linux-kernel - [PATCH V2 1/5] x86/intel_rdt: Intel Code Data Prioritization detection

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Date:	Thu,  1 Oct 2015 23:33:55 -0700
From:	Fenghua Yu <fenghua.yu@...el.com>
To:	"H Peter Anvin" <hpa@...or.com>, "Ingo Molnar" <mingo@...hat.com>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Peter Zijlstra" <peterz@...radead.org>
Cc:	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"x86" <x86@...nel.org>, "Fenghua Yu" <fenghua.yu@...el.com>,
	"Vikas Shivappa" <vikas.shivappa@...ux.intel.com>
Subject: [PATCH V2 1/5] x86/intel_rdt: Intel Code Data Prioritization detection

This patch adds enumeration support for Code Data Prioritization(CDP)
feature found in future Intel Xeon processors. It includes CPUID
enumeration routines for CDP.

CDP is an extension to Cache Allocation and lets threads allocate subset
of L3 cache for code and data separately. The allocation is represented
by the code or data cache capacity bit mask(cbm) MSRs
IA32_L3_QOS_MASK_n. Each Class of service would be associated with one
dcache_cbm and one icache_cbm MSR and hence the number of available
CLOSids is halved with CDP. The association for a CLOSid 'n' is shown
below :

data_cbm_address (n) = base + (n <<1)
code_cbm_address (n) = base + (n <<1) +1.
During scheduling the kernel writes the CLOSid
of the thread to IA32_PQR_ASSOC_MSR.

Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
---
 arch/x86/include/asm/cpufeature.h | 5 ++++-
 arch/x86/kernel/cpu/common.c      | 1 +
 arch/x86/kernel/cpu/intel_rdt.c   | 2 ++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 4e93006..6dc0701 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	14	/* N 32-bit words worth of info */
+#define NCAPINTS	15	/* N 32-bit words worth of info */
 #define NBUGINTS	1	/* N 32-bit bug flags */
 
 /*
@@ -259,6 +259,9 @@
 /* Intel-defined CPU features, CPUID level 0x00000010:0 (ebx), word 13 */
 #define X86_FEATURE_CAT_L3	(13*32 + 1) /* Cache Allocation L3 */
 
+/* Intel-defined CPU QoS Sub-leaf, CPUID level 0x00000010:1 (ecx), word 14 */
+#define X86_FEATURE_CDP_L3     (14*32 + 2) /* Code data prioritization L3 */
+
 /*
  * BUG word(s)
  */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 026a416..9886e23 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -666,6 +666,7 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 			cpuid_count(0x00000010, 1, &eax, &ebx, &ecx, &edx);
 			c->x86_cache_max_closid = edx + 1;
 			c->x86_cache_max_cbm_len = eax + 1;
+			c->x86_capability[14] = ecx;
 		}
 	}
 
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index cb4d2ef..29c8a19 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -561,6 +561,8 @@ static int __init intel_rdt_late_init(void)
 
 	static_key_slow_inc(&rdt_enable_key);
 	pr_info("Intel cache allocation enabled\n");
+	if (cpu_has(c, X86_FEATURE_CDP_L3))
+		pr_info("Intel code data prioritization detected\n");
 out_err:
 
 	return err;
-- 
1.8.1.2

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