From patchwork Fri Jun 28 00:28:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eduardo Habkost X-Patchwork-Id: 1123773 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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 ozlabs.org (Postfix) with ESMTPS id 45Zd9f5L1Gz9s7h for ; Fri, 28 Jun 2019 10:36:20 +1000 (AEST) Received: from localhost ([::1]:55430 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgesC-0006xD-9H for incoming@patchwork.ozlabs.org; Thu, 27 Jun 2019 20:36:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36334) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgelK-0000Y3-PY for qemu-devel@nongnu.org; Thu, 27 Jun 2019 20:29:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hgelJ-0006w7-RQ for qemu-devel@nongnu.org; Thu, 27 Jun 2019 20:29:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39716) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hgelJ-0006vL-J4 for qemu-devel@nongnu.org; Thu, 27 Jun 2019 20:29:09 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E3AC631628FF for ; Fri, 28 Jun 2019 00:29:08 +0000 (UTC) Received: from localhost (ovpn-116-7.gru2.redhat.com [10.97.116.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3448360BE0; Fri, 28 Jun 2019 00:29:05 +0000 (UTC) From: Eduardo Habkost To: qemu-devel@nongnu.org Date: Thu, 27 Jun 2019 21:28:43 -0300 Message-Id: <20190628002844.24894-9-ehabkost@redhat.com> In-Reply-To: <20190628002844.24894-1-ehabkost@redhat.com> References: <20190628002844.24894-1-ehabkost@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Fri, 28 Jun 2019 00:29:08 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 8/9] docs: Deprecate CPU model runnability guarantees 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, Igor Mammedov , Jiri Denemark , "Daniel P. Berrange" , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Document that CPU model runnability guarantees won't apply to unversioned CPU models anymore. Signed-off-by: Eduardo Habkost Reviewed-by: Daniel P. Berrangé --- Changes v1 -> v2: * (none) Cc: libvir-list@redhat.com --- qemu-deprecated.texi | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi index 9cba82d5ec..18f85f70e1 100644 --- a/qemu-deprecated.texi +++ b/qemu-deprecated.texi @@ -276,3 +276,22 @@ Note that if you are exposing the export via /dev/nbd0, it is easier to just export the entire image and then mount only /dev/nbd0p1 than it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a subset of the image. + +@section Backwards compatibility + +@subsection Runnability guarantee of CPU models (since 4.1.0) + +Previous versions of QEMU never changed existing CPU models in +ways that introduced additional host software or hardware +requirements to the VM. This allowed management software to +safely change the machine type of an existing VM without +introducing new requirements ("runnability guarantee"). This +prevented CPU models from being updated to include CPU +vulnerability mitigations, leaving guests vulnerable in the +default configuration. + +The CPU model runnability guarantee won't apply anymore to +existing CPU models. Management software that needs runnability +guarantees must resolve the CPU model aliases using te +``alias-of'' field returned by the ``query-cpu-definitions'' QMP +command.