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=unavailable 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 27442C433E0 for ; Tue, 26 Jan 2021 16:28:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC3B12074A for ; Tue, 26 Jan 2021 16:28:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390142AbhAZQ1a (ORCPT ); Tue, 26 Jan 2021 11:27:30 -0500 Received: from mga06.intel.com ([134.134.136.31]:64033 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405307AbhAZQ1U (ORCPT ); Tue, 26 Jan 2021 11:27:20 -0500 IronPort-SDR: kFkIZKoKRDFSeBncQRLLxfZgQTh747oMaR/CYhxdnakeifPT151Ec1laa11HQpOCafaB3LAV1v dRV5gm+1RIBg== X-IronPort-AV: E=McAfee;i="6000,8403,9876"; a="241458294" X-IronPort-AV: E=Sophos;i="5.79,375,1602572400"; d="scan'208";a="241458294" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2021 08:26:23 -0800 IronPort-SDR: BtBCh3ShU89UuBNymlK0+t8vwR12RjTCD9XTyMw7JUgr/JDYw5YYiIH5AhOXOJEOHoMhqxBx1W hIW7wAwjlx+Q== X-IronPort-AV: E=Sophos;i="5.79,375,1602572400"; d="scan'208";a="369154366" Received: from ekfraser-mobl1.amr.corp.intel.com (HELO [10.209.173.94]) ([10.209.173.94]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2021 08:26:22 -0800 Subject: Re: [RFC PATCH v3 07/27] x86/cpu/intel: Allow SGX virtualization without Launch Control support To: Kai Huang , linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org Cc: 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, jethro@fortanix.com, b.thiel@posteo.de References: 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: 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 1/26/21 1:30 AM, Kai Huang wrote: > --- a/arch/x86/kernel/cpu/feat_ctl.c > +++ b/arch/x86/kernel/cpu/feat_ctl.c > @@ -105,7 +105,8 @@ early_param("nosgx", nosgx); > void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > { > bool tboot = tboot_enabled(); > - bool enable_sgx; > + bool enable_vmx; > + bool enable_sgx_any, enable_sgx_kvm, enable_sgx_driver; > u64 msr; > > if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) { > @@ -114,13 +115,22 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > return; > } > > + enable_vmx = cpu_has(c, X86_FEATURE_VMX) && > + IS_ENABLED(CONFIG_KVM_INTEL); The reason it's called 'enable_sgx' below is because this code is actually going to "enable sgx". This code does not "enable vmx". That makes this a badly-named variable. "vmx_enabled" or "vmx_available" would be better. > /* > - * Enable SGX if and only if the kernel supports SGX and Launch Control > - * is supported, i.e. disable SGX if the LE hash MSRs can't be written. > + * Enable SGX if and only if the kernel supports SGX. Require Launch > + * Control support if SGX virtualization is *not* supported, i.e. > + * disable SGX if the LE hash MSRs can't be written and SGX can't be > + * exposed to a KVM guest (which might support non-LC configurations). > */ I hate this comment. /* * Separate out bare-metal SGX enabling from KVM. This allows * KVM guests to use SGX even if the kernel refuses to use it on * bare-metal. This happens if flexible Faunch Control is not * available. * > - enable_sgx = cpu_has(c, X86_FEATURE_SGX) && > - cpu_has(c, X86_FEATURE_SGX_LC) && > - IS_ENABLED(CONFIG_X86_SGX); > + enable_sgx_any = cpu_has(c, X86_FEATURE_SGX) && > + cpu_has(c, X86_FEATURE_SGX1) && > + IS_ENABLED(CONFIG_X86_SGX); The X86_FEATURE_SGX1 check seems to have snuck in here. Why? > + enable_sgx_driver = enable_sgx_any && > + cpu_has(c, X86_FEATURE_SGX_LC); > + enable_sgx_kvm = enable_sgx_any && enable_vmx && > + IS_ENABLED(CONFIG_X86_SGX_KVM); > > if (msr & FEAT_CTL_LOCKED) > goto update_caps; > @@ -136,15 +146,18 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > * i.e. KVM is enabled, to avoid unnecessarily adding an attack vector > * for the kernel, e.g. using VMX to hide malicious code. > */ > - if (cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL)) { > + if (enable_vmx) { > msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX; > > if (tboot) > msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX; > } > > - if (enable_sgx) > - msr |= FEAT_CTL_SGX_ENABLED | FEAT_CTL_SGX_LC_ENABLED; > + if (enable_sgx_kvm || enable_sgx_driver) { > + msr |= FEAT_CTL_SGX_ENABLED; > + if (enable_sgx_driver) > + msr |= FEAT_CTL_SGX_LC_ENABLED; > + } > > wrmsrl(MSR_IA32_FEAT_CTL, msr); > > @@ -167,10 +180,29 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > } > > update_sgx: > - if (!(msr & FEAT_CTL_SGX_ENABLED) || > - !(msr & FEAT_CTL_SGX_LC_ENABLED) || !enable_sgx) { > - if (enable_sgx) > - pr_err_once("SGX disabled by BIOS\n"); > + if (!(msr & FEAT_CTL_SGX_ENABLED)) { > + if (enable_sgx_kvm || enable_sgx_driver) > + pr_err_once("SGX disabled by BIOS.\n"); > clear_cpu_cap(c, X86_FEATURE_SGX); > + return; > + } Isn't there a pr_fmt here already? Won't these just look like: sgx: SGX disabled by BIOS. That seems a bit silly.