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x86/cpufeature: Detect CPUID faulting support 

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>
hifive-unleashed-5.1
Kyle Huey 2017-03-20 01:16:25 -07:00 committed by Thomas Gleixner
parent 79170fda31
commit 90218ac77d
3 changed files with 26 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/cpufeatures.h
View File

@ -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 */

2
arch/x86/include/asm/msr-index.h
View File

@ -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)

24
arch/x86/kernel/cpu/intel.c
View File

@ -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