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bpf, ixgbe: add meta data support

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Implement support for transferring XDP meta data into skb for
ixgbe driver; before calling into the program, xdp.data_meta points
to xdp.data, where on program return with pass verdict, we call
into skb_metadata_set().

We implement this for the default ixgbe_build_skb() variant. For the
ixgbe_construct_skb() that is used when legacy-rx buffer mananagement
mode is turned on via ethtool, I found that XDP gets 0 headroom, so
neither xdp_adjust_head() nor xdp_adjust_meta() can be used with this.
Just add a comment with explanation for this operating mode.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2017-09-25 02:25:55 +02:00 committed by David S. Miller
parent 65d88fd0ba
commit 366a88fe2f
1 changed files with 26 additions and 4 deletions
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30
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
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@ -2133,6 +2133,21 @@ static struct sk_buff *ixgbe_construct_skb(struct ixgbe_ring *rx_ring,
#if L1_CACHE_BYTES < 128
prefetch(xdp->data + L1_CACHE_BYTES);
#endif
/* Note, we get here by enabling legacy-rx via:
*
* ethtool --set-priv-flags <dev> legacy-rx on
*
* In this mode, we currently get 0 extra XDP headroom as
* opposed to having legacy-rx off, where we process XDP
* packets going to stack via ixgbe_build_skb(). The latter
* provides us currently with 192 bytes of headroom.
*
* For ixgbe_construct_skb() mode it means that the
* xdp->data_meta will always point to xdp->data, since
* the helper cannot expand the head. Should this ever
* change in future for legacy-rx mode on, then lets also
* add xdp->data_meta handling here.
*/
/* allocate a skb to store the frags */
skb = napi_alloc_skb(&rx_ring->q_vector->napi, IXGBE_RX_HDR_SIZE);
@ -2165,6 +2180,7 @@ static struct sk_buff *ixgbe_build_skb(struct ixgbe_ring *rx_ring,
struct xdp_buff *xdp,
union ixgbe_adv_rx_desc *rx_desc)
{
unsigned int metasize = xdp->data - xdp->data_meta;
#if (PAGE_SIZE < 8192)
unsigned int truesize = ixgbe_rx_pg_size(rx_ring) / 2;
#else
@ -2174,10 +2190,14 @@ static struct sk_buff *ixgbe_build_skb(struct ixgbe_ring *rx_ring,
#endif
struct sk_buff *skb;
/* prefetch first cache line of first page */
prefetch(xdp->data);
/* Prefetch first cache line of first page. If xdp->data_meta
* is unused, this points extactly as xdp->data, otherwise we
* likely have a consumer accessing first few bytes of meta
* data, and then actual data.
*/
prefetch(xdp->data_meta);
#if L1_CACHE_BYTES < 128
prefetch(xdp->data + L1_CACHE_BYTES);
prefetch(xdp->data_meta + L1_CACHE_BYTES);
#endif
/* build an skb to around the page buffer */
@ -2188,6 +2208,8 @@ static struct sk_buff *ixgbe_build_skb(struct ixgbe_ring *rx_ring,
/* update pointers within the skb to store the data */
skb_reserve(skb, xdp->data - xdp->data_hard_start);
__skb_put(skb, xdp->data_end - xdp->data);
if (metasize)
skb_metadata_set(skb, metasize);
/* record DMA address if this is the start of a chain of buffers */
if (!ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP))
@ -2326,7 +2348,7 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
if (!skb) {
xdp.data = page_address(rx_buffer->page) +
rx_buffer->page_offset;
xdp_set_data_meta_invalid(&xdp);
xdp.data_meta = xdp.data;
xdp.data_hard_start = xdp.data -
ixgbe_rx_offset(rx_ring);
xdp.data_end = xdp.data + size;