[PATCH] i386: Disable nmi watchdog on all ThinkPads

Even newer Thinkpads have bugs in SMM code that causes hangs with
NMI watchdog.
Signed-off-by: Andi Kleen <ak@suse.de>

arch/i386/kernel/nmi.c

@@ -219,11 +219,11 @@ static int __init check_nmi_watchdog(void)
 	int cpu;
 
 	/* Enable NMI watchdog for newer systems.
-           Actually it should be safe for most systems before 2004 too except
-	   for some IBM systems that corrupt registers when NMI happens
-	   during SMM. Unfortunately we don't have more exact information
- 	   on these and use this coarse check. */
-	if (nmi_watchdog == NMI_DEFAULT && dmi_get_year(DMI_BIOS_DATE) >= 2004)
+	   Probably safe on most older systems too, but let's be careful.
+	   IBM ThinkPads use INT10 inside SMM and that allows early NMI inside SMM
+	   which hangs the system. Disable watchdog for all thinkpads */
+	if (nmi_watchdog == NMI_DEFAULT && dmi_get_year(DMI_BIOS_DATE) >= 2004 &&
+		!dmi_name_in_vendors("ThinkPad"))
 		nmi_watchdog = NMI_LOCAL_APIC;
 
 	if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DEFAULT))

drivers/firmware/dmi_scan.c

@@ -326,6 +326,26 @@ char *dmi_get_system_info(int field)
 }
 EXPORT_SYMBOL(dmi_get_system_info);
 
+
+/**
+ *	dmi_name_in_vendors - Check if string is anywhere in the DMI vendor information.
+ *	@str: 	Case sensitive Name
+ */
+int dmi_name_in_vendors(char *str)
+{
+	static int fields[] = { DMI_BIOS_VENDOR, DMI_BIOS_VERSION, DMI_SYS_VENDOR,
+				DMI_PRODUCT_NAME, DMI_PRODUCT_VERSION, DMI_BOARD_VENDOR,
+				DMI_BOARD_NAME, DMI_BOARD_VERSION, DMI_NONE };
+	int i;
+	for (i = 0; fields[i] != DMI_NONE; i++) {
+		int f = fields[i];
+		if (dmi_ident[f] && strstr(dmi_ident[f], str))
+			return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(dmi_name_in_vendors);
+
 /**
  *	dmi_find_device - find onboard device by type/name
  *	@type: device type or %DMI_DEV_TYPE_ANY to match all device types

include/linux/dmi.h

@@ -69,6 +69,7 @@ extern struct dmi_device * dmi_find_device(int type, const char *name,
 	struct dmi_device *from);
 extern void dmi_scan_machine(void);
 extern int dmi_get_year(int field);
+extern int dmi_name_in_vendors(char *str);
 
 #else
 
@@ -77,6 +78,7 @@ static inline char * dmi_get_system_info(int field) { return NULL; }
 static inline struct dmi_device * dmi_find_device(int type, const char *name,
 	struct dmi_device *from) { return NULL; }
 static inline int dmi_get_year(int year) { return 0; }
+static inline int dmi_name_in_vendors(char *s) { return 0; }
 
 #endif