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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 A6D91C433C1 for ; Mon, 29 Mar 2021 22:43:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DD046191F for ; Mon, 29 Mar 2021 22:43:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230500AbhC2WnV (ORCPT ); Mon, 29 Mar 2021 18:43:21 -0400 Received: from mga01.intel.com ([192.55.52.88]:45995 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230161AbhC2WnB (ORCPT ); Mon, 29 Mar 2021 18:43:01 -0400 IronPort-SDR: IrDIstuF2mvzeRV3NeguReGOO8PwuvjxQIv0fthU9O08kFh0QXiFN85del6LRrYW/NrQor1Jef ZMdA6EyCvdXg== X-IronPort-AV: E=McAfee;i="6000,8403,9938"; a="211842365" X-IronPort-AV: E=Sophos;i="5.81,289,1610438400"; d="scan'208";a="211842365" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2021 15:42:59 -0700 IronPort-SDR: rAzl/u12UhV5AsFp1B8Fst+yy4vupG/DRj2BhmvDTxDGCd/hloM55dj6uXNd6RBZnCkpyVAHuu U4we0eHzQB9g== X-IronPort-AV: E=Sophos;i="5.81,289,1610438400"; d="scan'208";a="444814260" Received: from ajzangar-mobl1.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.212.145.70]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Mar 2021 15:42:58 -0700 Subject: Re: [PATCH v2 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD To: Dave Hansen , Peter Zijlstra , Andy Lutomirski Cc: Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Dan Williams , Raj Ashok , Sean Christopherson , linux-kernel@vger.kernel.org References: <91C0F6F1-B8C3-4130-B903-C63CD4B87F3F@amacapital.net> <498f078c-5196-a608-7f1a-8425ff056135@intel.com> <8e02ce39-f672-e652-b314-418b7ec5f52a@linux.intel.com> <0356a84a-765e-b20b-2efd-c5d94fc2347e@intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: Date: Mon, 29 Mar 2021 15:42:55 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <0356a84a-765e-b20b-2efd-c5d94fc2347e@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/29/21 3:12 PM, Dave Hansen wrote: > On 3/29/21 3:09 PM, Kuppuswamy, Sathyanarayanan wrote: >>>>>> +    case EXIT_REASON_MWAIT_INSTRUCTION: >>>>>> +        /* MWAIT is supressed, not supposed to reach here. */ >>>>>> +        WARN(1, "MWAIT unexpected #VE Exception\n"); >>>>>> +        return -EFAULT; >>>>> >>>>> How is MWAIT "supppressed"? >>>> I am clearing the MWAIT feature flag in early init code. We should also >>>> disable this feature in firmware. >>>> setup_clear_cpu_cap(X86_FEATURE_MWAIT); >>> >>> I'd be more explicit about that.  Maybe even reference the code that >>> clears the X86_FEATURE. >> This change is part of the same patch. > > Right, but if someone goes and looks at the switch() statement in 10 > years is it going to be obvious how MWAIT was "suppressed"? Ok. I can add a comment line for it. > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer