linux-kernel - [PATCH v3 1/4] Add R3MWAIT register and bit to msr-info.h

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Date:   Thu, 13 Oct 2016 16:02:22 +0200
From:   Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>
To:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, x86@...nel.org
Cc:     bp@...e.de, dave.hansen@...ux.intel.com,
        linux-kernel@...r.kernel.org, lukasz.daniluk@...el.com,
        james.h.cownie@...el.com, jacob.jun.pan@...el.com,
        Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>
Subject: [PATCH v3 1/4] Add R3MWAIT register and bit to msr-info.h

Intel Xeon Phi x200 (codenamed Knights Landing) has MSR
MISC_THD_FEATURE_ENABLE 0x140.

Setting its 2nd bit make MONITOR and MWAIT instructions do not cause
invalid-opcode exception.

This commit adds this register prefixed by PHI and bit to msr-info.h
Reference:
https://software.intel.com/en-us/blogs/2016/10/06/intel-xeon-phi-product-family-x200-knl-user-mode-ring-3-monitor-and-mwait
Blog entry is a temporary solution, MSR will be present in the next SDM.

Signed-off-by: Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>
---
 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 56f4c66..df9d8d3 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -540,6 +540,11 @@
 #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)
 
+/* Intel Xeon Phi x200 ring 3 MONITOR/MWAIT */
+#define MSR_PHI_MISC_THD_FEATURE	0x00000140
+#define MSR_PHI_MISC_THD_FEATURE_R3MWAIT_BIT	1
+#define MSR_PHI_MISC_THD_FEATURE_R3MWAIT	(1ULL << MSR_PHI_MISC_THD_FEATURE_R3MWAIT_BIT)
+
 #define MSR_IA32_TSC_DEADLINE		0x000006E0
 
 /* P4/Xeon+ specific */
-- 
2.5.1