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, 158 insertions, 0 deletions

diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
new file mode 100644
index 000000000..fe8e357a7
--- /dev/null
+++ b/hw/virtio-serial.h
@@ -0,0 +1,158 @@
+/*
+ * Virtio Serial / Console Support
+ *
+ * Copyright IBM, Corp. 2008
+ * Copyright Red Hat, Inc. 2009
+ *
+ * Authors:
+ *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
+ *  Amit Shah <amit.shah@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+#ifndef _QEMU_VIRTIO_SERIAL_H
+#define _QEMU_VIRTIO_SERIAL_H
+
+#include <stdbool.h>
+#include "qdev.h"
+#include "virtio.h"
+
+/* == Interface shared between the guest kernel and qemu == */
+
+/* The Virtio ID for virtio console / serial ports */
+#define VIRTIO_ID_CONSOLE		3
+
+/* 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 max_nr_ports;
+    uint32_t nr_ports;
+} __attribute__((packed));
+
+struct virtio_console_control {
+    uint32_t id;		/* Port number */
+    uint16_t event;		/* The kind of control event (see below) */
+    uint16_t value;		/* Extra information for the key */
+};
+
+/* Some events for the internal messages (control packets) */
+#define VIRTIO_CONSOLE_PORT_READY	0
+#define VIRTIO_CONSOLE_CONSOLE_PORT	1
+#define VIRTIO_CONSOLE_RESIZE		2
+
+/* == In-qemu interface == */
+
+typedef struct VirtIOSerial VirtIOSerial;
+typedef struct VirtIOSerialBus VirtIOSerialBus;
+typedef struct VirtIOSerialPort VirtIOSerialPort;
+typedef struct VirtIOSerialPortInfo VirtIOSerialPortInfo;
+
+typedef struct VirtIOSerialDevice {
+    DeviceState qdev;
+    VirtIOSerialPortInfo *info;
+} VirtIOSerialDevice;
+
+/*
+ * This is the state that's shared between all the ports.  Some of the
+ * state is configurable via command-line options. Some of it can be
+ * set by individual devices in their initfn routines. Some of the
+ * state is set by the generic qdev device init routine.
+ */
+struct VirtIOSerialPort {
+    DeviceState dev;
+    VirtIOSerialPortInfo *info;
+
+    QTAILQ_ENTRY(VirtIOSerialPort) next;
+
+    /*
+     * This field gives us the virtio device as well as the qdev bus
+     * that we are associated with
+     */
+    VirtIOSerial *vser;
+
+    VirtQueue *ivq, *ovq;
+
+    /*
+     * This id helps identify ports between the guest and the host.
+     * The guest sends a "header" with this id with each data packet
+     * that it sends and the host can then find out which associated
+     * device to send out this data to
+     */
+    uint32_t id;
+
+    /* Identify if this is a port that binds with hvc in the guest */
+    uint8_t is_console;
+};
+
+struct VirtIOSerialPortInfo {
+    DeviceInfo qdev;
+    /*
+     * The per-port (or per-app) init function that's called when a
+     * new device is found on the bus.
+     */
+    int (*init)(VirtIOSerialDevice *dev);
+    /*
+     * Per-port exit function that's called when a port gets
+     * hot-unplugged or removed.
+     */
+    int (*exit)(VirtIOSerialDevice *dev);
+
+    /* Callbacks for guest events */
+        /* Guest opened device. */
+    void (*guest_open)(VirtIOSerialPort *port);
+        /* Guest closed device. */
+    void (*guest_close)(VirtIOSerialPort *port);
+
+        /* Guest is now ready to accept data (virtqueues set up). */
+    void (*guest_ready)(VirtIOSerialPort *port);
+
+    /*
+     * Guest wrote some data to the port. This data is handed over to
+     * the app via this callback. The app should return the number of
+     * bytes it successfully consumed.
+     */
+    size_t (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len);
+};
+
+/* Interface to the virtio-serial bus */
+
+/*
+ * Individual ports/apps should call this function to register the port
+ * with the virtio-serial bus
+ */
+void virtio_serial_port_qdev_register(VirtIOSerialPortInfo *info);
+
+/*
+ * Open a connection to the port
+ *   Returns 0 on success (always).
+ */
+int virtio_serial_open(VirtIOSerialPort *port);
+
+/*
+ * Close the connection to the port
+ *   Returns 0 on success (always).
+ */
+int virtio_serial_close(VirtIOSerialPort *port);
+
+/*
+ * Send data to Guest
+ */
+ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
+                            size_t size);
+
+/*
+ * Query whether a guest is ready to receive data.
+ */
+size_t virtio_serial_guest_ready(VirtIOSerialPort *port);
+
+#endif