@@ -101,6 +101,31 @@ int dell_smbios_smm_call(struct calling_interface_buffer *input)
return 0;
}
+/* When enabled this indicates that SMM won't work */
+static int test_wsmt_enabled(void)
+{
+ struct calling_interface_token *token;
+
+ /* if token doesn't exist, SMM will work */
+ token = dell_smbios_find_token(WSMT_EN_TOKEN);
+ if (!token)
+ return 0;
+
+ /* if token exists, try to access over SMM */
+ buffer->class = CLASS_TOKEN_READ;
+ buffer->select = SELECT_TOKEN_STD;
+ memset(buffer, 0, sizeof(struct calling_interface_buffer));
+ buffer->input[0] = token->location;
+ dell_smbios_smm_call(buffer);
+
+ /* if lookup failed, we know WSMT was enabled */
+ if (buffer->output[0] != 0)
+ return 1;
+
+ /* query token status if it didn't fail */
+ return (buffer->output[1] == token->value);
+}
+
static int __init dell_smbios_smm_init(void)
{
int ret;
@@ -114,6 +139,13 @@ static int __init dell_smbios_smm_init(void)
dmi_walk(find_cmd_address, NULL);
+ ret = test_wsmt_enabled();
+ pr_debug("WSMT enable test: %d\n", ret);
+ if (ret) {
+ ret = -ENODEV;
+ goto fail_wsmt;
+ }
+
platform_device = platform_device_alloc("dell-smbios", 1);
if (!platform_device) {
ret = -ENOMEM;
@@ -137,6 +169,7 @@ static int __init dell_smbios_smm_init(void)
fail_platform_device_add:
platform_device_put(platform_device);
+fail_wsmt:
fail_platform_device_alloc:
free_page((unsigned long)buffer);
return ret;
@@ -44,6 +44,8 @@
#define KBD_LED_AUTO_100_TOKEN 0x02F6
#define GLOBAL_MIC_MUTE_ENABLE 0x0364
#define GLOBAL_MIC_MUTE_DISABLE 0x0365
+#define WSMT_EN_TOKEN 0x04EC
+#define WSMT_DIS_TOKEN 0x04ED
struct notifier_block;
WSMT is as an attestation to the OS that the platform won't modify memory outside of pre-defined areas. If a platform has WSMT enabled in BIOS setup, SMM calls through dcdbas will fail. The only way to access platform data in these instances is through the WMI SMBIOS calling interface. Signed-off-by: Mario Limonciello <mario.limonciello@dell.com> --- drivers/platform/x86/dell-smbios-smm.c | 33 +++++++++++++++++++++++++++++++++ drivers/platform/x86/dell-smbios.h | 2 ++ 2 files changed, 35 insertions(+)