Message-Id: <1188404984.13140.6.camel@squirrel>
Date:	Wed, 29 Aug 2007 11:29:44 -0500
From:	Anthony Liguori <anthony@...emonkey.ws>
To:	Eric Van Hensbergen <ericvh@...il.com>
Cc:	linux-kernel@...r.kernel.org, kvm-devel@...ts.sourceforge.net,
	v9fs-developer@...ts.sourceforge.net, lguest@...abs.org
Subject: Re: [kvm-devel] [RFC] 9p: add KVM/QEMU pci transport

I think that it would be nicer to implement the p9 transport on top of
virtio instead of directly on top of PCI.  I think your PCI transport
would make a pretty nice start of a PCI virtio transport though.

Regards,

Anthony Liguori

On Tue, 2007-08-28 at 13:52 -0500, Eric Van Hensbergen wrote:
> From: Latchesar Ionkov <lucho@...kov.net>
> 
> This adds a shared memory transport for a synthetic 9p device for
> paravirtualized file system support under KVM/QEMU.
> 
> Signed-off-by: Latchesar Ionkov <lucho@...kov.net>
> Signed-off-by: Eric Van Hensbergen <ericvh@...il.com>
> ---
>  Documentation/filesystems/9p.txt |    2 +
>  net/9p/Kconfig                   |   10 ++-
>  net/9p/Makefile                  |    4 +
>  net/9p/trans_pci.c               |  295 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 310 insertions(+), 1 deletions(-)
>  create mode 100644 net/9p/trans_pci.c
> 
> diff --git a/Documentation/filesystems/9p.txt b/Documentation/filesystems/9p.txt
> index 1a5f50d..e1879bd 100644
> --- a/Documentation/filesystems/9p.txt
> +++ b/Documentation/filesystems/9p.txt
> @@ -46,6 +46,8 @@ OPTIONS
>   			tcp  - specifying a normal TCP/IP connection
>   			fd   - used passed file descriptors for connection
>                                  (see rfdno and wfdno)
> +			pci  - use a PCI pseudo device for 9p communication
> +				over shared memory between a guest and host
>  
>    uname=name	user name to attempt mount as on the remote server.  The
>    		server may override or ignore this value.  Certain user
> diff --git a/net/9p/Kconfig b/net/9p/Kconfig
> index 09566ae..8517560 100644
> --- a/net/9p/Kconfig
> +++ b/net/9p/Kconfig
> @@ -16,13 +16,21 @@ menuconfig NET_9P
>  config NET_9P_FD
>  	depends on NET_9P
>  	default y if NET_9P
> -	tristate "9P File Descriptor Transports (Experimental)"
> +	tristate "9p File Descriptor Transports (Experimental)"
>  	help
>  	  This builds support for file descriptor transports for 9p
>  	  which includes support for TCP/IP, named pipes, or passed
>  	  file descriptors.  TCP/IP is the default transport for 9p,
>  	  so if you are going to use 9p, you'll likely want this.  
>  
> +config NET_9P_PCI
> +	depends on NET_9P
> +	tristate "9p PCI Shared Memory Transport (Experimental)"
> +	help
> +	  This builds support for a PCI psuedo-device currently available
> +	  under KVM/QEMU which allows for 9p transactions over shared
> +	  memory between the guest and the host.
> +
>  config NET_9P_DEBUG
>  	bool "Debug information"
>  	depends on NET_9P
> diff --git a/net/9p/Makefile b/net/9p/Makefile
> index 7b2a67a..26ce89d 100644
> --- a/net/9p/Makefile
> +++ b/net/9p/Makefile
> @@ -1,5 +1,6 @@
>  obj-$(CONFIG_NET_9P) := 9pnet.o
>  obj-$(CONFIG_NET_9P_FD) += 9pnet_fd.o
> +obj-$(CONFIG_NET_9P_PCI) += 9pnet_pci.o
>  
>  9pnet-objs := \
>  	mod.o \
> @@ -14,3 +15,6 @@ obj-$(CONFIG_NET_9P_FD) += 9pnet_fd.o
>  
>  9pnet_fd-objs := \
>  	trans_fd.o \
> +
> +9pnet_pci-objs := \
> +	trans_pci.o \
> diff --git a/net/9p/trans_pci.c b/net/9p/trans_pci.c
> new file mode 100644
> index 0000000..36ddc5f
> --- /dev/null
> +++ b/net/9p/trans_pci.c
> @@ -0,0 +1,295 @@
> +/*
> + * net/9p/trans_pci.c
> + *
> + * 9P over PCI transport layer. For use with KVM/QEMU.
> + *
> + *  Copyright (C) 2007 by Latchesar Ionkov <lucho@...kov.net>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2
> + *  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:
> + *  Free Software Foundation
> + *  51 Franklin Street, Fifth Floor
> + *  Boston, MA  02111-1301  USA
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/compiler.h>
> +#include <linux/pci.h>
> +#include <linux/init.h>
> +#include <linux/ioport.h>
> +#include <linux/completion.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/uaccess.h>
> +#include <linux/irq.h>
> +#include <linux/poll.h>
> +#include <net/9p/9p.h>
> +#include <net/9p/transport.h>
> +
> +#define P9PCI_DRIVER_NAME "9P PCI Device"
> +#define P9PCI_DRIVER_VERSION "1"
> +
> +#define PCI_VENDOR_ID_9P	0x5002
> +#define PCI_DEVICE_ID_9P	0x000D
> +
> +#define MAX_PCI_BUF		(4*1024) /* TODO: Get a number from lucho */
> +
> +struct p9pci_trans {
> +	struct pci_dev		*pdev;
> +	void __iomem		*ioaddr;
> +	void __iomem		*tx;
> +	void __iomem		*rx;
> +	int			irq;
> +	int			pos;
> +	int			len;
> +	wait_queue_head_t	wait;
> +};
> +static struct p9pci_trans *p9pci_trans; /* single channel for now */
> +
> +static struct pci_device_id p9pci_tbl[] = {
> +	{PCI_VENDOR_ID_9P, PCI_DEVICE_ID_9P, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
> +	{0,}
> +};
> +
> +static irqreturn_t p9pci_interrupt(int irq, void *dev)
> +{
> +	p9pci_trans = dev;
> +	p9pci_trans->len = le32_to_cpu(readl(p9pci_trans->rx));
> +	P9_DPRINTK(P9_DEBUG_TRANS, "%p len %d\n", p9pci_trans->pdev,
> +							p9pci_trans->len);
> +	iowrite32(0, p9pci_trans->ioaddr + 4);
> +	wake_up_interruptible(&p9pci_trans->wait);
> +	return IRQ_HANDLED;
> +}
> +
> +static int p9pci_read(struct p9_trans *trans, void *v, int len)
> +{
> +	struct p9pci_trans *ts;
> +
> +	if (!trans || trans->status == Disconnected || !trans->priv)
> +		return -EREMOTEIO;
> +
> +	ts = trans->priv;
> +
> +	P9_DPRINTK(P9_DEBUG_TRANS, "trans %p rx %p tx %p buf %p len %d\n",
> +						trans, ts->rx, ts->tx, v, len);
> +	if (len > ts->len)
> +		len = ts->len;
> +
> +	if (len) {
> +		memcpy_fromio(v, ts->rx, len);
> +		ts->len = 0;
> +		/* let the host knows the message is consumed */
> +		writel(0, ts->rx);
> +		iowrite32(0, p9pci_trans->ioaddr + 4);
> +		P9_DPRINTK(P9_DEBUG_TRANS, "zero rxlen %d txlen %d\n",
> +						readl(ts->rx), readl(ts->tx));
> +	}
> +
> +	return len;
> +}
> +
> +static int p9pci_write(struct p9_trans *trans, void *v, int len)
> +{
> +	struct p9pci_trans *ts;
> +
> +	if (!trans || trans->status == Disconnected || !trans->priv)
> +		return -EREMOTEIO;
> +
> +	ts = trans->priv;
> +	P9_DPRINTK(P9_DEBUG_TRANS, "trans %p rx %p tx %p buf %p len %d\n",
> +						trans, ts->rx, ts->tx, v, len);
> +	P9_DPRINTK(P9_DEBUG_TRANS, "rxlen %d\n", readl(ts->rx));
> +	if (readb(ts->tx) != 0)
> +		return 0;
> +
> +	P9_DPRINTK(P9_DEBUG_TRANS, "tx addr %p io addr %p\n", ts->tx,
> +								ts->ioaddr);
> +	memcpy_toio(ts->tx, v, len);
> +	iowrite32(len, ts->ioaddr);
> +	return len;
> +}
> +
> +static unsigned int
> +p9pci_poll(struct p9_trans *trans, struct poll_table_struct *pt)
> +{
> +	int ret;
> +	struct p9pci_trans *ts;
> +
> +	P9_DPRINTK(P9_DEBUG_TRANS, "trans %p\n", trans);
> +	if (!trans || trans->status != Connected || !trans->priv)
> +		return -EREMOTEIO;
> +
> +	ts = trans->priv;
> +	poll_wait(NULL, &ts->wait, pt);
> +	ret = 0;
> +	if (!readl(ts->tx))
> +		ret |= POLLOUT;
> +	if (readl(ts->rx))
> +		ret |= POLLIN;
> +
> +	P9_DPRINTK(P9_DEBUG_TRANS, "txlen %d rxlen %d\n", readl(ts->tx),
> +								readl(ts->rx));
> +	return ret;
> +}
> +
> +/**
> + * p9_sock_close - shutdown socket
> + * @trans: private socket structure
> + *
> + */
> +static void p9pci_close(struct p9_trans *trans)
> +{
> +	P9_DPRINTK(P9_DEBUG_TRANS, "trans %p\n", trans);
> +}
> +
> +static struct p9_trans *p9pci_trans_create(const char *name, char *arg)
> +{
> +	struct p9_trans *trans;
> +
> +	P9_DPRINTK(P9_DEBUG_TRANS, "\n");
> +	trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
> +	if (!trans)
> +		return ERR_PTR(-ENOMEM);
> +
> +	trans->status = Connected;
> +	trans->write = p9pci_write;
> +	trans->read = p9pci_read;
> +	trans->close = p9pci_close;
> +	trans->poll = p9pci_poll;
> +	trans->priv = p9pci_trans;
> +	writel(0, p9pci_trans->tx);
> +	writel(0, p9pci_trans->rx);
> +
> +	return trans;
> +}
> +
> +static int __devinit p9pci_probe(struct pci_dev *pdev,
> +		const struct pci_device_id *ent)
> +{
> +	int err;
> +	u8 pci_rev;
> +
> +	if (p9pci_trans)
> +		return -1;
> +
> +	pci_read_config_byte(pdev, PCI_REVISION_ID, &pci_rev);
> +
> +	if (pdev->vendor == PCI_VENDOR_ID_9P &&
> +	    pdev->device == PCI_DEVICE_ID_9P)
> +		printk(KERN_INFO "pci dev %s (id %04x:%04x rev %02x) is a 9P\n",
> +		       pci_name(pdev), pdev->vendor, pdev->device, pci_rev);
> +
> +	P9_DPRINTK(P9_DEBUG_TRANS, "%p\n", pdev);
> +	p9pci_trans = kzalloc(sizeof(*p9pci_trans), GFP_KERNEL);
> +	p9pci_trans->irq = -1;
> +	init_waitqueue_head(&p9pci_trans->wait);
> +	err = pci_enable_device(pdev);
> +	if (err)
> +		goto error;
> +
> +	p9pci_trans->pdev = pdev;
> +	err = pci_request_regions(pdev, "9p");
> +	if (err)
> +		goto error;
> +
> +	p9pci_trans->ioaddr = pci_iomap(pdev, 0, 8);
> +	if (!p9pci_trans->ioaddr) {
> +		P9_DPRINTK(P9_DEBUG_ERROR, "Cannot remap MMIO, aborting\n");
> +		err = -EIO;
> +		goto error;
> +	}
> +
> +	p9pci_trans->tx = pci_iomap(pdev, 1, 0x20000);
> +	p9pci_trans->rx = pci_iomap(pdev, 2, 0x20000);
> +	pci_set_drvdata(pdev, p9pci_trans);
> +	err = request_irq(pdev->irq, &p9pci_interrupt, 0, "p9pci", p9pci_trans);
> +	if (err)
> +		goto error;
> +
> +	p9pci_trans->irq = pdev->irq;
> +	return 0;
> +
> +error:
> +	P9_DPRINTK(P9_DEBUG_ERROR, "error %d\n", err);
> +	if (p9pci_trans->irq >= 0) {
> +		synchronize_irq(p9pci_trans->irq);
> +		free_irq(p9pci_trans->irq, p9pci_trans);
> +	}
> +
> +	if (p9pci_trans->pdev) {
> +		pci_release_regions(pdev);
> +		pci_iounmap(pdev, p9pci_trans->ioaddr);
> +		pci_set_drvdata(pdev, NULL);
> +		pci_disable_device(pdev);
> +	}
> +
> +	kfree(p9pci_trans);
> +	return -1;
> +}
> +
> +static void __devexit p9pci_remove(struct pci_dev *pdev)
> +{
> +	P9_DPRINTK(P9_DEBUG_TRANS, "%p\n", pdev);
> +	p9pci_trans = pci_get_drvdata(pdev);
> +	if (!p9pci_trans)
> +		return;
> +
> +	if (p9pci_trans->irq) {
> +		synchronize_irq(p9pci_trans->irq);
> +		free_irq(p9pci_trans->irq, p9pci_trans);
> +	}
> +
> +	pci_release_regions(pdev);
> +	pci_iounmap(pdev, p9pci_trans->ioaddr);
> +	pci_set_drvdata(pdev, NULL);
> +	kfree(p9pci_trans);
> +	pci_disable_device(pdev);
> +}
> +
> +static struct pci_driver p9pci_driver = {
> +	.name		= P9PCI_DRIVER_NAME,
> +	.id_table	= p9pci_tbl,
> +	.probe		= p9pci_probe,
> +	.remove		= __devexit_p(p9pci_remove),
> +};
> +
> +static struct p9_trans_module p9_pci_trans = {
> +	.name = "pci",
> +	.maxsize = MAX_PCI_BUF,
> +	.def = 0,
> +	.create = p9pci_trans_create,
> +};
> +
> +static int __init p9pci_init_module(void)
> +{
> +	v9fs_register_trans(&p9_pci_trans);
> +	return pci_register_driver(&p9pci_driver);
> +}
> +
> +static void __exit p9pci_cleanup_module(void)
> +{
> +	pci_unregister_driver(&p9pci_driver);
> +	printk(KERN_ERR "Removal of 9p transports not implemented\n");
> +	BUG();
> +}
> +
> +module_init(p9pci_init_module);
> +module_exit(p9pci_cleanup_module);
> +
> +MODULE_DEVICE_TABLE(pci, p9pci_tbl);
> +MODULE_AUTHOR("Latchesar Ionkov <lucho@...kov.net>");
> +MODULE_DESCRIPTION(P9PCI_DRIVER_NAME);
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(P9PCI_DRIVER_VERSION);

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