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