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=-0.8 required=3.0 tests=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 B0434C433E0 for ; Thu, 2 Jul 2020 11:34:11 +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 7C0A620780 for ; Thu, 2 Jul 2020 11:34:11 +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="RpGLQw8b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C0A620780 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]:43500 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jqxTm-0008Aa-PM for qemu-devel@archiver.kernel.org; Thu, 02 Jul 2020 07:34:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56692) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jqxIv-0004hd-PS for qemu-devel@nongnu.org; Thu, 02 Jul 2020 07:22:57 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:28914 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 1jqxIu-0005uN-5a for qemu-devel@nongnu.org; Thu, 02 Jul 2020 07:22:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593688975; 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=glITbbIFjSdFWE2tOz0GOAbU9DGa51+5b4U4Sz1oLYs=; b=RpGLQw8bogbQ6pNU94BVNEojLX+KBTTfox09yzKFrCdVdkQ7PSvmag2rF1BNDvMbNwk1Ur s90nmpeYeh2RLXAECMvrXg4pAWLnt2SweSU6Iyagbn4QQWrJJ6Y96JSeKCPy9P7FRlC/jf TPgLX9h0WncD/40UtYDGs5smoCFtblc= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-358-yqSiduS8NeqFHUo32iiaUw-1; Thu, 02 Jul 2020 07:22:54 -0400 X-MC-Unique: yqSiduS8NeqFHUo32iiaUw-1 Received: by mail-wm1-f69.google.com with SMTP id t145so28402585wmt.2 for ; Thu, 02 Jul 2020 04:22:54 -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=glITbbIFjSdFWE2tOz0GOAbU9DGa51+5b4U4Sz1oLYs=; b=ZUfGYVdUuPknR0KxJmqO6bwUtvf8l2F0V5TejVbb0agwrtXt+7Nt7pvLgD/51Z91XH iJmr8NgkfzHD0VpuhFUOaURSfsYHr0LhSpgylCBOqxJ+HuMdFRlxRUvYUB8U9UPiiBDh XNam5PKeUTu+HF7Rd0HQRfvmNrUQmUrtHOAKBFbOD3pmPN4XloiOQM8NvW0qpR+MKkvg BjpHsrcaiNWtpUlNoVRCPogPJL1dpYtL8fupdS1A+geRiyPmwEbVXpFloui/WOzITF0A ru4yHWNwM6EOb9UOq9koZrYq23M1/d49Ldr+y/ocqG/g16T8I1ZjWg0NtGuYvPqk+5QW EfhQ== X-Gm-Message-State: AOAM530KNMgUuQk1MJxlDYKZ6SDbH4/PNDPu6WzMithRszrRCM1jDnmD 2tyszcMhnSjcAh3zro8bUnt/9drIYKsq8QaMz8v4KGIi+u+UQ37CiQeO2L6ZHqlUgfQDUQF4XUp IA+LGM40vpP5QJ8k= X-Received: by 2002:a1c:8117:: with SMTP id c23mr29847574wmd.157.1593688972616; Thu, 02 Jul 2020 04:22:52 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxR7crz0nacv/vetwmKuOz8yhCMz690BDWcM7vk2nDXWJ0Czg75XQu/Z5oYC2yPGFMrATB93Q== X-Received: by 2002:a1c:8117:: with SMTP id c23mr29847551wmd.157.1593688972397; Thu, 02 Jul 2020 04:22:52 -0700 (PDT) Received: from redhat.com ([93.157.82.4]) by smtp.gmail.com with ESMTPSA id h84sm11037451wme.22.2020.07.02.04.22.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Jul 2020 04:22:51 -0700 (PDT) Date: Thu, 2 Jul 2020 07:22:49 -0400 From: "Michael S. Tsirkin" To: Cornelia Huck Subject: Re: [PATCH RFC] virtio-fs: force virtio 1.x usage Message-ID: <20200702071627-mutt-send-email-mst@kernel.org> References: <20200629102758.421552-1-cohuck@redhat.com> <20200630121037.GC91444@stefanha-x1.localdomain> <20200630142504.688aa989.cohuck@redhat.com> <20200630090327-mutt-send-email-mst@kernel.org> <20200701181917.62538421.cohuck@redhat.com> <20200702060555-mutt-send-email-mst@kernel.org> <20200702124538.0ba5d334.cohuck@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200702124538.0ba5d334.cohuck@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@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=205.139.110.61; envelope-from=mst@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/02 03:42:59 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: 2 X-Spam_score: 0.2 X-Spam_bar: / X-Spam_report: (0.2 / 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, RCVD_IN_SBL_CSS=3.335, 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 Thu, Jul 02, 2020 at 12:45:38PM +0200, Cornelia Huck wrote: > On Thu, 2 Jul 2020 06:16:06 -0400 > "Michael S. Tsirkin" wrote: > > > On Wed, Jul 01, 2020 at 06:19:17PM +0200, Cornelia Huck wrote: > > > On Tue, 30 Jun 2020 09:04:38 -0400 > > > "Michael S. Tsirkin" wrote: > > > > > > > On Tue, Jun 30, 2020 at 02:25:04PM +0200, Cornelia Huck wrote: > > > > > > > > What bothers me most is that you need to explicitly request a device to > > > > > be modern-only, while that should be the default for any newly added > > > > > device. Hence the approach with the centralized list of device types > > > > > mentioned in a parallel thread. The main problem with that is that the > > > > > proxy device starts getting realized before the virtio device with its > > > > > id is present... I failed to find a solution so far. But I'd really > > > > > like an approach that can work for all transports. > > > > > > > > So how about simply validating that the device is modern only, > > > > unless it's one of the whitelist? > > > > > > Who would do the validation, the virtio core? How can it distinguish > > > between transitional and non-transitional? But maybe I'm just not > > > getting your idea. > > > > OK I've been thinking about two ideas, we can use them both: > > 1. virtio core: that can detect VIRTIO_1 being clear > > in virtio_validate_features. > > After feature negotiation is complete? That feels like a regression in > behaviour: You would be able to add a device that may not be usable > (and you'll only find out after the guest tried to use it), instead of > making sure that only a non-transitional device can be added to start > with. I mean, we can still have transports validate, that is point 2. It seems prudent to check though, since guest could be buggy ignoring bits that it got. > (We do not validate if the guest did not negotiate VERSION_1, but we > can certainly add a special case for the "guest did not accept offered > VERSION_1" case.) exaclty. > > > 2. transports: could use a core API to detect whether > > device can be a legacy one, to block device creation. > > That would be the best, but how do we get around the "transport does > not know the device type until it is too late" problem? Unless you want > to redo the internal interfaces. Oh. I think I am missing something. So I'm considering virtio_pci_device_plugged for example. static void virtio_pci_device_plugged(DeviceState *d, Error **errp) { VirtIOPCIProxy *proxy = VIRTIO_PCI(d); VirtioBusState *bus = &proxy->bus; bool legacy = virtio_pci_legacy(proxy); bool modern; bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY; uint8_t *config; uint32_t size; VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); /* .. } can't we check device type here and make sure it matches the "legacy" flag? > > > > > > > Also, ccw does not currently have a way to explicitly configure a > > > device non-transitional; the revisions can be used to fence off newer > > > features, going down to legacy-only, but fencing off older features is > > > not possible (that is only done by the device, if it has no legacy > > > support). > > > > I guess for ccw only option 1 works. > > > > Or keep it as-is, and disallow legacy for the individual device types, > with the validate check as a safety net during development. Problem is people cut and paste from transitional devices. -- MST