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=-13.8 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 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 3FED9C433DB for ; Mon, 1 Feb 2021 05:41:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0832E64E15 for ; Mon, 1 Feb 2021 05:41:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231591AbhBAFlU (ORCPT ); Mon, 1 Feb 2021 00:41:20 -0500 Received: from mga02.intel.com ([134.134.136.20]:49638 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229629AbhBAFjL (ORCPT ); Mon, 1 Feb 2021 00:39:11 -0500 IronPort-SDR: rlRxVM9ViubdJ737z12W5DPK7fDfKHkoQrfw0FI7nCehlIrC88TjGruIDhqZAggoegfFiwJPZC 1gYilH1GZYgA== X-IronPort-AV: E=McAfee;i="6000,8403,9881"; a="167740574" X-IronPort-AV: E=Sophos;i="5.79,391,1602572400"; d="scan'208";a="167740574" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2021 21:38:29 -0800 IronPort-SDR: GZ3ZRxcb6RaN0Yhe+da82mltfqCEwGthb9d8uryyzSUYmhi6PchBKQJ4UWSePK2SjBQgUuf+t1 1lGdnYzZOPig== X-IronPort-AV: E=Sophos;i="5.79,391,1602572400"; d="scan'208";a="412141280" Received: from jaramosm-mobl.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.254.79.53]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2021 21:38:24 -0800 Date: Mon, 1 Feb 2021 18:38:22 +1300 From: Kai Huang To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, seanjc@google.com, luto@kernel.org, dave.hansen@intel.com, 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 Subject: Re: [RFC PATCH v3 07/27] x86/cpu/intel: Allow SGX virtualization without Launch Control support Message-Id: <20210201183822.d30fe56535de72087584c116@intel.com> In-Reply-To: References: X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Sat, 30 Jan 2021 16:42:56 +0200 Jarkko Sakkinen wrote: > On Tue, Jan 26, 2021 at 10:30:54PM +1300, Kai Huang wrote: > > From: Sean Christopherson > > > > 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. > > > > 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 > > --- > > v2->v3: > > > > - Added to use 'enable_sgx_any', per Dave. > > - Changed to call clear_cpu_cap() directly, rather than using clear_sgx_caps() > > and clear_sgx_lc(). > > - Changed to use CONFIG_X86_SGX_KVM, instead of CONFIG_X86_SGX_VIRTUALIZATION. > > > > v1->v2: > > > > - Refined commit message per Dave's comments. > > - Added check to only enable SGX virtualization when VMX is supported, per > > Dave's comment. > > - Refined error msg print to explicitly call out SGX virtualization will be > > supported when LC is locked by BIOS, per Dave's comment. > > > > --- > > arch/x86/kernel/cpu/feat_ctl.c | 58 ++++++++++++++++++++++++++-------- > > 1 file changed, 45 insertions(+), 13 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c > > index 27533a6e04fa..0fc202550fcc 100644 > > --- 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; > > Move the declaration first (reverse christmas tree). Will do. Thanks. > > > 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); > > + > > /* > > - * 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_any = cpu_has(c, X86_FEATURE_SGX) && > > + cpu_has(c, X86_FEATURE_SGX1) && > > + IS_ENABLED(CONFIG_X86_SGX); > > + 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; > > + } > > + > > + /* > > + * VMX feature bit may be cleared due to being disabled in BIOS, > > + * in which case SGX virtualization cannot be supported either. > > + */ > > + if (!cpu_has(c, X86_FEATURE_VMX) && enable_sgx_kvm) { > > + pr_err_once("SGX virtualization disabled due to lack of VMX.\n"); > > + enable_sgx_kvm = 0; > > + } > > + > > + if (!(msr & FEAT_CTL_SGX_LC_ENABLED) && enable_sgx_driver) { > > + if (!enable_sgx_kvm) { > > + pr_err_once("SGX Launch Control is locked. Disable SGX.\n"); > > + clear_cpu_cap(c, X86_FEATURE_SGX); > > + } else { > > + pr_err_once("SGX Launch Control is locked. Support SGX virtualization only.\n"); > > + clear_cpu_cap(c, X86_FEATURE_SGX_LC); > > + } > > } > > } > > -- > > 2.29.2 > > > > > > /Jarkko