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=-4.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,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 2A98AC07E96 for ; Thu, 15 Jul 2021 11:56:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EC9B56117A for ; Thu, 15 Jul 2021 11:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230427AbhGOL7b (ORCPT ); Thu, 15 Jul 2021 07:59:31 -0400 Received: from mga17.intel.com ([192.55.52.151]:25240 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229500AbhGOL7b (ORCPT ); Thu, 15 Jul 2021 07:59:31 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10045"; a="190903231" X-IronPort-AV: E=Sophos;i="5.84,240,1620716400"; d="scan'208";a="190903231" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2021 04:56:37 -0700 X-IronPort-AV: E=Sophos;i="5.84,240,1620716400"; d="scan'208";a="495403405" Received: from xiaoyaol-mobl.ccr.corp.intel.com (HELO [10.255.30.133]) ([10.255.30.133]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2021 04:56:34 -0700 Subject: Re: [PATCH v3 03/11] x86/cpufeatures: Add TDX Guest CPU feature To: Kuppuswamy Sathyanarayanan , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Andy Lutomirski Cc: Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , x86@kernel.org, linux-kernel@vger.kernel.org References: <20210618225755.662725-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210618225755.662725-4-sathyanarayanan.kuppuswamy@linux.intel.com> From: Xiaoyao Li Message-ID: <64bf7394-ff82-86f7-7a52-ed12508276ac@intel.com> Date: Thu, 15 Jul 2021 19:56:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210618225755.662725-4-sathyanarayanan.kuppuswamy@linux.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 6/19/2021 6:57 AM, Kuppuswamy Sathyanarayanan wrote: > Add CPU feature detection for Trusted Domain Extensions support. TDX > feature adds capabilities to keep guest register state and memory > isolated from hypervisor. > > For TDX guest platforms, executing CPUID(eax=0x21, ecx=0) will return > following values in EAX, EBX, ECX and EDX. > > EAX: Maximum sub-leaf number: 0 > EBX/EDX/ECX: Vendor string: > > EBX = "Inte" > EDX = "lTDX" > ECX = " " > > So when above condition is true, set X86_FEATURE_TDX_GUEST feature cap > bit. > ... > +static inline bool cpuid_has_tdx_guest(void) > +{ > + u32 eax, sig[3]; > + > + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) > + return false; > + > + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[1], &sig[2]); As change log describes, EBX + EDX + ECX is "IntelTDX ", not EBX + ECX + EDX. So it should be cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]); Please also correct early_cpuid_has_tdx_guest() > + > + return !memcmp("IntelTDX ", sig, 12); > +} > + > +void __init tdx_early_init(void) > +{ > + if (!cpuid_has_tdx_guest()) > + return; > + > + setup_force_cpu_cap(X86_FEATURE_TDX_GUEST); > + > + pr_info("Guest initialized\n"); > +} >