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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 01573C433DF for ; Thu, 23 Jul 2020 12:56:52 +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 BFE2F20768 for ; Thu, 23 Jul 2020 12:56:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Y4ApkufW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFE2F20768 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]:43396 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jyamJ-0003dA-2w for qemu-devel@archiver.kernel.org; Thu, 23 Jul 2020 08:56:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42188) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jyak4-0000CM-4i for qemu-devel@nongnu.org; Thu, 23 Jul 2020 08:54:32 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:31557 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jyak2-0007gG-7K for qemu-devel@nongnu.org; Thu, 23 Jul 2020 08:54:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595508869; 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: in-reply-to:in-reply-to:references:references; bh=gTJhLqXBmxj/4dVTaPvLm1Yk734MNLQxS+qR5/YkRHU=; b=Y4ApkufWDPvtlnjIq+feqg3dgUs1Ep3QRncA9drP89rFcdhwYXBEsrqlvGKvqABDIMBgl8 kmDXRaRbSK/LKpQ6QSjVMZRl/XC+HryfdN7oQlT+f1FaWSLUGzVTYPI2dDN/B6uw6xz7F+ QOBgNkiZSGaB47bQiUiETRlMCZeRgCM= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-154-lANMCmYYOaCdTRg2VHZ_mQ-1; Thu, 23 Jul 2020 08:54:26 -0400 X-MC-Unique: lANMCmYYOaCdTRg2VHZ_mQ-1 Received: by mail-wm1-f71.google.com with SMTP id u68so2330918wmu.3 for ; Thu, 23 Jul 2020 05:54:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=gTJhLqXBmxj/4dVTaPvLm1Yk734MNLQxS+qR5/YkRHU=; b=MNPtFqUCvUZ+fjm0dO7CnwXMQTobiS1jm8RGYVxLr6njuRneJDzG/SzpRnjSssUSZS Pl4mKzqXJe8QdzNb4I4JqiHKdCOBrR7oV87p4uKXgEQcY4kOOMNdWiKbJ9yBAZoCBXfw ORIwyLYjQg68Mfc419821dhpQm+o4Kwg1uZSUJz2UcPJYxAg86Mpqm+f8OGnxEu7gwg3 5ejCQZD3KGcHDiobEiCZNR650r9WVgLvUQALsSF7PDE0exJybwRIX8hT//W+sI8+hR78 ZUNyeLrY5drMHSnaxCrzOKL4qV5kC9oULpn5kUGmjGop4lOfMAZtqrmp6cjx0CGHVOG1 N+eQ== X-Gm-Message-State: AOAM530oYH9n3mRwgVY64I6WFHot05d1v5tSxMAPzFCTOWNcKt6nBxFr HVeonz7b6kr4Sg59bfAo/Qr/WDJj4bIsDJD2N2y2v5iJ9fkqchMOxZVi3bf5BjVvgsynfPxHvW1 T3mqfIwq4E7YC/VQ= X-Received: by 2002:adf:df89:: with SMTP id z9mr3899386wrl.395.1595508865391; Thu, 23 Jul 2020 05:54:25 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy1IqX8aJfbN1V82tdEO0faLQNAQT7ORMSqd6/ZyQJeTyv6yGBvpW/Ip+TD7txN/Dz4KKSw8w== X-Received: by 2002:adf:df89:: with SMTP id z9mr3899370wrl.395.1595508865181; Thu, 23 Jul 2020 05:54:25 -0700 (PDT) Received: from redhat.com (bzq-79-179-105-63.red.bezeqint.net. [79.179.105.63]) by smtp.gmail.com with ESMTPSA id z16sm3640366wrr.35.2020.07.23.05.54.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jul 2020 05:54:24 -0700 (PDT) Date: Thu, 23 Jul 2020 08:54:22 -0400 From: "Michael S. Tsirkin" To: Cornelia Huck Subject: Re: [PATCH 0/2] virtio: non-legacy device handling Message-ID: <20200723085313-mutt-send-email-mst@kernel.org> References: <20200707105446.677966-1-cohuck@redhat.com> <51e457ef-106e-1c1a-778d-4d53d9e48d8e@redhat.com> <20200720050215-mutt-send-email-mst@kernel.org> <4309b9dd-cc94-e183-60f8-67e4ec36c666@redhat.com> <20200723083313.49e3502a.cohuck@redhat.com> <20200723141507.2e3004d8.cohuck@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200723141507.2e3004d8.cohuck@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=mst@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/23 06:04:25 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Halil Pasic , Eric Auger , qemu-s390x@nongnu.org, qemu-devel@nongnu.org, David Hildenbrand Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jul 23, 2020 at 02:15:07PM +0200, Cornelia Huck wrote: > On Thu, 23 Jul 2020 13:57:08 +0200 > David Hildenbrand wrote: > > > On 23.07.20 08:33, Cornelia Huck wrote: > > > On Mon, 20 Jul 2020 11:07:51 +0200 > > > David Hildenbrand wrote: > > > > > >> On 20.07.20 11:03, Michael S. Tsirkin wrote: > > >>> On Mon, Jul 20, 2020 at 10:09:57AM +0200, David Hildenbrand wrote: > > >>>> On 07.07.20 12:54, Cornelia Huck wrote: > > >>>>> As discussed in "virtio-fs: force virtio 1.x usage", it seems like > > >>>>> a good idea to make sure that any new virtio device (which does not > > >>>>> support legacy virtio) is indeed a non-transitional device, just to > > >>>>> catch accidental misconfigurations. We can easily compile a list > > >>>>> of virtio devices with legacy support and have transports verify > > >>>>> in their plugged callbacks that legacy support is off for any device > > >>>>> not in that list. > > >>>>> > > >>>>> Most new virtio devices force non-transitional already, so nothing > > >>>>> changes for them. vhost-user-fs-pci even does not allow to configure > > >>>>> a non-transitional device, so it is fine as well. > > >>>>> > > >>>>> One problematic device, however, is virtio-iommu-pci. It currently > > >>>>> offers both the transitional and the non-transitional variety of the > > >>>>> device, and does not force anything. I'm unsure whether we should > > >>>>> consider transitional virtio-iommu unsupported, or if we should add > > >>>>> some compat handling. (The support for legacy or not generally may > > >>>>> change based upon the bus, IIUC, so I'm unsure how to come up with > > >>>>> something generic.) > > >>>>> > > >>>>> Cornelia Huck (2): > > >>>>> virtio: list legacy-capable devices > > >>>>> virtio: verify that legacy support is not accidentally on > > >>>> > > >>>> I'd squash both patches. Looking at patch #1, I wonder why we don't > > >>>> store that information along with the device implementation? What was > > >>>> the motivation to define this information separately? > > >>> > > >>> Because people seem to cut and paste code, so when one > > >>> enables it in an old device, it gets pasted into a new one. > > >>> With a list in a central place, it's easier to figure out > > >>> what's going on. > > >> > > >> Makes sense, I suggest adding that to the patch description. > > > > > > "The list of devices supporting legacy is supposed to be static. We > > > keep it in a central place to make sure that new devices do not enable > > > legacy by accident." > > > > > > ? > > > > Ack! > > > > > > > >> > > >> Both patches look sane to me (- squashing them). > > >> > > > > > > Patch 1 does not change behaviour, while patch 2 does (for > > > virtio-iommu-pci). Still would like an opinion whether changing the > > > behaviour for virtio-iommu-pci with no compat handling is ok. > > > > > > (I could be persuaded to squash them.) > > > > I'm a friend of introducing helper functions along with code that > > actually uses it. But I agree that the change in behavior might be > > hairy. Maybe we can split that out somehow to give it more attention? > > It should not really be noticeable for anything but virtio-iommu. > > However, I see these are already in a pull request... Yea, sorry about being hasty. -- MST