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 <dan...@iogearbox.net>
Acked-by: Alexei Starovoitov <a...@kernel.org>
Acked-by: John Fastabend <john.fastab...@gmail.com>
---
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 30 +++++++++++++++++++++++----
1 file changed, 26 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 04bb03b..3942c62 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -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;
--
1.9.3
