178 #endif
179
180 #endif /* _NET_DEVMEM_H */
181
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