static void ivshmem_read(void *opaque, const uint8_t *buf, int size) { IVShmemState *s = opaque; int incoming_fd, tmp_fd; int guest_max_eventfd; long incoming_posn; if (fifo8_is_empty(&s->incoming_fifo) && size == sizeof(incoming_posn)) { memcpy(&incoming_posn, buf, size); } else { const uint8_t *p; uint32_t num; IVSHMEM_DPRINTF("short read of %d bytes\n", size); num = MAX(size, sizeof(long) - fifo8_num_used(&s->incoming_fifo)); fifo8_push_all(&s->incoming_fifo, buf, num); if (fifo8_num_used(&s->incoming_fifo) < sizeof(incoming_posn)) { return; } size -= num; buf += num; p = fifo8_pop_buf(&s->incoming_fifo, sizeof(incoming_posn), &num); g_assert(num == sizeof(incoming_posn)); memcpy(&incoming_posn, p, sizeof(incoming_posn)); if (size > 0) { fifo8_push_all(&s->incoming_fifo, buf, size); } } if (incoming_posn < -1) { IVSHMEM_DPRINTF("invalid incoming_posn %ld\n", incoming_posn); return; } /* pick off s->server_chr->msgfd and store it, posn should accompany msg */ tmp_fd = qemu_chr_fe_get_msgfd(s->server_chr); IVSHMEM_DPRINTF("posn is %ld, fd is %d\n", incoming_posn, tmp_fd); /* make sure we have enough space for this guest */ if (incoming_posn >= s->nb_peers) { if (increase_dynamic_storage(s, incoming_posn) < 0) { error_report("increase_dynamic_storage() failed"); if (tmp_fd != -1) { } return; } } if (tmp_fd == -1) { /* if posn is positive and unseen before then this is our posn*/ if ((incoming_posn >= 0) && (s->peers[incoming_posn].eventfds == NULL)) { /* receive our posn */ s->vm_id = incoming_posn; return; } else { /* otherwise an fd == -1 means an existing guest has gone away */ IVSHMEM_DPRINTF("posn %ld has gone away\n", incoming_posn); close_guest_eventfds(s, incoming_posn); return; } } /* because of the implementation of get_msgfd, we need a dup */ incoming_fd = dup(tmp_fd); if (incoming_fd == -1) { fprintf(stderr, "could not allocate file descriptor %s\n", strerror(errno)); return; } /* if the position is -1, then it's shared memory region fd */ if (incoming_posn == -1) { void * map_ptr; s->max_peer = 0; if (check_shm_size(s, incoming_fd) == -1) { exit(-1); } /* mmap the region and map into the BAR2 */ map_ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED, incoming_fd, 0); memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), "ivshmem.bar2", s->ivshmem_size, map_ptr); vmstate_register_ram(&s->ivshmem, DEVICE(s)); IVSHMEM_DPRINTF("guest h/w addr = %p, size = %" PRIu64 "\n", map_ptr, s->ivshmem_size); memory_region_add_subregion(&s->bar, 0, &s->ivshmem); /* only store the fd if it is successfully mapped */ s->shm_fd = incoming_fd; return; } /* each guest has an array of eventfds, and we keep track of how many * guests for each VM */ guest_max_eventfd = s->peers[incoming_posn].nb_eventfds; if (guest_max_eventfd == 0) { /* one eventfd per MSI vector */ s->peers[incoming_posn].eventfds = g_new(EventNotifier, s->vectors); } /* this is an eventfd for a particular guest VM */ IVSHMEM_DPRINTF("eventfds[%ld][%d] = %d\n", incoming_posn, guest_max_eventfd, incoming_fd); event_notifier_init_fd(&s->peers[incoming_posn].eventfds[guest_max_eventfd], incoming_fd); /* increment count for particular guest */ s->peers[incoming_posn].nb_eventfds++; /* keep track of the maximum VM ID */ if (incoming_posn > s->max_peer) { s->max_peer = incoming_posn; } if (incoming_posn == s->vm_id) { s->eventfd_chr[guest_max_eventfd] = create_eventfd_chr_device(s, &s->peers[s->vm_id].eventfds[guest_max_eventfd], guest_max_eventfd); } if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) { ivshmem_add_eventfd(s, incoming_posn, guest_max_eventfd); } }