static void virtconsole_realize(DeviceState *dev, Error **errp) { VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev); VirtConsole *vcon = VIRTIO_CONSOLE(dev); VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(dev); if (port->id == 0 && !k->is_console) { error_setg(errp, "Port number 0 on virtio-serial devices reserved " "for virtconsole devices for backward compatibility."); return; } if (qemu_chr_fe_backend_connected(&vcon->chr)) { /* * For consoles we don't block guest data transfer just * because nothing is connected - we'll just let it go * whetherever the chardev wants - /dev/null probably. * * For serial ports we need 100% reliable data transfer * so we use the opened/closed signals from chardev to * trigger open/close of the device */ if (k->is_console) { qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read, NULL, chr_be_change, vcon, NULL, true); virtio_serial_open(port); } else { qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read, chr_event, chr_be_change, vcon, NULL, false); } } }
/* Callback function that's called when the guest sends us data */ static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, ssize_t len) { VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port); ssize_t ret; if (!vcon->chr) { /* If there's no backend, we can just say we consumed all data. */ return len; } ret = qemu_chr_fe_write(vcon->chr, buf, len); trace_virtio_console_flush_buf(port->id, len, ret); if (ret < len) { VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); /* * Ideally we'd get a better error code than just -1, but * that's what the chardev interface gives us right now. If * we had a finer-grained message, like -EPIPE, we could close * this connection. */ if (ret < 0) ret = 0; if (!k->is_console) { virtio_serial_throttle_port(port, true); if (!vcon->watch) { vcon->watch = qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, chr_write_unblocked, vcon); } } } return ret; }
/* Callback function that's called when the guest sends us data */ static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, ssize_t len) { VirtConsole *vcon = VIRTIO_CONSOLE(port); ssize_t ret; if (!qemu_chr_fe_backend_connected(&vcon->chr)) { /* If there's no backend, we can just say we consumed all data. */ return len; } ret = qemu_chr_fe_write(&vcon->chr, buf, len); trace_virtio_console_flush_buf(port->id, len, ret); if (ret < len) { VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); /* * Ideally we'd get a better error code than just -1, but * that's what the chardev interface gives us right now. If * we had a finer-grained message, like -EPIPE, we could close * this connection. */ if (ret < 0) ret = 0; /* XXX we should be queuing data to send later for the * console devices too rather than silently dropping * console data on EAGAIN. The Linux virtio-console * hvc driver though does sends with spinlocks held, * so if we enable throttling that'll stall the entire * guest kernel, not merely the process writing to the * console. * * While we could queue data for later write without * enabling throttling, this would result in the guest * being able to trigger arbitrary memory usage in QEMU * buffering data for later writes. * * So fixing this problem likely requires fixing the * Linux virtio-console hvc driver to not hold spinlocks * while writing, and instead merely block the process * that's writing. QEMU would then need some way to detect * if the guest had the fixed driver too, before we can * use throttling on host side. */ if (!k->is_console) { virtio_serial_throttle_port(port, true); if (!vcon->watch) { vcon->watch = qemu_chr_fe_add_watch(&vcon->chr, G_IO_OUT|G_IO_HUP, chr_write_unblocked, vcon); } } } return ret; }
/* Callback function that's called when the guest opens/closes the port */ static void set_guest_connected(VirtIOSerialPort *port, int guest_connected) { VirtConsole *vcon = VIRTIO_CONSOLE(port); DeviceState *dev = DEVICE(port); VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); if (!k->is_console) { qemu_chr_fe_set_open(&vcon->chr, guest_connected); } if (dev->id) { qapi_event_send_vserport_change(dev->id, guest_connected, &error_abort); } }
static int virtconsole_initfn(VirtIOSerialPort *port) { VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port); VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); if (port->id == 0 && !k->is_console) { error_report("Port number 0 on virtio-serial devices reserved for virtconsole devices for backward compatibility."); return -1; } if (vcon->chr) { qemu_chr_add_handlers(vcon->chr, chr_can_read, chr_read, chr_event, vcon); } return 0; }
static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable) { VirtConsole *vcon = VIRTIO_CONSOLE(port); if (!qemu_chr_fe_backend_connected(&vcon->chr)) { return; } if (enable) { VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read, k->is_console ? NULL : chr_event, chr_be_change, vcon, NULL, false); } else { qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL, NULL, NULL, NULL, false); } }
static int chr_be_change(void *opaque) { VirtConsole *vcon = opaque; VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon); VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port); if (k->is_console) { qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read, NULL, chr_be_change, vcon, NULL, true); } else { qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read, chr_event, chr_be_change, vcon, NULL, false); } if (vcon->watch) { g_source_remove(vcon->watch); vcon->watch = qemu_chr_fe_add_watch(&vcon->chr, G_IO_OUT | G_IO_HUP, chr_write_unblocked, vcon); } return 0; }