From 4fa8fcd3440101dbacf4fae91de69877ef751977 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 15 Nov 2021 21:36:25 +0100 Subject: [PATCH 1/2] igc: AF_XDP zero-copy metadata adjust breaks SKBs on XDP_PASS Driver already implicitly supports XDP metadata access in AF_XDP zero-copy mode, as xsk_buff_pool's xp_alloc() naturally set xdp_buff data_meta equal data. This works fine for XDP and AF_XDP, but if a BPF-prog adjust via bpf_xdp_adjust_meta() and choose to call XDP_PASS, then igc function igc_construct_skb_zc() will construct an invalid SKB packet. The function correctly include the xdp->data_meta area in the memcpy, but forgot to pull header to take metasize into account. Fixes: fc9df2a0b520 ("igc: Enable RX via AF_XDP zero-copy") Signed-off-by: Jesper Dangaard Brouer Tested-by: Nechama Kraus Acked-by: Maciej Fijalkowski Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/igc/igc_main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 8e448288ee265..76b0a73113695 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -2448,8 +2448,10 @@ static struct sk_buff *igc_construct_skb_zc(struct igc_ring *ring, skb_reserve(skb, xdp->data_meta - xdp->data_hard_start); memcpy(__skb_put(skb, totalsize), xdp->data_meta, totalsize); - if (metasize) + if (metasize) { skb_metadata_set(skb, metasize); + __skb_pull(skb, metasize); + } return skb; } From f51b5e2b5943d26387d2abb463bce2b4bd0a4a8d Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 15 Nov 2021 21:36:30 +0100 Subject: [PATCH 2/2] igc: enable XDP metadata in driver Enabling the XDP bpf_prog access to data_meta area is a very small change. Hint passing 'true' to xdp_prepare_buff(). The SKB layers can also access data_meta area, which required more driver changes to support. Reviewers, notice the igc driver have two different functions that can create SKBs, depending on driver config. Hint for testers, ethtool priv-flags legacy-rx enables the function igc_construct_skb() ethtool --set-priv-flags DEV legacy-rx on Signed-off-by: Jesper Dangaard Brouer Tested-by: Nechama Kraus Reviewed-by: Alexander Lobakin Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/igc/igc_main.c | 33 +++++++++++++++-------- 1 file changed, 22 insertions(+), 11 deletions(-) diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 76b0a73113695..142c57b7a4519 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1718,24 +1718,26 @@ static void igc_add_rx_frag(struct igc_ring *rx_ring, static struct sk_buff *igc_build_skb(struct igc_ring *rx_ring, struct igc_rx_buffer *rx_buffer, - union igc_adv_rx_desc *rx_desc, - unsigned int size) + struct xdp_buff *xdp) { - void *va = page_address(rx_buffer->page) + rx_buffer->page_offset; + unsigned int size = xdp->data_end - xdp->data; unsigned int truesize = igc_get_rx_frame_truesize(rx_ring, size); + unsigned int metasize = xdp->data - xdp->data_meta; struct sk_buff *skb; /* prefetch first cache line of first page */ - net_prefetch(va); + net_prefetch(xdp->data_meta); /* build an skb around the page buffer */ - skb = build_skb(va - IGC_SKB_PAD, truesize); + skb = build_skb(xdp->data_hard_start, truesize); if (unlikely(!skb)) return NULL; /* update pointers within the skb to store the data */ - skb_reserve(skb, IGC_SKB_PAD); + skb_reserve(skb, xdp->data - xdp->data_hard_start); __skb_put(skb, size); + if (metasize) + skb_metadata_set(skb, metasize); igc_rx_buffer_flip(rx_buffer, truesize); return skb; @@ -1746,6 +1748,7 @@ static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring, struct xdp_buff *xdp, ktime_t timestamp) { + unsigned int metasize = xdp->data - xdp->data_meta; unsigned int size = xdp->data_end - xdp->data; unsigned int truesize = igc_get_rx_frame_truesize(rx_ring, size); void *va = xdp->data; @@ -1753,10 +1756,11 @@ static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring, struct sk_buff *skb; /* prefetch first cache line of first page */ - net_prefetch(va); + net_prefetch(xdp->data_meta); /* allocate a skb to store the frags */ - skb = napi_alloc_skb(&rx_ring->q_vector->napi, IGC_RX_HDR_LEN); + skb = napi_alloc_skb(&rx_ring->q_vector->napi, + IGC_RX_HDR_LEN + metasize); if (unlikely(!skb)) return NULL; @@ -1769,7 +1773,13 @@ static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring, headlen = eth_get_headlen(skb->dev, va, IGC_RX_HDR_LEN); /* align pull length to size of long to optimize memcpy performance */ - memcpy(__skb_put(skb, headlen), va, ALIGN(headlen, sizeof(long))); + memcpy(__skb_put(skb, headlen + metasize), xdp->data_meta, + ALIGN(headlen + metasize, sizeof(long))); + + if (metasize) { + skb_metadata_set(skb, metasize); + __skb_pull(skb, metasize); + } /* update all of the pointers */ size -= headlen; @@ -2354,7 +2364,8 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget) if (!skb) { xdp_init_buff(&xdp, truesize, &rx_ring->xdp_rxq); xdp_prepare_buff(&xdp, pktbuf - igc_rx_offset(rx_ring), - igc_rx_offset(rx_ring) + pkt_offset, size, false); + igc_rx_offset(rx_ring) + pkt_offset, + size, true); skb = igc_xdp_run_prog(adapter, &xdp); } @@ -2378,7 +2389,7 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget) } else if (skb) igc_add_rx_frag(rx_ring, rx_buffer, skb, size); else if (ring_uses_build_skb(rx_ring)) - skb = igc_build_skb(rx_ring, rx_buffer, rx_desc, size); + skb = igc_build_skb(rx_ring, rx_buffer, &xdp); else skb = igc_construct_skb(rx_ring, rx_buffer, &xdp, timestamp);