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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FF3FC433EF for ; Wed, 6 Oct 2021 04:33:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0240D6112D for ; Wed, 6 Oct 2021 04:33:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230379AbhJFEfa (ORCPT ); Wed, 6 Oct 2021 00:35:30 -0400 Received: from mga09.intel.com ([134.134.136.24]:19894 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229579AbhJFEf3 (ORCPT ); Wed, 6 Oct 2021 00:35:29 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10128"; a="225806613" X-IronPort-AV: E=Sophos;i="5.85,350,1624345200"; d="scan'208";a="225806613" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2021 21:33:37 -0700 X-IronPort-AV: E=Sophos;i="5.85,350,1624345200"; d="scan'208";a="589623039" Received: from ptcotton-mobl1.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.212.211.164]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2021 21:33:37 -0700 Subject: Re: [PATCH v8 03/11] x86/cpufeatures: Add TDX Guest CPU feature To: Josh Poimboeuf Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Paolo Bonzini , David Hildenbrand , Andrea Arcangeli , Juergen Gross , Deep Shah , VMware Inc , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , linux-kernel@vger.kernel.org References: <20211005025205.1784480-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20211005025205.1784480-4-sathyanarayanan.kuppuswamy@linux.intel.com> <20211005210423.yfftpxxmj3cjprtv@treble> <15a07997-2659-6be1-b8a3-da57e72562b5@linux.intel.com> <20211006034218.ynamwigsvpgad7sr@treble> From: "Kuppuswamy, Sathyanarayanan" Message-ID: Date: Tue, 5 Oct 2021 21:33:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211006034218.ynamwigsvpgad7sr@treble> 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 10/5/21 8:42 PM, Josh Poimboeuf wrote: >> is_tdx_guest was mainly introduced to support cc_platform_has() >> API in early boot calls (similar to sme_me_mask in AMD code). >> Regarding FEATURE flag it will be useful for userspace tools to >> check the TDX feature support. > FEATURE flags can also be checked in the kernel, with boot_cpu_has(). > Or am I missing something? Yes, previously we have been using x86_feature_enabled() check in cc_platform_has() call. Now with the introduction of is_tdx_guest global variable, we don't use it in kernel. But I still want to keep the feature flag for user space use case. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer