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SubjectRe: [kvm-devel] [RFC] 9p: add KVM/QEMU pci transport
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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@ionkov.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@ionkov.net>
> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.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@ionkov.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@ionkov.net>");
> +MODULE_DESCRIPTION(P9PCI_DRIVER_NAME);
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(P9PCI_DRIVER_VERSION);

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