From patchwork Tue Dec 12 10:06:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Bianconi X-Patchwork-Id: 13488855 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C9A259524; Tue, 12 Dec 2023 10:06:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nfjkjmhq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25D96C433C8; Tue, 12 Dec 2023 10:06:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702375611; bh=/ToUaGg3Z1fHv105Ur3p76Jcy9CEpWlBEGYy915v3Sk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nfjkjmhq5TpRXknUhyJ+8KwUauwQ+1Eh3rpLJ/dEtt7Yzl4hxZFpSmfJf8fpWc6gf Bm//FZ5AfP1YGf4Orq0eXuLx+r7pkD2pM25ln7Qe6KWdq2ICL1IwLC4117Lo+Yu2Y7 69i51sU6DLvtHDr4VhSyv3znzJyLNICdvosVp1+vDbWUd7qbDtwyWRFo9KD/0WawQ+ YAl+Fgna2cGYKX/n5q5Yuh2862JwplF0RdQphRj9/s40r2TQmw26dnwDuebtR75s4n 2HP7E/gZQhSQMqOtnGeVdnky8l9t0mPocjCph2U5l8HsYcYvIokwU/R/sClsuLayDn RB2h4aBNi975Q== From: Lorenzo Bianconi To: netdev@vger.kernel.org Cc: lorenzo.bianconi@redhat.com, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, pabeni@redhat.com, bpf@vger.kernel.org, hawk@kernel.org, toke@redhat.com, willemdebruijn.kernel@gmail.com, jasowang@redhat.com, sdf@google.com Subject: [PATCH v4 net-next 3/3] xdp: add multi-buff support for xdp running in generic mode Date: Tue, 12 Dec 2023 11:06:15 +0100 Message-ID: <2d0f9388c6509192d88e359a402517a73124b50e.1702375338.git.lorenzo@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Similar to native xdp, do not always linearize the skb in netif_receive_generic_xdp routine but create a non-linear xdp_buff to be processed by the eBPF program. This allow to add multi-buffer support for xdp running in generic mode. Signed-off-by: Lorenzo Bianconi --- net/core/dev.c | 121 +++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 111 insertions(+), 10 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 14554698b1fa..3826e0ea08e3 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4854,6 +4854,12 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp, xdp_init_buff(xdp, frame_sz, &rxqueue->xdp_rxq); xdp_prepare_buff(xdp, hard_start, skb_headroom(skb) - mac_len, skb_headlen(skb) + mac_len, true); + if (skb_is_nonlinear(skb)) { + skb_shinfo(skb)->xdp_frags_size = skb->data_len; + xdp_buff_set_frags_flag(xdp); + } else { + xdp_buff_clear_frags_flag(xdp); + } orig_data_end = xdp->data_end; orig_data = xdp->data; @@ -4883,6 +4889,14 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp, skb->len += off; /* positive on grow, negative on shrink */ } + /* XDP frag metadata (e.g. nr_frags) are updated in eBPF helpers + * (e.g. bpf_xdp_adjust_tail), we need to update data_len here. + */ + if (xdp_buff_has_frags(xdp)) + skb->data_len = skb_shinfo(skb)->xdp_frags_size; + else + skb->data_len = 0; + /* check if XDP changed eth hdr such SKB needs update */ eth = (struct ethhdr *)xdp->data; if ((orig_eth_type != eth->h_proto) || @@ -4916,12 +4930,84 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp, return act; } +static int netif_skb_segment_for_xdp(struct sk_buff **pskb) +{ + struct softnet_data *sd = this_cpu_ptr(&softnet_data); + u32 size, truesize, len, max_head_size, off; + struct sk_buff *skb = *pskb, *nskb; + int err, i, head_off; + void *data; + + max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - XDP_PACKET_HEADROOM); + if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE) + return -ENOMEM; + + size = min_t(u32, skb->len, max_head_size); + truesize = SKB_HEAD_ALIGN(size) + XDP_PACKET_HEADROOM; + data = page_pool_dev_alloc_va(sd->page_pool, &truesize); + if (!data) + return -ENOMEM; + + nskb = napi_build_skb(data, truesize); + if (!nskb) { + page_pool_free_va(sd->page_pool, data, true); + return -ENOMEM; + } + + skb_reserve(nskb, XDP_PACKET_HEADROOM); + skb_copy_header(nskb, skb); + skb_mark_for_recycle(nskb); + + err = skb_copy_bits(skb, 0, nskb->data, size); + if (err) { + consume_skb(nskb); + return err; + } + skb_put(nskb, size); + + head_off = skb_headroom(nskb) - skb_headroom(skb); + skb_headers_offset_update(nskb, head_off); + + off = size; + len = skb->len - off; + for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) { + struct page *page; + u32 page_off; + + size = min_t(u32, len, PAGE_SIZE); + truesize = size; + + page = page_pool_dev_alloc(sd->page_pool, &page_off, + &truesize); + if (!data) { + consume_skb(nskb); + return -ENOMEM; + } + + skb_add_rx_frag(nskb, i, page, page_off, size, truesize); + err = skb_copy_bits(skb, off, page_address(page) + page_off, + size); + if (err) { + consume_skb(nskb); + return err; + } + + len -= size; + off += size; + } + + consume_skb(skb); + *pskb = nskb; + + return 0; +} + static u32 netif_receive_generic_xdp(struct sk_buff **pskb, struct xdp_buff *xdp, struct bpf_prog *xdp_prog) { struct sk_buff *skb = *pskb; - u32 act = XDP_DROP; + u32 mac_len, act = XDP_DROP; /* Reinjected packets coming from act_mirred or similar should * not get XDP generic processing. @@ -4929,12 +5015,10 @@ static u32 netif_receive_generic_xdp(struct sk_buff **pskb, if (skb_is_redirected(skb)) return XDP_PASS; - /* XDP packets must be linear and must have sufficient headroom - * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also - * native XDP provides, thus we need to do it here as well. + /* XDP does not support fraglist so we need to linearize + * the skb. */ - if (skb_cloned(skb) || skb_is_nonlinear(skb) || - skb_headroom(skb) < XDP_PACKET_HEADROOM) { + if (skb_has_frag_list(skb) || !xdp_prog->aux->xdp_has_frags) { int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb); int troom = skb->tail + skb->data_len - skb->end; @@ -4947,23 +5031,40 @@ static u32 netif_receive_generic_xdp(struct sk_buff **pskb, goto do_drop; if (skb_linearize(skb)) goto do_drop; + + goto do_xdp; } - act = bpf_prog_run_generic_xdp(skb, xdp, xdp_prog); + /* XDP packets must have sufficient headroom of XDP_PACKET_HEADROOM + * bytes. This is the guarantee that also native XDP provides, + * thus we need to do it here as well. + */ + mac_len = skb->data - skb_mac_header(skb); + __skb_push(skb, mac_len); + + if (skb_cloned(skb) || skb_shinfo(skb)->nr_frags || + skb_headroom(skb) < XDP_PACKET_HEADROOM) { + if (netif_skb_segment_for_xdp(pskb)) + goto do_drop; + } + + __skb_pull(*pskb, mac_len); +do_xdp: + act = bpf_prog_run_generic_xdp(*pskb, xdp, xdp_prog); switch (act) { case XDP_REDIRECT: case XDP_TX: case XDP_PASS: break; default: - bpf_warn_invalid_xdp_action(skb->dev, xdp_prog, act); + bpf_warn_invalid_xdp_action((*pskb)->dev, xdp_prog, act); fallthrough; case XDP_ABORTED: - trace_xdp_exception(skb->dev, xdp_prog, act); + trace_xdp_exception((*pskb)->dev, xdp_prog, act); fallthrough; case XDP_DROP: do_drop: - kfree_skb(skb); + kfree_skb(*pskb); break; }