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=-6.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 ED222C433E1 for ; Thu, 13 Aug 2020 10:41:28 +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 B926220771 for ; Thu, 13 Aug 2020 10:41:28 +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="E/QQHCDX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B926220771 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]:36532 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k6Afn-0005qu-Vd for qemu-devel@archiver.kernel.org; Thu, 13 Aug 2020 06:41:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51016) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k6AcG-0000f6-5v for qemu-devel@nongnu.org; Thu, 13 Aug 2020 06:37:48 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:53844 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 1k6AcD-0007RV-Bh for qemu-devel@nongnu.org; Thu, 13 Aug 2020 06:37:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597315064; 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=r5jhfmE78Ank/M8YTF7hOoOkIT3ARZ6eZkmx0dqwLpY=; b=E/QQHCDXqYddVRFrzvLjvQKrcP4c8Q9pFYYBPBAv2/E3aAk1gvkx1/Y08i3bz4+zEf86qP BKt5OVMi3aeDq9a0OKK/o6wOO3B1njpSGza2ThREndxA+FDGeojt1hocfP7yVF0wKuFX2q b62ytB4fPVw7LreWtcfEEL8KqQh6K/4= 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-570-9K5J73HaP2CUSh8JV8A2jg-1; Thu, 13 Aug 2020 06:37:42 -0400 X-MC-Unique: 9K5J73HaP2CUSh8JV8A2jg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 16204800465; Thu, 13 Aug 2020 10:37:41 +0000 (UTC) Received: from gondolin (ovpn-112-216.ams2.redhat.com [10.36.112.216]) by smtp.corp.redhat.com (Postfix) with ESMTP id AC8E754596; Thu, 13 Aug 2020 10:37:39 +0000 (UTC) Date: Thu, 13 Aug 2020 12:37:37 +0200 From: Cornelia Huck To: Stefano Garzarella Subject: Re: virtio-vsock requires 'disable-legacy=on' in QEMU 5.1 Message-ID: <20200813123737.25ba11d2.cohuck@redhat.com> In-Reply-To: <20200813102430.vjnc56anqjaxn4tw@steredhat.lan> References: <20200813112820.62ffd63e.cohuck@redhat.com> <20200813102430.vjnc56anqjaxn4tw@steredhat.lan> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com 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=205.139.110.120; envelope-from=cohuck@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/13 03:44:21 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 , Qinghua Cheng , qemu devel list , Stefan Hajnoczi , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 13 Aug 2020 12:24:30 +0200 Stefano Garzarella wrote: > On Thu, Aug 13, 2020 at 11:28:20AM +0200, Cornelia Huck wrote: > > On Thu, 13 Aug 2020 11:16:56 +0200 > > Stefano Garzarella wrote: > > > > > Hi, > > > > > > Qinghua discovered that virtio-vsock-pci requires 'disable-legacy=on' in > > > QEMU 5.1: > > > $ ./qemu-system-x86_64 ... -device vhost-vsock-pci,guest-cid=5 > > > qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=5: > > > device is modern-only, use disable-legacy=on > > > > > > Bisecting I found that this behaviour starts from this commit: > > > 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > > > > Oh, I had heard that from others already, was still trying to figure > > out what to do. > > > > > > > > IIUC virtio-vsock is modern-only, so I tried this patch and it works: > > > > > > diff --git a/hw/virtio/vhost-user-vsock-pci.c b/hw/virtio/vhost-user-vsock-pci.c > > > index f4cf95873d..6e4cc874cd 100644 > > > --- a/hw/virtio/vhost-user-vsock-pci.c > > > +++ b/hw/virtio/vhost-user-vsock-pci.c > > > @@ -40,6 +40,7 @@ static void vhost_user_vsock_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) > > > VHostUserVSockPCI *dev = VHOST_USER_VSOCK_PCI(vpci_dev); > > > DeviceState *vdev = DEVICE(&dev->vdev); > > > > > > + virtio_pci_force_virtio_1(vpci_dev); > > > qdev_realize(vdev, BUS(&vpci_dev->bus), errp); > > > } > > > > > > diff --git a/hw/virtio/vhost-vsock-pci.c b/hw/virtio/vhost-vsock-pci.c > > > index a815278e69..f641b974e9 100644 > > > --- a/hw/virtio/vhost-vsock-pci.c > > > +++ b/hw/virtio/vhost-vsock-pci.c > > > @@ -44,6 +44,7 @@ static void vhost_vsock_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) > > > VHostVSockPCI *dev = VHOST_VSOCK_PCI(vpci_dev); > > > DeviceState *vdev = DEVICE(&dev->vdev); > > > > > > + virtio_pci_force_virtio_1(vpci_dev); > > > qdev_realize(vdev, BUS(&vpci_dev->bus), errp); > > > } > > > > > > > > > Do you think this is the right approach or is there a better way to > > > solve this issue? > > > > We basically have three possible ways to deal with this: > > > > - Force it to modern (i.e., what you have been doing; would need the > > equivalent changes in ccw as well.) > > Oo, thanks for pointing out ccw! > I don't know ccw well, in this case should we set dev->max_rev to 1 or 2 > to force to modern? No, ->max_rev is the wrong side of the limit :) You want ccw_dev->force_revision_1 = true; in _instance_init() (see e.g. virtio-ccw-gpu.c). > > > Pro: looks like the cleanest approach. > > Con: not sure if we would need backwards compatibility support, > > which looks hairy. > > Not sure too. Yes, I'm not sure at all how to handle user-specified values for legacy/modern. > > > - Add vsock to the list of devices with legacy support. > > Pro: Existing setups continue to work. > > Con: If vsock is really virtio-1-only, we still carry around > > possibly broken legacy support. > > I'm not sure it is virtio-1-only, but virtio-vsock was introduced in > 2016, so I supposed it is modern-only. Yes, I would guess so as well. > > How can I verify that? Maybe forcing legacy mode and run some tests. Probably yes. The likeliest area with issues is probably endianness, so maybe with something big endian in the mix? > > > - Do nothing, have users force legacy off. Bad idea, as ccw has no way > > to do that on the command line. > > > > The first option is probably best. > > > > Yeah, I agree with you! Yes, it's really a pity we only noticed this after the release; this was supposed to stop new devices with legacy support creeping in, not to break existing command lines :(