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=-10.5 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 0A790C433E0 for ; Wed, 6 Jan 2021 22:22:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D68362313C for ; Wed, 6 Jan 2021 22:22:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727850AbhAFWWW (ORCPT ); Wed, 6 Jan 2021 17:22:22 -0500 Received: from mga02.intel.com ([134.134.136.20]:16907 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727819AbhAFWWV (ORCPT ); Wed, 6 Jan 2021 17:22:21 -0500 IronPort-SDR: Iis64iNKWV5VE1p+mnR84FX3AmsJ7gBt1YWNsq+cTqmIB5gPqiYT0VSp/htxAnitqBMEs5GFgc GFpBBoTle/AQ== X-IronPort-AV: E=McAfee;i="6000,8403,9856"; a="164414112" X-IronPort-AV: E=Sophos;i="5.79,328,1602572400"; d="scan'208";a="164414112" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jan 2021 14:21:41 -0800 IronPort-SDR: guH7OubbnxZ+ZaE3yPdnAa1UsLSWde9S75Zqjj+ZTOB4U95vkhQToi5Erpl3k9hoJyqaq5qXOh xv4KYvndZo9w== X-IronPort-AV: E=Sophos;i="5.79,328,1602572400"; d="scan'208";a="422333378" Received: from jmonroe1-mobl2.amr.corp.intel.com (HELO [10.212.12.85]) ([10.212.12.85]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jan 2021 14:21:40 -0800 Subject: Re: [RFC PATCH 04/23] x86/cpufeatures: Add SGX1 and SGX2 sub-features To: Kai Huang Cc: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, seanjc@google.com, jarkko@kernel.org, luto@kernel.org, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com References: <381b25a0dc0ed3e4579d50efb3634329132a2c02.1609890536.git.kai.huang@intel.com> <6d28e858-a5c0-6ce8-8c0d-2fdfbea3734b@intel.com> <20210107111206.c8207e64540a8361c04259b7@intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210107111206.c8207e64540a8361c04259b7@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On 1/6/21 2:12 PM, Kai Huang wrote: > On Wed, 6 Jan 2021 11:39:46 -0800 Dave Hansen wrote: >> On 1/5/21 5:55 PM, Kai Huang wrote: >>> --- a/arch/x86/kernel/cpu/feat_ctl.c >>> +++ b/arch/x86/kernel/cpu/feat_ctl.c >>> @@ -97,6 +97,8 @@ static void clear_sgx_caps(void) >>> { >>> setup_clear_cpu_cap(X86_FEATURE_SGX); >>> setup_clear_cpu_cap(X86_FEATURE_SGX_LC); >>> + setup_clear_cpu_cap(X86_FEATURE_SGX1); >>> + setup_clear_cpu_cap(X86_FEATURE_SGX2); >>> } >> Logically, I think you want this *after* the "Allow SGX virtualization >> without Launch Control support" patch. As it stands, this will totally >> disable SGX (including virtualization) if launch control is unavailable. > To me it is better to be here, since clear_sgx_caps(), which disables SGX > totally, should logically clear all SGX feature bits, no matter later patch's > behavior. So when new SGX bits are introduced, clear_sgx_caps() should clear > them too. Otherwise the logic of this patch (adding new SGX feature bits) is > not complete IMHO. > > And actually in later patch "Allow SGX virtualization without Launch Control > support", a new clear_sgx_lc() is added, and is called when LC is not > available but SGX virtualization is enabled, to make sure only SGX_LC bit is > cleared in this case. I don't quite understand why we need to clear SGX1 and > SGX2 in clear_sgx_caps() after the later patch. I was talking about patch ordering. It could be argued that this goes after the content of patch 05/23. Please _consider_ changing the ordering. If that doesn't work for some reason, please at least call out in the changelog that it leaves a temporarily funky situation.