Commit 134038b0 authored by Mario Limonciello's avatar Mario Limonciello Committed by Hans de Goede
Browse files

platform/x86: wmi: Allow duplicate GUIDs for drivers that use struct wmi_driver 



The WMI subsystem in the kernel currently tracks WMI devices by
a GUID string not by ACPI device.  The GUID used by the `wmi-bmof`
module however is available from many devices on nearly every machine.

This originally was thought to be a bug, but as it happens on most
machines it is a design mistake.  It has been fixed by tying an ACPI
device to the driver with struct wmi_driver. So drivers that have
moved over to struct wmi_driver can actually support multiple
instantiations of a GUID without any problem.

Add an allow list into wmi.c for GUIDs that the drivers that are known
to use struct wmi_driver.  The list is populated with `wmi-bmof` right
now. The additional instances of that in sysfs with be suffixed with -%d

Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20220829201500.6341-1-mario.limonciello@amd.com


Reviewed-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
parent a2bdf10c

drivers/platform/x86/wmi.c

+40 −9
Original line number Diff line number Diff line
@@ -105,6 +105,12 @@ static const struct acpi_device_id wmi_device_ids[] = { 
};

MODULE_DEVICE_TABLE(acpi, wmi_device_ids);



/* allow duplicate GUIDs as these device drivers use struct wmi_driver */

static const char * const allow_duplicates[] = {

	"05901221-D566-11D1-B2F0-00A0C9062910",	/* wmi-bmof */

	NULL

};



static struct platform_driver acpi_wmi_driver = {

	.driver = {

		.name = "acpi-wmi",
@@ -1073,6 +1079,23 @@ static const struct device_type wmi_type_data = { 
	.release = wmi_dev_release,

};



/*

 * _WDG is a static list that is only parsed at startup,

 * so it's safe to count entries without extra protection.

 */

static int guid_count(const guid_t *guid)

{

	struct wmi_block *wblock;

	int count = 0;



	list_for_each_entry(wblock, &wmi_block_list, list) {

		if (guid_equal(&wblock->gblock.guid, guid))

			count++;

	}



	return count;

}



static int wmi_create_device(struct device *wmi_bus_dev,

			     struct wmi_block *wblock,

			     struct acpi_device *device)
@@ -1080,6 +1103,7 @@ static int wmi_create_device(struct device *wmi_bus_dev, 
	struct acpi_device_info *info;

	char method[WMI_ACPI_METHOD_NAME_SIZE];

	int result;

	uint count;



	if (wblock->gblock.flags & ACPI_WMI_EVENT) {

		wblock->dev.dev.type = &wmi_type_event;
@@ -1134,6 +1158,10 @@ static int wmi_create_device(struct device *wmi_bus_dev, 
	wblock->dev.dev.bus = &wmi_bus_type;

	wblock->dev.dev.parent = wmi_bus_dev;



	count = guid_count(&wblock->gblock.guid);

	if (count)

		dev_set_name(&wblock->dev.dev, "%pUL-%d", &wblock->gblock.guid, count);

	else

		dev_set_name(&wblock->dev.dev, "%pUL", &wblock->gblock.guid);



	device_initialize(&wblock->dev.dev);
@@ -1154,11 +1182,20 @@ static void wmi_free_devices(struct acpi_device *device) 
	}

}



static bool guid_already_parsed(struct acpi_device *device, const guid_t *guid)

static bool guid_already_parsed_for_legacy(struct acpi_device *device, const guid_t *guid)

{

	struct wmi_block *wblock;



	list_for_each_entry(wblock, &wmi_block_list, list) {

		/* skip warning and register if we know the driver will use struct wmi_driver */

		for (int i = 0; allow_duplicates[i] != NULL; i++) {

			guid_t tmp;



			if (guid_parse(allow_duplicates[i], &tmp))

				continue;

			if (guid_equal(&tmp, guid))

				return false;

		}

		if (guid_equal(&wblock->gblock.guid, guid)) {

			/*

			 * Because we historically didn't track the relationship
@@ -1208,13 +1245,7 @@ static int parse_wdg(struct device *wmi_bus_dev, struct acpi_device *device) 
		if (debug_dump_wdg)

			wmi_dump_wdg(&gblock[i]);



		/*

		 * Some WMI devices, like those for nVidia hooks, have a

		 * duplicate GUID. It's not clear what we should do in this

		 * case yet, so for now, we'll just ignore the duplicate

		 * for device creation.

		 */

		if (guid_already_parsed(device, &gblock[i].guid))

		if (guid_already_parsed_for_legacy(device, &gblock[i].guid))

			continue;



		wblock = kzalloc(sizeof(*wblock), GFP_KERNEL);