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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 0F9FAC433E0 for ; Wed, 6 Jan 2021 19:55:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0E8423132 for ; Wed, 6 Jan 2021 19:55:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726521AbhAFTzn (ORCPT ); Wed, 6 Jan 2021 14:55:43 -0500 Received: from mga06.intel.com ([134.134.136.31]:8087 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726329AbhAFTzn (ORCPT ); Wed, 6 Jan 2021 14:55:43 -0500 IronPort-SDR: Vcvncf5GK47+N8kzU/Gn+nCMxg1VJM9O2Z+CJxy3t3EKORXE2cR1c+NtfFLAeGyVcogp7fhMa5 ZHkVnh1w1vFg== X-IronPort-AV: E=McAfee;i="6000,8403,9856"; a="238876206" X-IronPort-AV: E=Sophos;i="5.79,328,1602572400"; d="scan'208";a="238876206" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jan 2021 11:54:54 -0800 IronPort-SDR: xTGJJXf74L/ebcd9Bd7q+cb4JYrgcrduYZklcG3VNh/Y17yVZw/IDrzKbzgImsUKOJEQqf9Epa 2P+1YCO6aKaQ== X-IronPort-AV: E=Sophos;i="5.79,328,1602572400"; d="scan'208";a="422293903" 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 11:54:52 -0800 Subject: Re: [RFC PATCH 05/23] 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: <2f8a5cb73d9032e5c7ee32f0676e3786ebbc92f3.1609890536.git.kai.huang@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: <2f8a5cb73d9032e5c7ee32f0676e3786ebbc92f3.1609890536.git.kai.huang@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 1/5/21 5:55 PM, Kai Huang wrote: > From: Sean Christopherson > > Allow SGX virtualization on systems without Launch Control support, i.e. > allow KVM to expose SGX to guests that support non-LC configurations. Context, please. The kernel will currently disable all SGX support if the hardware does not support launch control. Make it more permissive to allow SGX virtualization on systems without Launch Control support. This will allow KVM to expose SGX to guests that have less-strict requirements on the availability of flexible launch control. > Introduce clear_sgx_lc() to clear SGX_LC feature bit only if SGX Launch > Control is locked by BIOS when SGX virtualization is enabled, to prevent > SGX driver being enabled. This is another run-on, and it makes it really hard to figure out what it is trying to say. > Improve error message to distinguish three cases: 1) SGX disabled > completely by BIOS; 2) SGX disabled completely due to SGX LC is locked > by BIOS, and SGX virtualization is also disabled; 3) Only SGX driver is > disabled due to SGX LC is locked by BIOS, but SGX virtualization is > enabled. Editing for grammar and clarity again... Improve error message to distinguish between three cases. There are two cases where SGX support is completely disabled: 1) SGX has been disabled completely by the BIOS 2) SGX LC is locked by the BIOS. Bare-metal support is disabled because of LC unavailability. SGX virtualization is unavailable (because of Kconfig). One where it is partially available: 3) SGX LC is locked by the BIOS. Bare-metal support is disabled because of LC unavailability. SGX virtualization is supported. > Signed-off-by: Sean Christopherson > Co-developed-by: Kai Huang > Signed-off-by: Kai Huang > --- > arch/x86/kernel/cpu/feat_ctl.c | 48 +++++++++++++++++++++++++--------- > 1 file changed, 36 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c > index 4fcd57fdc682..b07452b68538 100644 > --- a/arch/x86/kernel/cpu/feat_ctl.c > +++ b/arch/x86/kernel/cpu/feat_ctl.c > @@ -101,6 +101,11 @@ static void clear_sgx_caps(void) > setup_clear_cpu_cap(X86_FEATURE_SGX2); > } > > +static void clear_sgx_lc(void) > +{ > + setup_clear_cpu_cap(X86_FEATURE_SGX_LC); > +} > + > static int __init nosgx(char *str) > { > clear_sgx_caps(); > @@ -113,7 +118,7 @@ early_param("nosgx", nosgx); > void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > { > bool tboot = tboot_enabled(); > - bool enable_sgx; > + bool enable_sgx_virt, enable_sgx_driver; > u64 msr; > > if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) { > @@ -123,12 +128,19 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > } > > /* > - * 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). > */ > - enable_sgx = cpu_has(c, X86_FEATURE_SGX) && > - cpu_has(c, X86_FEATURE_SGX_LC) && > - IS_ENABLED(CONFIG_X86_SGX); > + enable_sgx_driver = cpu_has(c, X86_FEATURE_SGX) && > + cpu_has(c, X86_FEATURE_SGX1) && > + IS_ENABLED(CONFIG_X86_SGX) && > + cpu_has(c, X86_FEATURE_SGX_LC); > + enable_sgx_virt = cpu_has(c, X86_FEATURE_SGX) && > + cpu_has(c, X86_FEATURE_SGX1) && > + IS_ENABLED(CONFIG_X86_SGX) && > + IS_ENABLED(CONFIG_X86_SGX_VIRTUALIZATION); Don't we also need some runtime checks here? What if we boot on hardware that doesn't support KVM? > if (msr & FEAT_CTL_LOCKED) > goto update_caps; > @@ -151,8 +163,11 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX; > } > > - if (enable_sgx) > - msr |= FEAT_CTL_SGX_ENABLED | FEAT_CTL_SGX_LC_ENABLED; > + if (enable_sgx_driver || enable_sgx_virt) { > + msr |= FEAT_CTL_SGX_ENABLED; > + if (enable_sgx_driver) > + msr |= FEAT_CTL_SGX_LC_ENABLED; > + } > > wrmsrl(MSR_IA32_FEAT_CTL, msr); > > @@ -175,10 +190,19 @@ 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_driver || enable_sgx_virt) > + pr_err_once("SGX disabled by BIOS.\n"); > clear_sgx_caps(); > } > + if (!(msr & FEAT_CTL_SGX_LC_ENABLED) && > + (enable_sgx_driver || enable_sgx_virt)) { > + if (!enable_sgx_virt) { > + pr_err_once("SGX Launch Control is locked. Disable SGX.\n"); > + clear_sgx_caps(); > + } else if (enable_sgx_driver) { > + pr_err_once("SGX Launch Control is locked. Disable SGX driver.\n"); Should we have an explicit message for enabling virtualization? I'm not sure how many people will understand that "SGX driver" actually doesn't mean /dev/sgx_epc_virt. > + clear_sgx_lc(); > + } > + } > } >