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    Subject[RFC] 9p: add KVM/QEMU pci transport
    Date
    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);
    --
    1.5.0.2.gfbe3d-dirty
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