[PATCH] x86: fix reporting of Thermal Monitoring mechanism enabled

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: [PATCH] x86: fix reporting of Thermal Monitoring mechanism enabled

Early Pentium M models use different method for enabling TM2
(per paragraph 13.5.2.3 of the "Intel 64 and IA-32 Architectures
Software Developer's Manual Volume 3A: System Programming Guide,
Part 1").

Tested on the affected Pentium M variant (model == 13).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
 arch/x86/include/asm/msr-index.h         |    4 ++++
 arch/x86/kernel/cpu/mcheck/therm_throt.c |   13 ++++++++++---
 2 files changed, 14 insertions(+), 3 deletions(-)

Index: b/arch/x86/include/asm/msr-index.h
===================================================================
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -215,6 +215,10 @@
 
 #define THERM_STATUS_PROCHOT		(1 << 0)
 
+#define MSR_THERM2_CTL			0x0000019d
+
+#define MSR_THERM2_CTL_TM_SELECT	(1ULL << 16)
+
 #define MSR_IA32_MISC_ENABLE		0x000001a0
 
 /* MISC_ENABLE bits: architectural */
Index: b/arch/x86/kernel/cpu/mcheck/therm_throt.c
===================================================================
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -253,9 +253,6 @@ void intel_init_thermal(struct cpuinfo_x
 		return;
 	}
 
-	if (cpu_has(c, X86_FEATURE_TM2) && (l & MSR_IA32_MISC_ENABLE_TM2))
-		tm2 = 1;
-
 	/* Check whether a vector already exists */
 	if (h & APIC_VECTOR_MASK) {
 		printk(KERN_DEBUG
@@ -264,6 +261,16 @@ void intel_init_thermal(struct cpuinfo_x
 		return;
 	}
 
+	/* early Pentium M models use different method for enabling TM2 */
+	if (cpu_has(c, X86_FEATURE_TM2)) {
+		if (c->x86 == 6 && (c->x86_model == 9 || c->x86_model == 13)) {
+			rdmsr(MSR_THERM2_CTL, l, h);
+			if (l & MSR_THERM2_CTL_TM_SELECT)
+				tm2 = 1;
+		} else if (l & MSR_IA32_MISC_ENABLE_TM2)
+			tm2 = 1;
+	}
+
 	/* We'll mask the thermal vector in the lapic till we're ready: */
 	h = THERMAL_APIC_VECTOR | APIC_DM_FIXED | APIC_LVT_MASKED;
 	apic_write(APIC_LVTTHMR, h);