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![Michael S. Tsirkin](/assets/img/avatar_default.png)
This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations, and updates all drivers. This is needed for MSI support, because MSI needs to know the total number of vectors upfront. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)
391 lines
9.8 KiB
C
391 lines
9.8 KiB
C
/*
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* The Virtio 9p transport driver
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*
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* This is a block based transport driver based on the lguest block driver
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* code.
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*
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* Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
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*
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* Based on virtio console driver
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* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/in.h>
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#include <linux/module.h>
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#include <linux/net.h>
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#include <linux/ipv6.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/un.h>
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#include <linux/uaccess.h>
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#include <linux/inet.h>
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#include <linux/idr.h>
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#include <linux/file.h>
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#include <net/9p/9p.h>
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#include <linux/parser.h>
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#include <net/9p/client.h>
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#include <net/9p/transport.h>
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#include <linux/scatterlist.h>
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#include <linux/virtio.h>
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#include <linux/virtio_9p.h>
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#define VIRTQUEUE_NUM 128
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/* a single mutex to manage channel initialization and attachment */
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static DEFINE_MUTEX(virtio_9p_lock);
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/* global which tracks highest initialized channel */
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static int chan_index;
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/**
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* struct virtio_chan - per-instance transport information
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* @initialized: whether the channel is initialized
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* @inuse: whether the channel is in use
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* @lock: protects multiple elements within this structure
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* @vdev: virtio dev associated with this channel
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* @vq: virtio queue associated with this channel
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* @tagpool: accounting for tag ids (and request slots)
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* @reqs: array of request slots
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* @max_tag: current number of request_slots allocated
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* @sg: scatter gather list which is used to pack a request (protected?)
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*
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* We keep all per-channel information in a structure.
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* This structure is allocated within the devices dev->mem space.
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* A pointer to the structure will get put in the transport private.
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*
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*/
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static struct virtio_chan {
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bool initialized;
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bool inuse;
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spinlock_t lock;
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struct p9_client *client;
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struct virtio_device *vdev;
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struct virtqueue *vq;
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/* Scatterlist: can be too big for stack. */
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struct scatterlist sg[VIRTQUEUE_NUM];
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} channels[MAX_9P_CHAN];
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/* How many bytes left in this page. */
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static unsigned int rest_of_page(void *data)
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{
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return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
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}
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/**
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* p9_virtio_close - reclaim resources of a channel
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* @trans: transport state
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*
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* This reclaims a channel by freeing its resources and
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* reseting its inuse flag.
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*
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*/
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static void p9_virtio_close(struct p9_client *client)
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{
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struct virtio_chan *chan = client->trans;
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mutex_lock(&virtio_9p_lock);
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chan->inuse = false;
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mutex_unlock(&virtio_9p_lock);
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}
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/**
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* req_done - callback which signals activity from the server
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* @vq: virtio queue activity was received on
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*
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* This notifies us that the server has triggered some activity
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* on the virtio channel - most likely a response to request we
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* sent. Figure out which requests now have responses and wake up
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* those threads.
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*
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* Bugs: could do with some additional sanity checking, but appears to work.
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*
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*/
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static void req_done(struct virtqueue *vq)
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{
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struct virtio_chan *chan = vq->vdev->priv;
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struct p9_fcall *rc;
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unsigned int len;
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struct p9_req_t *req;
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P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
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while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
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P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
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P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
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req = p9_tag_lookup(chan->client, rc->tag);
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req->status = REQ_STATUS_RCVD;
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p9_client_cb(chan->client, req);
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}
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}
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/**
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* pack_sg_list - pack a scatter gather list from a linear buffer
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* @sg: scatter/gather list to pack into
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* @start: which segment of the sg_list to start at
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* @limit: maximum segment to pack data to
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* @data: data to pack into scatter/gather list
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* @count: amount of data to pack into the scatter/gather list
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*
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* sg_lists have multiple segments of various sizes. This will pack
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* arbitrary data into an existing scatter gather list, segmenting the
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* data as necessary within constraints.
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*
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*/
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static int
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pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
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int count)
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{
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int s;
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int index = start;
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while (count) {
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s = rest_of_page(data);
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if (s > count)
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s = count;
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sg_set_buf(&sg[index++], data, s);
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count -= s;
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data += s;
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BUG_ON(index > limit);
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}
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return index-start;
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}
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/* We don't currently allow canceling of virtio requests */
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static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
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{
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return 1;
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}
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/**
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* p9_virtio_request - issue a request
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* @t: transport state
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* @tc: &p9_fcall request to transmit
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* @rc: &p9_fcall to put reponse into
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*
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*/
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static int
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p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
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{
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int in, out;
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struct virtio_chan *chan = client->trans;
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char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
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P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
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out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
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req->tc->size);
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in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
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client->msize);
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req->status = REQ_STATUS_SENT;
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if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc)) {
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P9_DPRINTK(P9_DEBUG_TRANS,
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"9p debug: virtio rpc add_buf returned failure");
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return -EIO;
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}
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chan->vq->vq_ops->kick(chan->vq);
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P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
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return 0;
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}
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/**
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* p9_virtio_probe - probe for existence of 9P virtio channels
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* @vdev: virtio device to probe
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*
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* This probes for existing virtio channels. At present only
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* a single channel is in use, so in the future more work may need
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* to be done here.
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*
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*/
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static int p9_virtio_probe(struct virtio_device *vdev)
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{
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int err;
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struct virtio_chan *chan;
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int index;
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mutex_lock(&virtio_9p_lock);
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index = chan_index++;
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chan = &channels[index];
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mutex_unlock(&virtio_9p_lock);
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if (chan_index > MAX_9P_CHAN) {
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printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
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BUG();
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err = -ENOMEM;
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goto fail;
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}
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chan->vdev = vdev;
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/* We expect one virtqueue, for requests. */
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chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
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if (IS_ERR(chan->vq)) {
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err = PTR_ERR(chan->vq);
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goto out_free_vq;
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}
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chan->vq->vdev->priv = chan;
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spin_lock_init(&chan->lock);
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sg_init_table(chan->sg, VIRTQUEUE_NUM);
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chan->inuse = false;
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chan->initialized = true;
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return 0;
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out_free_vq:
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vdev->config->del_vqs(vdev);
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fail:
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mutex_lock(&virtio_9p_lock);
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chan_index--;
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mutex_unlock(&virtio_9p_lock);
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return err;
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}
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/**
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* p9_virtio_create - allocate a new virtio channel
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* @client: client instance invoking this transport
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* @devname: string identifying the channel to connect to (unused)
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* @args: args passed from sys_mount() for per-transport options (unused)
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*
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* This sets up a transport channel for 9p communication. Right now
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* we only match the first available channel, but eventually we couldlook up
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* alternate channels by matching devname versus a virtio_config entry.
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* We use a simple reference count mechanism to ensure that only a single
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* mount has a channel open at a time.
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*
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* Bugs: doesn't allow identification of a specific channel
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* to allocate, channels are allocated sequentially. This was
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* a pragmatic decision to get things rolling, but ideally some
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* way of identifying the channel to attach to would be nice
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* if we are going to support multiple channels.
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*
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*/
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static int
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p9_virtio_create(struct p9_client *client, const char *devname, char *args)
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{
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struct virtio_chan *chan = channels;
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int index = 0;
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mutex_lock(&virtio_9p_lock);
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while (index < MAX_9P_CHAN) {
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if (chan->initialized && !chan->inuse) {
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chan->inuse = true;
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break;
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} else {
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index++;
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chan = &channels[index];
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}
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}
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mutex_unlock(&virtio_9p_lock);
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if (index >= MAX_9P_CHAN) {
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printk(KERN_ERR "9p: no channels available\n");
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return -ENODEV;
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}
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client->trans = (void *)chan;
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chan->client = client;
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return 0;
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}
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/**
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* p9_virtio_remove - clean up resources associated with a virtio device
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* @vdev: virtio device to remove
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*
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*/
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static void p9_virtio_remove(struct virtio_device *vdev)
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{
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struct virtio_chan *chan = vdev->priv;
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BUG_ON(chan->inuse);
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if (chan->initialized) {
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vdev->config->del_vqs(vdev);
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chan->initialized = false;
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}
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}
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#define VIRTIO_ID_9P 9
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static struct virtio_device_id id_table[] = {
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{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
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{ 0 },
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};
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/* The standard "struct lguest_driver": */
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static struct virtio_driver p9_virtio_drv = {
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.driver.name = KBUILD_MODNAME,
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.driver.owner = THIS_MODULE,
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.id_table = id_table,
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.probe = p9_virtio_probe,
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.remove = p9_virtio_remove,
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};
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static struct p9_trans_module p9_virtio_trans = {
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.name = "virtio",
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.create = p9_virtio_create,
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.close = p9_virtio_close,
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.request = p9_virtio_request,
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.cancel = p9_virtio_cancel,
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.maxsize = PAGE_SIZE*16,
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.def = 0,
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.owner = THIS_MODULE,
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};
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/* The standard init function */
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static int __init p9_virtio_init(void)
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{
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int count;
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for (count = 0; count < MAX_9P_CHAN; count++)
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channels[count].initialized = false;
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v9fs_register_trans(&p9_virtio_trans);
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return register_virtio_driver(&p9_virtio_drv);
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}
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static void __exit p9_virtio_cleanup(void)
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{
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unregister_virtio_driver(&p9_virtio_drv);
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v9fs_unregister_trans(&p9_virtio_trans);
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}
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module_init(p9_virtio_init);
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module_exit(p9_virtio_cleanup);
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MODULE_DEVICE_TABLE(virtio, id_table);
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MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
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MODULE_DESCRIPTION("Virtio 9p Transport");
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MODULE_LICENSE("GPL");
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