From patchwork Wed Jul 3 21:08:17 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eduardo Habkost X-Patchwork-Id: 11030521 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C83DE13A4 for ; Wed, 3 Jul 2019 21:50:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BA88B28662 for ; Wed, 3 Jul 2019 21:50:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AEA8E28A13; Wed, 3 Jul 2019 21:50:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5DBD628662 for ; Wed, 3 Jul 2019 21:50:16 +0000 (UTC) Received: from localhost ([::1]:40988 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hin8p-0007zO-OT for patchwork-qemu-devel@patchwork.kernel.org; Wed, 03 Jul 2019 17:50:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38503) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1himW6-0006az-GG for qemu-devel@nongnu.org; Wed, 03 Jul 2019 17:10:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1himW4-0007V4-Ak for qemu-devel@nongnu.org; Wed, 03 Jul 2019 17:10:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42655) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1himW4-0007LD-4Q for qemu-devel@nongnu.org; Wed, 03 Jul 2019 17:10:12 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 53A675945D; Wed, 3 Jul 2019 21:10:01 +0000 (UTC) Received: from localhost (ovpn-116-30.gru2.redhat.com [10.97.116.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id CF3AE891A4; Wed, 3 Jul 2019 21:10:00 +0000 (UTC) From: Eduardo Habkost To: Peter Maydell , Paolo Bonzini , qemu-devel@nongnu.org, Marcel Apfelbaum , Richard Henderson Date: Wed, 3 Jul 2019 18:08:17 -0300 Message-Id: <20190703210821.27550-40-ehabkost@redhat.com> In-Reply-To: <20190703210821.27550-1-ehabkost@redhat.com> References: <20190703210821.27550-1-ehabkost@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 03 Jul 2019 21:10:01 +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] [PULL v5 39/43] 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: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Document that CPU model runnability guarantees won't apply to unversioned CPU models anymore. Signed-off-by: Eduardo Habkost Message-Id: <20190628002844.24894-9-ehabkost@redhat.com> Reviewed-by: Daniel P. Berrangé Signed-off-by: Eduardo Habkost --- 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.