From 0da0fb062841d0dcd8ba47e4a989d2e952cdf0ff Mon Sep 17 00:00:00 2001 From: Jingqi Liu Date: Fri, 4 May 2018 11:57:33 +0800 Subject: [PATCH] x86/cpu: Enable CLDEMOTE(Demote Cache Line) cpu feature The CLDEMOTE instruction hints to hardware that the cache line that contains the linear address should be moved("demoted") from the cache(s) closest to the processor core to a level more distant from the processor core. This may accelerate subsequent accesses to the line by other cores in the same coherence domain, especially if the line was written by the core that demotes the line. Intel Snow Ridge has added new cpu feature, CLDEMOTE. The new cpu feature needs to be exposed to guest VM. The bit definition: CPUID.(EAX=7,ECX=0):ECX[bit 25] CLDEMOTE The release document ref below link: https://software.intel.com/sites/default/files/managed/c5/15/\ architecture-instruction-set-extensions-programming-reference.pdf Signed-off-by: Jingqi Liu Message-Id: <1525406253-54846-1-git-send-email-jingqi.liu@intel.com> Reviewed-by: Eduardo Habkost Signed-off-by: Eduardo Habkost --- target/i386/cpu.c | 2 +- target/i386/cpu.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 52fd35b6a1..4b39ab5dd4 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -494,7 +494,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { "avx512bitalg", NULL, "avx512-vpopcntdq", NULL, "la57", NULL, NULL, NULL, NULL, NULL, "rdpid", NULL, - NULL, NULL, NULL, NULL, + NULL, "cldemote", NULL, NULL, NULL, NULL, NULL, NULL, }, .cpuid_eax = 7, diff --git a/target/i386/cpu.h b/target/i386/cpu.h index b58b779bff..8fbe1537c1 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -680,6 +680,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; #define CPUID_7_0_ECX_AVX512_VPOPCNTDQ (1U << 14) /* POPCNT for vectors of DW/QW */ #define CPUID_7_0_ECX_LA57 (1U << 16) #define CPUID_7_0_ECX_RDPID (1U << 22) +#define CPUID_7_0_ECX_CLDEMOTE (1U << 25) /* CLDEMOTE Instruction */ #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural Network Instructions */ #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply Accumulation Single Precision */ -- 2.39.5