From patchwork Fri Dec 1 13:48:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Bianconi X-Patchwork-Id: 13475856 X-Patchwork-Delegate: bpf@iogearbox.net 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 1D1BF3B2B8; Fri, 1 Dec 2023 13:49:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D0h1hrfv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D41DC433C8; Fri, 1 Dec 2023 13:49:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701438545; bh=n03eQ42yvpWJiBG9uy5hHe6OXMG8YRx0Oicl8t7Lovg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D0h1hrfvRmN8pXy12GIG3ZBQ0fRkJNj61rGYrguCJ2HaPG6a+ITuH4wQAX5pgmpwD G2GIHQHv9OKy1vXy3V9+PZvhKwpNE0SVntRgHPhPYKa6vlK2a4b/oPmU3mT6BNq7aN E2E8rsIOx12+LTt/A+eFZv85aMqf784oDnZ6N2i1POp7lAVc21sfISXOJR4D9w5j2p su+uFoqobhu+yD6WGdJKz/4QDZ39bUIR7UXSt4qF5rgmABx16HayIPICwLxt4Aw+lP CpNRzvrSAmT76fVuwb4bkn67M9E/91y/sVTjtHRsxCyUfkna9pAuGwHS+6983Wcztm ste0yx+mQeSGg== From: Lorenzo Bianconi To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, lorenzo.bianconi@redhat.com, bpf@vger.kernel.org, hawk@kernel.org, toke@redhat.com, aleksander.lobakin@intel.com, willemdebruijn.kernel@gmail.com, jasowang@redhat.com, sdf@google.com Subject: [PATCH v3 net-next 2/2] xdp: add multi-buff support for xdp running in generic mode Date: Fri, 1 Dec 2023 14:48:26 +0100 Message-ID: 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 | 151 +++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 126 insertions(+), 25 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 4df68d7f04a2..ed827b443d48 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4853,6 +4853,12 @@ 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; @@ -4882,6 +4888,14 @@ 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) || @@ -4915,54 +4929,141 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp, return act; } -static u32 netif_receive_generic_xdp(struct sk_buff **pskb, - struct xdp_buff *xdp, - struct bpf_prog *xdp_prog) +static int netif_skb_check_for_generic_xdp(struct sk_buff **pskb, + struct bpf_prog *prog) { struct sk_buff *skb = *pskb; - u32 act = XDP_DROP; - - /* Reinjected packets coming from act_mirred or similar should - * not get XDP generic processing. - */ - if (skb_is_redirected(skb)) - return XDP_PASS; + int err; - /* 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) || !prog->aux->xdp_has_frags) { int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb); int troom = skb->tail + skb->data_len - skb->end; /* In case we have to go down the path and also linearize, * then lets do the pskb_expand_head() work just once here. */ - if (pskb_expand_head(skb, - hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0, - troom > 0 ? troom + 128 : 0, GFP_ATOMIC)) - goto do_drop; - if (skb_linearize(skb)) - goto do_drop; + err = pskb_expand_head(skb, + hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0, + troom > 0 ? troom + 128 : 0, GFP_ATOMIC); + if (err) + return err; + + err = skb_linearize(skb); + if (err) + return err; + + return 0; } - 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. + */ + if (skb_cloned(skb) || skb_shinfo(skb)->nr_frags || + skb_headroom(skb) < XDP_PACKET_HEADROOM) { + u32 mac_len = skb->data - skb_mac_header(skb); + u32 size, truesize, len, max_head_size, off; + struct sk_buff *nskb; + int i, head_off; + void *data; + + __skb_push(skb, mac_len); + 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 = napi_alloc_frag(truesize); + if (!data) + return -ENOMEM; + + nskb = napi_build_skb(data, truesize); + if (!nskb) { + skb_free_frag(data); + return -ENOMEM; + } + + skb_reserve(nskb, XDP_PACKET_HEADROOM); + skb_copy_header(nskb, skb); + + 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; + + size = min_t(u32, len, PAGE_SIZE); + data = napi_alloc_frag(size); + if (!data) { + consume_skb(nskb); + return -ENOMEM; + } + + page = virt_to_head_page(data); + skb_add_rx_frag(nskb, i, page, + data - page_address(page), size, size); + err = skb_copy_bits(skb, off, data, size); + if (err) { + consume_skb(nskb); + return err; + } + + len -= size; + off += size; + } + + consume_skb(skb); + *pskb = nskb; + __skb_pull(nskb, mac_len); + } + + return 0; +} + +static u32 netif_receive_generic_xdp(struct sk_buff **pskb, + struct xdp_buff *xdp, + struct bpf_prog *xdp_prog) +{ + u32 act = XDP_DROP; + + /* Reinjected packets coming from act_mirred or similar should + * not get XDP generic processing. + */ + if (skb_is_redirected(*pskb)) + return XDP_PASS; + + if (netif_skb_check_for_generic_xdp(pskb, xdp_prog)) + goto do_drop; + + 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; }