From nobody Mon Feb 9 14:33:33 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1562087109; cv=none; d=zoho.com; s=zohoarc; b=h6O1ZHznEJoAVHkKenjx+MvHmleXhiuOhyPBcyP13GrkpAGBJB7DoMIoYOy7ZFGH9T+MNoLpdZTh4TC+bZltlim75H8vIP3OZxolM+7OK4ptpgCBf65jNLMUqh3fn7f+E6oteN8JUkXvwreYwZNIwuWbK8j9TjlJe4j0xlXhgMA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1562087109; h=Content-Type:Content-Transfer-Encoding:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=7SrTmbQQbldnJsvdMavIoujAtnvbzg/FaqjKfAMhy8g=; b=gX2DbgWk7G5FQ65M+5BZ7iSuX5gjuG6LmzAK/zgIKhUuWMQ9AHEOQpetgDtyI8s9VTbWn2NEk0Kn80sN6Pdpe8/MDz3aj9xzpMBxu7B4MQbMxKQqsy79FaPFiLgNBEQstarnuGiDN6qs0XCEWrDm1yyfbUyfVqQGXPhJMqKYDrU= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1562087109245332.88037315651206; Tue, 2 Jul 2019 10:05:09 -0700 (PDT) Received: from localhost ([::1]:55362 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hiMDJ-0005AL-Af for importer@patchew.org; Tue, 02 Jul 2019 13:05:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38156) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hiKqa-0000xe-Rv for qemu-devel@nongnu.org; Tue, 02 Jul 2019 11:37:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hiKqY-00072v-LJ for qemu-devel@nongnu.org; Tue, 02 Jul 2019 11:37:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41604) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hiKqY-00070r-EU for qemu-devel@nongnu.org; Tue, 02 Jul 2019 11:37:30 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BF99546202; Tue, 2 Jul 2019 15:37:28 +0000 (UTC) Received: from localhost (ovpn-116-30.gru2.redhat.com [10.97.116.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4D3426F94E; Tue, 2 Jul 2019 15:37:28 +0000 (UTC) From: Eduardo Habkost To: Peter Maydell , Paolo Bonzini , qemu-devel@nongnu.org, Marcel Apfelbaum , Richard Henderson Date: Tue, 2 Jul 2019 12:35:32 -0300 Message-Id: <20190702153535.9851-40-ehabkost@redhat.com> In-Reply-To: <20190702153535.9851-1-ehabkost@redhat.com> References: <20190702153535.9851-1-ehabkost@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 02 Jul 2019 15:37:28 +0000 (UTC) Content-Transfer-Encoding: quoted-printable 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 v3 39/42] 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" 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. Berrang=C3=A9 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. --=20 2.18.0.rc1.1.g3f1ff2140