Net driver using virtio

The network driver uses two virtqueues: one for input packets and one
for output packets.  This has nice locking properties (ie. we don't do
any for recv vs send).

TODO:
	1) Big packets.
	2) Multi-client devices (maybe separate driver?).
	3) Resolve freeing of old xmit skbs (Christian Borntraeger)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: netdev@vger.kernel.org
This commit is contained in:
Rusty Russell 2007-10-22 11:03:37 +10:00
parent ec3d41c4db
commit 296f96fcfc
5 changed files with 479 additions and 0 deletions

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@ -3100,4 +3100,10 @@ config NETPOLL_TRAP
config NET_POLL_CONTROLLER
def_bool NETPOLL
config VIRTIO_NET
tristate "Virtio network driver (EXPERIMENTAL)"
depends on EXPERIMENTAL && VIRTIO
---help---
This is the virtual network driver for lguest. Say Y or M.
endif # NETDEVICES

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@ -243,3 +243,4 @@ obj-$(CONFIG_FS_ENET) += fs_enet/
obj-$(CONFIG_NETXEN_NIC) += netxen/
obj-$(CONFIG_NIU) += niu.o
obj-$(CONFIG_VIRTIO_NET) += virtio_net.o

435
drivers/net/virtio_net.c Normal file
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@ -0,0 +1,435 @@
/* A simple network driver using virtio.
*
* Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//#define DEBUG
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_net.h>
#include <linux/scatterlist.h>
/* FIXME: MTU in config. */
#define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)
struct virtnet_info
{
struct virtio_device *vdev;
struct virtqueue *rvq, *svq;
struct net_device *dev;
struct napi_struct napi;
/* Number of input buffers, and max we've ever had. */
unsigned int num, max;
/* Receive & send queues. */
struct sk_buff_head recv;
struct sk_buff_head send;
};
static inline struct virtio_net_hdr *skb_vnet_hdr(struct sk_buff *skb)
{
return (struct virtio_net_hdr *)skb->cb;
}
static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
{
sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
}
static bool skb_xmit_done(struct virtqueue *rvq)
{
struct virtnet_info *vi = rvq->vdev->priv;
/* In case we were waiting for output buffers. */
netif_wake_queue(vi->dev);
return true;
}
static void receive_skb(struct net_device *dev, struct sk_buff *skb,
unsigned len)
{
struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
pr_debug("%s: short packet %i\n", dev->name, len);
dev->stats.rx_length_errors++;
goto drop;
}
len -= sizeof(struct virtio_net_hdr);
BUG_ON(len > MAX_PACKET_LEN);
skb_trim(skb, len);
skb->protocol = eth_type_trans(skb, dev);
pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
ntohs(skb->protocol), skb->len, skb->pkt_type);
dev->stats.rx_bytes += skb->len;
dev->stats.rx_packets++;
if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
pr_debug("Needs csum!\n");
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = hdr->csum_start;
skb->csum_offset = hdr->csum_offset;
if (skb->csum_start > skb->len - 2
|| skb->csum_offset > skb->len - 2) {
if (net_ratelimit())
printk(KERN_WARNING "%s: csum=%u/%u len=%u\n",
dev->name, skb->csum_start,
skb->csum_offset, skb->len);
goto frame_err;
}
}
if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
pr_debug("GSO!\n");
switch (hdr->gso_type) {
case VIRTIO_NET_HDR_GSO_TCPV4:
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
break;
case VIRTIO_NET_HDR_GSO_TCPV4_ECN:
skb_shinfo(skb)->gso_type = SKB_GSO_TCP_ECN;
break;
case VIRTIO_NET_HDR_GSO_UDP:
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
break;
case VIRTIO_NET_HDR_GSO_TCPV6:
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
break;
default:
if (net_ratelimit())
printk(KERN_WARNING "%s: bad gso type %u.\n",
dev->name, hdr->gso_type);
goto frame_err;
}
skb_shinfo(skb)->gso_size = hdr->gso_size;
if (skb_shinfo(skb)->gso_size == 0) {
if (net_ratelimit())
printk(KERN_WARNING "%s: zero gso size.\n",
dev->name);
goto frame_err;
}
/* Header must be checked, and gso_segs computed. */
skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
skb_shinfo(skb)->gso_segs = 0;
}
netif_receive_skb(skb);
return;
frame_err:
dev->stats.rx_frame_errors++;
drop:
dev_kfree_skb(skb);
}
static void try_fill_recv(struct virtnet_info *vi)
{
struct sk_buff *skb;
struct scatterlist sg[1+MAX_SKB_FRAGS];
int num, err;
for (;;) {
skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
if (unlikely(!skb))
break;
skb_put(skb, MAX_PACKET_LEN);
vnet_hdr_to_sg(sg, skb);
num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
skb_queue_head(&vi->recv, skb);
err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
if (err) {
skb_unlink(skb, &vi->recv);
kfree_skb(skb);
break;
}
vi->num++;
}
if (unlikely(vi->num > vi->max))
vi->max = vi->num;
vi->rvq->vq_ops->kick(vi->rvq);
}
static bool skb_recv_done(struct virtqueue *rvq)
{
struct virtnet_info *vi = rvq->vdev->priv;
netif_rx_schedule(vi->dev, &vi->napi);
/* Suppress further interrupts. */
return false;
}
static int virtnet_poll(struct napi_struct *napi, int budget)
{
struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
struct sk_buff *skb = NULL;
unsigned int len, received = 0;
again:
while (received < budget &&
(skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
__skb_unlink(skb, &vi->recv);
receive_skb(vi->dev, skb, len);
vi->num--;
received++;
}
/* FIXME: If we oom and completely run out of inbufs, we need
* to start a timer trying to fill more. */
if (vi->num < vi->max / 2)
try_fill_recv(vi);
/* All done? */
if (!skb) {
netif_rx_complete(vi->dev, napi);
if (unlikely(!vi->rvq->vq_ops->restart(vi->rvq))
&& netif_rx_reschedule(vi->dev, napi))
goto again;
}
return received;
}
static void free_old_xmit_skbs(struct virtnet_info *vi)
{
struct sk_buff *skb;
unsigned int len;
while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
pr_debug("Sent skb %p\n", skb);
__skb_unlink(skb, &vi->send);
vi->dev->stats.tx_bytes += len;
vi->dev->stats.tx_packets++;
kfree_skb(skb);
}
}
static int start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
int num, err;
struct scatterlist sg[1+MAX_SKB_FRAGS];
struct virtio_net_hdr *hdr;
const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
DECLARE_MAC_BUF(mac);
pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));
free_old_xmit_skbs(vi);
/* Encode metadata header at front. */
hdr = skb_vnet_hdr(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL) {
hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
hdr->csum_start = skb->csum_start - skb_headroom(skb);
hdr->csum_offset = skb->csum_offset;
} else {
hdr->flags = 0;
hdr->csum_offset = hdr->csum_start = 0;
}
if (skb_is_gso(skb)) {
hdr->gso_size = skb_shinfo(skb)->gso_size;
if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4_ECN;
else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
else
BUG();
} else {
hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
hdr->gso_size = 0;
}
vnet_hdr_to_sg(sg, skb);
num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
__skb_queue_head(&vi->send, skb);
err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
if (err) {
pr_debug("%s: virtio not prepared to send\n", dev->name);
skb_unlink(skb, &vi->send);
netif_stop_queue(dev);
return NETDEV_TX_BUSY;
}
vi->svq->vq_ops->kick(vi->svq);
return 0;
}
static int virtnet_open(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
try_fill_recv(vi);
/* If we didn't even get one input buffer, we're useless. */
if (vi->num == 0)
return -ENOMEM;
napi_enable(&vi->napi);
return 0;
}
static int virtnet_close(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
struct sk_buff *skb;
napi_disable(&vi->napi);
/* networking core has neutered skb_xmit_done/skb_recv_done, so don't
* worry about races vs. get(). */
vi->rvq->vq_ops->shutdown(vi->rvq);
while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
kfree_skb(skb);
vi->num--;
}
vi->svq->vq_ops->shutdown(vi->svq);
while ((skb = __skb_dequeue(&vi->send)) != NULL)
kfree_skb(skb);
BUG_ON(vi->num != 0);
return 0;
}
static int virtnet_probe(struct virtio_device *vdev)
{
int err;
unsigned int len;
struct net_device *dev;
struct virtnet_info *vi;
void *token;
/* Allocate ourselves a network device with room for our info */
dev = alloc_etherdev(sizeof(struct virtnet_info));
if (!dev)
return -ENOMEM;
/* Set up network device as normal. */
ether_setup(dev);
dev->open = virtnet_open;
dev->stop = virtnet_close;
dev->hard_start_xmit = start_xmit;
dev->features = NETIF_F_HIGHDMA;
SET_NETDEV_DEV(dev, &vdev->dev);
/* Do we support "hardware" checksums? */
token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_F, &len);
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_NO_CSUM)) {
/* This opens up the world of extra features. */
dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4))
dev->features |= NETIF_F_TSO;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_UFO))
dev->features |= NETIF_F_UFO;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4_ECN))
dev->features |= NETIF_F_TSO_ECN;
if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO6))
dev->features |= NETIF_F_TSO6;
}
/* Configuration may specify what MAC to use. Otherwise random. */
token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_MAC_F, &len);
if (token) {
dev->addr_len = len;
vdev->config->get(vdev, token, dev->dev_addr, len);
} else
random_ether_addr(dev->dev_addr);
/* Set up our device-specific information */
vi = netdev_priv(dev);
netif_napi_add(dev, &vi->napi, virtnet_poll, 16);
vi->dev = dev;
vi->vdev = vdev;
/* We expect two virtqueues, receive then send. */
vi->rvq = vdev->config->find_vq(vdev, skb_recv_done);
if (IS_ERR(vi->rvq)) {
err = PTR_ERR(vi->rvq);
goto free;
}
vi->svq = vdev->config->find_vq(vdev, skb_xmit_done);
if (IS_ERR(vi->svq)) {
err = PTR_ERR(vi->svq);
goto free_recv;
}
/* Initialize our empty receive and send queues. */
skb_queue_head_init(&vi->recv);
skb_queue_head_init(&vi->send);
err = register_netdev(dev);
if (err) {
pr_debug("virtio_net: registering device failed\n");
goto free_send;
}
pr_debug("virtnet: registered device %s\n", dev->name);
vdev->priv = vi;
return 0;
free_send:
vdev->config->del_vq(vi->svq);
free_recv:
vdev->config->del_vq(vi->rvq);
free:
free_netdev(dev);
return err;
}
static void virtnet_remove(struct virtio_device *vdev)
{
unregister_netdev(vdev->priv);
free_netdev(vdev->priv);
}
static struct virtio_device_id id_table[] = {
{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static struct virtio_driver virtio_net = {
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtnet_probe,
.remove = __devexit_p(virtnet_remove),
};
static int __init init(void)
{
return register_virtio_driver(&virtio_net);
}
static void __exit fini(void)
{
unregister_virtio_driver(&virtio_net);
}
module_init(init);
module_exit(fini);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio network driver");
MODULE_LICENSE("GPL");

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@ -344,6 +344,7 @@ unifdef-y += utsname.h
unifdef-y += videodev2.h
unifdef-y += videodev.h
unifdef-y += virtio_config.h
unifdef-y += virtio_net.h
unifdef-y += wait.h
unifdef-y += wanrouter.h
unifdef-y += watchdog.h

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@ -0,0 +1,36 @@
#ifndef _LINUX_VIRTIO_NET_H
#define _LINUX_VIRTIO_NET_H
#include <linux/virtio_config.h>
/* The ID for virtio_net */
#define VIRTIO_ID_NET 1
/* The bitmap of config for virtio net */
#define VIRTIO_CONFIG_NET_F 0x40
#define VIRTIO_NET_F_NO_CSUM 0
#define VIRTIO_NET_F_TSO4 1
#define VIRTIO_NET_F_UFO 2
#define VIRTIO_NET_F_TSO4_ECN 3
#define VIRTIO_NET_F_TSO6 4
/* The config defining mac address. */
#define VIRTIO_CONFIG_NET_MAC_F 0x41
/* This is the first element of the scatter-gather list. If you don't
* specify GSO or CSUM features, you can simply ignore the header. */
struct virtio_net_hdr
{
#define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 // Use csum_start, csum_offset
__u8 flags;
#define VIRTIO_NET_HDR_GSO_NONE 0 // Not a GSO frame
#define VIRTIO_NET_HDR_GSO_TCPV4 1 // GSO frame, IPv4 TCP (TSO)
/* FIXME: Do we need this? If they said they can handle ECN, do they care? */
#define VIRTIO_NET_HDR_GSO_TCPV4_ECN 2 // GSO frame, IPv4 TCP w/ ECN
#define VIRTIO_NET_HDR_GSO_UDP 3 // GSO frame, IPv4 UDP (UFO)
#define VIRTIO_NET_HDR_GSO_TCPV6 4 // GSO frame, IPv6 TCP
__u8 gso_type;
__u16 gso_size;
__u16 csum_start;
__u16 csum_offset;
};
#endif /* _LINUX_VIRTIO_NET_H */