platform/x86: think-lmi: Add bulk save feature

On Lenovo platforms there is a limitation in the number of times an
attribute can be saved. This is an architectural limitation and it limits
the number of attributes that can be modified to 48.
A solution for this is instead of the attribute being saved after every
modification allow a user to bulk set the attributes and then trigger a
final save. This allows unlimited attributes.

This patch introduces a save_settings attribute that can be configured to
either single or bulk mode by the user.
Single mode is the default but customers who want to avoid the 48
attribute limit can enable bulk mode.

Displaying the save_settings attribute will display the enabled mode.

When in bulk mode writing 'save' to the save_settings attribute will
trigger a save. Once this has been done a reboot is required before more
attributes can be modified.

Signed-off-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Link: https://lore.kernel.org/r/20230919141530.4805-1-mpearson-lenovo@squebb.ca
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 137 insertions, 15 deletions

diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 79346881cadb..d329626720df 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -985,6 +985,13 @@ static ssize_t current_value_store(struct kobject *kobj,
 	if (!tlmi_priv.can_set_bios_settings)
 		return -EOPNOTSUPP;
 
+	/*
+	 * If we are using bulk saves a reboot should be done once save has
+	 * been called
+	 */
+	if (tlmi_priv.save_mode == TLMI_SAVE_BULK && tlmi_priv.reboot_required)
+		return -EPERM;
+
 	new_setting = kstrdup(buf, GFP_KERNEL);
 	if (!new_setting)
 		return -ENOMEM;
@@ -1011,10 +1018,11 @@ static ssize_t current_value_store(struct kobject *kobj,
 		ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTING_CERT_GUID, set_str);
 		if (ret)
 			goto out;
-		ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID,
-				tlmi_priv.pwd_admin->save_signature);
-		if (ret)
-			goto out;
+		if (tlmi_priv.save_mode == TLMI_SAVE_BULK)
+			tlmi_priv.save_required = true;
+		else
+			ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID,
+					       tlmi_priv.pwd_admin->save_signature);
 	} else if (tlmi_priv.opcode_support) {
 		/*
 		 * If opcode support is present use that interface.
@@ -1033,14 +1041,17 @@ static ssize_t current_value_store(struct kobject *kobj,
 		if (ret)
 			goto out;
 
-		if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
-			ret = tlmi_opcode_setting("WmiOpcodePasswordAdmin",
-						  tlmi_priv.pwd_admin->password);
-			if (ret)
-				goto out;
+		if (tlmi_priv.save_mode == TLMI_SAVE_BULK) {
+			tlmi_priv.save_required = true;
+		} else {
+			if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
+				ret = tlmi_opcode_setting("WmiOpcodePasswordAdmin",
+							  tlmi_priv.pwd_admin->password);
+				if (ret)
+					goto out;
+			}
+			ret = tlmi_save_bios_settings("");
 		}
-
-		ret = tlmi_save_bios_settings("");
 	} else { /* old non-opcode based authentication method (deprecated) */
 		if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
 			auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
@@ -1068,10 +1079,14 @@ static ssize_t current_value_store(struct kobject *kobj,
 		if (ret)
 			goto out;
 
-		if (auth_str)
-			ret = tlmi_save_bios_settings(auth_str);
-		else
-			ret = tlmi_save_bios_settings("");
+		if (tlmi_priv.save_mode == TLMI_SAVE_BULK) {
+			tlmi_priv.save_required = true;
+		} else {
+			if (auth_str)
+				ret = tlmi_save_bios_settings(auth_str);
+			else
+				ret = tlmi_save_bios_settings("");
+		}
 	}
 	if (!ret && !tlmi_priv.pending_changes) {
 		tlmi_priv.pending_changes = true;
@@ -1152,6 +1167,107 @@ static ssize_t pending_reboot_show(struct kobject *kobj, struct kobj_attribute *
 
 static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
 
+static const char * const save_mode_strings[] = {
+	[TLMI_SAVE_SINGLE] = "single",
+	[TLMI_SAVE_BULK] = "bulk",
+	[TLMI_SAVE_SAVE] = "save"
+};
+
+static ssize_t save_settings_show(struct kobject *kobj, struct kobj_attribute *attr,
+				  char *buf)
+{
+	/* Check that setting is valid */
+	if (WARN_ON(tlmi_priv.save_mode < TLMI_SAVE_SINGLE ||
+		    tlmi_priv.save_mode > TLMI_SAVE_BULK))
+		return -EIO;
+	return sysfs_emit(buf, "%s\n", save_mode_strings[tlmi_priv.save_mode]);
+}
+
+static ssize_t save_settings_store(struct kobject *kobj, struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	char *auth_str = NULL;
+	int ret = 0;
+	int cmd;
+
+	cmd = sysfs_match_string(save_mode_strings, buf);
+	if (cmd < 0)
+		return cmd;
+
+	/* Use lock in case multiple WMI operations needed */
+	mutex_lock(&tlmi_mutex);
+
+	switch (cmd) {
+	case TLMI_SAVE_SINGLE:
+	case TLMI_SAVE_BULK:
+		tlmi_priv.save_mode = cmd;
+		goto out;
+	case TLMI_SAVE_SAVE:
+		/* Check if supported*/
+		if (!tlmi_priv.can_set_bios_settings ||
+		    tlmi_priv.save_mode == TLMI_SAVE_SINGLE) {
+			ret = -EOPNOTSUPP;
+			goto out;
+		}
+		/* Check there is actually something to save */
+		if (!tlmi_priv.save_required) {
+			ret = -ENOENT;
+			goto out;
+		}
+		/* Check if certificate authentication is enabled and active */
+		if (tlmi_priv.certificate_support && tlmi_priv.pwd_admin->cert_installed) {
+			if (!tlmi_priv.pwd_admin->signature ||
+			    !tlmi_priv.pwd_admin->save_signature) {
+				ret = -EINVAL;
+				goto out;
+			}
+			ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID,
+					       tlmi_priv.pwd_admin->save_signature);
+			if (ret)
+				goto out;
+		} else if (tlmi_priv.opcode_support) {
+			if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
+				ret = tlmi_opcode_setting("WmiOpcodePasswordAdmin",
+							  tlmi_priv.pwd_admin->password);
+				if (ret)
+					goto out;
+			}
+			ret = tlmi_save_bios_settings("");
+		} else { /* old non-opcode based authentication method (deprecated) */
+			if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
+				auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
+						     tlmi_priv.pwd_admin->password,
+						     encoding_options[tlmi_priv.pwd_admin->encoding],
+						     tlmi_priv.pwd_admin->kbdlang);
+				if (!auth_str) {
+					ret = -ENOMEM;
+					goto out;
+				}
+			}
+
+			if (auth_str)
+				ret = tlmi_save_bios_settings(auth_str);
+			else
+				ret = tlmi_save_bios_settings("");
+		}
+		tlmi_priv.save_required = false;
+		tlmi_priv.reboot_required = true;
+
+		if (!ret && !tlmi_priv.pending_changes) {
+			tlmi_priv.pending_changes = true;
+			/* let userland know it may need to check reboot pending again */
+			kobject_uevent(&tlmi_priv.class_dev->kobj, KOBJ_CHANGE);
+		}
+		break;
+	}
+out:
+	mutex_unlock(&tlmi_mutex);
+	kfree(auth_str);
+	return ret ?: count;
+}
+
+static struct kobj_attribute save_settings = __ATTR_RW(save_settings);
+
 /* ---- Debug interface--------------------------------------------------------- */
 static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr,
 				const char *buf, size_t count)
@@ -1221,6 +1337,8 @@ static void tlmi_release_attr(void)
 		}
 	}
 	sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &pending_reboot.attr);
+	sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &save_settings.attr);
+
 	if (tlmi_priv.can_debug_cmd && debug_support)
 		sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr);
 
@@ -1302,6 +1420,10 @@ static int tlmi_sysfs_init(void)
 	if (ret)
 		goto fail_create_attr;
 
+	ret = sysfs_create_file(&tlmi_priv.attribute_kset->kobj, &save_settings.attr);
+	if (ret)
+		goto fail_create_attr;
+
 	if (tlmi_priv.can_debug_cmd && debug_support) {
 		ret = sysfs_create_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr);
 		if (ret)