qemu

virtio-serial-bus.c (34866B)

---

 /*
  * A bus for connecting virtio serial and console ports
  *
  * Copyright (C) 2009, 2010 Red Hat, Inc.
  *
  * Author(s):
  *  Amit Shah <amit.shah@redhat.com>
  *
  * Some earlier parts are:
  *  Copyright IBM, Corp. 2008
  * authored by
  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
  *
  * Contributions after 2012-01-13 are licensed under the terms of the
  * GNU GPL, version 2 or (at your option) any later version.
  */
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/iov.h"
 #include "qemu/main-loop.h"
 #include "qemu/module.h"
 #include "migration/qemu-file-types.h"
 #include "monitor/monitor.h"
 #include "qemu/error-report.h"
 #include "qemu/queue.h"
 #include "hw/qdev-properties.h"
 #include "trace.h"
 #include "hw/virtio/virtio-serial.h"
 #include "hw/virtio/virtio-access.h"
 
 static struct VirtIOSerialDevices {
     QLIST_HEAD(, VirtIOSerial) devices;
 } vserdevices;
 
 static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
 {
     VirtIOSerialPort *port;
 
     if (id == VIRTIO_CONSOLE_BAD_ID) {
         return NULL;
     }
 
     QTAILQ_FOREACH(port, &vser->ports, next) {
         if (port->id == id)
             return port;
     }
     return NULL;
 }
 
 static VirtIOSerialPort *find_port_by_vq(VirtIOSerial *vser, VirtQueue *vq)
 {
     VirtIOSerialPort *port;
 
     QTAILQ_FOREACH(port, &vser->ports, next) {
         if (port->ivq == vq || port->ovq == vq)
             return port;
     }
     return NULL;
 }
 
 static VirtIOSerialPort *find_port_by_name(char *name)
 {
     VirtIOSerial *vser;
 
     QLIST_FOREACH(vser, &vserdevices.devices, next) {
         VirtIOSerialPort *port;
 
         QTAILQ_FOREACH(port, &vser->ports, next) {
             if (port->name && !strcmp(port->name, name)) {
                 return port;
             }
         }
     }
     return NULL;
 }
 
 static VirtIOSerialPort *find_first_connected_console(VirtIOSerial *vser)
 {
     VirtIOSerialPort *port;
 
     QTAILQ_FOREACH(port, &vser->ports, next) {
         VirtIOSerialPortClass const *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
         if (vsc->is_console && port->host_connected) {
             return port;
         }
     }
     return NULL;
 }
 
 static bool use_multiport(VirtIOSerial *vser)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
     return virtio_vdev_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT);
 }
 
 static size_t write_to_port(VirtIOSerialPort *port,
                             const uint8_t *buf, size_t size)
 {
     VirtQueueElement *elem;
     VirtQueue *vq;
     size_t offset;
 
     vq = port->ivq;
     if (!virtio_queue_ready(vq)) {
         return 0;
     }
 
     offset = 0;
     while (offset < size) {
         size_t len;
 
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
             break;
         }
 
         len = iov_from_buf(elem->in_sg, elem->in_num, 0,
                            buf + offset, size - offset);
         offset += len;
 
         virtqueue_push(vq, elem, len);
         g_free(elem);
     }
 
     virtio_notify(VIRTIO_DEVICE(port->vser), vq);
     return offset;
 }
 
 static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev)
 {
     VirtQueueElement *elem;
 
     if (!virtio_queue_ready(vq)) {
         return;
     }
     for (;;) {
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
             break;
         }
         virtqueue_push(vq, elem, 0);
         g_free(elem);
     }
     virtio_notify(vdev, vq);
 }
 
 static void discard_throttle_data(VirtIOSerialPort *port)
 {
     if (port->elem) {
         virtqueue_detach_element(port->ovq, port->elem, 0);
         g_free(port->elem);
         port->elem = NULL;
     }
 }
 
 static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
                                  VirtIODevice *vdev)
 {
     VirtIOSerialPortClass *vsc;
 
     assert(port);
     assert(virtio_queue_ready(vq));
 
     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
     while (!port->throttled) {
         unsigned int i;
 
         /* Pop an elem only if we haven't left off a previous one mid-way */
         if (!port->elem) {
             port->elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
             if (!port->elem) {
                 break;
             }
             port->iov_idx = 0;
             port->iov_offset = 0;
         }
 
         for (i = port->iov_idx; i < port->elem->out_num; i++) {
             size_t buf_size;
             ssize_t ret;
 
             buf_size = port->elem->out_sg[i].iov_len - port->iov_offset;
             ret = vsc->have_data(port,
                                   port->elem->out_sg[i].iov_base
                                   + port->iov_offset,
                                   buf_size);
             if (!port->elem) { /* bail if we got disconnected */
                 return;
             }
             if (port->throttled) {
                 port->iov_idx = i;
                 if (ret > 0) {
                     port->iov_offset += ret;
                 }
                 break;
             }
             port->iov_offset = 0;
         }
         if (port->throttled) {
             break;
         }
         virtqueue_push(vq, port->elem, 0);
         g_free(port->elem);
         port->elem = NULL;
     }
     virtio_notify(vdev, vq);
 }
 
 static void flush_queued_data(VirtIOSerialPort *port)
 {
     assert(port);
 
     if (!virtio_queue_ready(port->ovq)) {
         return;
     }
     do_flush_queued_data(port, port->ovq, VIRTIO_DEVICE(port->vser));
 }
 
 static size_t send_control_msg(VirtIOSerial *vser, void *buf, size_t len)
 {
     VirtQueueElement *elem;
     VirtQueue *vq;
 
     vq = vser->c_ivq;
     if (!virtio_queue_ready(vq)) {
         return 0;
     }
 
     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
     if (!elem) {
         return 0;
     }
 
     /* TODO: detect a buffer that's too short, set NEEDS_RESET */
     iov_from_buf(elem->in_sg, elem->in_num, 0, buf, len);
 
     virtqueue_push(vq, elem, len);
     virtio_notify(VIRTIO_DEVICE(vser), vq);
     g_free(elem);
 
     return len;
 }
 
 static size_t send_control_event(VirtIOSerial *vser, uint32_t port_id,
                                  uint16_t event, uint16_t value)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
     struct virtio_console_control cpkt;
 
     virtio_stl_p(vdev, &cpkt.id, port_id);
     virtio_stw_p(vdev, &cpkt.event, event);
     virtio_stw_p(vdev, &cpkt.value, value);
 
     trace_virtio_serial_send_control_event(port_id, event, value);
     return send_control_msg(vser, &cpkt, sizeof(cpkt));
 }
 
 /* Functions for use inside qemu to open and read from/write to ports */
 int virtio_serial_open(VirtIOSerialPort *port)
 {
     /* Don't allow opening an already-open port */
     if (port->host_connected) {
         return 0;
     }
     /* Send port open notification to the guest */
     port->host_connected = true;
     send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 1);
 
     return 0;
 }
 
 int virtio_serial_close(VirtIOSerialPort *port)
 {
     port->host_connected = false;
     /*
      * If there's any data the guest sent which the app didn't
      * consume, reset the throttling flag and discard the data.
      */
     port->throttled = false;
     discard_throttle_data(port);
     discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
 
     send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 0);
 
     return 0;
 }
 
 /* Individual ports/apps call this function to write to the guest. */
 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
                             size_t size)
 {
     if (!port || !port->host_connected || !port->guest_connected) {
         return 0;
     }
     return write_to_port(port, buf, size);
 }
 
 /*
  * Readiness of the guest to accept data on a port.
  * Returns max. data the guest can receive
  */
 size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(port->vser);
     VirtQueue *vq = port->ivq;
     unsigned int bytes;
 
     if (!virtio_queue_ready(vq) ||
         !(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) ||
         virtio_queue_empty(vq)) {
         return 0;
     }
     if (use_multiport(port->vser) && !port->guest_connected) {
         return 0;
     }
     virtqueue_get_avail_bytes(vq, &bytes, NULL, 4096, 0);
     return bytes;
 }
 
 static void flush_queued_data_bh(void *opaque)
 {
     VirtIOSerialPort *port = opaque;
 
     flush_queued_data(port);
 }
 
 void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle)
 {
     if (!port) {
         return;
     }
 
     trace_virtio_serial_throttle_port(port->id, throttle);
     port->throttled = throttle;
     if (throttle) {
         return;
     }
     qemu_bh_schedule(port->bh);
 }
 
 /* Guest wants to notify us of some event */
 static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
     struct VirtIOSerialPort *port;
     VirtIOSerialPortClass *vsc;
     struct virtio_console_control cpkt, *gcpkt;
     uint8_t *buffer;
     size_t buffer_len;
 
     gcpkt = buf;
 
     if (len < sizeof(cpkt)) {
         /* The guest sent an invalid control packet */
         return;
     }
 
     cpkt.event = virtio_lduw_p(vdev, &gcpkt->event);
     cpkt.value = virtio_lduw_p(vdev, &gcpkt->value);
 
     trace_virtio_serial_handle_control_message(cpkt.event, cpkt.value);
 
     if (cpkt.event == VIRTIO_CONSOLE_DEVICE_READY) {
         if (!cpkt.value) {
             error_report("virtio-serial-bus: Guest failure in adding device %s",
                          vser->bus.qbus.name);
             return;
         }
         /*
          * The device is up, we can now tell the device about all the
          * ports we have here.
          */
         QTAILQ_FOREACH(port, &vser->ports, next) {
             send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_ADD, 1);
         }
         return;
     }
 
     port = find_port_by_id(vser, virtio_ldl_p(vdev, &gcpkt->id));
     if (!port) {
         error_report("virtio-serial-bus: Unexpected port id %u for device %s",
                      virtio_ldl_p(vdev, &gcpkt->id), vser->bus.qbus.name);
         return;
     }
 
     trace_virtio_serial_handle_control_message_port(port->id);
 
     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
     switch(cpkt.event) {
     case VIRTIO_CONSOLE_PORT_READY:
         if (!cpkt.value) {
             error_report("virtio-serial-bus: Guest failure in adding port %u for device %s",
                          port->id, vser->bus.qbus.name);
             break;
         }
         /*
          * Now that we know the guest asked for the port name, we're
          * sure the guest has initialised whatever state is necessary
          * for this port. Now's a good time to let the guest know if
          * this port is a console port so that the guest can hook it
          * up to hvc.
          */
         if (vsc->is_console) {
             send_control_event(vser, port->id, VIRTIO_CONSOLE_CONSOLE_PORT, 1);
         }
 
         if (port->name) {
             virtio_stl_p(vdev, &cpkt.id, port->id);
             virtio_stw_p(vdev, &cpkt.event, VIRTIO_CONSOLE_PORT_NAME);
             virtio_stw_p(vdev, &cpkt.value, 1);
 
             buffer_len = sizeof(cpkt) + strlen(port->name) + 1;
             buffer = g_malloc(buffer_len);
 
             memcpy(buffer, &cpkt, sizeof(cpkt));
             memcpy(buffer + sizeof(cpkt), port->name, strlen(port->name));
             buffer[buffer_len - 1] = 0;
 
             send_control_msg(vser, buffer, buffer_len);
             g_free(buffer);
         }
 
         if (port->host_connected) {
             send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 1);
         }
 
         /*
          * When the guest has asked us for this information it means
          * the guest is all setup and has its virtqueues
          * initialised. If some app is interested in knowing about
          * this event, let it know.
          */
         if (vsc->guest_ready) {
             vsc->guest_ready(port);
         }
         break;
 
     case VIRTIO_CONSOLE_PORT_OPEN:
         port->guest_connected = cpkt.value;
         if (vsc->set_guest_connected) {
             /* Send the guest opened notification if an app is interested */
             vsc->set_guest_connected(port, cpkt.value);
         }
         break;
     }
 }
 
 static void control_in(VirtIODevice *vdev, VirtQueue *vq)
 {
 }
 
 static void control_out(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtQueueElement *elem;
     VirtIOSerial *vser;
     uint8_t *buf;
     size_t len;
 
     vser = VIRTIO_SERIAL(vdev);
 
     len = 0;
     buf = NULL;
     for (;;) {
         size_t cur_len;
 
         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
         if (!elem) {
             break;
         }
 
         cur_len = iov_size(elem->out_sg, elem->out_num);
         /*
          * Allocate a new buf only if we didn't have one previously or
          * if the size of the buf differs
          */
         if (cur_len > len) {
             g_free(buf);
 
             buf = g_malloc(cur_len);
             len = cur_len;
         }
         iov_to_buf(elem->out_sg, elem->out_num, 0, buf, cur_len);
 
         handle_control_message(vser, buf, cur_len);
         virtqueue_push(vq, elem, 0);
         g_free(elem);
     }
     g_free(buf);
     virtio_notify(vdev, vq);
 }
 
 /* Guest wrote something to some port. */
 static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOSerial *vser;
     VirtIOSerialPort *port;
 
     vser = VIRTIO_SERIAL(vdev);
     port = find_port_by_vq(vser, vq);
 
     if (!port || !port->host_connected) {
         discard_vq_data(vq, vdev);
         return;
     }
 
     if (!port->throttled) {
         do_flush_queued_data(port, vq, vdev);
         return;
     }
 }
 
 static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
 {
     /*
      * Users of virtio-serial would like to know when guest becomes
      * writable again -- i.e. if a vq had stuff queued up and the
      * guest wasn't reading at all, the host would not be able to
      * write to the vq anymore.  Once the guest reads off something,
      * we can start queueing things up again.  However, this call is
      * made for each buffer addition by the guest -- even though free
      * buffers existed prior to the current buffer addition.  This is
      * done so as not to maintain previous state, which will need
      * additional live-migration-related changes.
      */
     VirtIOSerial *vser;
     VirtIOSerialPort *port;
     VirtIOSerialPortClass *vsc;
 
     vser = VIRTIO_SERIAL(vdev);
     port = find_port_by_vq(vser, vq);
 
     if (!port) {
         return;
     }
     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
     /*
      * If guest_connected is false, this call is being made by the
      * early-boot queueing up of descriptors, which is just noise for
      * the host apps -- don't disturb them in that case.
      */
     if (port->guest_connected && port->host_connected && vsc->guest_writable) {
         vsc->guest_writable(port);
     }
 }
 
 static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
                              Error **errp)
 {
     VirtIOSerial *vser;
 
     vser = VIRTIO_SERIAL(vdev);
 
     features |= vser->host_features;
     if (vser->bus.max_nr_ports > 1) {
         virtio_add_feature(&features, VIRTIO_CONSOLE_F_MULTIPORT);
     }
     return features;
 }
 
 /* Guest requested config info */
 static void get_config(VirtIODevice *vdev, uint8_t *config_data)
 {
     VirtIOSerial *vser = VIRTIO_SERIAL(vdev);
     struct virtio_console_config *config =
         (struct virtio_console_config *)config_data;
 
     config->cols = 0;
     config->rows = 0;
     config->max_nr_ports = virtio_tswap32(vdev,
                                           vser->serial.max_virtserial_ports);
 }
 
 /* Guest sent new config info */
 static void set_config(VirtIODevice *vdev, const uint8_t *config_data)
 {
     VirtIOSerial *vser = VIRTIO_SERIAL(vdev);
     struct virtio_console_config *config =
         (struct virtio_console_config *)config_data;
     VirtIOSerialPort *port = find_first_connected_console(vser);
     VirtIOSerialPortClass *vsc;
     uint8_t emerg_wr_lo;
 
     if (!virtio_has_feature(vser->host_features,
         VIRTIO_CONSOLE_F_EMERG_WRITE) || !config->emerg_wr) {
         return;
     }
 
     emerg_wr_lo = le32_to_cpu(config->emerg_wr);
     /* Make sure we don't misdetect an emergency write when the guest
      * does a short config write after an emergency write. */
     config->emerg_wr = 0;
     if (!port) {
         return;
     }
     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
     (void)vsc->have_data(port, &emerg_wr_lo, 1);
 }
 
 static void guest_reset(VirtIOSerial *vser)
 {
     VirtIOSerialPort *port;
     VirtIOSerialPortClass *vsc;
 
     QTAILQ_FOREACH(port, &vser->ports, next) {
         vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
         discard_throttle_data(port);
 
         if (port->guest_connected) {
             port->guest_connected = false;
             if (vsc->set_guest_connected) {
                 vsc->set_guest_connected(port, false);
             }
         }
     }
 }
 
 static void set_status(VirtIODevice *vdev, uint8_t status)
 {
     VirtIOSerial *vser;
     VirtIOSerialPort *port;
 
     vser = VIRTIO_SERIAL(vdev);
     port = find_port_by_id(vser, 0);
 
     if (port && !use_multiport(port->vser)
         && (status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         /*
          * Non-multiport guests won't be able to tell us guest
          * open/close status.  Such guests can only have a port at id
          * 0, so set guest_connected for such ports as soon as guest
          * is up.
          */
         port->guest_connected = true;
     }
     if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         guest_reset(vser);
     }
 
     QTAILQ_FOREACH(port, &vser->ports, next) {
         VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
         if (vsc->enable_backend) {
             vsc->enable_backend(port, vdev->vm_running);
         }
     }
 }
 
 static void vser_reset(VirtIODevice *vdev)
 {
     VirtIOSerial *vser;
 
     vser = VIRTIO_SERIAL(vdev);
     guest_reset(vser);
 }
 
 static void virtio_serial_save_device(VirtIODevice *vdev, QEMUFile *f)
 {
     VirtIOSerial *s = VIRTIO_SERIAL(vdev);
     VirtIOSerialPort *port;
     uint32_t nr_active_ports;
     unsigned int i, max_nr_ports;
     struct virtio_console_config config;
 
     /* The config space (ignored on the far end in current versions) */
     get_config(vdev, (uint8_t *)&config);
     qemu_put_be16(f, config.cols);
     qemu_put_be16(f, config.rows);
     qemu_put_be32(f, config.max_nr_ports);
 
     /* The ports map */
     max_nr_ports = s->serial.max_virtserial_ports;
     for (i = 0; i < DIV_ROUND_UP(max_nr_ports, 32); i++) {
         qemu_put_be32s(f, &s->ports_map[i]);
     }
 
     /* Ports */
 
     nr_active_ports = 0;
     QTAILQ_FOREACH(port, &s->ports, next) {
         nr_active_ports++;
     }
 
     qemu_put_be32s(f, &nr_active_ports);
 
     /*
      * Items in struct VirtIOSerialPort.
      */
     QTAILQ_FOREACH(port, &s->ports, next) {
         uint32_t elem_popped;
 
         qemu_put_be32s(f, &port->id);
         qemu_put_byte(f, port->guest_connected);
         qemu_put_byte(f, port->host_connected);
 
         elem_popped = 0;
         if (port->elem) {
             elem_popped = 1;
         }
         qemu_put_be32s(f, &elem_popped);
         if (elem_popped) {
             qemu_put_be32s(f, &port->iov_idx);
             qemu_put_be64s(f, &port->iov_offset);
             qemu_put_virtqueue_element(vdev, f, port->elem);
         }
     }
 }
 
 static void virtio_serial_post_load_timer_cb(void *opaque)
 {
     uint32_t i;
     VirtIOSerial *s = VIRTIO_SERIAL(opaque);
     VirtIOSerialPort *port;
     uint8_t host_connected;
     VirtIOSerialPortClass *vsc;
 
     if (!s->post_load) {
         return;
     }
     for (i = 0 ; i < s->post_load->nr_active_ports; ++i) {
         port = s->post_load->connected[i].port;
         host_connected = s->post_load->connected[i].host_connected;
         if (host_connected != port->host_connected) {
             /*
              * We have to let the guest know of the host connection
              * status change
              */
             send_control_event(s, port->id, VIRTIO_CONSOLE_PORT_OPEN,
                                port->host_connected);
         }
         vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
         if (vsc->set_guest_connected) {
             vsc->set_guest_connected(port, port->guest_connected);
         }
     }
     g_free(s->post_load->connected);
     timer_free(s->post_load->timer);
     g_free(s->post_load);
     s->post_load = NULL;
 }
 
 static int fetch_active_ports_list(QEMUFile *f,
                                    VirtIOSerial *s, uint32_t nr_active_ports)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
     uint32_t i;
 
     s->post_load = g_malloc0(sizeof(*s->post_load));
     s->post_load->nr_active_ports = nr_active_ports;
     s->post_load->connected =
         g_malloc0(sizeof(*s->post_load->connected) * nr_active_ports);
 
     s->post_load->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
                                             virtio_serial_post_load_timer_cb,
                                             s);
 
     /* Items in struct VirtIOSerialPort */
     for (i = 0; i < nr_active_ports; i++) {
         VirtIOSerialPort *port;
         uint32_t elem_popped;
         uint32_t id;
 
         id = qemu_get_be32(f);
         port = find_port_by_id(s, id);
         if (!port) {
             return -EINVAL;
         }
 
         port->guest_connected = qemu_get_byte(f);
         s->post_load->connected[i].port = port;
         s->post_load->connected[i].host_connected = qemu_get_byte(f);
 
         qemu_get_be32s(f, &elem_popped);
         if (elem_popped) {
             qemu_get_be32s(f, &port->iov_idx);
             qemu_get_be64s(f, &port->iov_offset);
 
             port->elem =
                 qemu_get_virtqueue_element(vdev, f, sizeof(VirtQueueElement));
 
             /*
              *  Port was throttled on source machine.  Let's
              *  unthrottle it here so data starts flowing again.
              */
             virtio_serial_throttle_port(port, false);
         }
     }
     timer_mod(s->post_load->timer, 1);
     return 0;
 }
 
 static int virtio_serial_load_device(VirtIODevice *vdev, QEMUFile *f,
                                      int version_id)
 {
     VirtIOSerial *s = VIRTIO_SERIAL(vdev);
     uint32_t max_nr_ports, nr_active_ports, ports_map;
     unsigned int i;
     int ret;
     uint32_t tmp;
 
     /* Unused */
     qemu_get_be16s(f, (uint16_t *) &tmp);
     qemu_get_be16s(f, (uint16_t *) &tmp);
     qemu_get_be32s(f, &tmp);
 
     max_nr_ports = s->serial.max_virtserial_ports;
     for (i = 0; i < DIV_ROUND_UP(max_nr_ports, 32); i++) {
         qemu_get_be32s(f, &ports_map);
 
         if (ports_map != s->ports_map[i]) {
             /*
              * Ports active on source and destination don't
              * match. Fail migration.
              */
             return -EINVAL;
         }
     }
 
     qemu_get_be32s(f, &nr_active_ports);
 
     if (nr_active_ports) {
         ret = fetch_active_ports_list(f, s, nr_active_ports);
         if (ret) {
             return ret;
         }
     }
     return 0;
 }
 
 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
 
 static Property virtser_props[] = {
     DEFINE_PROP_UINT32("nr", VirtIOSerialPort, id, VIRTIO_CONSOLE_BAD_ID),
     DEFINE_PROP_STRING("name", VirtIOSerialPort, name),
     DEFINE_PROP_END_OF_LIST()
 };
 
 static void virtser_bus_class_init(ObjectClass *klass, void *data)
 {
     BusClass *k = BUS_CLASS(klass);
     k->print_dev = virtser_bus_dev_print;
 }
 
 static const TypeInfo virtser_bus_info = {
     .name = TYPE_VIRTIO_SERIAL_BUS,
     .parent = TYPE_BUS,
     .instance_size = sizeof(VirtIOSerialBus),
     .class_init = virtser_bus_class_init,
 };
 
 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
 {
     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(qdev);
 
     monitor_printf(mon, "%*sport %d, guest %s, host %s, throttle %s\n",
                    indent, "", port->id,
                    port->guest_connected ? "on" : "off",
                    port->host_connected ? "on" : "off",
                    port->throttled ? "on" : "off");
 }
 
 /* This function is only used if a port id is not provided by the user */
 static uint32_t find_free_port_id(VirtIOSerial *vser)
 {
     unsigned int i, max_nr_ports;
 
     max_nr_ports = vser->serial.max_virtserial_ports;
     for (i = 0; i < DIV_ROUND_UP(max_nr_ports, 32); i++) {
         uint32_t map, zeroes;
 
         map = vser->ports_map[i];
         zeroes = ctz32(~map);
         if (zeroes != 32) {
             return zeroes + i * 32;
         }
     }
     return VIRTIO_CONSOLE_BAD_ID;
 }
 
 static void mark_port_added(VirtIOSerial *vser, uint32_t port_id)
 {
     unsigned int i;
 
     i = port_id / 32;
     vser->ports_map[i] |= 1U << (port_id % 32);
 }
 
 static void add_port(VirtIOSerial *vser, uint32_t port_id)
 {
     mark_port_added(vser, port_id);
     send_control_event(vser, port_id, VIRTIO_CONSOLE_PORT_ADD, 1);
 }
 
 static void remove_port(VirtIOSerial *vser, uint32_t port_id)
 {
     VirtIOSerialPort *port;
 
     /*
      * Don't mark port 0 removed -- we explicitly reserve it for
      * backward compat with older guests, ensure a virtconsole device
      * unplug retains the reservation.
      */
     if (port_id) {
         unsigned int i;
 
         i = port_id / 32;
         vser->ports_map[i] &= ~(1U << (port_id % 32));
     }
 
     port = find_port_by_id(vser, port_id);
     /*
      * This function is only called from qdev's unplug callback; if we
      * get a NULL port here, we're in trouble.
      */
     assert(port);
 
     /* Flush out any unconsumed buffers first */
     discard_throttle_data(port);
     discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
 
     send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_REMOVE, 1);
 }
 
 static void virtser_port_device_realize(DeviceState *dev, Error **errp)
 {
     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
     VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
     VirtIOSerialBus *bus = VIRTIO_SERIAL_BUS(qdev_get_parent_bus(dev));
     int max_nr_ports;
     bool plugging_port0;
     Error *err = NULL;
 
     port->vser = bus->vser;
 
     assert(vsc->have_data);
 
     /*
      * Is the first console port we're seeing? If so, put it up at
      * location 0. This is done for backward compatibility (old
      * kernel, new qemu).
      */
     plugging_port0 = vsc->is_console && !find_port_by_id(port->vser, 0);
 
     if (find_port_by_id(port->vser, port->id)) {
         error_setg(errp, "virtio-serial-bus: A port already exists at id %u",
                    port->id);
         return;
     }
 
     if (port->name != NULL && find_port_by_name(port->name)) {
         error_setg(errp, "virtio-serial-bus: A port already exists by name %s",
                    port->name);
         return;
     }
 
     if (port->id == VIRTIO_CONSOLE_BAD_ID) {
         if (plugging_port0) {
             port->id = 0;
         } else {
             port->id = find_free_port_id(port->vser);
             if (port->id == VIRTIO_CONSOLE_BAD_ID) {
                 error_setg(errp, "virtio-serial-bus: Maximum port limit for "
                                  "this device reached");
                 return;
             }
         }
     }
 
     max_nr_ports = port->vser->serial.max_virtserial_ports;
     if (port->id >= max_nr_ports) {
         error_setg(errp, "virtio-serial-bus: Out-of-range port id specified, "
                          "max. allowed: %u", max_nr_ports - 1);
         return;
     }
 
     vsc->realize(dev, &err);
     if (err != NULL) {
         error_propagate(errp, err);
         return;
     }
 
     port->bh = qemu_bh_new(flush_queued_data_bh, port);
     port->elem = NULL;
 }
 
 static void virtser_port_device_plug(HotplugHandler *hotplug_dev,
                                      DeviceState *dev, Error **errp)
 {
     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
 
     QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
     port->ivq = port->vser->ivqs[port->id];
     port->ovq = port->vser->ovqs[port->id];
 
     add_port(port->vser, port->id);
 
     /* Send an update to the guest about this new port added */
     virtio_notify_config(VIRTIO_DEVICE(hotplug_dev));
 }
 
 static void virtser_port_device_unrealize(DeviceState *dev)
 {
     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
     VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(dev);
     VirtIOSerial *vser = port->vser;
 
     qemu_bh_delete(port->bh);
     remove_port(port->vser, port->id);
 
     QTAILQ_REMOVE(&vser->ports, port, next);
 
     if (vsc->unrealize) {
         vsc->unrealize(dev);
     }
 }
 
 static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
     uint32_t i, max_supported_ports;
     size_t config_size = sizeof(struct virtio_console_config);
 
     if (!vser->serial.max_virtserial_ports) {
         error_setg(errp, "Maximum number of serial ports not specified");
         return;
     }
 
     /* Each port takes 2 queues, and one pair is for the control queue */
     max_supported_ports = VIRTIO_QUEUE_MAX / 2 - 1;
 
     if (vser->serial.max_virtserial_ports > max_supported_ports) {
         error_setg(errp, "maximum ports supported: %u", max_supported_ports);
         return;
     }
 
     if (!virtio_has_feature(vser->host_features,
                             VIRTIO_CONSOLE_F_EMERG_WRITE)) {
         config_size = offsetof(struct virtio_console_config, emerg_wr);
     }
     virtio_init(vdev, VIRTIO_ID_CONSOLE, config_size);
 
     /* Spawn a new virtio-serial bus on which the ports will ride as devices */
     qbus_init(&vser->bus, sizeof(vser->bus), TYPE_VIRTIO_SERIAL_BUS,
               dev, vdev->bus_name);
     qbus_set_hotplug_handler(BUS(&vser->bus), OBJECT(vser));
     vser->bus.vser = vser;
     QTAILQ_INIT(&vser->ports);
 
     vser->bus.max_nr_ports = vser->serial.max_virtserial_ports;
     vser->ivqs = g_new(VirtQueue *, vser->serial.max_virtserial_ports);
     vser->ovqs = g_new(VirtQueue *, vser->serial.max_virtserial_ports);
 
     /* Add a queue for host to guest transfers for port 0 (backward compat) */
     vser->ivqs[0] = virtio_add_queue(vdev, 128, handle_input);
     /* Add a queue for guest to host transfers for port 0 (backward compat) */
     vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output);
 
     /* TODO: host to guest notifications can get dropped
      * if the queue fills up. Implement queueing in host,
      * this might also make it possible to reduce the control
      * queue size: as guest preposts buffers there,
      * this will save 4Kbyte of guest memory per entry. */
 
     /* control queue: host to guest */
     vser->c_ivq = virtio_add_queue(vdev, 32, control_in);
     /* control queue: guest to host */
     vser->c_ovq = virtio_add_queue(vdev, 32, control_out);
 
     for (i = 1; i < vser->bus.max_nr_ports; i++) {
         /* Add a per-port queue for host to guest transfers */
         vser->ivqs[i] = virtio_add_queue(vdev, 128, handle_input);
         /* Add a per-per queue for guest to host transfers */
         vser->ovqs[i] = virtio_add_queue(vdev, 128, handle_output);
     }
 
     vser->ports_map = g_malloc0((DIV_ROUND_UP(vser->serial.max_virtserial_ports, 32))
         * sizeof(vser->ports_map[0]));
     /*
      * Reserve location 0 for a console port for backward compat
      * (old kernel, new qemu)
      */
     mark_port_added(vser, 0);
 
     vser->post_load = NULL;
 
     QLIST_INSERT_HEAD(&vserdevices.devices, vser, next);
 }
 
 static void virtio_serial_port_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *k = DEVICE_CLASS(klass);
 
     set_bit(DEVICE_CATEGORY_INPUT, k->categories);
     k->bus_type = TYPE_VIRTIO_SERIAL_BUS;
     k->realize = virtser_port_device_realize;
     k->unrealize = virtser_port_device_unrealize;
     device_class_set_props(k, virtser_props);
 }
 
 static const TypeInfo virtio_serial_port_type_info = {
     .name = TYPE_VIRTIO_SERIAL_PORT,
     .parent = TYPE_DEVICE,
     .instance_size = sizeof(VirtIOSerialPort),
     .abstract = true,
     .class_size = sizeof(VirtIOSerialPortClass),
     .class_init = virtio_serial_port_class_init,
 };
 
 static void virtio_serial_device_unrealize(DeviceState *dev)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
     int i;
 
     QLIST_REMOVE(vser, next);
 
     virtio_delete_queue(vser->c_ivq);
     virtio_delete_queue(vser->c_ovq);
     for (i = 0; i < vser->bus.max_nr_ports; i++) {
         virtio_delete_queue(vser->ivqs[i]);
         virtio_delete_queue(vser->ovqs[i]);
     }
 
     g_free(vser->ivqs);
     g_free(vser->ovqs);
     g_free(vser->ports_map);
     if (vser->post_load) {
         g_free(vser->post_load->connected);
         timer_free(vser->post_load->timer);
         g_free(vser->post_load);
     }
 
     qbus_set_hotplug_handler(BUS(&vser->bus), NULL);
 
     virtio_cleanup(vdev);
 }
 
 /* Note: 'console' is used for backwards compatibility */
 static const VMStateDescription vmstate_virtio_console = {
     .name = "virtio-console",
     .minimum_version_id = 3,
     .version_id = 3,
     .fields = (VMStateField[]) {
         VMSTATE_VIRTIO_DEVICE,
         VMSTATE_END_OF_LIST()
     },
 };
 
 static Property virtio_serial_properties[] = {
     DEFINE_PROP_UINT32("max_ports", VirtIOSerial, serial.max_virtserial_ports,
                                                   31),
     DEFINE_PROP_BIT64("emergency-write", VirtIOSerial, host_features,
                       VIRTIO_CONSOLE_F_EMERG_WRITE, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
 static void virtio_serial_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
     HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
 
     QLIST_INIT(&vserdevices.devices);
 
     device_class_set_props(dc, virtio_serial_properties);
     dc->vmsd = &vmstate_virtio_console;
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
     vdc->realize = virtio_serial_device_realize;
     vdc->unrealize = virtio_serial_device_unrealize;
     vdc->get_features = get_features;
     vdc->get_config = get_config;
     vdc->set_config = set_config;
     vdc->set_status = set_status;
     vdc->reset = vser_reset;
     vdc->save = virtio_serial_save_device;
     vdc->load = virtio_serial_load_device;
     hc->plug = virtser_port_device_plug;
     hc->unplug = qdev_simple_device_unplug_cb;
 }
 
 static const TypeInfo virtio_device_info = {
     .name = TYPE_VIRTIO_SERIAL,
     .parent = TYPE_VIRTIO_DEVICE,
     .instance_size = sizeof(VirtIOSerial),
     .class_init = virtio_serial_class_init,
     .interfaces = (InterfaceInfo[]) {
         { TYPE_HOTPLUG_HANDLER },
         { }
     }
 };
 
 static void virtio_serial_register_types(void)
 {
     type_register_static(&virtser_bus_info);
     type_register_static(&virtio_serial_port_type_info);
     type_register_static(&virtio_device_info);
 }
 
 type_init(virtio_serial_register_types)