From: Kyle Huey <me@kylehuey.com>
To: "Robert O'Callahan" <robert@ocallahan.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
Dmitry Safonov <dsafonov@virtuozzo.com>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Shuah Khan <shuah@kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Len Brown <len.brown@intel.com>
Cc: linux-kernel@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net,
user-mode-linux-user@lists.sourceforge.net,
linux-kselftest@vger.kernel.org, linux-api@vger.kernel.org
Subject: [PATCH v7 5/6] x86/cpufeature: Detect CPUID faulting support
Date: Tue, 18 Oct 2016 19:03:32 -0700 [thread overview]
Message-ID: <20161019020333.3766-6-khuey@kylehuey.com> (raw)
In-Reply-To: <20161019020333.3766-1-khuey@kylehuey.com>
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
http://www.intel.com/content/dam/www/public/us/en/documents/application-notes/virtualization-technology-flexmigration-application-note.pdf
Detect support for this feature and expose it as X86_FEATURE_CPUID_FAULT.
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kernel/cpu/scattered.c | 13 +++++++++++++
3 files changed, 15 insertions(+)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 1188bc8..a918f98 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -189,6 +189,7 @@
#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_CPUID_FAULT ( 7*32+ 4) /* Intel CPUID faulting */
#define X86_FEATURE_HW_PSTATE ( 7*32+ 8) /* AMD HW-PState */
#define X86_FEATURE_PROC_FEEDBACK ( 7*32+ 9) /* AMD ProcFeedbackInterface */
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 56f4c66..39aa563 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -41,6 +41,7 @@
#define MSR_IA32_PERFCTR1 0x000000c2
#define MSR_FSB_FREQ 0x000000cd
#define MSR_PLATFORM_INFO 0x000000ce
+#define PLATINFO_CPUID_FAULT (1UL << 31)
#define MSR_NHM_SNB_PKG_CST_CFG_CTL 0x000000e2
#define NHM_C3_AUTO_DEMOTE (1UL << 25)
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 8cb57df..7901481 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -24,6 +24,16 @@ enum cpuid_regs {
CR_EBX
};
+static bool supports_cpuid_faulting(void)
+{
+ unsigned int lo, hi;
+
+ if (rdmsr_safe(MSR_PLATFORM_INFO, &lo, &hi))
+ return false;
+
+ return lo & PLATINFO_CPUID_FAULT;
+}
+
void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
{
u32 max_level;
@@ -54,4 +64,7 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
if (regs[cb->reg] & (1 << cb->bit))
set_cpu_cap(c, cb->feature);
}
+
+ if (supports_cpuid_faulting())
+ set_cpu_cap(c, X86_FEATURE_CPUID_FAULT);
}
--
2.10.1
next prev parent reply other threads:[~2016-10-19 2:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-19 2:03 [PATCH v7 0/6] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey
2016-10-19 2:03 ` [PATCH v7 1/6] x86/arch_prctl/64: Use SYSCALL_DEFINE2 to define sys_arch_prctl Kyle Huey
2016-10-19 2:03 ` [PATCH v7 2/6] x86/arch_prctl/64: Rename do_arch_prctl to do_arch_prctl_64 Kyle Huey
2016-10-19 2:03 ` [PATCH v7 3/6] x86/arch_prctl: Add do_arch_prctl_common Kyle Huey
2016-10-19 2:03 ` [PATCH v7 4/6] x86/syscalls/32: Wire up arch_prctl on x86-32 Kyle Huey
2016-10-19 2:03 ` Kyle Huey [this message]
2016-10-27 8:21 ` [PATCH v7 5/6] x86/cpufeature: Detect CPUID faulting support Thomas Gleixner
2016-10-19 2:03 ` [PATCH v7 6/6] x86/arch_prctl: Add ARCH_[GET|SET]_CPUID Kyle Huey
2016-10-27 11:15 ` Thomas Gleixner
2016-10-27 22:34 ` Andy Lutomirski
2016-10-27 22:38 ` Thomas Gleixner
2016-10-25 5:30 ` [PATCH v7 0/6] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey
2016-10-25 16:47 ` Thomas Gleixner
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