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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 0155CC43387 for ; Wed, 16 Jan 2019 14:42:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CDA4C206C2 for ; Wed, 16 Jan 2019 14:42:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404678AbfAPOmn (ORCPT ); Wed, 16 Jan 2019 09:42:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57882 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729639AbfAPOmn (ORCPT ); Wed, 16 Jan 2019 09:42:43 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 93415C074EF3; Wed, 16 Jan 2019 14:42:42 +0000 (UTC) Received: from localhost (ovpn-200-21.brq.redhat.com [10.40.200.21]) by smtp.corp.redhat.com (Postfix) with ESMTP id 27C666107F; Wed, 16 Jan 2019 14:42:32 +0000 (UTC) Date: Wed, 16 Jan 2019 15:42:30 +0100 From: Jesper Dangaard Brouer To: Quentin Monnet Cc: Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org, oss-drivers@netronome.com, Arnaldo Carvalho de Melo , Stanislav Fomichev , brouer@redhat.com, Eric Leblond , Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= Subject: Re: [PATCH bpf-next v4 8/9] tools: bpftool: add probes for a network device Message-ID: <20190116154230.43b1e562@redhat.com> In-Reply-To: <20190116142119.8358-9-quentin.monnet@netronome.com> References: <20190116142119.8358-1-quentin.monnet@netronome.com> <20190116142119.8358-9-quentin.monnet@netronome.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 16 Jan 2019 14:42:43 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 16 Jan 2019 14:21:18 +0000 Quentin Monnet wrote: > bpftool gained support for probing the current system in order to see > what program and map types, and what helpers are available on that > system. This patch adds the possibility to pass an interface index to > libbpf (and hence to the kernel) when trying to load the programs or to > create the maps, in order to see what items a given network device can > support. > > A new keyword "dev " can be used as an alternative to "kernel" > to indicate that the given device should be tested. If no target ("dev" > or "kernel") is specified bpftool defaults to probing the kernel. > > Sample output: > > # bpftool -p feature probe dev lo > { > "syscall_config": { > "have_bpf_syscall": true > }, > "program_types": { > "have_sched_cls_prog_type": false, > "have_xdp_prog_type": false > }, > ... > } > > As the target is a network device, /proc/ parameters and kernel > configuration are NOT dumped. Availability of the bpf() syscall is > still probed, so we can return early if that syscall is not usable > (since there is no point in attempting the remaining probes in this > case). > > Among the program types, only the ones that can be offloaded are probed. Do you imagine we (later) can use this probe dev interface for probing e.g. what XDP actions a given driver supports? and e.g. if driver have data_meta support. Use-case: I've very interested in finding a solution for probing for XDP_REDIRECT support, as Suricata need this information, so it can choose to fallback to offloading elefant flows via TC-cls_bpf (if XDP_REDIRECT is not avail). > All map types are probed, as there is no specific rule telling which one > could or could not be supported by a device in the future. All helpers > are probed (but only for offload-able program types). > > Caveat: as bpftool does not attempt to attach programs to the device at > the moment, probes do not entirely reflect what the device accepts: > typically, for Netronome's nfp, results will announce that TC cls > offload is available even if support has been deactivated (with e.g. > ethtool -K eth1 hw-tc-offload off). > > v2: > - All helpers are probed, whereas previous version would only probe the > ones compatible with an offload-able program type. This is because we > do not keep a default compatible program type for each helper anymore. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer