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 9028BC433FE for ; Tue, 28 Sep 2021 12:56:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7850861262 for ; Tue, 28 Sep 2021 12:56:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240875AbhI1M5s (ORCPT ); Tue, 28 Sep 2021 08:57:48 -0400 Received: from mga04.intel.com ([192.55.52.120]:34584 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240848AbhI1M5p (ORCPT ); Tue, 28 Sep 2021 08:57:45 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10120"; a="222796674" X-IronPort-AV: E=Sophos;i="5.85,329,1624345200"; d="scan'208";a="222796674" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2021 05:56:06 -0700 X-IronPort-AV: E=Sophos;i="5.85,329,1624345200"; d="scan'208";a="553982639" Received: from oogunmoy-mobl1.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.212.221.219]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2021 05:56:03 -0700 Subject: Re: [PATCH v6 04/11] x86/tdx: Add protected guest support for TDX guest To: Joerg Roedel Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Paolo Bonzini , Juergen Gross , Deep Shah , VMware Inc , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , linux-kernel@vger.kernel.org References: <20210903172812.1097643-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210903172812.1097643-5-sathyanarayanan.kuppuswamy@linux.intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <20fc6806-0c46-15d6-930b-6b4e90dfee6d@linux.intel.com> Date: Tue, 28 Sep 2021 05:56:03 -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: 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 9/28/21 4:46 AM, Joerg Roedel wrote: > On Fri, Sep 03, 2021 at 10:28:05AM -0700, Kuppuswamy Sathyanarayanan wrote: >> static inline bool prot_guest_has(unsigned int attr) >> { >> if (sme_me_mask) >> return amd_prot_guest_has(attr); >> + else if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) >> + return intel_prot_guest_has(attr); > > This causes a function call on every Intel machine this code runs. is > there an easier to check whether TDX is enabled, like the sme_me_mask > check on AMD? This will only be called when CONFIG_ARCH_HAS_CC_PLATFORM is set by a platform. So it won't be called for all platforms. Also, intel_prot_guest_has() is a generic Intel platform branch call (so we can't directly check for TDX here). > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer