From: Geoff Gustafson <grgustaf@redhat.com>
Date: Wed, 5 Dec 2007 19:03:09 -0500
Subject: [x86] cpuinfo: list dynamic acceleration technology
Message-id: 20071206000309.GA29597@samurai.boston.redhat.com
O-Subject: Re: [RHEL5.2 PATCH] intel dynamic acceleration technology (bz 252229)
Bugzilla: 252229

This feature does something like overclocking one core when there's only one
CPU-intensive task and the other core is running slowly enough that the overall
"thermal envelope" of the chip is not exceeded in so doing. It's pretty much
automatic, although there is some OS control of the feature that we deem too
invasive for an update release.

This patch just lets you know the feature is present, by displaying the "ida"
feature flag in /proc/cpuinfo. When it went in upstream, the community wanted
a new capability section created for it, but that would increase the size of
cpu_data and boot_cpu_data and break kABI. I've made as much as possible match
the upstream patch.

AFAIK there's no big reason why the RHEL kernel has to use the same bit as
upstream. Please consider that and correct me if I'm wrong. One (the?) impact
to this implementation is "ida" will show up at a different place in the list.
It can still be consistent through the life of RHEL5 though.

Tested this version on i386 build and it works too. Just that one change.

Please ACK.

- Geoff

Acked-by: Prarit Bhargava <prarit@redhat.com>

diff --git a/arch/i386/kernel/cpu/Makefile b/arch/i386/kernel/cpu/Makefile
index 753f1d7..9a56914 100644
--- a/arch/i386/kernel/cpu/Makefile
+++ b/arch/i386/kernel/cpu/Makefile
@@ -8,7 +8,7 @@ obj-y	+=	amd.o
 obj-y	+=	cyrix.o
 obj-y	+=	centaur.o
 obj-y	+=	transmeta.o
-obj-y	+=	intel.o intel_cacheinfo.o
+obj-y	+=	intel.o intel_cacheinfo.o addon_cpuid_features.o
 obj-y	+=	rise.o
 obj-y	+=	nexgen.o
 obj-y	+=	umc.o
diff --git a/arch/i386/kernel/cpu/addon_cpuid_features.c b/arch/i386/kernel/cpu/addon_cpuid_features.c
new file mode 100644
index 0000000..39c41cc
--- /dev/null
+++ b/arch/i386/kernel/cpu/addon_cpuid_features.c
@@ -0,0 +1,51 @@
+
+/*
+ *	Routines to indentify additional cpu features that are scattered in
+ *	cpuid space.
+ */
+
+#include <linux/cpu.h>
+#include <linux/init.h>
+
+#include <asm/processor.h>
+
+struct cpuid_bit {
+	u16 feature;
+	u8 reg;
+	u8 bit;
+	u32 level;
+};
+
+enum cpuid_regs {
+	CR_EAX = 0,
+	CR_ECX,
+	CR_EDX,
+	CR_EBX
+};
+
+void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c)
+{
+	u32 max_level;
+	u32 regs[4];
+	const struct cpuid_bit *cb;
+
+	static const struct cpuid_bit cpuid_bits[] = {
+		{ X86_FEATURE_IDA, CR_EAX, 1, 0x00000006 },
+		{ 0, 0, 0, 0 }
+	};
+
+	for (cb = cpuid_bits; cb->feature; cb++) {
+
+		/* Verify that the level is valid */
+		max_level = cpuid_eax(cb->level & 0xffff0000);
+		if (max_level < cb->level ||
+		    max_level > (cb->level | 0xffff))
+			continue;
+
+		cpuid(cb->level, &regs[CR_EAX], &regs[CR_EBX],
+			&regs[CR_ECX], &regs[CR_EDX]);
+
+		if (regs[cb->reg] & (1 << cb->bit))
+			set_bit(cb->feature, c->x86_capability);
+	}
+}
diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
index 7dda85f..f279008 100644
--- a/arch/i386/kernel/cpu/common.c
+++ b/arch/i386/kernel/cpu/common.c
@@ -314,6 +314,8 @@ void __cpuinit generic_identify(struct cpuinfo_x86 * c)
 			if ( xlvl >= 0x80000004 )
 				get_model_name(c); /* Default name */
 		}
+
+		init_scattered_cpuid_features(c);
 	}
 
 	early_intel_workaround(c);
diff --git a/arch/i386/kernel/cpu/proc.c b/arch/i386/kernel/cpu/proc.c
index 89e79f2..01a4f4e 100644
--- a/arch/i386/kernel/cpu/proc.c
+++ b/arch/i386/kernel/cpu/proc.c
@@ -41,7 +41,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		"cxmmx", "k6_mtrr", "cyrix_arr", "centaur_mcr",
 		NULL, NULL, NULL, NULL,
 		"constant_tsc", "up", NULL, NULL, NULL, NULL, NULL, NULL,
-		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+		"ida", NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 
 		/* Intel-defined (#2) */
diff --git a/arch/x86_64/kernel/Makefile b/arch/x86_64/kernel/Makefile
index db4e737..f6b0cf5 100644
--- a/arch/x86_64/kernel/Makefile
+++ b/arch/x86_64/kernel/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_MODULES)		+= module.o
 
 obj-y				+= topology.o
 obj-y				+= intel_cacheinfo.o
+obj-y				+= addon_cpuid_features.o
 
 CFLAGS_vsyscall.o		:= $(PROFILING) -g0
 
@@ -53,6 +54,7 @@ cpuid-$(subst m,y,$(CONFIG_X86_CPUID))  += ../../i386/kernel/cpuid.o
 topology-y                     += ../../i386/kernel/topology.o
 microcode-$(subst m,y,$(CONFIG_MICROCODE))  += ../../i386/kernel/microcode.o
 intel_cacheinfo-y		+= ../../i386/kernel/cpu/intel_cacheinfo.o
+addon_cpuid_features-y		+= ../../i386/kernel/cpu/addon_cpuid_features.o
 quirks-y			+= ../../i386/kernel/quirks.o
 i8237-y				+= ../../i386/kernel/i8237.o
 msr-$(subst m,y,$(CONFIG_X86_MSR))  += ../../i386/kernel/msr.o
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 7b8f1ea..5597749 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -1137,6 +1137,8 @@ void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 			c->x86_capability[2] = cpuid_edx(0x80860001);
 	}
 
+	init_scattered_cpuid_features(c);
+
 	c->apicid = phys_pkg_id(0);
 
 	/*
@@ -1243,7 +1245,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		"cxmmx", NULL, "cyrix_arr", "centaur_mcr", NULL,
 		"constant_tsc", NULL, NULL,
 		"up", NULL, NULL, NULL, NULL, NULL, NULL, NULL,
-		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+		"ida", NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 
 		/* Intel-defined (#2) */
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index d314ebb..dfd126f 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -73,6 +73,7 @@
 #define X86_FEATURE_UP		(3*32+ 9) /* smp kernel running on up */
 #define X86_FEATURE_FXSAVE_LEAK (3*32+10) /* FXSAVE leaks FOP/FIP/FOP */
 #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */
+#define X86_FEATURE_IDA		(3*32+16) /* Intel Dynamic Acceleration */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3	(4*32+ 0) /* Streaming SIMD Extensions-3 */
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index 964fd1e..c108225 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -113,6 +113,7 @@ extern char ignore_fpu_irq;
 
 extern void identify_cpu(struct cpuinfo_x86 *);
 extern void print_cpu_info(struct cpuinfo_x86 *);
+extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
 extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
 extern unsigned short num_cache_leaves;
 
diff --git a/include/asm-x86_64/cpufeature.h b/include/asm-x86_64/cpufeature.h
index ee792fa..6ac3053 100644
--- a/include/asm-x86_64/cpufeature.h
+++ b/include/asm-x86_64/cpufeature.h
@@ -68,6 +68,7 @@
 #define X86_FEATURE_FXSAVE_LEAK (3*32+7)  /* FIP/FOP/FDP leaks through FXSAVE */
 #define X86_FEATURE_UP		(3*32+8) /* SMP kernel running on UP */
 #define X86_FEATURE_ARCH_PERFMON (3*32+9) /* Intel Architectural PerfMon */
+#define X86_FEATURE_IDA		(3*32+16) /* Intel Dynamic Acceleration */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3	(4*32+ 0) /* Streaming SIMD Extensions-3 */
@@ -89,6 +90,11 @@
 #define X86_FEATURE_LAHF_LM	(6*32+ 0) /* LAHF/SAHF in long mode */
 #define X86_FEATURE_CMP_LEGACY	(6*32+ 1) /* If yes HyperThreading not valid */
 
+/*
+ * Auxiliary flags: Linux defined - For features scattered in various
+ * CPUID levels like 0x6, 0xA etc
+ */
+
 #define cpu_has(c, bit)                test_bit(bit, (c)->x86_capability)
 #define boot_cpu_has(bit)      test_bit(bit, boot_cpu_data.x86_capability)
 
diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h
index de9c314..2dd19a7 100644
--- a/include/asm-x86_64/processor.h
+++ b/include/asm-x86_64/processor.h
@@ -99,6 +99,7 @@ extern char ignore_irq13;
 
 extern void identify_cpu(struct cpuinfo_x86 *);
 extern void print_cpu_info(struct cpuinfo_x86 *);
+extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
 extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
 extern unsigned short num_cache_leaves;