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=-0.6 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 C859BC432C0 for ; Wed, 20 Nov 2019 18:44:14 +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 9A3E72071C for ; Wed, 20 Nov 2019 18:44:14 +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="IDHwkLSH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A3E72071C 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]:33458 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iXUxZ-00021p-LV for qemu-devel@archiver.kernel.org; Wed, 20 Nov 2019 13:44:13 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39559) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iXUwV-0001NK-C0 for qemu-devel@nongnu.org; Wed, 20 Nov 2019 13:43:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iXUwS-00059m-WD for qemu-devel@nongnu.org; Wed, 20 Nov 2019 13:43:05 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:28054 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iXUwS-00059Z-JS for qemu-devel@nongnu.org; Wed, 20 Nov 2019 13:43:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574275383; 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=798g9wLEGX/NCbaZwe+VMddNLoz0xnNYBxMUseP6R0c=; b=IDHwkLSHY53OU/dIg981jKDwkFIbpog/X/sk+X7+LEM4FFQ1TfuZ1WUM7UXtPFp5BOS8i/ ZDUIihvTcNdWsmv4QzHFcslGJqur0ZILWBL8VDI9cDt4D4GIFn1NGAAfUmeBgfW6Tl0EOU aOD+1qAuX2/Il+LROAKNSEOFv/GiaoE= 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-25-nNLTuyfzMBOBivDG8GUV-Q-1; Wed, 20 Nov 2019 13:43:02 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AC8E5107ACC9; Wed, 20 Nov 2019 18:43:00 +0000 (UTC) Received: from localhost (ovpn-116-6.gru2.redhat.com [10.97.116.6]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1E98F1042B7D; Wed, 20 Nov 2019 18:42:59 +0000 (UTC) Date: Wed, 20 Nov 2019 15:42:58 -0300 From: Eduardo Habkost To: Paolo Bonzini Subject: Re: [PATCH for-4.2 1/2] i386: Add new versions of Skylake/Cascadelake/Icelake without TSX Message-ID: <20191120184258.GS3812@habkost.net> References: <20191120164912.32384-1-ehabkost@redhat.com> <20191120164912.32384-2-ehabkost@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: nNLTuyfzMBOBivDG8GUV-Q-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: Jiri Denemark , Kashyap Chamarthy , qemu-devel@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Nov 20, 2019 at 06:40:06PM +0100, Paolo Bonzini wrote: > On 20/11/19 17:49, Eduardo Habkost wrote: > > One of the mitigation methods for TAA[1] is to disable TSX > > support on the host system. Linux added a mechanism to disable > > TSX globally through the kernel command line, and many Linux > > distributions now default to tsx=3Doff. This makes existing CPU > > models that have HLE and RTM enabled not usable anymore. > >=20 > > Add new versions of all CPU models that have the HLE and RTM > > features enabled, that can be used when TSX is disabled in the > > host system. >=20 > What is the effect of this when using "-cpu CascadeLake-Server" and > upgrading QEMU? Would it automatically switch to the new version? If > so, would it be better to include a duplicate of the models (and if so, > that would conflict with my VMX features patch, which is also for 4.2). It won't, because PCMachineClass::default_cpu_version=3D=3D1 for all versioned PC machine-types, currently. The plan is to set default_cpu_version=3DCPU_VERSION_LATEST on pc-*-5.0 (or, more likely, 5.1). But this will happen only after libvirt starts resolving CPU model versions. See the "Runnability guarantee of CPU models" section at qemu-deprecated.texi. --=20 Eduardo