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 beeing 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 <limits.h> 30 #include <sys/select.h> 31 #include <stdint.h> 32 #include <stdbool.h> 33 34 #include "qemu/event_notifier.h" 35 #include "qemu/queue.h" 36 #include "hw/misc/ivshmem.h" 37 38 /** 39 * Maximum number of notification vectors supported by the server 40 */ 41 #define IVSHMEM_SERVER_MAX_VECTORS 64 42 43 /** 44 * Structure storing a peer 45 * 46 * Each time a client connects to an ivshmem server, a new 47 * IvshmemServerPeer structure is created. This peer and all its 48 * vectors are advertised to all connected clients through the connected 49 * unix sockets. 50 */ 51 typedef struct IvshmemServerPeer { 52 QTAILQ_ENTRY(IvshmemServerPeer) next; /**< next in list*/ 53 int sock_fd; /**< connected unix sock */ 54 int64_t id; /**< the id of the peer */ 55 EventNotifier vectors[IVSHMEM_SERVER_MAX_VECTORS]; /**< one per vector */ 56 unsigned vectors_count; /**< number of vectors */ 57 } IvshmemServerPeer; 58 QTAILQ_HEAD(IvshmemServerPeerList, IvshmemServerPeer); 59 60 typedef struct IvshmemServerPeerList IvshmemServerPeerList; 61 62 /** 63 * Structure describing an ivshmem server 64 * 65 * This structure stores all information related to our server: the name 66 * of the server unix socket and the list of connected peers. 67 */ 68 typedef struct IvshmemServer { 69 char unix_sock_path[PATH_MAX]; /**< path to unix socket */ 70 int sock_fd; /**< unix sock file descriptor */ 71 char shm_path[PATH_MAX]; /**< path to shm */ 72 size_t shm_size; /**< size of shm */ 73 int shm_fd; /**< shm file descriptor */ 74 unsigned n_vectors; /**< number of vectors */ 75 uint16_t cur_id; /**< id to be given to next client */ 76 bool verbose; /**< true in verbose mode */ 77 IvshmemServerPeerList peer_list; /**< list of peers */ 78 } IvshmemServer; 79 80 /** 81 * Initialize an ivshmem server 82 * 83 * @server: A pointer to an uninitialized IvshmemServer structure 84 * @unix_sock_path: The pointer to the unix socket file name 85 * @shm_path: Path to the shared memory. The path corresponds to a POSIX 86 * shm name or a hugetlbfs mount point. 87 * @shm_size: Size of shared memory 88 * @n_vectors: Number of interrupt vectors per client 89 * @verbose: True to enable verbose mode 90 * 91 * Returns: 0 on success, or a negative value on error 92 */ 93 int 94 ivshmem_server_init(IvshmemServer *server, const char *unix_sock_path, 95 const char *shm_path, size_t shm_size, unsigned n_vectors, 96 bool verbose); 97 98 /** 99 * Open the shm, then create and bind to the unix socket 100 * 101 * @server: The pointer to the initialized IvshmemServer structure 102 * 103 * Returns: 0 on success, or a negative value on error 104 */ 105 int ivshmem_server_start(IvshmemServer *server); 106 107 /** 108 * Close the server 109 * 110 * Close connections to all clients, close the unix socket and the 111 * shared memory file descriptor. The structure remains initialized, so 112 * it is possible to call ivshmem_server_start() again after a call to 113 * ivshmem_server_close(). 114 * 115 * @server: The ivshmem server 116 */ 117 void ivshmem_server_close(IvshmemServer *server); 118 119 /** 120 * Fill a fd_set with file descriptors to be monitored 121 * 122 * This function will fill a fd_set with all file descriptors that must 123 * be polled (unix server socket and peers unix socket). The function 124 * will not initialize the fd_set, it is up to the caller to do it. 125 * 126 * @server: The ivshmem server 127 * @fds: The fd_set to be updated 128 * @maxfd: Must be set to the max file descriptor + 1 in fd_set. This value is 129 * updated if this function adds a greater fd in fd_set. 130 */ 131 void 132 ivshmem_server_get_fds(const IvshmemServer *server, fd_set *fds, int *maxfd); 133 134 /** 135 * Read and handle new messages 136 * 137 * Given a fd_set (for instance filled by a call to select()), handle 138 * incoming messages from peers. 139 * 140 * @server: The ivshmem server 141 * @fds: The fd_set containing the file descriptors to be checked. Note that 142 * file descriptors that are not related to our server are ignored. 143 * @maxfd: The maximum fd in fd_set, plus one. 144 * 145 * Returns: 0 on success, or a negative value on error 146 */ 147 int ivshmem_server_handle_fds(IvshmemServer *server, fd_set *fds, int maxfd); 148 149 /** 150 * Search a peer from its identifier 151 * 152 * @server: The ivshmem server 153 * @peer_id: The identifier of the peer structure 154 * 155 * Returns: The peer structure, or NULL if not found 156 */ 157 IvshmemServerPeer * 158 ivshmem_server_search_peer(IvshmemServer *server, int64_t peer_id); 159 160 /** 161 * Dump information of this ivshmem server and its peers on stdout 162 * 163 * @server: The ivshmem server 164 */ 165 void ivshmem_server_dump(const IvshmemServer *server); 166 167 #endif /* _IVSHMEM_SERVER_H_ */ 168