Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1573705

[tip:x86/cpufeature] x86/msr: Add MSR_MISC_FEATURE_ENABLES and RING3MWAIT bit

Show all headers | View raw

Commit-ID:  ae47eda905e61ef6ba0b6f79b967c9de15ca4f8e
Gitweb:     http://git.kernel.org/tip/ae47eda905e61ef6ba0b6f79b967c9de15ca4f8e
Author:     Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
AuthorDate: Fri, 20 Jan 2017 14:22:33 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 4 Feb 2017 08:51:09 +0100

x86/msr: Add MSR_MISC_FEATURE_ENABLES and RING3MWAIT bit

Define new MSR MISC_FEATURE_ENABLES (0x140).

On supported CPUs if bit 1 of this MSR is set, then calling MONITOR and
MWAIT instructions outside of ring 0 will not cause invalid-opcode
exception.

The MSR MISC_FEATURE_ENABLES is not yet documented in the SDM. Here is the
relevant documentation:

Hex   Dec  Name                     Scope
140H  320  MISC_FEATURE_ENABLES     Thread
           0    Reserved
           1    If set to 1, the MONITOR and MWAIT instructions do not
                cause invalid-opcode exceptions when executed with CPL > 0
                or in virtual-8086 mode. If MWAIT is executed when CPL > 0
                or in virtual-8086 mode, and if EAX indicates a C-state
                other than C0 or C1, the instruction operates as if EAX
                indicated the C-state C1.
           63:2 Reserved

Signed-off-by: Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
Cc: Piotr.Luc@intel.com
Cc: dave.hansen@linux.intel.com
Link: http://lkml.kernel.org/r/1484918557-15481-2-git-send-email-grzegorz.andrejczuk@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 arch/x86/include/asm/msr-index.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 710273c..00293a9 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -543,6 +543,11 @@
 #define MSR_IA32_MISC_ENABLE_IP_PREF_DISABLE_BIT	39
 #define MSR_IA32_MISC_ENABLE_IP_PREF_DISABLE		(1ULL << MSR_IA32_MISC_ENABLE_IP_PREF_DISABLE_BIT)
 
+/* MISC_FEATURE_ENABLES non-architectural features */
+#define MSR_MISC_FEATURE_ENABLES	0x00000140
+
+#define MSR_MISC_FEATURE_ENABLES_RING3MWAIT_BIT		1
+
 #define MSR_IA32_TSC_DEADLINE		0x000006E0
 
 /* P4/Xeon+ specific */

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

[tip:x86/cpufeature] x86/msr: Add MSR_MISC_FEATURE_ENABLES and  RING3MWAIT bit tip-bot for Grzegorz Andrejczuk <tipbot@zytor.com> - 2017-02-04 17:40 +0100

csiph-web