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 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_ */