linux-kernel - [tip:x86/urgent] x86/cpufeatures: Enumerate cldemote instruction

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Message-ID: <tip-9124130573950dcfc06b6a59306edfda2fc33ec7@git.kernel.org>
Date:   Wed, 25 Apr 2018 22:33:48 -0700
From:   tip-bot for Fenghua Yu <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ashok.raj@...el.com, fenghua.yu@...el.com, hpa@...ux.intel.com,
        mingo@...nel.org, linux-kernel@...r.kernel.org, hpa@...or.com,
        tglx@...utronix.de, ravi.v.shankar@...el.com
Subject: [tip:x86/urgent] x86/cpufeatures: Enumerate cldemote instruction

Commit-ID:  9124130573950dcfc06b6a59306edfda2fc33ec7
Gitweb:     https://git.kernel.org/tip/9124130573950dcfc06b6a59306edfda2fc33ec7
Author:     Fenghua Yu <fenghua.yu@...el.com>
AuthorDate: Mon, 23 Apr 2018 11:29:22 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 26 Apr 2018 07:31:12 +0200

x86/cpufeatures: Enumerate cldemote instruction

cldemote is a new instruction in future x86 processors. It hints
to hardware that a specified cache line should be moved ("demoted")
from the cache(s) closest to the processor core to a level more
distant from the processor core. This instruction is faster than
snooping to make the cache line available for other cores.

cldemote instruction is indicated by the presence of the CPUID
feature flag CLDEMOTE (CPUID.(EAX=0x7, ECX=0):ECX[bit25]).

More details on cldemote instruction can be found in the latest
Intel Architecture Instruction Set Extensions and Future Features
Programming Reference.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: "Ravi V Shankar" <ravi.v.shankar@...el.com>
Cc: "H. Peter Anvin" <hpa@...ux.intel.com>
Cc: "Ashok Raj" <ashok.raj@...el.com>
Link: https://lkml.kernel.org/r/1524508162-192587-1-git-send-email-fenghua.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index d554c11e01ff..578793e97431 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -320,6 +320,7 @@
 #define X86_FEATURE_AVX512_VPOPCNTDQ	(16*32+14) /* POPCNT for vectors of DW/QW */
 #define X86_FEATURE_LA57		(16*32+16) /* 5-level page tables */
 #define X86_FEATURE_RDPID		(16*32+22) /* RDPID instruction */
+#define X86_FEATURE_CLDEMOTE		(16*32+25) /* CLDEMOTE instruction */
 
 /* AMD-defined CPU features, CPUID level 0x80000007 (EBX), word 17 */
 #define X86_FEATURE_OVERFLOW_RECOV	(17*32+ 0) /* MCA overflow recovery support */