From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FUZZY_XPILL,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 720C4C3F2CD for ; Tue, 3 Mar 2020 09:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4CAF82166E for ; Tue, 3 Mar 2020 09:08:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iV9qbltz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727957AbgCCJIe (ORCPT ); Tue, 3 Mar 2020 04:08:34 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:35954 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727644AbgCCJIe (ORCPT ); Tue, 3 Mar 2020 04:08:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583226513; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EBfUnvvXsqNrrqNEeFrR6BTh0wBjxNHO7nDOkZ5dRnM=; b=iV9qbltz7xzRVfIfOA3Dd85B09iA4fq1b5Vfl5CvLCrY9NLmKAM3AdU0B6ehLqvOwVBfdi W9JeGTxCrJojGY7GWLkW3f0Nc63KNqjLdKfUWGXtbJ0MBWRaY5OGSFey6DzyIG541+l3qL f2pEzJd91WZaIjfE0f5/fJgqFTwsq+Q= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-203-_umTDSosM1ezGs0qqsowWw-1; Tue, 03 Mar 2020 04:08:29 -0500 X-MC-Unique: _umTDSosM1ezGs0qqsowWw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 35A95100DFC2; Tue, 3 Mar 2020 09:08:27 +0000 (UTC) Received: from carbon (ovpn-200-19.brq.redhat.com [10.40.200.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id E7DEA5D9C9; Tue, 3 Mar 2020 09:08:13 +0000 (UTC) Date: Tue, 3 Mar 2020 10:08:12 +0100 From: Jesper Dangaard Brouer To: David Ahern Cc: Alexei Starovoitov , David Ahern , netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, prashantbhole.linux@gmail.com, jasowang@redhat.com, toke@redhat.com, mst@redhat.com, toshiaki.makita1@gmail.com, daniel@iogearbox.net, john.fastabend@gmail.com, ast@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com, dsahern@gmail.com, brouer@redhat.com Subject: Re: [PATCH RFC v4 bpf-next 09/11] tun: Support xdp in the Tx path for xdp_frames Message-ID: <20200303100812.2e98d7f1@carbon> In-Reply-To: <318c0a44-b540-1c7f-9667-c01da5a8ac73@digitalocean.com> References: <20200227032013.12385-1-dsahern@kernel.org> <20200227032013.12385-10-dsahern@kernel.org> <20200302183040.tgnrg6tkblrjwsqj@ast-mbp> <318c0a44-b540-1c7f-9667-c01da5a8ac73@digitalocean.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 2 Mar 2020 21:27:08 -0700 David Ahern wrote: > On 3/2/20 11:30 AM, Alexei Starovoitov wrote: > > On Wed, Feb 26, 2020 at 08:20:11PM -0700, David Ahern wrote: > >> + > >> + act = bpf_prog_run_xdp(xdp_prog, &xdp); > >> + switch (act) { > >> + case XDP_TX: /* for Tx path, XDP_TX == XDP_PASS */ > >> + act = XDP_PASS; > >> + break; > >> + case XDP_PASS: > >> + break; > >> + case XDP_REDIRECT: > >> + /* fall through */ > >> + default: > >> + bpf_warn_invalid_xdp_action(act); > >> + /* fall through */ > >> + case XDP_ABORTED: > >> + trace_xdp_exception(tun->dev, xdp_prog, act); > >> + /* fall through */ > >> + case XDP_DROP: > >> + break; > >> + } > > > > patch 8 has very similar switch. Can you share the code? > > Most likely; I'll take a look. > > > > > I'm worried that XDP_TX is a silent alias to XDP_PASS. > > What were the reasons to go with this approach? > > As I stated in the cover letter: > > "XDP_TX on Rx means send the packet out the device it arrived > on; given that, XDP_Tx for the Tx path is treated as equivalent to > XDP_PASS - ie., continue on the Tx path." I'm not really buying this. IHMO XDP_PASS should mean continue on the Tx path, as this is a tx/egress XDP hook. I don't see a reason to basically "remove" the XDP_TX return code at this point. > > imo it's less error prone and extensible to warn on XDP_TX. > > Which will mean that both XDP_TX and XDP_REDICT are not supported > > for egress atm. I agree. I more see "XDP_TX" as a mirror facility... maybe there is a use-case for bouncing packets back in the TX/Egress hook? That is future work, but not reason disable the option now. > I personally don't care either way; I was going with the simplest > concept from a user perspective. > > > > > Patches 8 and 9 cover tun only. I'd like to see egress hook to be > > implemented in at least one physical NIC. Pick any hw. Something > > that handles real frames. Adding this hook to virtual NIC is easy, > > but it doesn't demonstrate design trade-offs one would need to > > think through by adding egress hook to physical nic. That's why I > > think it's mandatory to have it as part of the patch set. > > > > Patch 11 exposes egress to samples/bpf. It's nice, but without > > selftests it's no go. All new features must be exercised as part of > > selftests/bpf. > > Patches that exercise the rtnetlink uapi are fairly easy to do on > single node; anything traffic related requires multiple nodes or > namespace level capabilities. Unless I am missing something that is > why all current XDP tests ride on top of veth; veth changes are not > part of this set. > > So to be clear you are saying that all new XDP features require > patches to a h/w nic, veth and whatever the author really cares about > before new features like this go in? I would say yes. XDP is founded for physical HW NICs, and we need to show it makes sense for physical HW NICs. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer