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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EEACFC432C3 for ; Thu, 14 Nov 2019 00:55:25 +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 F38E4206E6 for ; Thu, 14 Nov 2019 00:55:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F38E4206E6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52564 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iV3Pv-0003ux-VX for qemu-devel@archiver.kernel.org; Wed, 13 Nov 2019 19:55:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50270) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iV3Lo-0002vn-55 for qemu-devel@nongnu.org; Wed, 13 Nov 2019 19:51:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iV3Lj-0001nj-IJ for qemu-devel@nongnu.org; Wed, 13 Nov 2019 19:51:05 -0500 Received: from mga14.intel.com ([192.55.52.115]:9940) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iV3Lj-0000bl-4v for qemu-devel@nongnu.org; Wed, 13 Nov 2019 19:51:03 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Nov 2019 16:50:50 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,302,1569308400"; d="scan'208";a="235481219" Received: from unknown (HELO [10.239.196.128]) ([10.239.196.128]) by fmsmga002.fm.intel.com with ESMTP; 13 Nov 2019 16:50:49 -0800 Subject: Re: About MONITOR/MWAIT in i386 CPU model To: Eduardo Habkost References: <20191113224717.GN3812@habkost.net> From: Tao Xu Message-ID: Date: Thu, 14 Nov 2019 08:50:49 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20191113224717.GN3812@habkost.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.115 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: "Lai, Paul C" , "qemu-devel@nongnu.org" , "Guo, Xuelian" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/14/2019 6:47 AM, Eduardo Habkost wrote: > On Wed, Nov 13, 2019 at 04:42:25PM +0800, Tao Xu wrote: >> Hi Eduardo， >> >> After kvm use "-overcommit cpu-pm=on" to expose MONITOR/MWAIT >> (commit id 6f131f13e68d648a8e4f083c667ab1acd88ce4cd), the MONITOR/MWAIT >> feature in CPU model (phenom core2duo coreduo n270 Opteron_G3 EPYC Snowridge >> Denverton) may be unused. For example, when we boot a guest with Denverton >> cpu model, guest cannot detect MONITOR and boot with no warning. Should we >> remove this feature from some CPU model? > > Good catch, thanks! > > Yes, we should remove them from Opteron_G3, EPYC, Snowridge, and > Denverton, at least. The other older CPU models can be left > alone: they are more useful for use with TCG than with KVM, and > TCG supports MONITOR/MWAIT. > > I would like to understand why this wasn't detected during > testing by Intel. I suggest always testing CPU models using the > "enforce" flag to make sure warnings don't go unnoticed. > OK we will improve the testing.