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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 344F2C47094 for ; Thu, 10 Jun 2021 14:28:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16E5160C40 for ; Thu, 10 Jun 2021 14:28:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231409AbhFJOaV (ORCPT ); Thu, 10 Jun 2021 10:30:21 -0400 Received: from mga17.intel.com ([192.55.52.151]:9167 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230322AbhFJOaU (ORCPT ); Thu, 10 Jun 2021 10:30:20 -0400 IronPort-SDR: tkhPH+rJUjjD4LSsZY63jeEWIIguvZ4iXGISvn1dvHDaHHTBAsaSf8MsoWCddsYcMg9tJGFY7Y yzlwi25w7I/g== X-IronPort-AV: E=McAfee;i="6200,9189,10011"; a="185681550" X-IronPort-AV: E=Sophos;i="5.83,263,1616482800"; d="scan'208";a="185681550" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jun 2021 07:28:23 -0700 IronPort-SDR: gdc1JaUk+mCc0rIKGlnNP14h0p2dIsyA9q02fnA1I17kllGCJiLAtmM73ByHbSw9KmcScjf4wu Yjie9lZQZmmw== X-IronPort-AV: E=Sophos;i="5.83,263,1616482800"; d="scan'208";a="486191404" Received: from miishak-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.212.54.237]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jun 2021 07:28:22 -0700 Subject: Re: [PATCH v1 03/11] x86/cpufeatures: Add TDX Guest CPU feature To: Borislav Petkov Cc: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Andy Lutomirski , Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Kuppuswamy Sathyanarayanan , Sean Christopherson , linux-kernel@vger.kernel.org, x86@kernel.org References: <20210602022136.2186759-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210602022136.2186759-4-sathyanarayanan.kuppuswamy@linux.intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <0e19b754-1903-45bf-0d81-470e1e656337@linux.intel.com> Date: Thu, 10 Jun 2021 07:28:20 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: 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 Hi, On 6/10/21 5:28 AM, Borislav Petkov wrote: > On Tue, Jun 01, 2021 at 07:21:28PM -0700, 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(0x21, 0) will return > > I'm assuming that 0 is ECX? Correct. I will clarify it in commit log. > >> 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 > ^ > Fullstop. Will fix it in next version. > >> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h >> index ac37830ae941..dddc3a27cc8a 100644 >> --- a/arch/x86/include/asm/cpufeatures.h >> +++ b/arch/x86/include/asm/cpufeatures.h >> @@ -238,6 +238,7 @@ >> #define X86_FEATURE_VMW_VMMCALL ( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */ >> #define X86_FEATURE_PVUNLOCK ( 8*32+20) /* "" PV unlock function */ >> #define X86_FEATURE_VCPUPREEMPT ( 8*32+21) /* "" PV vcpu_is_preempted function */ >> +#define X86_FEATURE_TDX_GUEST ( 8*32+22) /* Trusted Domain Extensions Guest */ > > What's the name of the feature bit? "TDX guest"? Why not only > X86_FEATURE_TDX and then you can have "tdx" in cpuinfo? Make sense. I can change it to "TDX". I guess we will not a feature bit for "tdx host" > >> >> /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */ >> #define X86_FEATURE_FSGSBASE ( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/ >> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h >> new file mode 100644 >> index 000000000000..679500e807f3 >> --- /dev/null >> +++ b/arch/x86/include/asm/tdx.h >> @@ -0,0 +1,20 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* Copyright (C) 2020 Intel Corporation */ >> +#ifndef _ASM_X86_TDX_H >> +#define _ASM_X86_TDX_H >> + >> +#define TDX_CPUID_LEAF_ID 0x21 >> + >> +#ifdef CONFIG_INTEL_TDX_GUEST >> + >> +#include > > As before - put the include at the top. I will change it. > >> +void __init tdx_early_init(void); >> + >> +#else // !CONFIG_INTEL_TDX_GUEST > > No need for that // - comment I will remove it in next version. > >> diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c >> new file mode 100644 >> index 000000000000..5b14b72e41c5 >> --- /dev/null >> +++ b/arch/x86/kernel/tdx.c >> @@ -0,0 +1,30 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* Copyright (C) 2020 Intel Corporation */ >> + >> +#include >> + >> +static inline bool cpuid_has_tdx_guest(void) >> +{ >> + u32 eax, signature[3]; > > Shorten that array name to "sig" so that you don't have to break the > cpuid_count() line below. I will fix it in next version. > >> + >> + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) >> + return false; >> + >> + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &signature[0], >> + &signature[1], &signature[2]); >> + >> + if (memcmp("IntelTDX ", signature, 12)) >> + return false; >> + >> + return true; > > or simply: > > return !memcmp(... Got it. I will change it in next version. > >> +} >> + >> +void __init tdx_early_init(void) >> +{ >> + if (!cpuid_has_tdx_guest()) >> + return; >> + >> + setup_force_cpu_cap(X86_FEATURE_TDX_GUEST); >> + >> + pr_info("TDX guest is initialized\n"); > > Use pr_fmt in this file: > > #undef pr_fmt > #define pr_fmt(fmt) "x86/tdx: " fmt > > and then do > > pr_info("Guest initialized\n"); Patch titled "x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions" add it. It makes sense to move it to this patch. > > Thx. > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer