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* [PATCH] x86/cpufeatures: Enumerate cldemote instruction
@ 2018-04-23 18:29 Fenghua Yu
  2018-04-25  9:01 ` [tip:x86/urgent] " tip-bot for Fenghua Yu
  2018-04-26  5:33 ` tip-bot for Fenghua Yu
  0 siblings, 2 replies; 3+ messages in thread
From: Fenghua Yu @ 2018-04-23 18:29 UTC (permalink / raw)
  To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Ashok Raj,
	Ravi V Shankar, x86, linux-kernel
  Cc: Fenghua Yu

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@intel.com>
---
 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 */
-- 
2.5.0

^ permalink raw reply	[flat|nested] 3+ messages in thread

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2018-04-23 18:29 [PATCH] x86/cpufeatures: Enumerate cldemote instruction Fenghua Yu
2018-04-25  9:01 ` [tip:x86/urgent] " tip-bot for Fenghua Yu
2018-04-26  5:33 ` tip-bot for Fenghua Yu

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