1 /*
2  * Copyright 6WIND S.A., 2014
3  *
4  * This work is licensed under the terms of the GNU GPL, version 2 or
5  * (at your option) any later version.  See the COPYING file in the
6  * top-level directory.
7  */
8 
9 #ifndef IVSHMEM_CLIENT_H
10 #define IVSHMEM_CLIENT_H
11 
12 /**
13  * This file provides helper to implement an ivshmem client. It is used
14  * on the host to ask QEMU to send an interrupt to an ivshmem PCI device in a
15  * guest. QEMU also implements an ivshmem client similar to this one, they both
16  * connect to an ivshmem server.
17  *
18  * A standalone ivshmem client based on this file is provided for debug/test
19  * purposes.
20  */
21 
22 #include <sys/select.h>
23 
24 #include "qemu/queue.h"
25 #include "hw/misc/ivshmem.h"
26 
27 /**
28  * Maximum number of notification vectors supported by the client
29  */
30 #define IVSHMEM_CLIENT_MAX_VECTORS 64
31 
32 /**
33  * Structure storing a peer
34  *
35  * Each time a client connects to an ivshmem server, it is advertised to
36  * all connected clients through the unix socket. When our ivshmem
37  * client receives a notification, it creates a IvshmemClientPeer
38  * structure to store the infos of this peer.
39  *
40  * This structure is also used to store the information of our own
41  * client in (IvshmemClient)->local.
42  */
43 typedef struct IvshmemClientPeer {
44     QTAILQ_ENTRY(IvshmemClientPeer) next;    /**< next in list*/
45     int64_t id;                              /**< the id of the peer */
46     int vectors[IVSHMEM_CLIENT_MAX_VECTORS]; /**< one fd per vector */
47     unsigned vectors_count;                  /**< number of vectors */
48 } IvshmemClientPeer;
49 
50 typedef struct IvshmemClient IvshmemClient;
51 
52 /**
53  * Typedef of callback function used when our IvshmemClient receives a
54  * notification from a peer.
55  */
56 typedef void (*IvshmemClientNotifCb)(
57     const IvshmemClient *client,
58     const IvshmemClientPeer *peer,
59     unsigned vect, void *arg);
60 
61 /**
62  * Structure describing an ivshmem client
63  *
64  * This structure stores all information related to our client: the name
65  * of the server unix socket, the list of peers advertised by the
66  * server, our own client information, and a pointer the notification
67  * callback function used when we receive a notification from a peer.
68  */
69 struct IvshmemClient {
70     char unix_sock_path[PATH_MAX];      /**< path to unix sock */
71     int sock_fd;                        /**< unix sock filedesc */
72     int shm_fd;                         /**< shm file descriptor */
73 
74     QTAILQ_HEAD(, IvshmemClientPeer) peer_list;    /**< list of peers */
75     IvshmemClientPeer local;            /**< our own infos */
76 
77     IvshmemClientNotifCb notif_cb;      /**< notification callback */
78     void *notif_arg;                    /**< notification argument */
79 
80     bool verbose;                       /**< true to enable debug */
81 };
82 
83 /**
84  * Initialize an ivshmem client
85  *
86  * @client:         A pointer to an uninitialized IvshmemClient structure
87  * @unix_sock_path: The pointer to the unix socket file name
88  * @notif_cb:       If not NULL, the pointer to the function to be called when
89  *                  our IvshmemClient receives a notification from a peer
90  * @notif_arg:      Opaque pointer given as-is to the notification callback
91  *                  function
92  * @verbose:        True to enable debug
93  *
94  * Returns:         0 on success, or a negative value on error
95  */
96 int ivshmem_client_init(IvshmemClient *client, const char *unix_sock_path,
97                         IvshmemClientNotifCb notif_cb, void *notif_arg,
98                         bool verbose);
99 
100 /**
101  * Connect to the server
102  *
103  * Connect to the server unix socket, and read the first initial
104  * messages sent by the server, giving the ID of the client and the file
105  * descriptor of the shared memory.
106  *
107  * @client: The ivshmem client
108  *
109  * Returns: 0 on success, or a negative value on error
110  */
111 int ivshmem_client_connect(IvshmemClient *client);
112 
113 /**
114  * Close connection to the server and free all peer structures
115  *
116  * @client: The ivshmem client
117  */
118 void ivshmem_client_close(IvshmemClient *client);
119 
120 /**
121  * Fill a fd_set with file descriptors to be monitored
122  *
123  * This function will fill a fd_set with all file descriptors
124  * that must be polled (unix server socket and peers eventfd). The
125  * function will not initialize the fd_set, it is up to the caller
126  * to do this.
127  *
128  * @client: The ivshmem client
129  * @fds:    The fd_set to be updated
130  * @maxfd:  Must be set to the max file descriptor + 1 in fd_set. This value is
131  *          updated if this function adds a greater fd in fd_set.
132  */
133 void ivshmem_client_get_fds(const IvshmemClient *client, fd_set *fds,
134                             int *maxfd);
135 
136 /**
137  * Read and handle new messages
138  *
139  * Given a fd_set filled by select(), handle incoming messages from
140  * server or peers.
141  *
142  * @client: The ivshmem client
143  * @fds:    The fd_set containing the file descriptors to be checked. Note
144  *          that file descriptors that are not related to our client are
145  *          ignored.
146  * @maxfd:  The maximum fd in fd_set, plus one.
147  *
148  * Returns: 0 on success, or a negative value on error
149  */
150 int ivshmem_client_handle_fds(IvshmemClient *client, fd_set *fds, int maxfd);
151 
152 /**
153  * Send a notification to a vector of a peer
154  *
155  * @client: The ivshmem client
156  * @peer:   The peer to be notified
157  * @vector: The number of the vector
158  *
159  * Returns: 0 on success, or a negative value on error
160  */
161 int ivshmem_client_notify(const IvshmemClient *client,
162                           const IvshmemClientPeer *peer, unsigned vector);
163 
164 /**
165  * Send a notification to all vectors of a peer
166  *
167  * @client: The ivshmem client
168  * @peer:   The peer to be notified
169  *
170  * Returns: 0 on success, or a negative value on error (at least one
171  *          notification failed)
172  */
173 int ivshmem_client_notify_all_vects(const IvshmemClient *client,
174                                     const IvshmemClientPeer *peer);
175 
176 /**
177  * Broadcast a notification to all vectors of all peers
178  *
179  * @client: The ivshmem client
180  *
181  * Returns: 0 on success, or a negative value on error (at least one
182  *          notification failed)
183  */
184 int ivshmem_client_notify_broadcast(const IvshmemClient *client);
185 
186 /**
187  * Search a peer from its identifier
188  *
189  * Return the peer structure from its peer_id. If the given peer_id is
190  * the local id, the function returns the local peer structure.
191  *
192  * @client:  The ivshmem client
193  * @peer_id: The identifier of the peer structure
194  *
195  * Returns:  The peer structure, or NULL if not found
196  */
197 IvshmemClientPeer *
198 ivshmem_client_search_peer(IvshmemClient *client, int64_t peer_id);
199 
200 /**
201  * Dump information of this ivshmem client on stdout
202  *
203  * Dump the id and the vectors of the given ivshmem client and the list
204  * of its peers and their vectors on stdout.
205  *
206  * @client: The ivshmem client
207  */
208 void ivshmem_client_dump(const IvshmemClient *client);
209 
210 #endif /* IVSHMEM_CLIENT_H */
211