[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>

3 files changed, 27 insertions, 5 deletions

diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index 3e8e3adb0489..eaafe233a5da 100644
--- a/arch/i386/kernel/nmi.c
+++ b/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))
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index b8b596d5778d..37deee6c0c1c 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/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
diff --git a/include/linux/dmi.h b/include/linux/dmi.h
index 38dc403be70b..904bf3d2d90b 100644
--- a/include/linux/dmi.h
+++ b/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