[PATCH 4/9] x86/intel_rdt: Add support for Cache Allocation detection

[Vikas Shivappa <vikas.shivappa@linux.intel.com>]

This patch includes CPUID enumeration routines for Cache allocation and
new values to track resources to the cpuinfo_x86 structure.

Cache allocation provides a way for the Software (OS/VMM) to restrict
cache allocation to a defined 'subset' of cache which may be overlapping
with other 'subsets'. This feature is used when allocating a line in
cache ie when pulling new data into the cache. The programming of the
hardware is done via programming MSRs (model specific registers).

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
---
 arch/x86/include/asm/cpufeature.h |  6 +++++-
 arch/x86/include/asm/processor.h  |  3 +++
 arch/x86/kernel/cpu/Makefile      |  1 +
 arch/x86/kernel/cpu/common.c      | 15 +++++++++++++++
 arch/x86/kernel/cpu/intel_rdt.c   | 40 +++++++++++++++++++++++++++++++++++++++
 init/Kconfig                      | 11 +++++++++++
 6 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kernel/cpu/intel_rdt.c

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 3d6606f..ae5ae9d 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 */
 
 /*
@@ -229,6 +229,7 @@
 #define X86_FEATURE_RTM		( 9*32+11) /* Restricted Transactional Memory */
 #define X86_FEATURE_CQM		( 9*32+12) /* Cache QoS Monitoring */
 #define X86_FEATURE_MPX		( 9*32+14) /* Memory Protection Extension */
+#define X86_FEATURE_RDT		( 9*32+15) /* Resource Allocation */
 #define X86_FEATURE_AVX512F	( 9*32+16) /* AVX-512 Foundation */
 #define X86_FEATURE_RDSEED	( 9*32+18) /* The RDSEED instruction */
 #define X86_FEATURE_ADX		( 9*32+19) /* The ADCX and ADOX instructions */
@@ -252,6 +253,9 @@
 /* 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 */
 
+/* Intel-defined CPU features, CPUID level 0x00000010:0 (ebx), word 13 */
+#define X86_FEATURE_CAT_L3	(13*32 + 1) /* Cache Allocation L3 */
+
 /*
  * BUG word(s)
  */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 944f178..0a1a1bc 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -120,6 +120,9 @@ struct cpuinfo_x86 {
 	int			x86_cache_occ_scale;	/* scale to bytes */
 	int			x86_power;
 	unsigned long		loops_per_jiffy;
+	/* Cache Allocation values: */
+	u16			x86_cache_max_cbm_len;
+	u16			x86_cache_max_closid;
 	/* cpuid returned max cores value: */
 	u16			 x86_max_cores;
 	u16			apicid;
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 9bff687..4ff7a1f 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_PERF_EVENTS_INTEL_UNCORE)	+= perf_event_intel_uncore.o \
 					   perf_event_intel_uncore_nhmex.o
 endif
 
+obj-$(CONFIG_CGROUP_RDT) 		+= intel_rdt.o
 
 obj-$(CONFIG_X86_MCE)			+= mcheck/
 obj-$(CONFIG_MTRR)			+= mtrr/
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index cb9e5df..5bb46d9 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -653,6 +653,21 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 		}
 	}
 
+	/* Additional Intel-defined flags: level 0x00000010 */
+	if (c->cpuid_level >= 0x00000010) {
+		u32 eax, ebx, ecx, edx;
+
+		cpuid_count(0x00000010, 0, &eax, &ebx, &ecx, &edx);
+		c->x86_capability[13] = ebx;
+
+		if (cpu_has(c, X86_FEATURE_CAT_L3)) {
+
+			cpuid_count(0x00000010, 1, &eax, &ebx, &ecx, &edx);
+			c->x86_cache_max_closid = edx + 1;
+			c->x86_cache_max_cbm_len = eax + 1;
+		}
+	}
+
 	/* AMD-defined flags: level 0x80000001 */
 	xlvl = cpuid_eax(0x80000000);
 	c->extended_cpuid_level = xlvl;
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
new file mode 100644
index 0000000..f49e970
--- /dev/null
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -0,0 +1,40 @@
+/*
+ * Resource Director Technology(RDT)
+ * - Cache Allocation code.
+ *
+ * Copyright (C) 2014 Intel Corporation
+ *
+ * 2015-05-25 Written by
+ *    Vikas Shivappa <vikas.shivappa@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * More information about RDT be found in the Intel (R) x86 Architecture
+ * Software Developer Manual June 2015, volume 3, section 17.15.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <linux/err.h>
+
+static int __init intel_rdt_late_init(void)
+{
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
+	if (!cpu_has(c, X86_FEATURE_CAT_L3))
+		return -ENODEV;
+
+	pr_info("Intel cache allocation detected\n");
+
+	return 0;
+}
+
+late_initcall(intel_rdt_late_init);
diff --git a/init/Kconfig b/init/Kconfig
index af09b4f..7f10d40 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -971,6 +971,17 @@ config CPUSETS
 
 	  Say N if unsure.
 
+config CGROUP_RDT
+	bool "Resource Director Technology cgroup subsystem"
+	depends on X86_64 && CPU_SUP_INTEL
+	help
+	  This option provides a cgroup to allocate Platform shared
+	  resources. Among the shared resources, current implementation
+	  focuses on L3 Cache. Using the interface user can specify the
+	  amount of L3 cache space into which an application can fill.
+
+	  Say N if unsure.
+
 config PROC_PID_CPUSET
 	bool "Include legacy /proc/<pid>/cpuset file"
 	depends on CPUSETS
-- 
1.9.1