x86/intel_rdt: Add CONFIG, Makefile, and basic initialization

Introduce CONFIG_INTEL_RDT_A (default: no, dependent on CPU_SUP_INTEL) to
control inclusion of Resource Director Technology in the build.

Simple init() routine just checks which features are present. If they are
pr_info() one line summary for each feature for now.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "David Carrillo-Cisneros" <davidcc@google.com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Stephane Eranian" <eranian@google.com>
Cc: "Dave Hansen" <dave.hansen@intel.com>
Cc: "Shaohua Li" <shli@fb.com>
Cc: "Nilay Vaish" <nilayvaish@gmail.com>
Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com>
Cc: "Ingo Molnar" <mingo@elte.hu>
Cc: "Borislav Petkov" <bp@suse.de>
Cc: "H. Peter Anvin" <h.peter.anvin@intel.com>
Link: http://lkml.kernel.org/r/1477142405-32078-7-git-send-email-fenghua.yu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig

@@ -407,6 +407,18 @@ config GOLDFISH
        def_bool y
        depends on X86_GOLDFISH
 
+config INTEL_RDT_A
+	bool "Intel Resource Director Technology Allocation support"
+	default n
+	depends on X86 && CPU_SUP_INTEL
+	help
+	  Select to enable resource allocation which is a sub-feature of
+	  Intel Resource Director Technology(RDT). More information about
+	  RDT can be found in the Intel x86 Architecture Software
+	  Developer Manual.
+
+	  Say N if unsure.
+
 if X86_32
 config X86_EXTENDED_PLATFORM
 	bool "Support for extended (non-PC) x86 platforms"

arch/x86/kernel/cpu/Makefile

@@ -34,6 +34,8 @@ obj-$(CONFIG_CPU_SUP_CENTAUR)		+= centaur.o
 obj-$(CONFIG_CPU_SUP_TRANSMETA_32)	+= transmeta.o
 obj-$(CONFIG_CPU_SUP_UMC_32)		+= umc.o
 
+obj-$(CONFIG_INTEL_RDT_A)	+= intel_rdt.o
+
 obj-$(CONFIG_X86_MCE)			+= mcheck/
 obj-$(CONFIG_MTRR)			+= mtrr/
 obj-$(CONFIG_MICROCODE)			+= microcode/

arch/x86/kernel/cpu/intel_rdt.c

@@ -0,0 +1,54 @@
+/*
+ * Resource Director Technology(RDT)
+ * - Cache Allocation code.
+ *
+ * Copyright (C) 2016 Intel Corporation
+ *
+ * Authors:
+ *    Fenghua Yu <fenghua.yu@intel.com>
+ *    Tony Luck <tony.luck@intel.com>
+ *    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 2016, volume 3, section 17.17.
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <linux/err.h>
+
+static inline bool get_rdt_resources(void)
+{
+	bool ret = false;
+
+	if (!boot_cpu_has(X86_FEATURE_RDT_A))
+		return false;
+	if (boot_cpu_has(X86_FEATURE_CAT_L3))
+		ret = true;
+
+	return ret;
+}
+
+static int __init intel_rdt_late_init(void)
+{
+	if (!get_rdt_resources())
+		return -ENODEV;
+
+	pr_info("Intel RDT cache allocation detected\n");
+	if (boot_cpu_has(X86_FEATURE_CDP_L3))
+		pr_info("Intel RDT code data prioritization detected\n");
+
+	return 0;
+}
+
+late_initcall(intel_rdt_late_init);