From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 12 Oct 2007 21:04:07 +0000 (+0200)
Subject: x86: disable apic timer for AMD C1E enabled CPUs
X-Git-Tag: v2.6.24-rc1~1397^2~15
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fb79d22e1d4b06385796cc0db0084a2e07beccee;p=linux-2.6

x86: disable apic timer for AMD C1E enabled CPUs

AMDs C1E enabled CPUs stop the local apic timer, when both cores are
idle. This is a hardware feature which breaks highres/dynticks.
Add the same quirk as we have for 32 bit already.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---

diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index b0237caff7..118830cba1 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -44,7 +44,7 @@ int apic_verbosity;
 int apic_runs_main_timer;
 int apic_calibrate_pmtmr __initdata;
 
-int disable_apic_timer __initdata;
+int disable_apic_timer __cpuinitdata;
 
 /* Local APIC timer works in C2? */
 int local_apic_timer_c2_ok;
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index af838f6b0b..32054bf5ba 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -546,6 +546,37 @@ static void __init amd_detect_cmp(struct cpuinfo_x86 *c)
 #endif
 }
 
+#define ENABLE_C1E_MASK		0x18000000
+#define CPUID_PROCESSOR_SIGNATURE	1
+#define CPUID_XFAM		0x0ff00000
+#define CPUID_XFAM_K8		0x00000000
+#define CPUID_XFAM_10H		0x00100000
+#define CPUID_XFAM_11H		0x00200000
+#define CPUID_XMOD		0x000f0000
+#define CPUID_XMOD_REV_F	0x00040000
+
+/* AMD systems with C1E don't have a working lAPIC timer. Check for that. */
+static __cpuinit int amd_apic_timer_broken(void)
+{
+	u32 lo, hi;
+	u32 eax = cpuid_eax(CPUID_PROCESSOR_SIGNATURE);
+	switch (eax & CPUID_XFAM) {
+	case CPUID_XFAM_K8:
+		if ((eax & CPUID_XMOD) < CPUID_XMOD_REV_F)
+			break;
+	case CPUID_XFAM_10H:
+	case CPUID_XFAM_11H:
+		rdmsr(MSR_K8_ENABLE_C1E, lo, hi);
+		if (lo & ENABLE_C1E_MASK)
+			return 1;
+		break;
+	default:
+		/* err on the side of caution */
+		return 1;
+	}
+	return 0;
+}
+
 static void __cpuinit init_amd(struct cpuinfo_x86 *c)
 {
 	unsigned level;
@@ -617,6 +648,9 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
 	/* Family 10 doesn't support C states in MWAIT so don't use it */
 	if (c->x86 == 0x10 && !force_mwait)
 		clear_bit(X86_FEATURE_MWAIT, &c->x86_capability);
+
+	if (amd_apic_timer_broken())
+		disable_apic_timer = 1;
 }
 
 static void __cpuinit detect_ht(struct cpuinfo_x86 *c)
diff --git a/include/asm-x86/apic_64.h b/include/asm-x86/apic_64.h
index 81335e9536..f32f654d1f 100644
--- a/include/asm-x86/apic_64.h
+++ b/include/asm-x86/apic_64.h
@@ -19,6 +19,7 @@
 extern int apic_verbosity;
 extern int apic_runs_main_timer;
 extern int ioapic_force;
+extern int disable_apic_timer;
 
 /*
  * Define the default level of output to be very little