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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 23D2EC48BCD for ; Tue, 8 Jun 2021 14:24:29 +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 BA45461360 for ; Tue, 8 Jun 2021 14:24:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA45461360 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51182 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lqceZ-0001kW-H3 for qemu-devel@archiver.kernel.org; Tue, 08 Jun 2021 10:24:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57224) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lqcdq-0000Ri-1r for qemu-devel@nongnu.org; Tue, 08 Jun 2021 10:23:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36971) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lqcdm-0001sR-Ja for qemu-devel@nongnu.org; Tue, 08 Jun 2021 10:23:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623162217; 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=vS4C9I+815v3Nlwhu9/4hRyU+7WEptJxpvYJTy++NHE=; b=fbot8G2Gci2hb37oQk3yhh7G1bvMOxswNFOuW0ah8V/kN6YNlNpNn5L+u348B3LU1+j7Zy LmsqgQmlKVIO4KWLVN4KIcPhU1Sg56Lthxi2ZHQ7YiU0QvPeRkEnaOitXkXAGoh+a+4M4q Tb7S8MLrIVN355uzIQdvNlz/lnwH/wc= 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-541-Dbe23FSbNa6v2AXJx6xTug-1; Tue, 08 Jun 2021 10:23:34 -0400 X-MC-Unique: Dbe23FSbNa6v2AXJx6xTug-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D52181883526; Tue, 8 Jun 2021 14:23:32 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-222.ams2.redhat.com [10.36.112.222]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3627B10016FB; Tue, 8 Jun 2021 14:23:25 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 949FB113865F; Tue, 8 Jun 2021 16:23:23 +0200 (CEST) From: Markus Armbruster To: Eugenio Perez Martin Subject: Re: [RFC v3 04/29] vhost: Add x-vhost-enable-shadow-vq qmp References: <20210519162903.1172366-1-eperezma@redhat.com> <20210519162903.1172366-5-eperezma@redhat.com> <87y2c8pnx0.fsf@dusky.pond.sub.org> Date: Tue, 08 Jun 2021 16:23:23 +0200 In-Reply-To: (Eugenio Perez Martin's message of "Mon, 24 May 2021 09:13:39 +0200") Message-ID: <87k0n4xwo4.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.197, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: Parav Pandit , "Michael S. Tsirkin" , Jason Wang , Juan Quintela , qemu-level , virtualization@lists.linux-foundation.org, Harpreet Singh Anand , Xiao W Wang , Stefan Hajnoczi , Eli Cohen , Michael Lilja , Stefano Garzarella Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Eugenio Perez Martin writes: > On Fri, May 21, 2021 at 9:05 AM Markus Armbruster wro= te: >> >> Eugenio P=C3=A9rez writes: >> >> > Command to enable shadow virtqueue looks like: >> > >> > { "execute": "x-vhost-enable-shadow-vq", >> > "arguments": { "name": "dev0", "enable": true } } >> > >> > Signed-off-by: Eugenio P=C3=A9rez >> > --- >> > qapi/net.json | 22 ++++++++++++++++++++++ >> > hw/virtio/vhost.c | 6 ++++++ >> > 2 files changed, 28 insertions(+) >> > >> > diff --git a/qapi/net.json b/qapi/net.json >> > index c31748c87f..660feafdd2 100644 >> > --- a/qapi/net.json >> > +++ b/qapi/net.json >> > @@ -77,6 +77,28 @@ >> > ## >> > { 'command': 'netdev_del', 'data': {'id': 'str'} } >> > >> > +## >> > +# @x-vhost-enable-shadow-vq: >> > +# >> > +# Use vhost shadow virtqueue. >> > +# >> > +# @name: the device name of the VirtIO device >> > +# >> > +# @enable: true to use he alternate shadow VQ notification path [...] >> > +# >> > +# Returns: Error if failure, or 'no error' for success. Not found if = vhost is not enabled. >> >> This is confusing. What do you mean by "Not found"? >> >> If you mean DeviceNotFound: >> >> 1. Not actually true: qmp_x_vhost_enable_shadow_vq() always fails with >> GenericError. Perhaps later patches will change that. [...] >> 2. Do you really need to distinguish "vhost is not enabled" from other >> errors? >> > > SVQ cannot work if the device backend is not vhost, like qemu VirtIO > dev. What I meant is that "qemu will only look for its name in the set > of vhost devices, so you will have a device not found if the device is > not a vhost one", which may not be 100% clear at first glance. Maybe > this wording is better? We might be talking past each other. Let me try again :) The following question is *not* about the doc comment, it's about the *code*: what practical problem is solved by using DeviceNotFound instead of GenericError for some errors? [...]