[Qemu-devel] [PATCH 3/4] virtio-console: Add support for multiple ports for generic guest-host communication

[Amit Shah]

This interface extends the virtio-console device to handle
multiple ports that present a char device from which bits can
be sent and read.

Sample uses for such a device can be obtaining info from the
guest like the file systems used, apps installed, etc. for
offline usage and logged-in users, clipboard copy-paste, etc.
for online usage.

For requirements, use-cases and some history see

    http://www.linux-kvm.org/page/VMchannel_Requirements

Signed-off-by: Amit Shah <address@hidden>
---
 Makefile.target         |    2 +-
 hw/pc.c                 |    9 -
 hw/qdev.c               |    9 +-
 hw/virtio-console-bus.c |  111 ++++++++
 hw/virtio-console.c     |  646 +++++++++++++++++++++++++++++++++++++++++++----
 hw/virtio-console.h     |   73 ++++++
 qemu-options.hx         |    8 -
 sysemu.h                |    7 +-
 vl.c                    |   37 ---
 9 files changed, 781 insertions(+), 121 deletions(-)
 create mode 100644 hw/virtio-console-bus.c

diff --git a/Makefile.target b/Makefile.target
index 609015b..22a2644 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -173,7 +173,7 @@ obj-y = vl.o monitor.o pci.o isa_mmio.o machine.o \
         gdbstub.o gdbstub-xml.o
 # virtio has to be here due to weird dependency between PCI and virtio-net.
 # need to fix this properly
-obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-console.o 
virtio-pci.o
+obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-console.o 
virtio-console-bus.o virtio-pci.o
 obj-$(CONFIG_KVM) += kvm.o kvm-all.o
 
 LIBS+=-lz
diff --git a/hw/pc.c b/hw/pc.c
index 240cfe0..70b1ce9 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -1463,15 +1463,6 @@ static void pc_init1(ram_addr_t ram_size,
        extboot_init(info->bdrv, 1);
     }
 
-    /* Add virtio console devices */
-    if (pci_enabled) {
-        for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-            if (virtcon_hds[i]) {
-                pci_create_simple(pci_bus, -1, "virtio-console-pci");
-            }
-        }
-    }
-
 #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
     if (kvm_enabled()) {
         add_assigned_devices(pci_bus, assigned_devices, 
assigned_devices_index);
diff --git a/hw/qdev.c b/hw/qdev.c
index 43b1beb..1d79db0 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -243,13 +243,8 @@ void qdev_free(DeviceState *dev)
 CharDriverState *qdev_init_chardev(DeviceState *dev)
 {
     static int next_serial;
-    static int next_virtconsole;
-    /* FIXME: This is a nasty hack that needs to go away.  */
-    if (strncmp(dev->info->name, "virtio", 6) == 0) {
-        return virtcon_hds[next_virtconsole++];
-    } else {
-        return serial_hds[next_serial++];
-    }
+
+    return serial_hds[next_serial++];
 }
 
 BusState *qdev_get_parent_bus(DeviceState *dev)
diff --git a/hw/virtio-console-bus.c b/hw/virtio-console-bus.c
new file mode 100644
index 0000000..d8be5bb
--- /dev/null
+++ b/hw/virtio-console-bus.c
@@ -0,0 +1,111 @@
+/*
+ * A bus for connecting virtio-console ports
+ *
+ * Copyright (c) 2009 Red Hat, Inc.
+ *
+ * Author(s):
+ *  Amit Shah <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "sysbus.h"
+#include "virtio-console.h"
+
+/* The virtio-console bus on top of which the ports will ride as devices */
+struct VirtConBus {
+    BusState qbus;
+    uint32_t assigned;
+};
+static VirtConBus *virtcon_bus;
+
+static void virtcon_bus_dev_print(Monitor *mon, DeviceState *dev, int indent);
+
+static struct BusInfo virtcon_bus_info = {
+    .name      = "virtio-console-bus",
+    .size      = sizeof(VirtConBus),
+    .print_dev = virtcon_bus_dev_print,
+};
+
+VirtConBus *virtcon_bus_new(DeviceState *dev)
+{
+    if (virtcon_bus) {
+        fprintf(stderr, "Can't create a second virtio-console bus\n");
+        return NULL;
+    }
+    if (!dev) {
+        dev = qdev_create(NULL, "virtio-console-sysbus");
+        qdev_init(dev);
+    }
+
+    virtcon_bus = FROM_QBUS(VirtConBus, qbus_create(&virtcon_bus_info, dev, 
NULL));
+    return virtcon_bus;
+}
+
+static int virtcon_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
+{
+    VirtConDevice *dev = DO_UPCAST(VirtConDevice, qdev, qdev);
+    VirtConPortDeviceInfo *info = DO_UPCAST(VirtConPortDeviceInfo, qdev, base);
+
+    return info->init(dev);
+}
+
+void virtcon_port_qdev_register(VirtConPortDeviceInfo *info)
+{
+    info->qdev.init = virtcon_port_qdev_init;
+    info->qdev.bus_info = &virtcon_bus_info;
+    qdev_register(&info->qdev);
+}
+
+VirtConDevice *virtcon_create(const char *name)
+{
+    DeviceState *dev;
+
+    if (!virtcon_bus) {
+        qemu_error("Tried to create a port %s with no virtio-console bus 
present.\n",
+                  name);
+        return NULL;
+    }
+    dev = qdev_create(&virtcon_bus->qbus, name);
+    return DO_UPCAST(VirtConDevice, qdev, dev);
+}
+
+VirtConDevice *virtcon_create_simple(const char *name)
+{
+    VirtConDevice *dev;
+
+    dev = virtcon_create(name);
+    if (qdev_init(&dev->qdev) != 0) {
+        qdev_free(&dev->qdev);
+        return NULL;
+    }
+    return dev;
+}
+
+static void virtcon_bus_dev_print(Monitor *mon, DeviceState *dev, int indent)
+{
+    VirtConDevice *d = DO_UPCAST(VirtConDevice, qdev, dev);
+    if (&d->qdev) {
+      ;
+    }
+}
+
+static int virtcon_bus_init(SysBusDevice *dev)
+{
+    return 0;
+}
+
+static SysBusDeviceInfo virtcon_sysbus_info = {
+    .init = virtcon_bus_init,
+    .qdev.name  = "virtio-console-sysbus",
+    .qdev.size  = sizeof(SysBusDevice),
+    .qdev.no_user = 1,
+};
+
+static void virtcon_sysbus_register_devices(void)
+{
+    sysbus_register_withprop(&virtcon_sysbus_info);
+}
+
+device_init(virtcon_sysbus_register_devices)
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 92c953c..d750c8e 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -2,9 +2,11 @@
  * Virtio Console Device
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <address@hidden>
+ *  Amit Shah <address@hidden>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -12,39 +14,320 @@
  */
 
 #include "hw.h"
+#include "monitor.h"
+#include "qemu-queue.h"
 #include "qemu-char.h"
+#include "sysbus.h"
 #include "virtio.h"
 #include "virtio-console.h"
 
-
 typedef struct VirtIOConsole
 {
     VirtIODevice vdev;
     VirtQueue *ivq, *ovq;
-    CharDriverState *chr;
+
+    VirtIOConsolePort* ports[MAX_VIRTIO_CONSOLE_PORTS];
+    struct virtio_console_config config;
+
+    uint32_t guest_features;
 } VirtIOConsole;
 
-static VirtIOConsole *to_virtio_console(VirtIODevice *vdev)
+/* This struct holds individual buffers received for each port */
+typedef struct VirtIOConsolePortBuffer {
+    QTAILQ_ENTRY(VirtIOConsolePortBuffer) next;
+
+    uint8_t *buf;
+
+    size_t len; /* length of the buffer */
+
+    /* The size of one write request as issued by the guest. The
+     * buffer could be split in this list but using the size value in
+     * the first buffer for each write we can identify complete
+     * writes
+     */
+    size_t size;
+} VirtIOConsolePortBuffer;
+
+struct VirtIOConsolePort {
+    DeviceState dev;
+
+    VirtIOConsole *vcon;
+    CharDriverState *hd;
+
+    char *name;
+
+    QTAILQ_HEAD(, VirtIOConsolePortBuffer) unflushed_buffer_head;
+
+    bool guest_connected;
+    bool host_connected;
+};
+
+static VirtIOConsole *virtio_console;
+
+static VirtIOConsolePort *get_port_from_id(VirtIOConsole *vcon, uint32_t id)
+{
+    if (id > MAX_VIRTIO_CONSOLE_PORTS)
+        return NULL;
+
+    return vcon->ports[id];
+}
+
+static int get_id_from_port(VirtIOConsolePort *port)
+{
+    uint32_t i;
+
+    for (i = 0; i < MAX_VIRTIO_CONSOLE_PORTS; i++) {
+        if (port == port->vcon->ports[i]) {
+            return i;
+        }
+    }
+    return VIRTIO_CONSOLE_BAD_ID;
+}
+
+static bool use_multiport(void)
+{
+    return virtio_console->guest_features & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static bool is_internal(uint32_t flags)
+{
+    return flags & VIRTIO_CONSOLE_ID_INTERNAL;
+}
+
+static bool is_console(uint32_t port_nr)
+{
+    return false;
+}
+
+static bool has_complete_data(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf;
+    size_t len, size;
+
+    len = 0;
+    size = 0;
+    QTAILQ_FOREACH(buf, &port->unflushed_buffer_head, next) {
+        if (!buf->size && buf == QTAILQ_FIRST(&port->unflushed_buffer_head)) {
+            /* We have a buffer that's lost its way; just flush it */
+            return true;
+        }
+        if (size && buf->size) {
+            /* Start of the next write request */
+            return true;
+        }
+        if (buf->size) {
+            size = buf->size;
+        }
+        len += buf->len;
+        if (len == size) {
+            return true;
+        }
+    }
+    return false;
+}
+
+static size_t flush_buf(VirtIOConsolePort *port, const uint8_t *buf, size_t 
len)
+{
+    if (!port->hd) {
+        return 0;
+    }
+    return qemu_chr_write(port->hd, buf, len);
+}
+
+static void flush_queue(VirtIOConsolePort *port)
+{
+    VirtIOConsolePortBuffer *buf, *buf2;
+    uint8_t *outbuf;
+    size_t outlen, outsize;
+
+    while (!QTAILQ_EMPTY(&port->unflushed_buffer_head)) {
+        if (!has_complete_data(port)) {
+            break;
+        }
+
+        buf = QTAILQ_FIRST(&port->unflushed_buffer_head);
+        if (!buf->size) {
+            /* This is a buf that didn't get consumed as part of a
+             * previous data stream. Bad thing, shouldn't
+             * happen. But let's handle it nonetheless
+             */
+            flush_buf(port, buf->buf, buf->len);
+            QTAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            continue;
+        }
+
+        outlen = 0;
+        outsize = buf->size;
+        outbuf = qemu_mallocz(outsize);
+        QTAILQ_FOREACH_SAFE(buf, &port->unflushed_buffer_head, next, buf2) {
+            memcpy(outbuf + outlen, buf->buf, buf->len);
+            outlen += buf->len;
+            QTAILQ_REMOVE(&port->unflushed_buffer_head, buf, next);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+
+            if (outlen == outsize)
+                break;
+        }
+        flush_buf(port, outbuf, outlen);
+        qemu_free(outbuf);
+    }
+}
+
+
+static size_t write_to_port(VirtIOConsolePort *port,
+                            const uint8_t *buf, size_t size, uint32_t flags)
 {
-    return (VirtIOConsole *)vdev;
+    VirtQueue *vq = port->vcon->ivq;
+    VirtQueueElement elem;
+    size_t offset = 0;
+    size_t len = 0;
+
+    if (!virtio_queue_ready(vq)) {
+        return 0;
+    }
+
+    if (!use_multiport() && is_internal(flags)) {
+        return 0;
+    }
+
+    while (offset < size) {
+        struct virtio_console_header header;
+        int i, header_len;
+
+        header_len = use_multiport() ? sizeof(header) : 0;
+
+        if (!virtqueue_pop(vq, &elem)) {
+            break;
+        }
+        if (elem.in_sg[0].iov_len < header_len) {
+            /* We can't even store our port number in this buffer. Bug? */
+            fprintf(stderr, "virtio-console: size %zd less than expected\n",
+                    elem.in_sg[0].iov_len);
+            exit(1);
+        }
+        header.id = cpu_to_le32(get_id_from_port(port));
+        header.flags = flags;
+        memcpy(elem.in_sg[0].iov_base, &header, header_len);
+
+        for (i = 0; offset < size && i < elem.in_num; i++) {
+            len = MIN(elem.in_sg[i].iov_len - header_len, size - offset);
+
+            memcpy(elem.in_sg[i].iov_base + header_len, buf + offset, len);
+            offset += len;
+            header_len = 0;
+        }
+        header_len = use_multiport() ? sizeof(header) : 0;
+        virtqueue_push(vq, &elem, len + header_len);
+    }
+    virtio_notify(&port->vcon->vdev, vq);
+    return offset;
 }
 
+/* Guest wants to notify us of some event */
+static void handle_control_message(VirtIOConsolePort *port,
+                                   struct virtio_console_control *cpkt)
+{
+    uint8_t *buffer;
+    size_t buffer_len;
+
+    switch(cpkt->event) {
+    case VIRTIO_CONSOLE_PORT_OPEN:
+        port->guest_connected = cpkt->value;
+        break;
+    case VIRTIO_CONSOLE_PORT_NAME:
+        if (!port->name) {
+            const char *default_string = "org.qemu.console";
+
+            port->name = qemu_malloc(strlen(default_string) + 1);
+            memcpy(port->name, default_string, strlen(default_string) + 1);
+        }
+        buffer_len = sizeof(*cpkt) + strlen(port->name) + 1;
+        buffer = qemu_malloc(buffer_len);
+
+        memcpy(buffer, cpkt, sizeof(*cpkt));
+        memcpy(buffer + sizeof(*cpkt), port->name, strlen(port->name));
+        buffer[buffer_len - 1] = 0;
+
+        write_to_port(port, buffer, buffer_len, VIRTIO_CONSOLE_ID_INTERNAL);
+        qemu_free(buffer);
+    }
+}
+
+/* Guest wrote something to some port.
+ *
+ * Flush the data in the entire chunk that we received rather than
+ * splitting it into multiple buffers. VNC clients don't consume split
+ * buffers
+ */
 static void virtio_console_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtIOConsole *s = to_virtio_console(vdev);
+    VirtIOConsole *vcon;
     VirtQueueElement elem;
 
+    vcon = DO_UPCAST(VirtIOConsole, vdev, vdev);
+
     while (virtqueue_pop(vq, &elem)) {
-        ssize_t len = 0;
-        int d;
+        VirtIOConsolePort *port;
+        VirtIOConsolePortBuffer *buf;
+        struct virtio_console_header header;
+        int header_len;
 
-        for (d = 0; d < elem.out_num; d++) {
-            len += qemu_chr_write(s->chr, (uint8_t *)elem.out_sg[d].iov_base,
-                                  elem.out_sg[d].iov_len);
+        buf = qemu_mallocz(sizeof(*buf));
+
+        if (use_multiport()) {
+            header_len = sizeof(header);
+
+            memcpy(&header, elem.out_sg[0].iov_base, header_len);
+            port = get_port_from_id(vcon, header.id);
+            if (!port) {
+                qemu_free(buf);
+                goto next_buf;
+            }
+        } else {
+            header_len = 0;
+            port = get_port_from_id(vcon, 0);
+        }
+
+        /* The guest always sends only one sg */
+        buf->len = elem.out_sg[0].iov_len - header_len;
+        buf->buf = qemu_mallocz(buf->len);
+        memcpy(buf->buf, elem.out_sg[0].iov_base + header_len, buf->len);
+
+        if (use_multiport() && is_internal(header.flags)) {
+            handle_control_message(port,
+                                   (struct virtio_console_control *)buf->buf);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
+        }
+       if (!use_multiport() || is_console(get_id_from_port(port))) {
+            flush_buf(port, buf->buf, buf->len);
+            qemu_free(buf->buf);
+            qemu_free(buf);
+            goto next_buf;
         }
-        virtqueue_push(vq, &elem, len);
-        virtio_notify(vdev, vq);
+        QTAILQ_INSERT_TAIL(&port->unflushed_buffer_head, buf, next);
+        if (use_multiport()) {
+            /* Only the first buffer in a stream will have this
+             * set. This will help us identify the first buffer and
+             * the remaining buffers in the stream based on length
+             */
+            buf->size = header.size;
+        } else {
+            /* We always want to flush all the buffers in this case */
+            buf->size = buf->len;
+        }
+        if (!port->host_connected) {
+            goto next_buf;
+        }
+        flush_queue(port);
+    next_buf:
+        virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
     }
+    virtio_notify(vdev, vq);
 }
 
 static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
@@ -53,94 +336,351 @@ static void virtio_console_handle_input(VirtIODevice 
*vdev, VirtQueue *vq)
 
 static uint32_t virtio_console_get_features(VirtIODevice *vdev)
 {
-    return 0;
+    return 1 << VIRTIO_CONSOLE_F_MULTIPORT;
+}
+
+static void virtio_console_set_features(VirtIODevice *vdev, uint32_t features)
+{
+    virtio_console->guest_features = features;
 }
 
+/* Guest requested config info */
+static void virtio_console_get_config(VirtIODevice *vdev, uint8_t *config_data)
+{
+    VirtIOConsole *vcon;
+
+    vcon = DO_UPCAST(VirtIOConsole, vdev, vdev);
+    memcpy(config_data, &vcon->config, sizeof(struct virtio_console_config));
+}
+
+static void virtio_console_set_config(VirtIODevice *vdev,
+                                      const uint8_t *config_data)
+{
+    struct virtio_console_config config;
+
+    memcpy(&config, config_data, sizeof(config));
+}
+
+static void send_control_event(VirtIOConsolePort *port,
+                               struct virtio_console_control *cpkt)
+{
+    write_to_port(port, (uint8_t *)cpkt, sizeof(*cpkt),
+                  VIRTIO_CONSOLE_ID_INTERNAL);
+}
+
+/* Readiness of the guest to accept data on a port */
 static int vcon_can_read(void *opaque)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
+    VirtIOConsolePort *port = opaque;
+    VirtQueue *vq = port->vcon->ivq;
+    int size, header_len;
 
-    if (!virtio_queue_ready(s->ivq) ||
-        !(s->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
-        virtio_queue_empty(s->ivq))
-        return 0;
+    if (use_multiport()) {
+        header_len = sizeof(struct virtio_console_header);
+    } else {
+        header_len = 0;
+    }
 
-    /* current implementations have a page sized buffer.
-     * We fall back to a one byte per read if there is not enough room.
-     * It would be cool to have a function that returns the available byte
-     * instead of checking for a limit */
-    if (virtqueue_avail_bytes(s->ivq, TARGET_PAGE_SIZE, 0))
-        return TARGET_PAGE_SIZE;
-    if (virtqueue_avail_bytes(s->ivq, 1, 0))
-        return 1;
+    if (!virtio_queue_ready(vq) ||
+        !(port->vcon->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
+        virtio_queue_empty(vq)) {
+        return 0;
+    }
+    if (!port->guest_connected) {
+        return 0;
+    }
+    size = TARGET_PAGE_SIZE;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
+    }
+    size = header_len + 1;
+    if (virtqueue_avail_bytes(vq, size, 0)) {
+        return size - header_len;
+    }
     return 0;
 }
 
+/* Send data from a char device over to the guest */
 static void vcon_read(void *opaque, const uint8_t *buf, int size)
 {
-    VirtIOConsole *s = (VirtIOConsole *) opaque;
-    VirtQueueElement elem;
-    int offset = 0;
+    VirtIOConsolePort *port = opaque;
 
-    /* The current kernel implementation has only one outstanding input
-     * buffer of PAGE_SIZE. Nevertheless, this function is prepared to
-     * handle multiple buffers with multiple sg element for input */
-    while (offset < size) {
-        int i = 0;
-        if (!virtqueue_pop(s->ivq, &elem))
-                break;
-        while (offset < size && i < elem.in_num) {
-            int len = MIN(elem.in_sg[i].iov_len, size - offset);
-            memcpy(elem.in_sg[i].iov_base, buf + offset, len);
-            offset += len;
-            i++;
-        }
-        virtqueue_push(s->ivq, &elem, size);
-    }
-    virtio_notify(&s->vdev, s->ivq);
+    write_to_port(port, buf, size, 0);
 }
 
 static void vcon_event(void *opaque, int event)
 {
-    /* we will ignore any event for the time being */
+    VirtIOConsolePort *port = opaque;
+    struct virtio_console_control cpkt;
+    bool update_needed;
+
+    cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+
+    update_needed = false;
+    switch (event) {
+    case CHR_EVENT_OPENED: {
+        cpkt.value = 1;
+        update_needed = true;
+        port->host_connected = true;
+
+        /* Flush any buffers that were pending while the chardev was
+         * disconnected
+         */
+        flush_queue(port);
+        break;
+    }
+    case CHR_EVENT_CLOSED:
+        cpkt.value = 0;
+        update_needed = true;
+        port->host_connected = false;
+        break;
+    default:
+        break;
+    }
+    if (!update_needed) {
+        return;
+    }
+    send_control_event(port, &cpkt);
+}
+
+static void set_active_in_map(uint32_t *map, uint32_t idx)
+{
+    int i;
+
+    i = idx / 32;
+    idx %= 32;
+
+    map[i] |= 1U << idx;
+}
+
+/*
+ * Get the guest_connected status after a migration since it's all
+ * packed in the same way as ports_map in the config space is packed.
+ *
+ * return VIRTIO_CONSOLE_BAD_ID if nothing was found in the map, else
+ * return the port number whose guest was connected before the
+ * migration
+ */
+static uint32_t find_next_active_in_map(uint32_t *map, unsigned int i)
+{
+    uint32_t port_nr;
+
+    port_nr = ffs(*map);
+    if (!port_nr) {
+        return VIRTIO_CONSOLE_BAD_ID;
+    }
+    /* We used ffs above */
+    port_nr--;
+
+    *map &= ~(1U << port_nr);
+
+    port_nr += i * 32;
+    return port_nr;
+}
+
+static int vcon_port_initfn(VirtConDevice *dev)
+{
+    VirtIOConsolePort *port;
+
+    port = DO_UPCAST(VirtIOConsolePort, dev, &dev->qdev);
+
+    QTAILQ_INIT(&port->unflushed_buffer_head);
+
+    port->vcon = virtio_console;
+
+    qemu_chr_add_handlers(port->hd, vcon_can_read, vcon_read, vcon_event, 
port);
+
+    port->vcon->ports[port->vcon->config.nr_active_ports++] = port;
+
+    /* Send an update to the guest about this new port added */
+    virtio_notify_config(&port->vcon->vdev);
+
+    return 0;
 }
 
 static void virtio_console_save(QEMUFile *f, void *opaque)
 {
     VirtIOConsole *s = opaque;
+    uint32_t guest_connected_map[MAX_VIRTIO_CONSOLE_PORTS / 32];
+    unsigned int i, nr_bufs, active_ports;
 
+    /* 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_active_ports);
+
+    active_ports = le32_to_cpu(s->config.nr_active_ports);
+
+    /* Items in struct VirtIOConsole */
+    qemu_put_be32s(f, &s->guest_features);
+
+    /*
+     * Items in struct VirtIOConsolePort
+     *   guest_connected is a single bit in each port; pack all these
+     *   bits in uint32_t words and then send them across
+     */
+    for (i = 0; i < active_ports / 32; i++) {
+        guest_connected_map[i] = 0;
+    }
+    for (i = 0; i < active_ports; i++) {
+        if (s->ports[i]->guest_connected) {
+            set_active_in_map(guest_connected_map, i);
+        }
+    }
+    for (i = 0; i < active_ports / 32; i++) {
+        qemu_put_be32s(f, &guest_connected_map[i]);
+    }
+
+    /* All the pending buffers from active ports */
+    for (i = 0; i < active_ports; i++) {
+        VirtIOConsolePortBuffer *buf;
+
+        nr_bufs = 0;
+        QTAILQ_FOREACH(buf, &s->ports[i]->unflushed_buffer_head, next) {
+            nr_bufs++;
+        }
+        /* First the port number, then the nr of bufs and then the bufs */
+        qemu_put_be32s(f, &i);
+        qemu_put_be32s(f, &nr_bufs);
+        if (!nr_bufs) {
+            continue;
+        }
+        QTAILQ_FOREACH(buf, &s->ports[i]->unflushed_buffer_head, next) {
+            qemu_put_be64s(f, &buf->len);
+            qemu_put_be64s(f, &buf->size);
+            qemu_put_buffer(f, buf->buf, buf->len);
+        }
+    }
 }
 
 static int virtio_console_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOConsole *s = opaque;
+    uint32_t guest_connected_map[MAX_VIRTIO_CONSOLE_PORTS / 32];
+    unsigned int i, active_ports;
 
-    if (version_id != 1)
+    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_active_ports = cpu_to_le32(qemu_get_be32(f));
+
+    active_ports = le32_to_cpu(s->config.nr_active_ports);
+
+    /* Items in struct VirtIOConsole */
+    qemu_get_be32s(f, &virtio_console->guest_features);
+
+    /* Items in struct VirtIOConsolePort */
+    for (i = 0; i < active_ports / 32; i++) {
+        guest_connected_map[i] = qemu_get_be32(f);
+    }
+
+    for (i = 0; i < active_ports / 32; i++) {
+        uint32_t port_nr, map;
+
+        map = guest_connected_map[i];
+        while (1) {
+            port_nr = find_next_active_in_map(&map, i);
+            if (port_nr == VIRTIO_CONSOLE_BAD_ID) {
+                break;
+            }
+            s->ports[port_nr]->guest_connected = true;
+        }
+    }
+
+    /* All the pending buffers from active ports */
+    for (i = 0; i < active_ports; i++) {
+        VirtIOConsolePortBuffer *buf;
+        unsigned int nr, nr_bufs;
+
+        /* First the port number, then the nr of bufs and then the bufs */
+        qemu_get_be32s(f, &nr);
+        qemu_get_be32s(f, &nr_bufs);
+        if (!nr_bufs) {
+            continue;
+        }
+        for (; nr_bufs; nr_bufs--) {
+            buf = qemu_malloc(sizeof(*buf));
+
+            qemu_get_be64s(f, &buf->len);
+            qemu_get_be64s(f, &buf->size);
+            buf->buf = qemu_malloc(buf->len);
+            qemu_get_buffer(f, buf->buf, buf->len);
+            QTAILQ_INSERT_TAIL(&s->ports[nr]->unflushed_buffer_head, buf, 
next);
+        }
+    }
+
     return 0;
 }
 
 VirtIODevice *virtio_console_init(DeviceState *dev)
 {
     VirtIOConsole *s;
+
+    if (virtio_console) {
+        /*
+         * Linux guests don't support more than one virtio-console devices
+         * at the moment
+         */
+        return NULL;
+    }
+
+    if (MAX_VIRTIO_CONSOLE_PORTS % 32) {
+        /* We require MAX_VIRTIO_CONSOLE_PORTS be a multiple of 32:
+         * We anyway use up that much space for the bitmap and it
+         * simplifies some calculations
+         */
+        return NULL;
+    }
+
     s = (VirtIOConsole *)virtio_common_init("virtio-console",
                                             VIRTIO_ID_CONSOLE,
-                                            0, sizeof(VirtIOConsole));
-    if (s == NULL)
-        return NULL;
+                                            sizeof(struct 
virtio_console_config),
+                                            sizeof(VirtIOConsole));
 
+    virtio_console = s;
     s->vdev.get_features = virtio_console_get_features;
+    s->vdev.set_features = virtio_console_set_features;
+    s->vdev.get_config = virtio_console_get_config;
+    s->vdev.set_config = virtio_console_set_config;
 
+    /* Add queue for host to guest transfers */
     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_input);
+    /* Add queue for guest to host transfers */
     s->ovq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
 
-    s->chr = qdev_init_chardev(dev);
-    qemu_chr_add_handlers(s->chr, vcon_can_read, vcon_read, vcon_event, s);
+    register_savevm("virtio-console", -1, 2, virtio_console_save,
+                    virtio_console_load, s);
 
-    register_savevm("virtio-console", -1, 1, virtio_console_save, 
virtio_console_load, s);
+    /* Spawn a new virtio-console bus on which the ports will ride as devices 
*/
+    virtcon_bus_new(NULL);
 
     return &s->vdev;
 }
+
+static VirtConPortDeviceInfo virtcon_port_info = {
+    .qdev.name     = "virtconport",
+    .qdev.size     = sizeof(VirtIOConsolePort),
+    .init          = vcon_port_initfn,
+    .qdev.props = (Property[]) {
+        DEFINE_PROP_CHR("chardev", VirtIOConsolePort, hd),
+        DEFINE_PROP_STRING("name", VirtIOConsolePort, name),
+        DEFINE_PROP_END_OF_LIST(),
+    },
+};
+
+static void virtcon_port_register(void)
+{
+    virtcon_port_qdev_register(&virtcon_port_info);
+}
+device_init(virtcon_port_register)
diff --git a/hw/virtio-console.h b/hw/virtio-console.h
index 84d0717..526713e 100644
--- a/hw/virtio-console.h
+++ b/hw/virtio-console.h
@@ -2,9 +2,11 @@
  * Virtio Console Support
  *
  * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
  *
  * Authors:
  *  Christian Ehrhardt <address@hidden>
+ *  Amit Shah <address@hidden>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -13,7 +15,78 @@
 #ifndef _QEMU_VIRTIO_CONSOLE_H
 #define _QEMU_VIRTIO_CONSOLE_H
 
+#include "sysemu.h"
+
+/* Interface shared between the guest kernel and qemu */
+
 /* The ID for virtio console */
 #define VIRTIO_ID_CONSOLE 3
 
+/* Invalid port number */
+#define VIRTIO_CONSOLE_BAD_ID          (~(uint32_t)0)
+
+/* Features supported */
+#define VIRTIO_CONSOLE_F_MULTIPORT     1
+
+struct virtio_console_config
+{
+    /*
+     * These two fields are used by VIRTIO_CONSOLE_F_SIZE which
+     * isn't implemented here yet
+     */
+    uint16_t cols;
+    uint16_t rows;
+
+    uint32_t nr_active_ports;
+} __attribute__((packed));
+
+struct virtio_console_control
+{
+    uint16_t event;
+    uint16_t value;
+};
+
+struct virtio_console_header {
+    uint32_t id; /* Port id */
+    uint32_t flags; /* Some message between host and guest */
+    uint32_t size; /* Size that's sent with the first buffer of each stream */
+} __attribute__((packed));
+
+/* Messages between host and guest */
+#define VIRTIO_CONSOLE_ID_INTERNAL     (1 << 0)
+
+/* Some events for the internal messages (control packets) */
+#define VIRTIO_CONSOLE_PORT_OPEN       0
+#define VIRTIO_CONSOLE_PORT_NAME       1
+
+typedef struct VirtConBus VirtConBus;
+
+/* In-qemu interface */
+
+/* Max. virtio console ports per device */
+#define MAX_VIRTIO_CONSOLE_PORTS       64
+
+typedef struct VirtConDevice {
+    DeviceState qdev;
+} VirtConDevice;
+
+typedef int (*virtcon_qdev_initfn)(VirtConDevice *dev);
+typedef int (*virtcon_port_qdev_initfn)(VirtConDevice *dev);
+
+typedef struct VirtConPortDeviceInfo {
+    DeviceInfo qdev;
+    virtcon_port_qdev_initfn init;
+} VirtConPortDeviceInfo;
+
+VirtConDevice *virtcon_create(const char *name);
+VirtConDevice *virtcon_create_simple(const char *name);
+
+void virtcon_port_qdev_register(VirtConPortDeviceInfo *info);
+
+VirtConBus *virtcon_bus_new(DeviceState *dev);
+
+typedef struct VirtIOConsolePort VirtIOConsolePort;
+void virtio_console_monitor_command(Monitor *mon,
+                                    const char *command, const char *param);
+
 #endif
diff --git a/qemu-options.hx b/qemu-options.hx
index 2f4291d..ca412bf 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1604,14 +1604,6 @@ character to Control-t.
 @end table
 ETEXI
 
-DEF("virtioconsole", HAS_ARG, QEMU_OPTION_virtiocon, \
-    "-virtioconsole c\n" \
-    "                set virtio console\n")
-STEXI
address@hidden -virtioconsole @var{c}
-Set virtio console.
-ETEXI
-
 DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \
     "-show-cursor    show cursor\n")
 STEXI
diff --git a/sysemu.h b/sysemu.h
index a8d1549..af0e7d8 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -2,6 +2,7 @@
 #define SYSEMU_H
 /* Misc. things related to the system emulator.  */
 
+#include <stdbool.h>
 #include "qemu-common.h"
 #include "qemu-option.h"
 #include "qemu-queue.h"
@@ -233,12 +234,6 @@ extern CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 
 extern CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 
-/* virtio consoles */
-
-#define MAX_VIRTIO_CONSOLES 1
-
-extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
-
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
 #ifdef HAS_AUDIO
diff --git a/vl.c b/vl.c
index 3b49c56..b5215b2 100644
--- a/vl.c
+++ b/vl.c
@@ -213,7 +213,6 @@ static int no_frame = 0;
 int no_quit = 0;
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
-CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
 #ifdef TARGET_I386
 int win2k_install_hack = 0;
 int rtc_td_hack = 0;
@@ -4690,8 +4689,6 @@ int main(int argc, char **argv, char **envp)
     int serial_device_index;
     const char *parallel_devices[MAX_PARALLEL_PORTS];
     int parallel_device_index;
-    const char *virtio_consoles[MAX_VIRTIO_CONSOLES];
-    int virtio_console_index;
     const char *loadvm = NULL;
     QEMUMachine *machine;
     const char *cpu_model;
@@ -4765,10 +4762,6 @@ int main(int argc, char **argv, char **envp)
         parallel_devices[i] = NULL;
     parallel_device_index = 0;
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++)
-        virtio_consoles[i] = NULL;
-    virtio_console_index = 0;
-
     monitor_devices[0] = "vc:80Cx24C";
     for (i = 1; i < MAX_MONITOR_DEVICES; i++) {
         monitor_devices[i] = NULL;
@@ -5228,14 +5221,6 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
-            case QEMU_OPTION_virtiocon:
-                if (virtio_console_index >= MAX_VIRTIO_CONSOLES) {
-                    fprintf(stderr, "qemu: too many virtio consoles\n");
-                    exit(1);
-                }
-                virtio_consoles[virtio_console_index] = optarg;
-                virtio_console_index++;
-                break;
             case QEMU_OPTION_parallel:
                 if (parallel_device_index >= MAX_PARALLEL_PORTS) {
                     fprintf(stderr, "qemu: too many parallel ports\n");
@@ -5827,20 +5812,6 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-        const char *devname = virtio_consoles[i];
-        if (devname && strcmp(devname, "none")) {
-            char label[32];
-            snprintf(label, sizeof(label), "virtcon%d", i);
-            virtcon_hds[i] = qemu_chr_open(label, devname, NULL);
-            if (!virtcon_hds[i]) {
-                fprintf(stderr, "qemu: could not open virtio console '%s'\n",
-                        devname);
-                exit(1);
-            }
-        }
-    }
-
     module_call_init(MODULE_INIT_DEVICE);
 
     if (watchdog) {
@@ -5968,14 +5939,6 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    for(i = 0; i < MAX_VIRTIO_CONSOLES; i++) {
-        const char *devname = virtio_consoles[i];
-        if (virtcon_hds[i] && devname) {
-            if (strstart(devname, "vc", 0))
-                qemu_chr_printf(virtcon_hds[i], "virtio console%d\r\n", i);
-        }
-    }
-
     if (gdbstub_dev && gdbserver_start(gdbstub_dev) < 0) {
         fprintf(stderr, "qemu: could not open gdbserver on device '%s'\n",
                 gdbstub_dev);
-- 
1.6.2.5