Re: [PATCH] virtio: add a virtio-console to the vbus backend

[Gregory Haskins <ghaskins@novell.com>]

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Gregory Haskins wrote:
> 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@novell.com>
>>>     
>>>       
>> 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@novell.com>
>>> + *
>>> + * 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>
>>>       
                                ^^^^^^^^^^^^^^^^^^^^^^^


For more details, see these two files in my tree.  Here is a direct link
via gitweb

http://git.kernel.org/?p=linux/kernel/git/ghaskins/vbus/linux-2.6.git;a=blob;f=include/linux/vbus_device.h;h=c91bce440e2d956a7a90bf4a111b3dfd6ef16c19;hb=6a7f28ebf83fc8b845aefb120121b1bb3c471876

and

http://git.kernel.org/?p=linux/kernel/git/ghaskins/vbus/linux-2.6.git;a=blob;f=include/linux/virtio_vbus.h;h=05791bf24b42900e09ae088e90591721db9180b6;hb=6a7f28ebf83fc8b845aefb120121b1bb3c471876


HTH

-Greg

>>> +#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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