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 CAE1FC433ED for ; Thu, 1 Apr 2021 21:15:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95DE4610A0 for ; Thu, 1 Apr 2021 21:15:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234446AbhDAVP5 (ORCPT ); Thu, 1 Apr 2021 17:15:57 -0400 Received: from mga09.intel.com ([134.134.136.24]:10951 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234406AbhDAVPz (ORCPT ); Thu, 1 Apr 2021 17:15:55 -0400 IronPort-SDR: 9RNyp/CswwWPJnfFyhvYgU3NO+Gi4K4TRHipOhRXAS/qQOeV5W3kDGaIt3CxZBCr4xA0vO1ciE lwJuiMqxs9iw== X-IronPort-AV: E=McAfee;i="6000,8403,9941"; a="192436624" X-IronPort-AV: E=Sophos;i="5.81,296,1610438400"; d="scan'208";a="192436624" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2021 14:15:54 -0700 IronPort-SDR: PhA53mSmCRZ1TXk7sv3w0JZVBESPPWVEmpjzLamuolrdoeFG0mcDUbQHVpx7udqHSRXMwNgGxr UnKJlIWkQZhA== X-IronPort-AV: E=Sophos;i="5.81,296,1610438400"; d="scan'208";a="446443736" Received: from akleen-mobl1.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.251.23.191]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2021 14:15:53 -0700 Subject: Re: [RFC v1 03/26] x86/cpufeatures: Add is_tdx_guest() interface 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, Sean Christopherson References: <83c8fcff9ac09f73924104cfb534258747e98bff.1612563142.git.sathyanarayanan.kuppuswamy@linux.intel.com> <0116481d-581b-9433-3641-47e39550b99a@intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <8f0bd4e5-195b-7e65-f780-f5e31d72cfe8@linux.intel.com> Date: Thu, 1 Apr 2021 14:15:52 -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: <0116481d-581b-9433-3641-47e39550b99a@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/1/21 2:08 PM, Dave Hansen wrote: > On 2/5/21 3:38 PM, Kuppuswamy Sathyanarayanan wrote: >> +bool is_tdx_guest(void) >> +{ >> + return static_cpu_has(X86_FEATURE_TDX_GUEST); >> +} > > Why do you need is_tdx_guest() as opposed to calling > cpu_feature_enabled(X86_FEATURE_TDX_GUEST) everywhere? is_tdx_guest() is also implemented/used in compressed code (which uses native_cpuid calls). I don't think we can use cpu_feature_enabled(X86_FEATURE_TDX_GUEST) in compressed code right? Also is_tdx_guest() looks easy to read and use. > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer