[PATCH] x86-64: Disable local APIC timer use on AMD systems with C1E

AMD dual core laptops with C1E do not run the APIC timer correctly
when they go idle. Previously the code assumed this only happened
on C2 or deeper.  But not all of these systems report support C2.

Use a AMD supplied snippet to detect C1E being enabled and then disable
local apic timer use.

This supercedes an earlier workaround using DMI detection of specific systems.

Thanks to Mark Langsdorf for the detection snippet.

Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 37 insertions, 29 deletions

diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index e88415282a6..93aa911646a 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -272,32 +272,6 @@ static void __devinit setup_APIC_timer(void)
 }
 
 /*
- * Detect systems with known broken BIOS implementations
- */
-static int __init lapic_check_broken_bios(struct dmi_system_id *d)
-{
-	printk(KERN_NOTICE "%s detected: disabling lapic timer.\n",
-		       d->ident);
-	local_apic_timer_disabled = 1;
-	return 0;
-}
-
-static struct dmi_system_id __initdata broken_bios_dmi_table[] = {
-	{
-		/*
-		 * BIOS exports only C1 state, but uses deeper power
-		 * modes behind the kernels back.
-		 */
-		  .callback = lapic_check_broken_bios,
-		  .ident = "HP nx6325",
-		  .matches = {
-			DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq nx6325"),
-		  },
-	 },
-	 {}
-};
-
-/*
  * In this functions we calibrate APIC bus clocks to the external timer.
  *
  * We want to do the calibration only once since we want to have local timer
@@ -372,12 +346,12 @@ void __init setup_boot_APIC_clock(void)
 	long delta, deltapm;
 	int pm_referenced = 0;
 
-	/* Detect know broken systems */
-	dmi_check_system(broken_bios_dmi_table);
+	if (boot_cpu_has(X86_FEATURE_LAPIC_TIMER_BROKEN))
+		local_apic_timer_disabled = 1;
 
 	/*
 	 * The local apic timer can be disabled via the kernel
-	 * commandline or from the dmi quirk above. Register the lapic
+	 * commandline or from the test above. Register the lapic
 	 * timer as a dummy clock event source on SMP systems, so the
 	 * broadcast mechanism is used. On UP systems simply ignore it.
 	 */
diff --git a/arch/i386/kernel/cpu/amd.c b/arch/i386/kernel/cpu/amd.c
index 41cfea57232..2d47db48297 100644
--- a/arch/i386/kernel/cpu/amd.c
+++ b/arch/i386/kernel/cpu/amd.c
@@ -22,6 +22,37 @@
 extern void vide(void);
 __asm__(".align 4\nvide: ret");
 
+#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)
 {
 	u32 l, h;
@@ -241,6 +272,9 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
 
 	if (cpuid_eax(0x80000000) >= 0x80000006)
 		num_cache_leaves = 3;
+
+	if (amd_apic_timer_broken())
+		set_bit(X86_FEATURE_LAPIC_TIMER_BROKEN, c->x86_capability);
 }
 
 static unsigned int __cpuinit amd_size_cache(struct cpuinfo_x86 * c, unsigned int size)