platform/x86: hp-wmi: Changing bios_args.data to be dynamically allocated

The purpose of this patch is to remove 128 bytes buffer limitation
imposed in bios_args structure.

A limiting factor discovered during this investigation was the struct
bios_args.data size restriction.  The data member size limits all
possible WMI commands to those requiring buffer size of 128 bytes or
less. Several WMI commands and queries require a buffer size larger
than 128 bytes hence limiting current and feature supported by the
driver. It is for this reason, struct bios_args.data changed and is
dynamically allocated.  hp_wmi_perform_query function changed to
handle the memory allocation and release of any required buffer size.

All changes were validated on a HP ZBook Workstation notebook,
HP EliteBook x360, and HP EliteBook 850 G8.  Additional
validation was included in the test process to ensure no other
commands were incorrectly handled.
Signed-off-by: Jorge Lopez <jorge.lopez2@hp.com>
Link: https://lore.kernel.org/r/20220310210853.28367-5-jorge.lopez2@hp.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/hp-wmi.c

@@ -82,12 +82,17 @@ enum hp_wmi_event_ids {
 	HPWMI_BATTERY_CHARGE_PERIOD	= 0x10,
 };
 
+/*
+ * struct bios_args buffer is dynamically allocated.  New WMI command types
+ * were introduced that exceeds 128-byte data size.  Changes to handle
+ * the data size allocation scheme were kept in hp_wmi_perform_qurey function.
+ */
 struct bios_args {
 	u32 signature;
 	u32 command;
 	u32 commandtype;
 	u32 datasize;
-	u8 data[128];
+	u8 data[];
 };
 
 enum hp_wmi_commandtype {
@@ -266,37 +271,43 @@ static inline int encode_outsize_for_pvsz(int outsize)
 static int hp_wmi_perform_query(int query, enum hp_wmi_command command,
 				void *buffer, int insize, int outsize)
 {
-	int mid;
+	struct acpi_buffer input, output = { ACPI_ALLOCATE_BUFFER, NULL };
 	struct bios_return *bios_return;
-	int actual_outsize;
-	union acpi_object *obj;
-	struct bios_args args = {
-		.signature = 0x55434553,
-		.command = command,
-		.commandtype = query,
-		.datasize = insize,
-		.data = { 0 },
-	};
-	struct acpi_buffer input = { sizeof(struct bios_args), &args };
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
-	int ret = 0;
+	union acpi_object *obj = NULL;
+	struct bios_args *args = NULL;
+	int mid, actual_outsize, ret;
+	size_t bios_args_size;
 
 	mid = encode_outsize_for_pvsz(outsize);
 	if (WARN_ON(mid < 0))
 		return mid;
 
-	if (WARN_ON(insize > sizeof(args.data)))
-		return -EINVAL;
-	memcpy(&args.data[0], buffer, insize);
+	bios_args_size = struct_size(args, data, insize);
+	args = kmalloc(bios_args_size, GFP_KERNEL);
+	if (!args)
+		return -ENOMEM;
 
-	wmi_evaluate_method(HPWMI_BIOS_GUID, 0, mid, &input, &output);
+	input.length = bios_args_size;
+	input.pointer = args;
 
-	obj = output.pointer;
+	args->signature = 0x55434553;
+	args->command = command;
+	args->commandtype = query;
+	args->datasize = insize;
+	memcpy(args->data, buffer, flex_array_size(args, data, insize));
 
-	if (!obj)
-		return -EINVAL;
+	ret = wmi_evaluate_method(HPWMI_BIOS_GUID, 0, mid, &input, &output);
+	if (ret)
+		goto out_free;
+
+	obj = output.pointer;
+	if (!obj) {
+		ret = -EINVAL;
+		goto out_free;
+	}
 
 	if (obj->type != ACPI_TYPE_BUFFER) {
+		pr_warn("query 0x%x returned an invalid object 0x%x\n", query, ret);
 		ret = -EINVAL;
 		goto out_free;
 	}
@@ -321,6 +332,7 @@ static int hp_wmi_perform_query(int query, enum hp_wmi_command command,
 
 out_free:
 	kfree(obj);
+	kfree(args);
 	return ret;
 }