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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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