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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6FFCC433F5 for ; Wed, 29 Sep 2021 10:36:19 +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 5420D61216 for ; Wed, 29 Sep 2021 10:36:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5420D61216 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:44346 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mVWwk-00086X-AI for qemu-devel@archiver.kernel.org; Wed, 29 Sep 2021 06:36:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57718) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mVWur-0006er-3q for qemu-devel@nongnu.org; Wed, 29 Sep 2021 06:34:25 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35452) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mVWul-0001ac-V7 for qemu-devel@nongnu.org; Wed, 29 Sep 2021 06:34:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632911649; 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=fHOIyeBbH1xixn67eSlSTKqD1GfMw31WUgMFt8N/Ns4=; b=EOHDGvRq25PQX4SFVNpxcp8DcGRiSsJPTiyXpVaD9KP1u3xPwC50a4Fh/1hn/DONM5MS2z 7eKf3iQ1OYMLyIxbRUER+bY7Oq43o39gBs5GlebcN2GzBam9qvplss+o5QwC9yC+84jZ9k dIL62hJub6F7GKWXOVyGpdQpnyi3c5g= 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-326-M8wARw_YOBGvnlFyWbuJjw-1; Wed, 29 Sep 2021 06:34:07 -0400 X-MC-Unique: M8wARw_YOBGvnlFyWbuJjw-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 7CDED1926DA0 for ; Wed, 29 Sep 2021 10:34:06 +0000 (UTC) Received: from localhost (unknown [10.39.194.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id D399460936; Wed, 29 Sep 2021 10:34:01 +0000 (UTC) Date: Wed, 29 Sep 2021 11:34:01 +0100 From: "Richard W.M. Jones" To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PATCH 0/1] vmx: Fix mapping Message-ID: <20210929103400.GJ3361@redhat.com> References: <20210929092044.GE3361@redhat.com> <20210929095719.GH3361@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=rjones@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=rjones@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, 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: libvir-list@redhat.com, Michal Privoznik , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Sep 29, 2021 at 11:10:35AM +0100, Daniel P. Berrangé wrote: > On Wed, Sep 29, 2021 at 10:57:19AM +0100, Richard W.M. Jones wrote: > > Looking at the qemu code the problem IMHO is: > > > > https://gitlab.com/qemu-project/qemu/-/blob/6b54a31bf7b403672a798b6443b1930ae6c74dea/docs/specs/vmgenid.txt#L189 > > https://gitlab.com/qemu-project/qemu/-/blob/6b54a31bf7b403672a798b6443b1930ae6c74dea/hw/acpi/vmgenid.c#L37 > > > > This byte swapping makes no sense to me. How do we know that the > > guest is little endian? What will this code do for BE guests? I > > think qemu would be better off treating the "GUID" as a list of bytes > > and writing that exactly into the guest memory. > > This is an artifact of the HyperV only caring about x86 and thus leaving > endianness unspecified in the spec for GenID. QEMU docs say > > > Endian-ness Considerations: > --------------------------- > > Although not specified in Microsoft's document, it is assumed that the > device is expected to use little-endian format. > > All GUID passed in via command line or monitor are treated as big-endian. > GUID values displayed via monitor are shown in big-endian format. > > > So by extension if libvirt is passing the value from its XML straight > to QEMU, then libvirt has effectively defined that the XML is storing > it big-endian too. > > This could be where the confusion with VMX config is coming into play, > though the byte re-ordering in v2v seems more complex than just an > endianess-fiddle ? qemu's qemu_uuid_bswap function only swaps some of the fields. I think even more that applying qemu_uuid_bswap to these (not really) "UUIDs" is a nonsense. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v