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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 94A54C433E0 for ; Mon, 29 Jun 2020 15:43:47 +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 6098025474 for ; Mon, 29 Jun 2020 15:43:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LOE+JtWk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6098025474 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]:57332 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jpvwg-0005q3-NE for qemu-devel@archiver.kernel.org; Mon, 29 Jun 2020 11:43:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37192) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jpvss-0001s3-Tt for qemu-devel@nongnu.org; Mon, 29 Jun 2020 11:39:50 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:32051 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 1jpvsr-0004H8-5a for qemu-devel@nongnu.org; Mon, 29 Jun 2020 11:39:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593445188; 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=1s/ZBhKXJh67z7lchcB4ai9mNvXXYMeQ9p8+kLlmwng=; b=LOE+JtWksFsk9v3Lt7xVapKvMHGl2YPhYXOWyXmyoxEOi+rx2r7nkOox9odfwAfm7jJdQ+ pVd6yBKMJdh/fTAu++ixlmkiBntzJ/7NUT+TbvNdBX9gBG53H7CIexQhWeaPrRo3RZfm2E JAhDSy5l+omAmzWq7lBF91WcHyEjzCc= 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-286-MhVxIeLNOWyBwGuZyOFbQQ-1; Mon, 29 Jun 2020 11:39:46 -0400 X-MC-Unique: MhVxIeLNOWyBwGuZyOFbQQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 86BB510059D0 for ; Mon, 29 Jun 2020 15:39:45 +0000 (UTC) Received: from gondolin (ovpn-113-61.ams2.redhat.com [10.36.113.61]) by smtp.corp.redhat.com (Postfix) with ESMTP id A34CD5D9E7; Mon, 29 Jun 2020 15:39:35 +0000 (UTC) Date: Mon, 29 Jun 2020 17:39:33 +0200 From: Cornelia Huck To: "Michael S. Tsirkin" Subject: Re: [PATCH RFC] virtio-fs: force virtio 1.x usage Message-ID: <20200629173933.35cea40f.cohuck@redhat.com> In-Reply-To: <20200629104948-mutt-send-email-mst@kernel.org> References: <20200629102758.421552-1-cohuck@redhat.com> <20200629104948-mutt-send-email-mst@kernel.org> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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 = 2020/06/29 01:10:03 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=_AUTOLEARN 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: "Dr. David Alan Gilbert" , Stefan Hajnoczi , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 29 Jun 2020 10:53:23 -0400 "Michael S. Tsirkin" wrote: > On Mon, Jun 29, 2020 at 12:27:58PM +0200, Cornelia Huck wrote: > > virtio-fs devices are only specified for virtio-1, so it is unclear > > how a legacy or transitional device should behave. > > > > Signed-off-by: Cornelia Huck > > --- > > > > Forcing off legacy now (after the virtio-fs device has already been > > available) may have unintended consequences, therefore RFC. > > > > By default, a virtio-pci device uses 'AUTO' for disable_legacy, which > > will resolve to different values based upon which bus the device has > > been plugged. Therefore, forcing disable_legacy may result in the same > > device or a quite different one. > > > > Even though pre-virtio-1 behaviour of virtio-fs devices is simply not > > specified, toggling disable_legacy will have implications for the BAR > > layout, IIRC, and therefore a guest might end up getting a different > > device, even if it always used it with virtio-1 anyway. > > > > Not sure what the best way to solve this problem is. Adding a compat > > property for disable_legacy=AUTO may be the right thing to do, but I'm > > not quite clear if there are any further implications here. > > Well I notice that this device is not migrateable. > So I think that we can just switch it over and be done with it. Oh, that makes things easier. (I'm wondering if libvirt already configures this correctly?) > > > > Whatever we do here, we should make sure that the ccw incarnation of > > this device indeed forces virtio-1. > > I agree. I notice that the API virtio_pci_force_virtio_1 turned out > to be too fragile. I propose that instead we have a whitelist of > devices which can be legacy or transitional. Force rest to modern. Also, there are further complications because the mechanism is per transport, and therefore easy to miss. bool virtio_legacy_allowed(VirtIODevice *vdev) { switch (vdev->device_id) { case <...>: return true; default: return false; } Seems straightforward enough. > > > > --- > > hw/virtio/vhost-user-fs-pci.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/virtio/vhost-user-fs-pci.c b/hw/virtio/vhost-user-fs-pci.c > > index e11c889d82b3..244205edf765 100644 > > --- a/hw/virtio/vhost-user-fs-pci.c > > +++ b/hw/virtio/vhost-user-fs-pci.c > > @@ -44,6 +44,7 @@ static void vhost_user_fs_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) > > vpci_dev->nvectors = dev->vdev.conf.num_request_queues + 2; > > } > > > > + virtio_pci_force_virtio_1(vpci_dev); > > qdev_realize(vdev, BUS(&vpci_dev->bus), errp); > > } > > > > -- > > 2.25.4 >