virtio-console: qdev conversion, new virtio-serial-bus

This commit converts the virtio-console device to create a new
virtio-serial bus that can host console and generic serial ports. The
file hosting this code is now called virtio-serial-bus.c.

The virtio console is now a very simple qdev device that sits on the
virtio-serial-bus and communicates between the bus and qemu's chardevs.

This commit also includes a few changes to the virtio backing code for
pci and s390 to spawn the virtio-serial bus.

As a result of the qdev conversion, we get rid of a lot of legacy code.
The old-style way of instantiating a virtio console using

    -virtioconsole ...

is maintained, but the new, preferred way is to use

    -device virtio-serial -device virtconsole,chardev=...

With this commit, multiple devices as well as multiple ports with a
single device can be supported.

For multiple ports support, each port gets an IO vq pair. Since the
guest needs to know in advance how many vqs a particular device will
need, we have to set this number as a property of the virtio-serial
device and also as a config option.

In addition, we also spawn a pair of control IO vqs. This is an internal
channel meant for guest-host communication for things like port
open/close, sending port properties over to the guest, etc.

This commit is a part of a series of other commits to get the full
implementation of multiport support. Future commits will add other
support as well as ride on the savevm version that we bump up here.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 507 insertions, 0 deletions

diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
new file mode 100644
index 0000000000..e8bbd7d3ee
--- /dev/null
+++ b/hw/virtio-serial-bus.c
@@ -0,0 +1,507 @@
+/*
+ * A bus for connecting virtio serial and console ports
+ *
+ * Copyright (C) 2009 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.
+ */
+
+#include "monitor.h"
+#include "qemu-queue.h"
+#include "sysbus.h"
+#include "virtio-serial.h"
+
+/* The virtio-serial bus on top of which the ports will ride as devices */
+struct VirtIOSerialBus {
+    BusState qbus;
+
+    /* This is the parent device that provides the bus for ports. */
+    VirtIOSerial *vser;
+
+    /* The maximum number of ports that can ride on top of this bus */
+    uint32_t max_nr_ports;
+};
+
+struct VirtIOSerial {
+    VirtIODevice vdev;
+
+    VirtQueue *c_ivq, *c_ovq;
+    /* Arrays of ivqs and ovqs: one per port */
+    VirtQueue **ivqs, **ovqs;
+
+    VirtIOSerialBus *bus;
+
+    QTAILQ_HEAD(, VirtIOSerialPort) ports;
+    struct virtio_console_config config;
+};
+
+static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
+{
+    VirtIOSerialPort *port;
+
+    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 size_t write_to_port(VirtIOSerialPort *port,
+                            const uint8_t *buf, size_t size)
+{
+    VirtQueueElement elem;
+    VirtQueue *vq;
+    size_t offset = 0;
+    size_t len = 0;
+
+    vq = port->ivq;
+    if (!virtio_queue_ready(vq)) {
+        return 0;
+    }
+    if (!size) {
+        return 0;
+    }
+
+    while (offset < size) {
+        int i;
+
+        if (!virtqueue_pop(vq, &elem)) {
+            break;
+        }
+
+        for (i = 0; offset < size && i < elem.in_num; i++) {
+            len = MIN(elem.in_sg[i].iov_len, size - offset);
+
+            memcpy(elem.in_sg[i].iov_base, buf + offset, len);
+            offset += len;
+        }
+        virtqueue_push(vq, &elem, len);
+    }
+
+    virtio_notify(&port->vser->vdev, vq);
+    return offset;
+}
+
+static size_t send_control_msg(VirtIOSerialPort *port, void *buf, size_t len)
+{
+    VirtQueueElement elem;
+    VirtQueue *vq;
+    struct virtio_console_control *cpkt;
+
+    vq = port->vser->c_ivq;
+    if (!virtio_queue_ready(vq)) {
+        return 0;
+    }
+    if (!virtqueue_pop(vq, &elem)) {
+        return 0;
+    }
+
+    cpkt = (struct virtio_console_control *)buf;
+    stl_p(&cpkt->id, port->id);
+    memcpy(elem.in_sg[0].iov_base, buf, len);
+
+    virtqueue_push(vq, &elem, len);
+    virtio_notify(&port->vser->vdev, vq);
+    return len;
+}
+
+static size_t send_control_event(VirtIOSerialPort *port, uint16_t event,
+                                 uint16_t value)
+{
+    struct virtio_console_control cpkt;
+
+    stw_p(&cpkt.event, event);
+    stw_p(&cpkt.value, value);
+
+    return send_control_msg(port, &cpkt, sizeof(cpkt));
+}
+
+/* Functions for use inside qemu to open and read from/write to ports */
+int virtio_serial_open(VirtIOSerialPort *port)
+{
+    return 0;
+}
+
+int virtio_serial_close(VirtIOSerialPort *port)
+{
+    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)
+{
+    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)
+{
+    VirtQueue *vq = port->ivq;
+
+    if (!virtio_queue_ready(vq) ||
+        !(port->vser->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
+        virtio_queue_empty(vq)) {
+        return 0;
+    }
+
+    if (virtqueue_avail_bytes(vq, 4096, 0)) {
+        return 4096;
+    }
+    if (virtqueue_avail_bytes(vq, 1, 0)) {
+        return 1;
+    }
+    return 0;
+}
+
+/* Guest wants to notify us of some event */
+static void handle_control_message(VirtIOSerial *vser, void *buf)
+{
+    struct VirtIOSerialPort *port;
+    struct virtio_console_control cpkt, *gcpkt;
+
+    gcpkt = buf;
+    port = find_port_by_id(vser, ldl_p(&gcpkt->id));
+    if (!port)
+        return;
+
+    cpkt.event = lduw_p(&gcpkt->event);
+    cpkt.value = lduw_p(&gcpkt->value);
+
+    switch(cpkt.event) {
+    case VIRTIO_CONSOLE_PORT_READY:
+        /*
+         * 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 (port->is_console) {
+            send_control_event(port, VIRTIO_CONSOLE_CONSOLE_PORT, 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 (port->info->guest_ready) {
+            port->info->guest_ready(port);
+        }
+        break;
+    }
+}
+
+static void control_in(VirtIODevice *vdev, VirtQueue *vq)
+{
+}
+
+static void control_out(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtQueueElement elem;
+    VirtIOSerial *vser;
+
+    vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
+
+    while (virtqueue_pop(vq, &elem)) {
+        handle_control_message(vser, elem.out_sg[0].iov_base);
+        virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
+    }
+    virtio_notify(vdev, vq);
+}
+
+/* Guest wrote something to some port. */
+static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIOSerial *vser;
+    VirtQueueElement elem;
+
+    vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
+
+    while (virtqueue_pop(vq, &elem)) {
+        VirtIOSerialPort *port;
+        size_t ret;
+
+        port = find_port_by_vq(vser, vq);
+        if (!port) {
+            ret = 0;
+            goto next_buf;
+        }
+
+        /*
+         * A port may not have any handler registered for consuming the
+         * data that the guest sends or it may not have a chardev associated
+         * with it. Just ignore the data in that case.
+         */
+        if (!port->info->have_data) {
+            ret = 0;
+            goto next_buf;
+        }
+
+        /* The guest always sends only one sg */
+        ret = port->info->have_data(port, elem.out_sg[0].iov_base,
+                                    elem.out_sg[0].iov_len);
+
+    next_buf:
+        virtqueue_push(vq, &elem, ret);
+    }
+    virtio_notify(vdev, vq);
+}
+
+static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
+{
+}
+
+static uint32_t get_features(VirtIODevice *vdev, uint32_t features)
+{
+    features |= (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+
+    return features;
+}
+
+/* Guest requested config info */
+static void get_config(VirtIODevice *vdev, uint8_t *config_data)
+{
+    VirtIOSerial *vser;
+
+    vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
+    memcpy(config_data, &vser->config, sizeof(struct virtio_console_config));
+}
+
+static void set_config(VirtIODevice *vdev, const uint8_t *config_data)
+{
+    struct virtio_console_config config;
+
+    memcpy(&config, config_data, sizeof(config));
+}
+
+static void virtio_serial_save(QEMUFile *f, void *opaque)
+{
+    VirtIOSerial *s = opaque;
+
+    /* The virtio device */
+    virtio_save(&s->vdev, f);
+
+    /* The config space */
+    qemu_put_be16s(f, &s->config.cols);
+    qemu_put_be16s(f, &s->config.rows);
+    qemu_put_be32s(f, &s->config.nr_ports);
+}
+
+static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
+{
+    VirtIOSerial *s = opaque;
+
+    if (version_id > 2) {
+        return -EINVAL;
+    }
+    /* The virtio device */
+    virtio_load(&s->vdev, f);
+
+    if (version_id < 2) {
+        return 0;
+    }
+
+    /* The config space */
+    qemu_get_be16s(f, &s->config.cols);
+    qemu_get_be16s(f, &s->config.rows);
+    s->config.nr_ports = qemu_get_be32(f);
+
+    return 0;
+}
+
+static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
+
+static struct BusInfo virtser_bus_info = {
+    .name      = "virtio-serial-bus",
+    .size      = sizeof(VirtIOSerialBus),
+    .print_dev = virtser_bus_dev_print,
+};
+
+static VirtIOSerialBus *virtser_bus_new(DeviceState *dev)
+{
+    VirtIOSerialBus *bus;
+
+    bus = FROM_QBUS(VirtIOSerialBus, qbus_create(&virtser_bus_info, dev,
+                                                 "virtio-serial-bus"));
+    bus->qbus.allow_hotplug = 1;
+
+    return bus;
+}
+
+static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
+{
+    VirtIOSerialDevice *dev = DO_UPCAST(VirtIOSerialDevice, qdev, qdev);
+    VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, &dev->qdev);
+
+    monitor_printf(mon, "%*s dev-prop-int: id: %u\n",
+                   indent, "", port->id);
+}
+
+static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
+{
+    VirtIOSerialDevice *dev = DO_UPCAST(VirtIOSerialDevice, qdev, qdev);
+    VirtIOSerialPortInfo *info = DO_UPCAST(VirtIOSerialPortInfo, qdev, base);
+    VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, &dev->qdev);
+    VirtIOSerialBus *bus = DO_UPCAST(VirtIOSerialBus, qbus, qdev->parent_bus);
+    int ret;
+    bool plugging_port0;
+
+    port->vser = bus->vser;
+
+    /*
+     * 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 = port->is_console && !find_port_by_id(port->vser, 0);
+
+    if (port->vser->config.nr_ports == bus->max_nr_ports && !plugging_port0) {
+        qemu_error("virtio-serial-bus: Maximum device limit reached\n");
+        return -1;
+    }
+    dev->info = info;
+
+    ret = info->init(dev);
+    if (ret) {
+        return ret;
+    }
+
+    port->id = plugging_port0 ? 0 : port->vser->config.nr_ports++;
+
+    QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
+    port->ivq = port->vser->ivqs[port->id];
+    port->ovq = port->vser->ovqs[port->id];
+
+    /* Send an update to the guest about this new port added */
+    virtio_notify_config(&port->vser->vdev);
+
+    return ret;
+}
+
+static int virtser_port_qdev_exit(DeviceState *qdev)
+{
+    VirtIOSerialDevice *dev = DO_UPCAST(VirtIOSerialDevice, qdev, qdev);
+    VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, &dev->qdev);
+    VirtIOSerial *vser = port->vser;
+
+    /*
+     * Don't decrement nr_ports here; thus we keep a linearly
+     * increasing port id. Not utilising an id again saves us a couple
+     * of complications:
+     *
+     * - Not having to bother about sending the port id to the guest
+     *   kernel on hotplug or on addition of new ports; the guest can
+     *   also linearly increment the port number. This is preferable
+     *   because the config space won't have the need to store a
+     *   ports_map.
+     *
+     * - Extra state to be stored for all the "holes" that got created
+     *   so that we keep filling in the ids from the least available
+     *   index.
+     *
+     * When such a functionality is desired, a control message to add
+     * a port can be introduced.
+     */
+    QTAILQ_REMOVE(&vser->ports, port, next);
+
+    if (port->info->exit)
+        port->info->exit(dev);
+
+    return 0;
+}
+
+void virtio_serial_port_qdev_register(VirtIOSerialPortInfo *info)
+{
+    info->qdev.init = virtser_port_qdev_init;
+    info->qdev.bus_info = &virtser_bus_info;
+    info->qdev.exit = virtser_port_qdev_exit;
+    info->qdev.unplug = qdev_simple_unplug_cb;
+    qdev_register(&info->qdev);
+}
+
+VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports)
+{
+    VirtIOSerial *vser;
+    VirtIODevice *vdev;
+    uint32_t i;
+
+    if (!max_nr_ports)
+        return NULL;
+
+    vdev = virtio_common_init("virtio-serial", VIRTIO_ID_CONSOLE,
+                              sizeof(struct virtio_console_config),
+                              sizeof(VirtIOSerial));
+
+    vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
+
+    /* Spawn a new virtio-serial bus on which the ports will ride as devices */
+    vser->bus = virtser_bus_new(dev);
+    vser->bus->vser = vser;
+    QTAILQ_INIT(&vser->ports);
+
+    vser->bus->max_nr_ports = max_nr_ports;
+    vser->ivqs = qemu_malloc(max_nr_ports * sizeof(VirtQueue *));
+    vser->ovqs = qemu_malloc(max_nr_ports * sizeof(VirtQueue *));
+
+    /* 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);
+
+    /* control queue: host to guest */
+    vser->c_ivq = virtio_add_queue(vdev, 16, control_in);
+    /* control queue: guest to host */
+    vser->c_ovq = virtio_add_queue(vdev, 16, 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->config.max_nr_ports = max_nr_ports;
+    /*
+     * Reserve location 0 for a console port for backward compat
+     * (old kernel, new qemu)
+     */
+    vser->config.nr_ports = 1;
+
+    vser->vdev.get_features = get_features;
+    vser->vdev.get_config = get_config;
+    vser->vdev.set_config = set_config;
+
+    /*
+     * Register for the savevm section with the virtio-console name
+     * to preserve backward compat
+     */
+    register_savevm("virtio-console", -1, 2, virtio_serial_save,
+                    virtio_serial_load, vser);
+
+    return vdev;
+}