[PATCH V15 04/11] x86/intel_rdt: Add support for Cache Allocation detection

From: Fenghua Yu
Date: Fri Oct 02 2015 - 02:30:21 EST

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@xxxxxxxxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
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 | 12 ++++++++++++
6 files changed, 76 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 e6cf2ad..4e93006 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 */

/*
@@ -231,6 +231,7 @@
#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 */
@@ -255,6 +256,9 @@
/* 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 19577dd..b932ec4 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 4eb065c..5e873c7 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_msr.o
obj-$(CONFIG_CPU_SUP_AMD) += perf_event_msr.o
endif

+obj-$(CONFIG_INTEL_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 de22ea7..026a416 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -654,6 +654,21 @@ 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@xxxxxxxxx>
+ *
+ * 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 c24b6f7..9fe3f11 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -938,6 +938,18 @@ menuconfig CGROUPS

Say N if unsure.

+config INTEL_RDT
+ bool "Intel Resource Director Technology support"
+ depends on X86_64 && CPU_SUP_INTEL
+ help
+ This option provides support for Cache allocation which is a
+ sub-feature of Intel Resource Director Technology(RDT).
+ Current implementation supports L3 cache allocation.
+ Using this feature a user can specify the amount of L3 cache space
+ into which an application can fill.
+
+ Say N if unsure.
+
if CGROUPS

config CGROUP_DEBUG
--
1.8.1.2

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