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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 E8695C10DCE for ; Thu, 12 Mar 2020 18:04:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D117C206F1 for ; Thu, 12 Mar 2020 18:04:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726669AbgCLSET (ORCPT ); Thu, 12 Mar 2020 14:04:19 -0400 Received: from mga05.intel.com ([192.55.52.43]:38331 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726328AbgCLSES (ORCPT ); Thu, 12 Mar 2020 14:04:18 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Mar 2020 11:04:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,545,1574150400"; d="scan'208";a="277908742" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by fmsmga002.fm.intel.com with ESMTP; 12 Mar 2020 11:04:16 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Toni Spets Subject: [PATCH] KVM: VMX: Condition ENCLS-exiting enabling on CPU support for SGX1 Date: Thu, 12 Mar 2020 11:04:16 -0700 Message-Id: <20200312180416.6679-1-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Enable ENCLS-exiting (and thus set vmcs.ENCLS_EXITING_BITMAP) only if the CPU supports SGX1. Per Intel's SDM, all ENCLS leafs #UD if SGX1 is not supported[*], i.e. intercepting ENCLS to inject a #UD is unnecessary. Avoiding ENCLS-exiting even when it is reported as supported by the CPU works around a reported issue where SGX is "hard" disabled after an S3 suspend/resume cycle, i.e. CPUID.0x7.SGX=0 and the VMCS field/control are enumerated as unsupported. While the root cause of the S3 issue is unknown, it's definitely _not_ a KVM (or kernel) bug, i.e. this is a workaround for what is most likely a hardware or firmware issue. As a bonus side effect, KVM saves a VMWRITE when first preparing vmcs01 and vmcs02. Query CPUID directly instead of going through cpu_data() or cpu_has() to ensure KVM is trapping ENCLS when it's supported in hardware, e.g. even if X86_FEATURE_SGX1 (which doesn't yet exist in upstream) were disabled by the kernel/user. Note, SGX must be disabled in BIOS to take advantage of this workaround [*] The additional ENCLS CPUID check on SGX1 exists so that SGX can be globally "soft" disabled post-reset, e.g. if #MC bits in MCi_CTL are cleared. Soft disabled meaning disabling SGX without clearing the primary CPUID bit (in leaf 0x7) and without poking into non-SGX CPU paths, e.g. for the VMCS controls. Fixes: 0b665d304028 ("KVM: vmx: Inject #UD for SGX ENCLS instruction in guest") Reported-by: Toni Spets Signed-off-by: Sean Christopherson --- This seems somewhat premature given that we don't yet know if the observed behavior is a logic bug, a one off manufacturing defect, firmware specific, etc... On the other hand, the change is arguably an optimization irrespective of using it as a workaround. arch/x86/kvm/vmx/vmx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 40b1e6138cd5..50cab98382e7 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2338,6 +2338,11 @@ static void hardware_disable(void) kvm_cpu_vmxoff(); } +static bool cpu_has_sgx(void) +{ + return cpuid_eax(0) >= 0x12 && (cpuid_eax(0x12) & BIT(0)); +} + static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt, u32 msr, u32 *result) { @@ -2418,8 +2423,9 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE | SECONDARY_EXEC_PT_USE_GPA | SECONDARY_EXEC_PT_CONCEAL_VMX | - SECONDARY_EXEC_ENABLE_VMFUNC | - SECONDARY_EXEC_ENCLS_EXITING; + SECONDARY_EXEC_ENABLE_VMFUNC; + if (cpu_has_sgx()) + opt2 |= SECONDARY_EXEC_ENCLS_EXITING; if (adjust_vmx_controls(min2, opt2, MSR_IA32_VMX_PROCBASED_CTLS2, &_cpu_based_2nd_exec_control) < 0) -- 2.24.1