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 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 bool use_shm_open; 70 size_t shm_size; /**< size of shm */ 71 int shm_fd; /**< shm file descriptor */ 72 unsigned n_vectors; /**< number of vectors */ 73 uint16_t cur_id; /**< id to be given to next client */ 74 bool verbose; /**< true in verbose mode */ 75 IvshmemServerPeerList peer_list; /**< list of peers */ 76 } IvshmemServer; 77 78 /** 79 * Initialize an ivshmem server 80 * 81 * @server: A pointer to an uninitialized IvshmemServer structure 82 * @unix_sock_path: The pointer to the unix socket file name 83 * @shm_path: Path to the shared memory. The path corresponds to a POSIX 84 * shm name or a hugetlbfs mount point. 85 * @shm_size: Size of shared memory 86 * @n_vectors: Number of interrupt vectors per client 87 * @verbose: True to enable verbose mode 88 * 89 * Returns: 0 on success, or a negative value on error 90 */ 91 int 92 ivshmem_server_init(IvshmemServer *server, const char *unix_sock_path, 93 const char *shm_path, bool use_shm_open, 94 size_t shm_size, unsigned n_vectors, 95 bool verbose); 96 97 /** 98 * Open the shm, then create and bind to the unix socket 99 * 100 * @server: The pointer to the initialized IvshmemServer structure 101 * 102 * Returns: 0 on success, or a negative value on error 103 */ 104 int ivshmem_server_start(IvshmemServer *server); 105 106 /** 107 * Close the server 108 * 109 * Close connections to all clients, close the unix socket and the 110 * shared memory file descriptor. The structure remains initialized, so 111 * it is possible to call ivshmem_server_start() again after a call to 112 * ivshmem_server_close(). 113 * 114 * @server: The ivshmem server 115 */ 116 void ivshmem_server_close(IvshmemServer *server); 117 118 /** 119 * Fill a fd_set with file descriptors to be monitored 120 * 121 * This function will fill a fd_set with all file descriptors that must 122 * be polled (unix server socket and peers unix socket). The function 123 * will not initialize the fd_set, it is up to the caller to do it. 124 * 125 * @server: The ivshmem server 126 * @fds: The fd_set to be updated 127 * @maxfd: Must be set to the max file descriptor + 1 in fd_set. This value is 128 * updated if this function adds a greater fd in fd_set. 129 */ 130 void 131 ivshmem_server_get_fds(const IvshmemServer *server, fd_set *fds, int *maxfd); 132 133 /** 134 * Read and handle new messages 135 * 136 * Given a fd_set (for instance filled by a call to select()), handle 137 * incoming messages from peers. 138 * 139 * @server: The ivshmem server 140 * @fds: The fd_set containing the file descriptors to be checked. Note that 141 * file descriptors that are not related to our server are ignored. 142 * @maxfd: The maximum fd in fd_set, plus one. 143 * 144 * Returns: 0 on success, or a negative value on error 145 */ 146 int ivshmem_server_handle_fds(IvshmemServer *server, fd_set *fds, int maxfd); 147 148 /** 149 * Search a peer from its identifier 150 * 151 * @server: The ivshmem server 152 * @peer_id: The identifier of the peer structure 153 * 154 * Returns: The peer structure, or NULL if not found 155 */ 156 IvshmemServerPeer * 157 ivshmem_server_search_peer(IvshmemServer *server, int64_t peer_id); 158 159 /** 160 * Dump information of this ivshmem server and its peers on stdout 161 * 162 * @server: The ivshmem server 163 */ 164 void ivshmem_server_dump(const IvshmemServer *server); 165 166 #endif /* IVSHMEM_SERVER_H */ 167