Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755973AbdCTQtU (ORCPT ); Mon, 20 Mar 2017 12:49:20 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:35102 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753223AbdCTIRO (ORCPT ); Mon, 20 Mar 2017 04:17:14 -0400 From: Kyle Huey X-Google-Original-From: Kyle Huey To: "Robert O'Callahan" , Thomas Gleixner , Andy Lutomirski , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Jeff Dike , Richard Weinberger , Alexander Viro , Shuah Khan , Dave Hansen , Borislav Petkov , Peter Zijlstra , Boris Ostrovsky , Len Brown , "Rafael J. Wysocki" , Dmitry Safonov , David Matlack , Nadav Amit , Andi Kleen , Grzegorz Andrejczuk Cc: linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH v16 07/10] x86/cpufeature: Detect CPUID faulting support Date: Mon, 20 Mar 2017 01:16:25 -0700 Message-Id: <20170320081628.18952-8-khuey@kylehuey.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170320081628.18952-1-khuey@kylehuey.com> References: <20170320081628.18952-1-khuey@kylehuey.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2978 Lines: 88 Intel supports faulting on the CPUID instruction beginning with Ivy Bridge. When enabled, the processor will fault on attempts to execute the CPUID instruction with CPL>0. This will allow a ptracer to emulate the CPUID instruction. Bit 31 of MSR_PLATFORM_INFO advertises support for this feature. It is documented in detail in Section 2.3.2 of https://bugzilla.kernel.org/attachment.cgi?id=243991 Detect support for this feature and expose it as X86_FEATURE_CPUID_FAULT. Signed-off-by: Kyle Huey Reviewed-by: Borislav Petkov --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/msr-index.h | 2 ++ arch/x86/kernel/cpu/intel.c | 24 +++++++++++++++++++++++- 3 files changed, 26 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index b04bb6dfed7f..0fe00446f9ca 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -187,6 +187,7 @@ * Reuse free bits when adding new feature flags! */ #define X86_FEATURE_RING3MWAIT ( 7*32+ 0) /* Ring 3 MONITOR/MWAIT */ +#define X86_FEATURE_CPUID_FAULT ( 7*32+ 1) /* Intel CPUID faulting */ #define X86_FEATURE_CPB ( 7*32+ 2) /* AMD Core Performance Boost */ #define X86_FEATURE_EPB ( 7*32+ 3) /* IA32_ENERGY_PERF_BIAS support */ #define X86_FEATURE_CAT_L3 ( 7*32+ 4) /* Cache Allocation Technology L3 */ diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index f429b70ebaef..b1f75daca34b 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -45,6 +45,8 @@ #define MSR_IA32_PERFCTR1 0x000000c2 #define MSR_FSB_FREQ 0x000000cd #define MSR_PLATFORM_INFO 0x000000ce +#define MSR_PLATFORM_INFO_CPUID_FAULT_BIT 31 +#define MSR_PLATFORM_INFO_CPUID_FAULT BIT_ULL(MSR_PLATFORM_INFO_CPUID_FAULT_BIT) #define MSR_PKG_CST_CONFIG_CONTROL 0x000000e2 #define NHM_C3_AUTO_DEMOTE (1UL << 25) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index e229318d7230..a07f8295c9ed 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -488,6 +488,28 @@ static void intel_bsp_resume(struct cpuinfo_x86 *c) init_intel_energy_perf(c); } +static void init_cpuid_fault(struct cpuinfo_x86 *c) +{ + u64 msr; + + if (!rdmsrl_safe(MSR_PLATFORM_INFO, &msr)) { + if (msr & MSR_PLATFORM_INFO_CPUID_FAULT) + set_cpu_cap(c, X86_FEATURE_CPUID_FAULT); + } +} + +static void init_intel_misc_features(struct cpuinfo_x86 *c) +{ + u64 msr; + + if (rdmsrl_safe(MSR_MISC_FEATURES_ENABLES, &msr)) + return; + + /* Check features and update capabilities */ + init_cpuid_fault(c); + probe_xeon_phi_r3mwait(c); +} + static void init_intel(struct cpuinfo_x86 *c) { unsigned int l2 = 0; @@ -602,7 +624,7 @@ static void init_intel(struct cpuinfo_x86 *c) init_intel_energy_perf(c); - probe_xeon_phi_r3mwait(c); + init_intel_misc_features(c); } #ifdef CONFIG_X86_32 -- 2.11.0