ivshmem-server.h (5649B)
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_SERVER_H 10 #define IVSHMEM_SERVER_H 11 12 /** 13 * The ivshmem server is a daemon that creates a unix socket in listen 14 * mode. The ivshmem clients (qemu or ivshmem-client) connect to this 15 * unix socket. For each client, the server will create some eventfd 16 * (see EVENTFD(2)), one per vector. These fd are transmitted to all 17 * clients using the SCM_RIGHTS cmsg message. Therefore, each client is 18 * able to send a notification to another client without being 19 * "profixied" by the server. 20 * 21 * We use this mechanism to send interruptions between guests. 22 * qemu is able to transform an event on a eventfd into a PCI MSI-x 23 * interruption in the guest. 24 * 25 * The ivshmem server is also able to share the file descriptor 26 * associated to the ivshmem shared memory. 27 */ 28 29 #include <sys/select.h> 30 31 #include "qemu/event_notifier.h" 32 #include "qemu/queue.h" 33 #include "hw/misc/ivshmem.h" 34 35 /** 36 * Maximum number of notification vectors supported by the server 37 */ 38 #define IVSHMEM_SERVER_MAX_VECTORS 64 39 40 /** 41 * Structure storing a peer 42 * 43 * Each time a client connects to an ivshmem server, a new 44 * IvshmemServerPeer structure is created. This peer and all its 45 * vectors are advertised to all connected clients through the connected 46 * unix sockets. 47 */ 48 typedef struct IvshmemServerPeer { 49 QTAILQ_ENTRY(IvshmemServerPeer) next; /**< next in list*/ 50 int sock_fd; /**< connected unix sock */ 51 int64_t id; /**< the id of the peer */ 52 EventNotifier vectors[IVSHMEM_SERVER_MAX_VECTORS]; /**< one per vector */ 53 unsigned vectors_count; /**< number of vectors */ 54 } IvshmemServerPeer; 55 56 /** 57 * Structure describing an ivshmem server 58 * 59 * This structure stores all information related to our server: the name 60 * of the server unix socket and the list of connected peers. 61 */ 62 typedef struct IvshmemServer { 63 char unix_sock_path[PATH_MAX]; /**< path to unix socket */ 64 int sock_fd; /**< unix sock file descriptor */ 65 char shm_path[PATH_MAX]; /**< path to shm */ 66 bool use_shm_open; 67 size_t shm_size; /**< size of shm */ 68 int shm_fd; /**< shm file descriptor */ 69 unsigned n_vectors; /**< number of vectors */ 70 uint16_t cur_id; /**< id to be given to next client */ 71 bool verbose; /**< true in verbose mode */ 72 QTAILQ_HEAD(, IvshmemServerPeer) peer_list; /**< list of peers */ 73 } IvshmemServer; 74 75 /** 76 * Initialize an ivshmem server 77 * 78 * @server: A pointer to an uninitialized IvshmemServer structure 79 * @unix_sock_path: The pointer to the unix socket file name 80 * @shm_path: Path to the shared memory. The path corresponds to a POSIX 81 * shm name or a hugetlbfs mount point. 82 * @shm_size: Size of shared memory 83 * @n_vectors: Number of interrupt vectors per client 84 * @verbose: True to enable verbose mode 85 * 86 * Returns: 0 on success, or a negative value on error 87 */ 88 int 89 ivshmem_server_init(IvshmemServer *server, const char *unix_sock_path, 90 const char *shm_path, bool use_shm_open, 91 size_t shm_size, unsigned n_vectors, 92 bool verbose); 93 94 /** 95 * Open the shm, then create and bind to the unix socket 96 * 97 * @server: The pointer to the initialized IvshmemServer structure 98 * 99 * Returns: 0 on success, or a negative value on error 100 */ 101 int ivshmem_server_start(IvshmemServer *server); 102 103 /** 104 * Close the server 105 * 106 * Close connections to all clients, close the unix socket and the 107 * shared memory file descriptor. The structure remains initialized, so 108 * it is possible to call ivshmem_server_start() again after a call to 109 * ivshmem_server_close(). 110 * 111 * @server: The ivshmem server 112 */ 113 void ivshmem_server_close(IvshmemServer *server); 114 115 /** 116 * Fill a fd_set with file descriptors to be monitored 117 * 118 * This function will fill a fd_set with all file descriptors that must 119 * be polled (unix server socket and peers unix socket). The function 120 * will not initialize the fd_set, it is up to the caller to do it. 121 * 122 * @server: The ivshmem server 123 * @fds: The fd_set to be updated 124 * @maxfd: Must be set to the max file descriptor + 1 in fd_set. This value is 125 * updated if this function adds a greater fd in fd_set. 126 */ 127 void 128 ivshmem_server_get_fds(const IvshmemServer *server, fd_set *fds, int *maxfd); 129 130 /** 131 * Read and handle new messages 132 * 133 * Given a fd_set (for instance filled by a call to select()), handle 134 * incoming messages from peers. 135 * 136 * @server: The ivshmem server 137 * @fds: The fd_set containing the file descriptors to be checked. Note that 138 * file descriptors that are not related to our server are ignored. 139 * @maxfd: The maximum fd in fd_set, plus one. 140 * 141 * Returns: 0 on success, or a negative value on error 142 */ 143 int ivshmem_server_handle_fds(IvshmemServer *server, fd_set *fds, int maxfd); 144 145 /** 146 * Search a peer from its identifier 147 * 148 * @server: The ivshmem server 149 * @peer_id: The identifier of the peer structure 150 * 151 * Returns: The peer structure, or NULL if not found 152 */ 153 IvshmemServerPeer * 154 ivshmem_server_search_peer(IvshmemServer *server, int64_t peer_id); 155 156 /** 157 * Dump information of this ivshmem server and its peers on stdout 158 * 159 * @server: The ivshmem server 160 */ 161 void ivshmem_server_dump(const IvshmemServer *server); 162 163 #endif /* IVSHMEM_SERVER_H */