diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/9p/Kconfig | 7 | ||||
| -rw-r--r-- | net/9p/Makefile | 4 | ||||
| -rw-r--r-- | net/9p/trans_virtio.c | 353 |
3 files changed, 364 insertions, 0 deletions
diff --git a/net/9p/Kconfig b/net/9p/Kconfig index 71bc110aebf8..bafc50c9e6ff 100644 --- a/net/9p/Kconfig +++ b/net/9p/Kconfig @@ -23,6 +23,13 @@ config NET_9P_FD 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_VIRTIO + depends on NET_9P && EXPERIMENTAL && VIRTIO + tristate "9P Virtio Transport (Experimental)" + help + This builds support for a transports between + guest partitions and a host partition. + config NET_9P_DEBUG bool "Debug information" depends on NET_9P diff --git a/net/9p/Makefile b/net/9p/Makefile index 5059bc06f8f3..d3abb246ccab 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-$(CONFIG_NET_9P_VIRTIO) += 9pnet_virtio.o 9pnet-objs := \ mod.o \ @@ -12,3 +13,6 @@ obj-$(CONFIG_NET_9P_FD) += 9pnet_fd.o 9pnet_fd-objs := \ trans_fd.o \ + +9pnet_virtio-objs := \ + trans_virtio.o \ diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c new file mode 100644 index 000000000000..40b71a29fc3f --- /dev/null +++ b/net/9p/trans_virtio.c @@ -0,0 +1,353 @@ +/* + * The Guest 9p transport driver + * + * This is a trivial pipe-based transport driver based on the lguest console + * code: we use lguest's DMA mechanism to send bytes out, and register a + * DMA buffer to receive bytes in. It is assumed to be present and available + * from the very beginning of boot. + * + * This may be have been done by just instaniating another HVC console, + * but HVC's blocksize of 16 bytes is annoying and painful to performance. + * + * A more efficient transport could be built based on the virtio block driver + * but it requires some changes in the 9p transport model (which are in + * progress) + * + */ +/* + * Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation + * + * Based on virtio console driver + * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation + * + * 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/in.h> +#include <linux/module.h> +#include <linux/net.h> +#include <linux/ipv6.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/un.h> +#include <linux/uaccess.h> +#include <linux/inet.h> +#include <linux/idr.h> +#include <linux/file.h> +#include <net/9p/9p.h> +#include <linux/parser.h> +#include <net/9p/transport.h> +#include <linux/scatterlist.h> +#include <linux/virtio.h> +#include <linux/virtio_9p.h> + +/* a single mutex to manage channel initialization and attachment */ +static DECLARE_MUTEX(virtio_9p_lock); +/* global which tracks highest initialized channel */ +static int chan_index; + +/* We keep all per-channel information in a structure. + * This structure is allocated within the devices dev->mem space. + * A pointer to the structure will get put in the transport private. + */ +static struct virtio_chan { + bool initialized; /* channel is initialized */ + bool inuse; /* channel is in use */ + + struct virtqueue *in_vq, *out_vq; + struct virtio_device *vdev; + + /* This is our input buffer, and how much data is left in it. */ + unsigned int in_len; + char *in, *inbuf; + + wait_queue_head_t wq; /* waitq for buffer */ +} channels[MAX_9P_CHAN]; + +/* How many bytes left in this page. */ +static unsigned int rest_of_page(void *data) +{ + return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE); +} + +static int p9_virtio_write(struct p9_trans *trans, void *buf, int count) +{ + struct virtio_chan *chan = (struct virtio_chan *) trans->priv; + struct virtqueue *out_vq = chan->out_vq; + struct scatterlist sg[1]; + unsigned int len; + + P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio write (%d)\n", count); + + /* keep it simple - make sure we don't overflow a page */ + if (rest_of_page(buf) < count) + count = rest_of_page(buf); + + sg_init_one(sg, buf, count); + + /* add_buf wants a token to identify this buffer: we hand it any + * non-NULL pointer, since there's only ever one buffer. */ + if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) { + /* Tell Host to go! */ + out_vq->vq_ops->kick(out_vq); + /* Chill out until it's done with the buffer. */ + while (!out_vq->vq_ops->get_buf(out_vq, &len)) + cpu_relax(); + } + + P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio wrote (%d)\n", count); + + /* We're expected to return the amount of data we wrote: all of it. */ + return count; +} + +/* Create a scatter-gather list representing our input buffer and put it in the + * queue. */ +static void add_inbuf(struct virtio_chan *chan) +{ + struct scatterlist sg[1]; + + sg_init_one(sg, chan->inbuf, PAGE_SIZE); + + /* We should always be able to add one buffer to an empty queue. */ + if (chan->in_vq->vq_ops->add_buf(chan->in_vq, sg, 0, 1, chan->inbuf)) + BUG(); + chan->in_vq->vq_ops->kick(chan->in_vq); +} + +static int p9_virtio_read(struct p9_trans *trans, void *buf, int count) +{ + struct virtio_chan *chan = (struct virtio_chan *) trans->priv; + struct virtqueue *in_vq = chan->in_vq; + + P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio read (%d)\n", count); + + /* If we don't have an input queue yet, we can't get input. */ + BUG_ON(!in_vq); + + /* No buffer? Try to get one. */ + if (!chan->in_len) { + chan->in = in_vq->vq_ops->get_buf(in_vq, &chan->in_len); + if (!chan->in) + return 0; + } + + /* You want more than we have to give? Well, try wanting less! */ + if (chan->in_len < count) + count = chan->in_len; + + /* Copy across to their buffer and increment offset. */ + memcpy(buf, chan->in, count); + chan->in += count; + chan->in_len -= count; + + /* Finished? Re-register buffer so Host will use it again. */ + if (chan->in_len == 0) + add_inbuf(chan); + + P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio finished read (%d)\n", + count); + + return count; +} + +/* The poll function is used by 9p transports to determine if there + * is there is activity available on a particular channel. In our case + * we use it to wait for a callback from the input routines. + */ +static unsigned int +p9_virtio_poll(struct p9_trans *trans, struct poll_table_struct *pt) +{ + struct virtio_chan *chan = (struct virtio_chan *)trans->priv; + struct virtqueue *in_vq = chan->in_vq; + int ret = POLLOUT; /* we can always handle more output */ + + poll_wait(NULL, &chan->wq, pt); + + /* No buffer? Try to get one. */ + if (!chan->in_len) + chan->in = in_vq->vq_ops->get_buf(in_vq, &chan->in_len); + + if (chan->in_len) + ret |= POLLIN; + + return ret; +} + +static void p9_virtio_close(struct p9_trans *trans) +{ + struct virtio_chan *chan = trans->priv; + + down(&virtio_9p_lock); + chan->inuse = false; + up(&virtio_9p_lock); + + kfree(trans); +} + +static bool p9_virtio_intr(struct virtqueue *q) +{ + struct virtio_chan *chan = q->vdev->priv; + + P9_DPRINTK(P9_DEBUG_TRANS, "9p poll_wakeup: %p\n", &chan->wq); + wake_up_interruptible(&chan->wq); + + return true; +} + +static int p9_virtio_probe(struct virtio_device *dev) +{ + int err; + struct virtio_chan *chan; + int index; + + down(&virtio_9p_lock); + index = chan_index++; + chan = &channels[index]; + up(&virtio_9p_lock); + + if (chan_index > MAX_9P_CHAN) { + printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n"); + BUG(); + } + + chan->vdev = dev; + + /* This is the scratch page we use to receive console input */ + chan->inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!chan->inbuf) { + err = -ENOMEM; + goto fail; + } + + /* Find the input queue. */ + dev->priv = chan; + chan->in_vq = dev->config->find_vq(dev, p9_virtio_intr); + if (IS_ERR(chan->in_vq)) { + err = PTR_ERR(chan->in_vq); + goto free; + } + + chan->out_vq = dev->config->find_vq(dev, NULL); + if (IS_ERR(chan->out_vq)) { + err = PTR_ERR(chan->out_vq); + goto free_in_vq; + } + + init_waitqueue_head(&chan->wq); + + /* Register the input buffer the first time. */ + add_inbuf(chan); + chan->inuse = false; + chan->initialized = true; + + return 0; + +free_in_vq: + dev->config->del_vq(chan->in_vq); +free: + kfree(chan->inbuf); +fail: + down(&virtio_9p_lock); + chan_index--; + up(&virtio_9p_lock); + return err; +} + +/* This sets up a transport channel for 9p communication. Right now + * we only match the first available channel, but eventually we couldlook up + * alternate channels by matching devname versus a virtio_config entry. + * We use a simple reference count mechanism to ensure that only a single + * mount has a channel open at a time. */ +static struct p9_trans *p9_virtio_create(const char *devname, char *args) +{ + struct p9_trans *trans; + int index = 0; + struct virtio_chan *chan = channels; + + down(&virtio_9p_lock); + while (index < MAX_9P_CHAN) { + if (chan->initialized && !chan->inuse) { + chan->inuse = true; + break; + } else { + index++; + chan = &channels[index]; + } + } + up(&virtio_9p_lock); + + if (index >= MAX_9P_CHAN) { + printk(KERN_ERR "9p: virtio: couldn't find a free channel\n"); + return NULL; + } + + trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL); + if (!trans) { + printk(KERN_ERR "9p: couldn't allocate transport\n"); + return ERR_PTR(-ENOMEM); + } + + trans->write = p9_virtio_write; + trans->read = p9_virtio_read; + trans->close = p9_virtio_close; + trans->poll = p9_virtio_poll; + trans->priv = chan; + + return trans; +} + +#define VIRTIO_ID_9P 9 + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +/* The standard "struct lguest_driver": */ +static struct virtio_driver p9_virtio_drv = { + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = p9_virtio_probe, +}; + +static struct p9_trans_module p9_virtio_trans = { + .name = "virtio", + .create = p9_virtio_create, + .maxsize = PAGE_SIZE, + .def = 0, +}; + +/* The standard init function */ +static int __init p9_virtio_init(void) +{ + int count; + + for (count = 0; count < MAX_9P_CHAN; count++) + channels[count].initialized = false; + + v9fs_register_trans(&p9_virtio_trans); + return register_virtio_driver(&p9_virtio_drv); +} + +module_init(p9_virtio_init); + +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); +MODULE_DESCRIPTION("Virtio 9p Transport"); +MODULE_LICENSE("GPL"); |