From 90218ac77d0582eaf2d0872d8d900cbd5bf1f205 Mon Sep 17 00:00:00 2001
From: Kyle Huey <me@kylehuey.com>
Date: Mon, 20 Mar 2017 01:16:25 -0700
Subject: x86/cpufeature: Detect CPUID faulting support
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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 <khuey@kylehuey.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
Cc: kvm@vger.kernel.org
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: linux-kselftest@vger.kernel.org
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Robert O'Callahan <robert@ocallahan.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: user-mode-linux-user@lists.sourceforge.net
Cc: David Matlack <dmatlack@google.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: http://lkml.kernel.org/r/20170320081628.18952-8-khuey@kylehuey.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'arch/x86/include/asm/cpufeatures.h')

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 */
-- 
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