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=-8.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9A070C433DB for ; Mon, 22 Feb 2021 13:27:24 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1F14D64E5C for ; Mon, 22 Feb 2021 13:27:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F14D64E5C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57552 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lEBFC-0001On-VT for qemu-devel@archiver.kernel.org; Mon, 22 Feb 2021 08:27:22 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60848) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lEBCd-0007nR-9Q for qemu-devel@nongnu.org; Mon, 22 Feb 2021 08:24:43 -0500 Received: from mail-wm1-x335.google.com ([2a00:1450:4864:20::335]:36806) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lEBCa-0004jR-Hu for qemu-devel@nongnu.org; Mon, 22 Feb 2021 08:24:42 -0500 Received: by mail-wm1-x335.google.com with SMTP id a207so14347829wmd.1 for ; Mon, 22 Feb 2021 05:24:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=references:user-agent:from:to:cc:subject:date:in-reply-to :message-id:mime-version:content-transfer-encoding; bh=LPnQD5pP/iEURNGtaVBlxBG671gzwlnLFwRdqRRGlF8=; b=hV8I9l9wRO4e8B/hjS7qLyCJmr69cPo8+mYtLoGKATXJHiKuqp0Xd1aPi8l8Ffvau9 jr40LN2y/0lNpkPtVlxjWJcg0zojKFxLKl4+itczIcyWBmfn6WKefIucBtdLIxivbj+Q UAIJMJUlK+hibLPfU9jIeBN0zb/H7GYy8NhESA1JeW19Wu6d28DqPQrQP7D6BN3BPh4C ukO+Ptx4vxw47U3oBHqR0g6uqzE0Qcgl18Xr7voPujz2llZ0H9weVCJ5ahaFEEAltq5k X0M6ENW62rds78p4GlZ0LAJPUSc5jLVN1KxN1UscN1OYkao7CXaOQbizh7a07jwlIzPc M9AA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject:date :in-reply-to:message-id:mime-version:content-transfer-encoding; bh=LPnQD5pP/iEURNGtaVBlxBG671gzwlnLFwRdqRRGlF8=; b=UfVRJMzjwBzbb9pPQWheg9NlBZNXRcJPjPF+RN5AhauaJXxToYAgH+6iX/eDkftBk+ UuJi6erb5zHyTZ3WZ+hhIzymJcWhcdqTkX7uYBa0cJ0fn1pA+emaOe9kajG7k8m35sNY 2yw/L2+bzMpSL9W5a0P2vzvQJEsiMP9ORQrIIYD8+W4Jh/zQraGz91C0Us+v8VJEjJWo B7w8OnKkt0IbKum31F2KesLO41Fu43JP1mpvCKDjGPR4EQl5qs5RS7LmYMv3V7S0jpjS 1j9tm2LIhNLCBvNluEClqA2yF0lSKScbM4uE3jOe7egbKaDZQ53EkLQVyUvBoABpe0xH I2vA== X-Gm-Message-State: AOAM5309rApwJ/n1dkH4m2sMrYoTNNF/NXUkE9ta1RVG9FV53ByyrBAU /6h3qGAjjFAZwYsoaiibrPS/SA== X-Google-Smtp-Source: ABdhPJyrrJ11xs6fRaCzmptMBvx2kyL0PLmsTCRMakV2CrBQa60Fn0/YwmeFPVhKnoCdtl3cL3K5LA== X-Received: by 2002:a1c:5a08:: with SMTP id o8mr19947048wmb.60.1614000277905; Mon, 22 Feb 2021 05:24:37 -0800 (PST) Received: from zen.linaroharston ([51.148.130.216]) by smtp.gmail.com with ESMTPSA id p6sm17682155wmg.37.2021.02.22.05.24.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Feb 2021 05:24:36 -0800 (PST) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 148101FF7E; Mon, 22 Feb 2021 13:24:36 +0000 (GMT) References: <8735xskm7j.fsf@linaro.org> User-agent: mu4e 1.5.8; emacs 28.0.50 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: "Dr. David Alan Gilbert" Subject: Re: vhost reply_ack negotiation (a.k.a differences in vhost-user behaviour with libvhost-user and vhost-user-backend.rs) Date: Mon, 22 Feb 2021 13:21:04 +0000 In-reply-to: Message-ID: <871rd86xrf.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::335; envelope-from=alex.bennee@linaro.org; helo=mail-wm1-x335.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sergio Lopez , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Stefan Hajnoczi , "rust-vmm@lists.opendev.org" , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Dr. David Alan Gilbert writes: > * Alex Benn=C3=A9e (alex.bennee@linaro.org) wrote: >> Hi, >>=20 >> I finally got a chance to get down into the guts of vhost-user while >> attempting to port my original C RPMB daemon to Rust using the >> vhost-user-backend and related crates. I ended up with this hang during >> negotiation: >>=20 >> startup >>=20 >> vhost_user_write req:1 flags:0x1 >> vhost_user_read_start >> vhost_user_read req:1 flags:0x5 >> vhost_user_backend_init: we got 170000000 GET_FEATURES >> vhost_user_write req:15 flags:0x1 >> vhost_user_read_start >> vhost_user_read req:15 flags:0x5 >> vhost_user_set_protocol_features: 2008 >> vhost_user_write req:16 flags:0x1 >> vhost_user_write req:3 flags:0x1 >> vhost_user_write req:1 flags:0x1 >> vhost_user_read_start >> vhost_user_read req:1 flags:0x5 >> vhost_user_write req:13 flags:0x1 >>=20 >> kernel initialises device >>=20 >> virtio_rpmb virtio1: init done! >> vhost_user_write req:13 flags:0x1 >> vhost_dev_set_features: 130000000 >> vhost_user_set_features: 130000000 SET_FEATURES >> vhost_user_write req:2 flags:0x1 >> vhost_user_write req:5 flags:0x9 >> vhost_user_read_start >>=20 >>=20 >> - Should QEMU have preserved VhostUserVirtioFeatures::PROTOCOL_FEATURES >> when doing the eventual VHOST_USER_SET_FEATURES reply? >>=20 >> - Is vhost.rs being to strict or libvhost-user too lax in interpreting >> the negotiated features before processing the ``need_reply`` [Bit 3] >> field of the messages? > > I think vhost.rs is being correctly strict - but there would be no harm > in it flagging that you'd hit an inconsistency if it finds a need_reply > without the feature. But the feature should have been negotiated. So unless the slave can assume it is enabled because it asked I think QEMU is in the wrong by not preserving the feature bits in it's SET_FEATURES reply. We just gets away with it with libvhostuser being willing to reply anyway. > >> - are VHOST_USER_SET_MEM_TABLE to VHOST_USER_SET_INFLIGHT_FD included >> in the "list of the ones that do" require replies or do they only >> reply when REPLY_ACK has been negotiated as the ambiguous "seealso::" >> box out seems to imply? > > set_mem_table gives a reply when postcopy is enabled (and then qemu > replies to the reply!) but otherwise doesn't. > (Note there's an issue opened for .rs to support ADD_MEM_REGION > since it's a lot better than SET_MEM_TABLE which has a fixed size table > that's small). Thanks for the heads up. > > Dave > >> Currently I have some hacks in: >>=20 >> https://github.com/stsquad/vhost/tree/my-hacks >>=20 >> which gets my daemon booting up to the point we actually need to do a >> transaction. However I won't submit a PR until I've worked out exactly >> where the problems are. >>=20 >> --=20 >> Alex Benn=C3=A9e >>=20 --=20 Alex Benn=C3=A9e