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Subject[PATCH 02/32] x86/intel_rdt: Add support for Cache Allocation detection
Date
From: 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>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/include/asm/cpufeatures.h | 10 +++++++---
arch/x86/include/asm/processor.h | 3 +++
arch/x86/kernel/cpu/Makefile | 2 ++
arch/x86/kernel/cpu/common.c | 15 ++++++++++++++
arch/x86/kernel/cpu/intel_rdt.c | 40 ++++++++++++++++++++++++++++++++++++++
5 files changed, 67 insertions(+), 3 deletions(-)
create mode 100644 arch/x86/kernel/cpu/intel_rdt.c

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 4a41348..667acf3 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -12,7 +12,7 @@
/*
* Defines x86 CPU feature bits
*/
-#define NCAPINTS 18 /* N 32-bit words worth of info */
+#define NCAPINTS 19 /* N 32-bit words worth of info */
#define NBUGINTS 1 /* N 32-bit bug flags */

/*
@@ -220,6 +220,7 @@
#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_AVX512DQ ( 9*32+17) /* AVX-512 DQ (Double/Quad granular) Instructions */
#define X86_FEATURE_RDSEED ( 9*32+18) /* The RDSEED instruction */
@@ -284,8 +285,11 @@

/* AMD-defined CPU features, CPUID level 0x80000007 (ebx), word 17 */
#define X86_FEATURE_OVERFLOW_RECOV (17*32+0) /* MCA overflow recovery support */
-#define X86_FEATURE_SUCCOR (17*32+1) /* Uncorrectable error containment and recovery */
-#define X86_FEATURE_SMCA (17*32+3) /* Scalable MCA */
+#define X86_FEATURE_SUCCOR (17*32+ 1) /* Uncorrectable error containment and recovery */
+#define X86_FEATURE_SMCA (17*32+ 3) /* Scalable MCA */
+
+/* Intel-defined CPU features, CPUID level 0x00000010:0 (ebx), word 18 */
+#define X86_FEATURE_CAT_L3 (18*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 62c6cc3..598c9bc 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -119,6 +119,9 @@ 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 4a8697f..39b8e6f 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -42,6 +42,8 @@ obj-$(CONFIG_X86_LOCAL_APIC) += perfctr-watchdog.o

obj-$(CONFIG_HYPERVISOR_GUEST) += vmware.o hypervisor.o mshyperv.o

+obj-$(CONFIG_INTEL_RDT) += intel_rdt.o
+
ifdef CONFIG_X86_FEATURE_NAMES
quiet_cmd_mkcapflags = MKCAP $@
cmd_mkcapflags = $(CONFIG_SHELL) $(srctree)/$(src)/mkcapflags.sh $< $@
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0fe6953..42c90cb 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -711,6 +711,21 @@ 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[14] = 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 */
eax = cpuid_eax(0x80000000);
c->extended_cpuid_level = eax;
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);
--
2.5.0
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