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#include <net/netmem.h>
14#include <net/netdev_netlink.h>
15
16struct netlink_ext_ack;
17
18struct net_devmem_dmabuf_binding {
19 struct dma_buf *dmabuf;
20 struct dma_buf_attachment *attachment;
21 struct sg_table *sgt;
22 struct net_device *dev;
23 struct gen_pool *chunk_pool;
24 /* Protect dev */
25 struct mutex lock;
26
27 /* The user holds a ref (via the netlink API) for as long as they want
28 * the binding to remain alive. Each page pool using this binding holds
29 * a ref to keep the binding alive. The page_pool does not release the
30 * ref until all the net_iovs allocated from this binding are released
31 * back to the page_pool.
32 *
33 * The binding undos itself and unmaps the underlying dmabuf once all
34 * those refs are dropped and the binding is no longer desired or in
35 * use.
36 *
37 * net_devmem_get_net_iov() on dmabuf net_iovs will increment this
38 * reference, making sure that the binding remains alive until all the
39 * net_iovs are no longer used. net_iovs allocated from this binding
40 * that are stuck in the TX path for any reason (such as awaiting
41 * retransmits) hold a reference to the binding until the skb holding
42 * them is freed.
43 */
44 refcount_t ref;
45
46 /* The list of bindings currently active. Used for netlink to notify us
47 * of the user dropping the bind.
48 */
49 struct list_head list;
50
51 /* rxq's this binding is active on. */
52 struct xarray bound_rxqs;
53
54 /* ID of this binding. Globally unique to all bindings currently
55 * active.
56 */
57 u32 id;
58
59 /* DMA direction, FROM_DEVICE for Rx binding, TO_DEVICE for Tx. */
60 enum dma_data_direction direction;
61
62 /* Array of net_iov pointers for this binding, sorted by virtual
63 * address. This array is convenient to map the virtual addresses to
64 * net_iovs in the TX path.
65 */
66 struct net_iov **tx_vec;
67
68 struct work_struct unbind_w;
69};
70
71#if defined(CONFIG_NET_DEVMEM)
72/* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist
73 * entry from the dmabuf is inserted into the genpool as a chunk, and needs
74 * this owner struct to keep track of some metadata necessary to create
75 * allocations from this chunk.
76 */
77struct dmabuf_genpool_chunk_owner {
78 struct net_iov_area area;
79 struct net_devmem_dmabuf_binding *binding;
80
81 /* dma_addr of the start of the chunk. */
82 dma_addr_t base_dma_addr;
83};
84
85void __net_devmem_dmabuf_binding_free(struct work_struct *wq);
86struct net_devmem_dmabuf_binding *
87net_devmem_bind_dmabuf(struct net_device *dev,
88 struct device *dma_dev,
89 enum dma_data_direction direction,
90 unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
91 struct netlink_ext_ack *extack);
92struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id);
93void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
94int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
95 struct net_devmem_dmabuf_binding *binding,
96 struct netlink_ext_ack *extack);
97
98static inline struct dmabuf_genpool_chunk_owner *
99net_devmem_iov_to_chunk_owner(const struct net_iov *niov)
100{
101 struct net_iov_area *owner = net_iov_owner(niov);
102
103 return container_of(owner, struct dmabuf_genpool_chunk_owner, area);
104}
105
106static inline struct net_devmem_dmabuf_binding *
107net_devmem_iov_binding(const struct net_iov *niov)
108{
109 return net_devmem_iov_to_chunk_owner(niov)->binding;
110}
111
112static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
113{
114 return net_devmem_iov_binding(niov)->id;
115}
116
117static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
118{
119 struct net_iov_area *owner = net_iov_owner(niov);
120
121 return owner->base_virtual +
122 ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
123}
124
125static inline bool
126net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
127{
128 return refcount_inc_not_zero(r: &binding->ref);
129}
130
131static inline void
132net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
133{
134 if (!refcount_dec_and_test(r: &binding->ref))
135 return;
136
137 INIT_WORK(&binding->unbind_w, __net_devmem_dmabuf_binding_free);
138 schedule_work(work: &binding->unbind_w);
139}
140
141void net_devmem_get_net_iov(struct net_iov *niov);
142void net_devmem_put_net_iov(struct net_iov *niov);
143
144struct net_iov *
145net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
146void net_devmem_free_dmabuf(struct net_iov *ppiov);
147
148bool net_is_devmem_iov(struct net_iov *niov);
149struct net_devmem_dmabuf_binding *
150net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id);
151struct net_iov *
152net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
153 size_t *off, size_t *size);
154
155#else
156struct net_devmem_dmabuf_binding;
157
158static inline void
159net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
160{
161}
162
163static inline void net_devmem_get_net_iov(struct net_iov *niov)
164{
165}
166
167static inline void net_devmem_put_net_iov(struct net_iov *niov)
168{
169}
170
171static inline struct net_devmem_dmabuf_binding *
172net_devmem_bind_dmabuf(struct net_device *dev,
173 struct device *dma_dev,
174 enum dma_data_direction direction,
175 unsigned int dmabuf_fd,
176 struct netdev_nl_sock *priv,
177 struct netlink_ext_ack *extack)
178{
179 return ERR_PTR(-EOPNOTSUPP);
180}
181
182static inline struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id)
183{
184 return NULL;
185}
186
187static inline void
188net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
189{
190}
191
192static inline int
193net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
194 struct net_devmem_dmabuf_binding *binding,
195 struct netlink_ext_ack *extack)
196
197{
198 return -EOPNOTSUPP;
199}
200
201static inline struct net_iov *
202net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
203{
204 return NULL;
205}
206
207static inline void net_devmem_free_dmabuf(struct net_iov *ppiov)
208{
209}
210
211static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
212{
213 return 0;
214}
215
216static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
217{
218 return 0;
219}
220
221static inline bool net_is_devmem_iov(struct net_iov *niov)
222{
223 return false;
224}
225
226static inline struct net_devmem_dmabuf_binding *
227net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id)
228{
229 return ERR_PTR(-EOPNOTSUPP);
230}
231
232static inline struct net_iov *
233net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
234 size_t *off, size_t *size)
235{
236 return NULL;
237}
238
239static inline struct net_devmem_dmabuf_binding *
240net_devmem_iov_binding(const struct net_iov *niov)
241{
242 return NULL;
243}
244#endif
245
246#endif /* _NET_DEVMEM_H */
247

source code of linux/net/core/devmem.h