From ae858286a957c7ab8f12320a4c4173c35c911513 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 9 Jun 2008 18:04:27 +0200
Subject: [PATCH] --- yaml --- r: 99429 b: refs/heads/master c:
 09fd4b4ef5bc7e5222c13acec1bee8cd252fb63f h: refs/heads/master i:   99427:
 690b759a1dea2b30828da8a658efa3c8e3a19907 v: v3

---
 [refs]                          |  2 +-
 trunk/arch/x86/kernel/process.c | 28 ++++++++++++++++++++--------
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/[refs] b/[refs]
index f3a8f3806f2b..8b341c4c1572 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 732d7be17b98ebfd59e5864c3490f19856fa832c
+refs/heads/master: 09fd4b4ef5bc7e5222c13acec1bee8cd252fb63f
diff --git a/trunk/arch/x86/kernel/process.c b/trunk/arch/x86/kernel/process.c
index b3078f4ce25b..fe415ba606e0 100644
--- a/trunk/arch/x86/kernel/process.c
+++ b/trunk/arch/x86/kernel/process.c
@@ -122,19 +122,31 @@ static void poll_idle(void)
  *
  * idle=mwait overrides this decision and forces the usage of mwait.
  */
+
+#define MWAIT_INFO			0x05
+#define MWAIT_ECX_EXTENDED_INFO		0x01
+#define MWAIT_EDX_C1			0xf0
+
 static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
 {
+	u32 eax, ebx, ecx, edx;
+
 	if (force_mwait)
 		return 1;
 
-	if (c->x86_vendor == X86_VENDOR_AMD) {
-		switch(c->x86) {
-		case 0x10:
-		case 0x11:
-			return 0;
-		}
-	}
-	return 1;
+	if (c->cpuid_level < MWAIT_INFO)
+		return 0;
+
+	cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
+	/* Check, whether EDX has extended info about MWAIT */
+	if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
+		return 1;
+
+	/*
+	 * edx enumeratios MONITOR/MWAIT extensions. Check, whether
+	 * C1  supports MWAIT
+	 */
+	return (edx & MWAIT_EDX_C1);
 }
 
 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)