2 files changed, 33 insertions, 17 deletions

diff --git a/Documentation/acpi/apei/einj.txt b/Documentation/acpi/apei/einj.txt
index dfab71848dc8..5cc699ba5453 100644
--- a/Documentation/acpi/apei/einj.txt
+++ b/Documentation/acpi/apei/einj.txt
@@ -48,12 +48,19 @@ directory apei/einj. The following files are provided.
 - param1
   This file is used to set the first error parameter value. Effect of
   parameter depends on error_type specified. For memory error, this is
-  physical memory address.
+  physical memory address.  Only available if param_extension module
+  parameter is specified.
 
 - param2
   This file is used to set the second error parameter value. Effect of
   parameter depends on error_type specified. For memory error, this is
-  physical memory address mask.
+  physical memory address mask.  Only available if param_extension
+  module parameter is specified.
+
+Injecting parameter support is a BIOS version specific extension, that
+is, it only works on some BIOS version.  If you want to use it, please
+make sure your BIOS version has the proper support and specify
+"param_extension=y" in module parameter.
 
 For more information about EINJ, please refer to ACPI specification
 version 4.0, section 17.5.
diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index ab821f1cfa1f..589b96c38704 100644
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -46,7 +46,8 @@
  * Some BIOSes allow parameters to the SET_ERROR_TYPE entries in the
  * EINJ table through an unpublished extension. Use with caution as
  * most will ignore the parameter and make their own choice of address
- * for error injection.
+ * for error injection.  This extension is used only if
+ * param_extension module parameter is specified.
  */
 struct einj_parameter {
         u64 type;
@@ -65,6 +66,9 @@ struct einj_parameter {
         ((struct acpi_whea_header *)((char *)(tab) +                    \
                                     sizeof(struct acpi_table_einj)))
 
+static bool param_extension;
+module_param(param_extension, bool, 0);
+
 static struct acpi_table_einj *einj_tab;
 
 static struct apei_resources einj_resources;
@@ -489,14 +493,6 @@ static int __init einj_init(void)
                                      einj_debug_dir, NULL, &error_type_fops);
         if (!fentry)
                 goto err_cleanup;
-        fentry = debugfs_create_x64("param1", S_IRUSR | S_IWUSR,
-                                    einj_debug_dir, &error_param1);
-        if (!fentry)
-                goto err_cleanup;
-        fentry = debugfs_create_x64("param2", S_IRUSR | S_IWUSR,
-                                    einj_debug_dir, &error_param2);
-        if (!fentry)
-                goto err_cleanup;
         fentry = debugfs_create_file("error_inject", S_IWUSR,
                                      einj_debug_dir, NULL, &error_inject_fops);
         if (!fentry)
@@ -513,12 +509,23 @@ static int __init einj_init(void)
         rc = apei_exec_pre_map_gars(&ctx);
         if (rc)
                 goto err_release;
-        param_paddr = einj_get_parameter_address();
-        if (param_paddr) {
-                einj_param = ioremap(param_paddr, sizeof(*einj_param));
-                rc = -ENOMEM;
-                if (!einj_param)
-                        goto err_unmap;
+        if (param_extension) {
+                param_paddr = einj_get_parameter_address();
+                if (param_paddr) {
+                        einj_param = ioremap(param_paddr, sizeof(*einj_param));
+                        rc = -ENOMEM;
+                        if (!einj_param)
+                                goto err_unmap;
+                        fentry = debugfs_create_x64("param1", S_IRUSR | S_IWUSR,
+                                                    einj_debug_dir, &error_param1);
+                        if (!fentry)
+                                goto err_unmap;
+                        fentry = debugfs_create_x64("param2", S_IRUSR | S_IWUSR,
+                                                    einj_debug_dir, &error_param2);
+                        if (!fentry)
+                                goto err_unmap;
+                } else
+                        pr_warn(EINJ_PFX "Parameter extension is not supported.\n");
         }
 
         pr_info(EINJ_PFX "Error INJection is initialized.\n");
@@ -526,6 +533,8 @@ static int __init einj_init(void)
         return 0;
 
 err_unmap:
+        if (einj_param)
+                iounmap(einj_param);
         apei_exec_post_unmap_gars(&ctx);
 err_release:
         apei_resources_release(&einj_resources);