linux-kernel - [PATCH V2 2/2] x86/cpufeature: Add CLZERO feature

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Message-ID: <1446059010-28010-3-git-send-email-Aravind.Gopalakrishnan@amd.com>
Date:	Wed, 28 Oct 2015 14:03:30 -0500
From:	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
To:	<tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
	<tony.luck@...el.com>, <bp@...en8.de>, <x86@...nel.org>
CC:	<ashok.raj@...el.com>, <linux-kernel@...r.kernel.org>,
	<linux-edac@...r.kernel.org>, <peterz@...radead.org>,
	<luto@...nel.org>, <dvlasenk@...hat.com>,
	<ross.zwisler@...ux.intel.com>, <dirk.j.brandewie@...el.com>,
	Wan Zongshun <Vincent.Wan@....com>,
	"Aravind Gopalakrishnan" <aravind.gopalakrishnan@....com>
Subject: [PATCH V2 2/2] x86/cpufeature: Add CLZERO feature

From: Wan Zongshun <Vincent.Wan@....com>

CLZERO instruction introduced in AMD Fam17h processors
zero's out a 64 byte cache line specified in RAX.

Add the bit here to allow /proc/cpuinfo to list the feature

Signed-off-by: Wan Zongshun <Vincent.Wan@....com>
[Wrap code in patch form, fix comments]
Signed-off-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
---
 arch/x86/include/asm/cpufeature.h | 5 ++++-
 arch/x86/kernel/cpu/common.c      | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 9727b3b..e4f8010 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -12,7 +12,7 @@
 #include <asm/disabled-features.h>
 #endif
 
-#define NCAPINTS	13	/* N 32-bit words worth of info */
+#define NCAPINTS	14	/* N 32-bit words worth of info */
 #define NBUGINTS	1	/* N 32-bit bug flags */
 
 /*
@@ -255,6 +255,9 @@
 /* Intel-defined CPU QoS Sub-leaf, CPUID level 0x0000000F:1 (edx), word 12 */
 #define X86_FEATURE_CQM_OCCUP_LLC (12*32+ 0) /* LLC occupancy monitoring if 1 */
 
+/* AMD-defined CPU features, CPUID level 0x80000008 (ebx), word 13 */
+#define X86_FEATURE_CLZERO	(13*32+0) /* CLZERO instruction */
+
 /*
  * BUG word(s)
  */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index de22ea7..4ddd780 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -670,6 +670,7 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 
 		c->x86_virt_bits = (eax >> 8) & 0xff;
 		c->x86_phys_bits = eax & 0xff;
+		c->x86_capability[13] = cpuid_ebx(0x80000008);
 	}
 #ifdef CONFIG_X86_32
 	else if (cpu_has(c, X86_FEATURE_PAE) || cpu_has(c, X86_FEATURE_PSE36))
-- 
2.6.1

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