From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 75A7FD307 for ; Wed, 4 Oct 2023 08:00:49 +0000 (UTC) Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54283B7; Wed, 4 Oct 2023 01:00:46 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1qnwo9-0008ME-VA; Wed, 04 Oct 2023 10:00:37 +0200 Date: Wed, 4 Oct 2023 10:00:37 +0200 From: Florian Westphal To: Henrik =?iso-8859-15?Q?Lindstr=F6m?= Cc: Florian Westphal , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: macvtap performs IP defragmentation, causing MTU problems for virtual machines Message-ID: <20231004080037.GC15013@breakpoint.cc> References: <20231002092010.GA30843@breakpoint.cc> <2197902.NgBsaNRSFp@pc> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2197902.NgBsaNRSFp@pc> User-Agent: Mutt/1.10.1 (2018-07-13) X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_PASS,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Henrik Lindström wrote: > Had to change "return 0" to "return vif" but other than that your changes > seem to work, even with macvlan defragmentation removed. Oh, right, that should have been "return vid" indeed. > I tested it by sending 8K fragmented multicast packets, with 5 macvlans on > the receiving side. I consistently received 6 copies of the packet (1 from the > real interface and 1 per macvlan). While doing this i had my VM running with > a macvtap, and it was receiving fragmented packets as expected. > > Here are the changes i was testing with, first time sending a diff over mail > so hope it works :-) Can you submit this formally, with proper changelog and Signed-off-by? See scripts/checkpatch.pl in the kernel tree. It might be a good idea to first mail the patch to yourself and see if you can apply it (sometimes tabs get munged into spaces, long lines get broken, etc). You could also mention in changelog that this is ipv4 only because ipv6 already considers the interface index during reassembly. Thanks!