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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 A87AAC433E1 for ; Thu, 23 Jul 2020 12:16:10 +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 7352620825 for ; Thu, 23 Jul 2020 12:16:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="SgKAR26p" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7352620825 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]:47546 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jya8v-0001xf-Oi for qemu-devel@archiver.kernel.org; Thu, 23 Jul 2020 08:16:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57802) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jya8D-0001Sa-VP for qemu-devel@nongnu.org; Thu, 23 Jul 2020 08:15:25 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:31638 helo=us-smtp-delivery-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 1jya8B-0001Ym-QV for qemu-devel@nongnu.org; Thu, 23 Jul 2020 08:15:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595506523; 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=+Js0LG+sFT/+31vmiu9Cc8YckwK1kNNamB61ypEfRDs=; b=SgKAR26pn3GacwQcm8BgxA6nP/20wHRy+xMwr+f7iXhvZfKe3RPbSmLmMfx68S3psOLZ5T joCu1+AVMji7Ooe+fPF/2NvS/PD3xQb/27BwQmuzJklpFj15TdLkqkQDBnVatNNo6pwOFc 5EDO0q2L/sULg+zcpq9S0qnEn6pNZ/Y= 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-355-d3Yeo_eZMdynAmP-dKMKug-1; Thu, 23 Jul 2020 08:15:20 -0400 X-MC-Unique: d3Yeo_eZMdynAmP-dKMKug-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9736DE919; Thu, 23 Jul 2020 12:15:19 +0000 (UTC) Received: from gondolin (ovpn-112-228.ams2.redhat.com [10.36.112.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 92E1378540; Thu, 23 Jul 2020 12:15:09 +0000 (UTC) Date: Thu, 23 Jul 2020 14:15:07 +0200 From: Cornelia Huck To: David Hildenbrand Subject: Re: [PATCH 0/2] virtio: non-legacy device handling Message-ID: <20200723141507.2e3004d8.cohuck@redhat.com> In-Reply-To: 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> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/23 02:26:42 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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: Halil Pasic , Eric Auger , qemu-s390x@nongnu.org, qemu-devel@nongnu.org, "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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...