ACPI: Disable _GTS and _BFS support by default

Executing BIOS code paths not exercised by Windows
tends to get Linux into trouble.

However, if a system does benefit from _GTS or _BFS,
acpi.gts=1 an acpi.bfs=1 are now available to enable them.

http://bugzilla.kernel.org/show_bug.cgi?id=13041

Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 53 insertions, 17 deletions

diff --git a/drivers/acpi/acpica/hwsleep.c b/drivers/acpi/acpica/hwsleep.c
index baa5fc05e124..db307a356f08 100644
--- a/drivers/acpi/acpica/hwsleep.c
+++ b/drivers/acpi/acpica/hwsleep.c
@@ -211,6 +211,12 @@ acpi_status acpi_enter_sleep_state_prep(u8 sleep_state)
 
 ACPI_EXPORT_SYMBOL(acpi_enter_sleep_state_prep)
 
+static unsigned int gts, bfs;
+module_param(gts, uint, 0644);
+module_param(bfs, uint, 0644);
+MODULE_PARM_DESC(gts, "Enable evaluation of _GTS on suspend.");
+MODULE_PARM_DESC(bfs, "Enable evaluation of _BFS on resume".);
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_enter_sleep_state
@@ -278,16 +284,18 @@ acpi_status asmlinkage acpi_enter_sleep_state(u8 sleep_state)
                 return_ACPI_STATUS(status);
         }
 
-        /* Execute the _GTS method */
+        if (gts) {
+                /* Execute the _GTS method */
 
-        arg_list.count = 1;
-        arg_list.pointer = &arg;
-        arg.type = ACPI_TYPE_INTEGER;
-        arg.integer.value = sleep_state;
+                arg_list.count = 1;
+                arg_list.pointer = &arg;
+                arg.type = ACPI_TYPE_INTEGER;
+                arg.integer.value = sleep_state;
 
-        status = acpi_evaluate_object(NULL, METHOD_NAME__GTS, &arg_list, NULL);
-        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
-                return_ACPI_STATUS(status);
+                status = acpi_evaluate_object(NULL, METHOD_NAME__GTS, &arg_list, NULL);
+                if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
+                        return_ACPI_STATUS(status);
+                }
         }
 
         /* Get current value of PM1A control */
@@ -513,18 +521,19 @@ acpi_status acpi_leave_sleep_state_prep(u8 sleep_state)
                 }
         }
 
-        /* Execute the _BFS method */
+        if (bfs) {
+                /* Execute the _BFS method */
 
-        arg_list.count = 1;
-        arg_list.pointer = &arg;
-        arg.type = ACPI_TYPE_INTEGER;
-        arg.integer.value = sleep_state;
+                arg_list.count = 1;
+                arg_list.pointer = &arg;
+                arg.type = ACPI_TYPE_INTEGER;
+                arg.integer.value = sleep_state;
 
-        status = acpi_evaluate_object(NULL, METHOD_NAME__BFS, &arg_list, NULL);
-        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
-                ACPI_EXCEPTION((AE_INFO, status, "During Method _BFS"));
+                status = acpi_evaluate_object(NULL, METHOD_NAME__BFS, &arg_list, NULL);
+                if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
+                        ACPI_EXCEPTION((AE_INFO, status, "During Method _BFS"));
+                }
         }
-
         return_ACPI_STATUS(status);
 }
 
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 779e4e500df4..9042875ac942 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -713,6 +713,32 @@ static void acpi_power_off(void)
         acpi_enter_sleep_state(ACPI_STATE_S5);
 }
 
+/*
+ * ACPI 2.0 created the optional _GTS and _BFS,
+ * but industry adoption has been neither rapid nor broad.
+ *
+ * Linux gets into trouble when it executes poorly validated
+ * paths through the BIOS, so disable _GTS and _BFS by default,
+ * but do speak up and offer the option to enable them.
+ */
+void __init acpi_gts_bfs_check(void)
+{
+        acpi_handle dummy;
+
+        if (ACPI_SUCCESS(acpi_get_handle(ACPI_ROOT_OBJECT, METHOD_NAME__GTS, &dummy)))
+        {
+                printk(KERN_NOTICE PREFIX "BIOS offers _GTS\n");
+                printk(KERN_NOTICE PREFIX "If \"acpi.gts=1\" improves suspend, "
+                        "please notify linux-acpi@vger.kernel.org\n");
+        }
+        if (ACPI_SUCCESS(acpi_get_handle(ACPI_ROOT_OBJECT, METHOD_NAME__BFS, &dummy)))
+        {
+                printk(KERN_NOTICE PREFIX "BIOS offers _BFS\n");
+                printk(KERN_NOTICE PREFIX "If \"acpi.bfs=1\" improves resume, "
+                        "please notify linux-acpi@vger.kernel.org\n");
+        }
+}
+
 int __init acpi_sleep_init(void)
 {
         acpi_status status;
@@ -771,5 +797,6 @@ int __init acpi_sleep_init(void)
          * object can also be evaluated when the system enters S5.
          */
         register_reboot_notifier(&tts_notifier);
+        acpi_gts_bfs_check();
         return 0;
 }