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virtio-net: support XDP_REDIRECT
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This patch tries to add XDP_REDIRECT for virtio-net. The changes are
not complex as we could use exist XDP_TX helpers for most of the
work. The rest is passing the XDP_TX to NAPI handler for implementing
batching.

Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jason Wang authored and David S. Miller committed Sep 20, 2017
1 parent 3124034 commit 186b3c9
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Showing 2 changed files with 62 additions and 15 deletions.
Empty file added drivers/net/virtio_net.
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77 changes: 62 additions & 15 deletions drivers/net/virtio_net.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/average.h>
#include <linux/filter.h>
#include <net/route.h>

static int napi_weight = NAPI_POLL_WEIGHT;
Expand Down Expand Up @@ -372,8 +373,20 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
return skb;
}

static bool virtnet_xdp_xmit(struct virtnet_info *vi,
struct xdp_buff *xdp)
static void virtnet_xdp_flush(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
struct send_queue *sq;
unsigned int qp;

qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
sq = &vi->sq[qp];

virtqueue_kick(sq->vq);
}

static bool __virtnet_xdp_xmit(struct virtnet_info *vi,
struct xdp_buff *xdp)
{
struct virtio_net_hdr_mrg_rxbuf *hdr;
unsigned int len;
Expand Down Expand Up @@ -407,10 +420,19 @@ static bool virtnet_xdp_xmit(struct virtnet_info *vi,
return false;
}

virtqueue_kick(sq->vq);
return true;
}

static int virtnet_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
{
struct virtnet_info *vi = netdev_priv(dev);
bool sent = __virtnet_xdp_xmit(vi, xdp);

if (!sent)
return -ENOSPC;
return 0;
}

static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
{
return vi->xdp_queue_pairs ? VIRTIO_XDP_HEADROOM : 0;
Expand Down Expand Up @@ -483,7 +505,8 @@ static struct sk_buff *receive_small(struct net_device *dev,
struct virtnet_info *vi,
struct receive_queue *rq,
void *buf, void *ctx,
unsigned int len)
unsigned int len,
bool *xdp_xmit)
{
struct sk_buff *skb;
struct bpf_prog *xdp_prog;
Expand All @@ -493,7 +516,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
unsigned int buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
struct page *page = virt_to_head_page(buf);
unsigned int delta = 0;
unsigned int delta = 0, err;
struct page *xdp_page;
len -= vi->hdr_len;

Expand Down Expand Up @@ -541,8 +564,16 @@ static struct sk_buff *receive_small(struct net_device *dev,
delta = orig_data - xdp.data;
break;
case XDP_TX:
if (unlikely(!virtnet_xdp_xmit(vi, &xdp)))
if (unlikely(!__virtnet_xdp_xmit(vi, &xdp)))
trace_xdp_exception(vi->dev, xdp_prog, act);
else
*xdp_xmit = true;
rcu_read_unlock();
goto xdp_xmit;
case XDP_REDIRECT:
err = xdp_do_redirect(dev, &xdp, xdp_prog);
if (!err)
*xdp_xmit = true;
rcu_read_unlock();
goto xdp_xmit;
default:
Expand Down Expand Up @@ -603,7 +634,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
struct receive_queue *rq,
void *buf,
void *ctx,
unsigned int len)
unsigned int len,
bool *xdp_xmit)
{
struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
Expand All @@ -613,6 +645,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
struct bpf_prog *xdp_prog;
unsigned int truesize;
unsigned int headroom = mergeable_ctx_to_headroom(ctx);
int err;

head_skb = NULL;

Expand Down Expand Up @@ -678,12 +711,20 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
}
break;
case XDP_TX:
if (unlikely(!virtnet_xdp_xmit(vi, &xdp)))
if (unlikely(!__virtnet_xdp_xmit(vi, &xdp)))
trace_xdp_exception(vi->dev, xdp_prog, act);
else
*xdp_xmit = true;
if (unlikely(xdp_page != page))
goto err_xdp;
rcu_read_unlock();
goto xdp_xmit;
case XDP_REDIRECT:
err = xdp_do_redirect(dev, &xdp, xdp_prog);
if (err)
*xdp_xmit = true;
rcu_read_unlock();
goto xdp_xmit;
default:
bpf_warn_invalid_xdp_action(act);
case XDP_ABORTED:
Expand Down Expand Up @@ -788,7 +829,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
}

static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
void *buf, unsigned int len, void **ctx)
void *buf, unsigned int len, void **ctx, bool *xdp_xmit)
{
struct net_device *dev = vi->dev;
struct sk_buff *skb;
Expand All @@ -809,11 +850,11 @@ static int receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
}

if (vi->mergeable_rx_bufs)
skb = receive_mergeable(dev, vi, rq, buf, ctx, len);
skb = receive_mergeable(dev, vi, rq, buf, ctx, len, xdp_xmit);
else if (vi->big_packets)
skb = receive_big(dev, vi, rq, buf, len);
else
skb = receive_small(dev, vi, rq, buf, ctx, len);
skb = receive_small(dev, vi, rq, buf, ctx, len, xdp_xmit);

if (unlikely(!skb))
return 0;
Expand Down Expand Up @@ -1071,7 +1112,7 @@ static void refill_work(struct work_struct *work)
}
}

static int virtnet_receive(struct receive_queue *rq, int budget)
static int virtnet_receive(struct receive_queue *rq, int budget, bool *xdp_xmit)
{
struct virtnet_info *vi = rq->vq->vdev->priv;
unsigned int len, received = 0, bytes = 0;
Expand All @@ -1083,13 +1124,13 @@ static int virtnet_receive(struct receive_queue *rq, int budget)

while (received < budget &&
(buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx))) {
bytes += receive_buf(vi, rq, buf, len, ctx);
bytes += receive_buf(vi, rq, buf, len, ctx, xdp_xmit);
received++;
}
} else {
while (received < budget &&
(buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
bytes += receive_buf(vi, rq, buf, len, NULL);
bytes += receive_buf(vi, rq, buf, len, NULL, xdp_xmit);
received++;
}
}
Expand Down Expand Up @@ -1161,15 +1202,19 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
struct receive_queue *rq =
container_of(napi, struct receive_queue, napi);
unsigned int received;
bool xdp_xmit = false;

virtnet_poll_cleantx(rq);

received = virtnet_receive(rq, budget);
received = virtnet_receive(rq, budget, &xdp_xmit);

/* Out of packets? */
if (received < budget)
virtqueue_napi_complete(napi, rq->vq, received);

if (xdp_xmit)
xdp_do_flush_map();

return received;
}

Expand Down Expand Up @@ -2069,6 +2114,8 @@ static const struct net_device_ops virtnet_netdev = {
.ndo_poll_controller = virtnet_netpoll,
#endif
.ndo_xdp = virtnet_xdp,
.ndo_xdp_xmit = virtnet_xdp_xmit,
.ndo_xdp_flush = virtnet_xdp_flush,
.ndo_features_check = passthru_features_check,
};

Expand Down

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