Michael S. Tsirkin wrote:
> On Fri, Jun 05, 2009 at 03:30:07PM -0400, Gregory Haskins wrote:
>
>> Hi Michael,
>> FYI: This was a patch I started to put together around the time vbus-v3 was
>> released to demonstrate the interface for virtio devices that we needed. I
>> just wanted to get it out to you so you have a working example to look at
>> what it takes to write something like virtio-net against virtio-vbus.
>>
>> What I will do next is make a minor v3.1 release of vbus on top of kvm.git
>> and get this patch cleaned up so we can actually run it. Note that v3.1
>> will just a minor port of v3 to kvm.git/HEAD, not the new iosignalfd/irqfd
>> stuff that I have queued for v4. Thats not ready for prime-time yet.
>>
>> ----------------------------
>>
>> virtio: add a virtio-console to the vbus backend
>>
>> A console probably doesnt need to live in the kernel since it is generally
>> not performance limited. However, its also a very simple example, so lets
>> make a vbus backend to demonstrate the virtio interfaces.
>>
>> Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
>>
>
> I'm a bit confused: does this live on the guest or host side?
>
Host side. The guest would run the existing virtio-console driver.
-Greg
>
>
>
>
>> ---
>>
>> drivers/vbus/devices/Kconfig | 9
>> drivers/vbus/devices/Makefile | 1
>> drivers/vbus/devices/virtio-console-backend.c | 461 +++++++++++++++++++++++++
>> 3 files changed, 471 insertions(+), 0 deletions(-)
>> create mode 100644 drivers/vbus/devices/virtio-console-backend.c
>>
>> diff --git a/drivers/vbus/devices/Kconfig b/drivers/vbus/devices/Kconfig
>> index 64e4731..0239e86 100644
>> --- a/drivers/vbus/devices/Kconfig
>> +++ b/drivers/vbus/devices/Kconfig
>> @@ -15,3 +15,12 @@ config VBUS_VENETTAP
>>
>> If unsure, say N
>>
>> +config VBUS_VIRTIO_CONSOLE
>> + tristate "Virtual-Bus Backend for virtio-console drivers"
>> + depends on VBUS_DEVICES
>> + select VBUS_VIRTIO_BACKEND
>> + default n
>> + help
>> + Provides a virtual console device within the vbus infrastructure
>> +
>> + If unsure, say N
>> diff --git a/drivers/vbus/devices/Makefile b/drivers/vbus/devices/Makefile
>> index 2ea7d2a..fd51cb6 100644
>> --- a/drivers/vbus/devices/Makefile
>> +++ b/drivers/vbus/devices/Makefile
>> @@ -1 +1,2 @@
>> obj-$(CONFIG_VBUS_VENETTAP) += venet-tap.o
>> +obj-$(CONFIG_VBUS_VIRTIO_CONSOLE) += virtio-console-backend.o
>> diff --git a/drivers/vbus/devices/virtio-console-backend.c b/drivers/vbus/devices/virtio-console-backend.c
>> new file mode 100644
>> index 0000000..bf30016
>> --- /dev/null
>> +++ b/drivers/vbus/devices/virtio-console-backend.c
>> @@ -0,0 +1,461 @@
>> +/*
>> + * virtio-console for the vbus backend
>> + *
>> + * Copyright (C) 2009 Novell, Gregory Haskins <ghaskins@xxxxxxxxxx>
>> + *
>> + * This file is free software; you can redistribute it and/or modify
>> + * it under the terms of version 2 of the GNU General Public License
>> + * as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, write to the Free Software Foundation,
>> + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/moduleparam.h>
>> +
>> +#include <linux/cdev.h>
>> +#include <linux/fs.h>
>> +#include <linux/major.h>
>> +
>> +#include <linux/vbus_device.h>
>> +#include <linux/virtio_vbus.h>
>> +#include <linux/virtio_console.h>
>> +
>> +MODULE_AUTHOR("Gregory Haskins");
>> +MODULE_LICENSE("GPL");
>> +
>> +#undef PDEBUG /* undef it, just in case */
>> +#ifdef VIRTIO_CONSOLE_DEBUG
>> +# define PDEBUG(fmt, args...) printk(KERN_DEBUG "virtio-console: " fmt, ## args)
>> +#else
>> +# define PDEBUG(fmt, args...) /* not debugging: nothing */
>> +#endif
>> +
>> +struct _virtio_console {
>> + spinlock_t lock;
>> + char *name;
>> + dev_t devno;
>> + struct cdev cdev;
>> + struct vbus_device dev;
>> + struct virtio_device_interface intf;
>> + struct virtio_connection conn;
>> + struct vbus_memctx *ctx;
>> + struct virtqueue *rx;
>> + struct virtqueue *tx;
>> + int enabled:1;
>> + int connected:1;
>> + int opened:1;
>> + int tty:1;
>> + int link:1;
>> +};
>> +
>> +static struct _virtio_console *
>> +conn_to_priv(struct virtio_connection *conn)
>> +{
>> + return container_of(conn, struct _virtio_console, conn);
>> +}
>> +
>> +static struct _virtio_console *
>> +intf_to_priv(struct virtio_device_interface *intf)
>> +{
>> + return container_of(intf, struct _virtio_console, intf);
>> +}
>> +
>> +static struct _virtio_console *
>> +vdev_to_priv(struct vbus_device *vdev)
>> +{
>> + return container_of(vdev, struct _virtio_console, dev);
>> +}
>> +
>> +/*
>> + * --------------------------------------------
>> + * Driver connection
>> + * --------------------------------------------
>> + */
>> +
>> +static void
>> +_virtio_console_add_vq(struct virtio_connection *vconn, int index,
>> + struct virtqueue *vq)
>> +{
>> + struct _virtio_console *priv = conn_to_priv(vconn);
>> +
>> + switch (index) {
>> + case 0:
>> + if (!priv->rx)
>> + priv->rx = vq;
>> + break;
>> + case 1:
>> + if (!priv->tx)
>> + priv->tx = vq;
>> + break;
>> + default:
>> + break;
>> + }
>> +}
>> +
>> +static void
>> +_virtio_console_del_vq(struct virtio_connection *vconn, int index)
>> +{
>> + struct _virtio_console *priv = conn_to_priv(vconn);
>> +
>> + switch (index) {
>> + case 0:
>> + priv->rx = NULL;
>> + break;
>> + case 1:
>> + priv->tx = NULL;
>> + break;
>> + default:
>> + break;
>> + }
>> +}
>> +
>> +static void
>> +_virtio_console_notify_vq(struct virtio_connection *vconn, int index)
>> +{
>> +
>> +}
>> +
>> +/*
>> + * This is called whenever the driver closes all references to our device
>> + */
>> +static void
>> +_virtio_console_release(struct virtio_connection *conn)
>> +{
>> + struct _virtio_console *priv = conn_to_priv(conn);
>> +
>> + priv->opened = false;
>> + vbus_memctx_put(priv->ctx);
>> +}
>> +
>> +static struct virtio_connection_ops virtio_console_connection_ops = {
>> + .add_vq = _virtio_console_add_vq,
>> + .del_vq = _virtio_console_del_vq,
>> + .notify_vq = _virtio_console_notify_vq,
>> + .release = _virtio_console_release,
>> +};
>> +
>> +/*
>> + * --------------------------------------------
>> + * Interface
>> + * --------------------------------------------
>> + */
>> +
>> +/*
>> + * This is called whenever a driver wants to open our device_interface
>> + * for communication. The connection is represented by a
>> + * virtio_connection object. It is up to the implementation to decide
>> + * if it allows more than one connection at a time. This simple example
>> + * does not.
>> + */
>> +static int
>> +virtio_console_intf_open(struct virtio_device_interface *intf,
>> + struct vbus_memctx *ctx,
>> + struct virtio_connection **conn)
>> +{
>> + struct _virtio_console *priv = intf_to_priv(intf);
>> + unsigned long flags;
>> +
>> + PDEBUG("open\n");
>> +
>> + spin_lock_irqsave(&priv->lock, flags);
>> +
>> + /*
>> + * We only allow one connection to this device
>> + */
>> + if (priv->opened) {
>> + spin_unlock_irqrestore(&priv->lock, flags);
>> + return -EBUSY;
>> + }
>> +
>> + memset(&priv->conn, 0, sizeof(priv->conn));
>> + priv->conn.ops = &virtio_console_connection_ops;
>> +
>> + priv->opened = true;
>> + priv->ctx = ctx;
>> +
>> + vbus_memctx_get(ctx);
>> +
>> + spin_unlock_irqrestore(&priv->lock, flags);
>> +
>> + *conn = &priv->conn;
>> +
>> + return 0;
>> +}
>> +
>> +static void
>> +virtio_console_intf_release(struct virtio_device_interface *intf)
>> +{
>> + kobject_put(intf->parent->dev->kobj); /* acquired on bus-connect */
>> +}
>> +
>> +static struct virtio_device_interface_ops virtio_console_intf_ops = {
>> + .open = virtio_console_intf_open,
>> + .release = virtio_console_intf_release,
>> +};
>> +
>> +/*
>> + * --------------------------------------------
>> + * Bus+Device interaction
>> + * --------------------------------------------
>> + */
>> +
>> +/*
>> + * This is called whenever the admin creates a symbolic link between
>> + * a bus in /config/vbus/buses and our device. It represents a bus
>> + * connection. Your device can chose to allow more than one bus to
>> + * connect, or it can restrict it to one bus. It can also choose to
>> + * register one or more device_interfaces on each bus that it
>> + * successfully connects to.
>> + *
>> + * This example device only registers a single interface
>> + */
>> +static int
>> +virtio_console_device_bus_connect(struct vbus_device *dev, struct vbus *vbus)
>> +{
>> + struct _virtio_console *priv = vdev_to_priv(dev);
>> + struct virtio_device_interface *intf = &priv->intf;
>> +
>> + /* We only allow one bus to connect */
>> + if (priv->connected)
>> + return -EBUSY;
>> +
>> + kobject_get(dev->kobj); /* released when we release the intf */
>> +
>> + intf->id.vendor = 0x1af4;
>> + intf->id.device = VIRTIO_ID_CONSOLE;
>> +
>> + intf->ops = &virtio_console_intf_ops;
>> +
>> + priv->connected = true;
>> +
>> + /*
>> + * Our example only registers one interface. If you need
>> + * more, simply call interface_register() multiple times
>> + */
>> + return virtio_device_interface_register(dev, vbus, intf);
>> +}
>> +
>> +/*
>> + * This is called whenever the admin removes the symbolic link between
>> + * a bus in /config/vbus/buses and our device.
>> + */
>> +static int
>> +virtio_console_device_bus_disconnect(struct vbus_device *dev, struct vbus *vbus)
>> +{
>> + struct _virtio_console *priv = vdev_to_priv(dev);
>> + struct virtio_device_interface *intf = &priv->intf;
>> +
>> + if (!priv->connected)
>> + return -EINVAL;
>> +
>> + virtio_device_interface_unregister(intf);
>> +
>> + priv->connected = false;
>> +
>> + return 0;
>> +}
>> +
>> +static void
>> +virtio_console_device_release(struct vbus_device *dev)
>> +{
>> + struct _virtio_console *priv = vdev_to_priv(dev);
>> +
>> + unregister_chrdev_region(priv->devno, 1);
>> + kfree(priv);
>> +
>> + module_put(THIS_MODULE);
>> +}
>> +
>> +
>> +static struct vbus_device_ops virtio_console_device_ops = {
>> + .bus_connect = virtio_console_device_bus_connect,
>> + .bus_disconnect = virtio_console_device_bus_disconnect,
>> + .release = virtio_console_device_release,
>> +};
>> +
>> +#define VIRTIO_CONSOLE_TYPE "virtio-console"
>> +
>> +/*
>> + * --------------------------------------------
>> + * Character Device
>> + * --------------------------------------------
>> + */
>> +
>> +static int
>> +virtio_console_chardev_open(struct inode *inode, struct file *filp)
>> +{
>> + struct _virtio_console *priv;
>> +
>> + priv = container_of(inode->i_cdev, struct _virtio_console, cdev);
>> +
>> + kobject_get(priv->dev.kobj); /* released when we release the cd */
>> + filp->private_data = priv;
>> +
>> + return 0;
>> +}
>> +
>> +static ssize_t
>> +virtio_console_chardev_read(struct file *filp, char __user *buf, size_t len,
>> + loff_t *ppos)
>> +{
>> + struct _virtio_console *priv = filp->private_data;
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static ssize_t
>> +virtio_console_chardev_write(struct file *filp, const char __user *buf,
>> + size_t len, loff_t *ppos)
>> +{
>> + struct _virtio_console *priv = filp->private_data;
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static int
>> +virtio_console_chardev_release(struct inode *inode, struct file *filp)
>> +{
>> + struct _virtio_console *priv = filp->private_data;
>> +
>> + kobject_put(priv->dev.kobj);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct file_operations virtio_console_chardev_ops = {
>> + .open = virtio_console_chardev_open,
>> + .read = virtio_console_chardev_read,
>> + .write = virtio_console_chardev_write,
>> + .release = virtio_console_chardev_release,
>> +};
>> +
>> +/*
>> + * --------------------------------------------
>> + * Attributes
>> + * --------------------------------------------
>> + */
>> +
>> +/*
>> + * Interface attributes show up as files under
>> + * /sys/vbus/devices/$devid
>> + */
>> +
>> +static ssize_t
>> +devno_show(struct vbus_device *dev, struct vbus_device_attribute *attr,
>> + char *buf)
>> +{
>> + struct _virtio_console *priv = vdev_to_priv(dev);
>> +
>> + return snprintf(buf, PAGE_SIZE, "%d:%d\n",
>> + MAJOR(priv->devno), MINOR(priv->devno));
>> +}
>> +
>> +static struct vbus_device_attribute attr_devno =
>> + __ATTR_RO(devno);
>> +
>> +static struct attribute *attrs[] = {
>> + &attr_devno.attr,
>> + NULL,
>> +};
>> +
>> +static struct attribute_group virtio_console_attr_group = {
>> + .attrs = attrs,
>> +};
>> +
>> +/*
>> + * --------------------------------------------
>> + * Device
>> + * --------------------------------------------
>> + */
>> +
>> +/*
>> + * This is called whenever the admin instantiates our devclass via
>> + * "mkdir /config/vbus/devices/$(inst)/virtio-console"
>> + */
>> +static int
>> +virtio_console_device_create(struct vbus_devclass *dc,
>> + struct vbus_device **vdev)
>> +{
>> + struct _virtio_console *priv;
>> + struct vbus_device *_vdev;
>> + int ret;
>> +
>> + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + spin_lock_init(&priv->lock);
>> +
>> + /*
>> + * cdev init
>> + */
>> + ret = alloc_chrdev_region(&priv->devno, TTY_MAJOR,
>> + 1, VIRTIO_CONSOLE_TYPE);
>> + if (ret < 0)
>> + goto out_free;
>> +
>> + cdev_init(&priv->cdev, &virtio_console_chardev_ops);
>> + priv->cdev.owner = THIS_MODULE;
>> + priv->cdev.ops = &virtio_console_chardev_ops;
>> + ret = cdev_add(&priv->cdev, priv->devno, 1);
>> + if (ret < 0)
>> + goto out;
>> +
>> + /*
>> + * vbus init
>> + */
>> + _vdev = &priv->dev;
>> +
>> + _vdev->type = VIRTIO_CONSOLE_TYPE;
>> + _vdev->ops = &virtio_console_device_ops;
>> + _vdev->attrs = &virtio_console_attr_group;
>> +
>> + *vdev = _vdev;
>> +
>> + /*
>> + * We don't need a try_get because the reference is held by the
>> + * infrastructure during a create() operation. This is released
>> + * when our device is released
>> + */
>> + __module_get(THIS_MODULE);
>> +
>> + return 0;
>> +
>> +out:
>> + unregister_chrdev_region(priv->devno, 1);
>> +out_free:
>> + kfree(priv);
>> + return ret;
>> +}
>> +
>> +static struct vbus_devclass_ops virtio_console_devclass_ops = {
>> + .create = virtio_console_device_create,
>> +};
>> +
>> +static struct vbus_devclass virtio_console_devclass = {
>> + .name = VIRTIO_CONSOLE_TYPE,
>> + .ops = &virtio_console_devclass_ops,
>> + .owner = THIS_MODULE,
>> +};
>> +
>> +static int __init virtio_console_init(void)
>> +{
>> + return vbus_devclass_register(&virtio_console_devclass);
>> +}
>> +
>> +static void __exit virtio_console_cleanup(void)
>> +{
>> + vbus_devclass_unregister(&virtio_console_devclass);
>> +}
>> +
>> +module_init(virtio_console_init);
>> +module_exit(virtio_console_cleanup);
>>
>
>
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