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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 819D5C433DB for ; Tue, 16 Feb 2021 02:16:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CAB564DE8 for ; Tue, 16 Feb 2021 02:16:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229919AbhBPCQp (ORCPT ); Mon, 15 Feb 2021 21:16:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:34152 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229917AbhBPCQk (ORCPT ); Mon, 15 Feb 2021 21:16:40 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1FAC664DEC; Tue, 16 Feb 2021 02:15:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613441759; bh=rwPyvSkRaZjNg1e1cChrEfHaJu6ECECq3HBijxdrKA0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KI+hPRNwlmomBsXCCmRkpNwBX5UzgmyFDTuBRn5qOVS0Cww/YXcvl1YVQWzbhGGOy rXeXKFdMfaf4R6/3CwyrKcZeDQzqQ2/yxuWruEa9Rbu4MKo5hZIOO6OuF0Q/KJibpi nq2S8pmqQNVgBk2yMFVBhvfxYdHhGfw1zWrc3a4ukEq9+x++LTbHnGzbZer93lB0Ji KBlmjzXpmWKMbTQ0Xtn2p/lo21gcwsHSpaCAapWjxhHksfaUo4BtO+EA3LBYuPqYXW d+urrRIuiUZ1XJ2eUIOk1vsTma3HmFsLS7VRaIhbg8ru5vVoEZO7p+k/6cvKz08x9s 6mlyQDhQZlecg== Date: Tue, 16 Feb 2021 04:15:46 +0200 From: Jarkko Sakkinen To: Kai Huang Cc: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, seanjc@google.com, luto@kernel.org, dave.hansen@intel.com, rick.p.edgecombe@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 v5 06/26] x86/cpu/intel: Allow SGX virtualization without Launch Control support Message-ID: References: <82c304d6f4e8ebfa9b35d1be74360a5004179c5f.1613221549.git.kai.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <82c304d6f4e8ebfa9b35d1be74360a5004179c5f.1613221549.git.kai.huang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Sun, Feb 14, 2021 at 02:29:05AM +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 > --- > v4->v5: > > - No code change. > > v3->v4: > > - Removed cpu_has(X86_FEATURE_SGX1) check in enable_sgx_any, since it logically > is not related to KVM SGX series, per Sean. > - Changed declaration of variables to be in reverse-christmas tree style, per > Jarkko. > > 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 | 57 ++++++++++++++++++++++++++-------- > 1 file changed, 44 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c > index 27533a6e04fa..96c370284913 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_sgx_any, enable_sgx_kvm, enable_sgx_driver; > + bool enable_vmx; > u64 msr; > > if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) { > @@ -114,13 +115,21 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c) > return; > } > > + enable_vmx = cpu_has(c, X86_FEATURE_VMX) && > + IS_ENABLED(CONFIG_KVM_INTEL); It's less than 100 characters: enable_vmx = cpu_has(c, X86_FEATURE_VMX) && IS_ENABLED(CONFIG_KVM_INTEL); This is better: enable_vmx = IS_ENABLED(CONFIG_KVM_INTEL) && cpu_has(c, X86_FEATURE_VMX); You only want to evaluate cpu_has() if COHNFIG_KVM_INTEL is enabled. > + > /* > - * 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. > + * Separate out SGX driver enabling from KVM. This allows KVM > + * guests to use SGX even if the kernel SGX driver refuses to > + * use it. 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) && > + 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 +145,18 @@ 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 +179,29 @@ 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); Empty line before return statement. > + 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