contrib/ivshmem-server/ivshmem-server.h

   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 */