platform/x86/amd/pmf: Use struct for cookie header

The cookie header consists of a sign field and a length field.
Combine both in a single struct to make accesses simpler.

Compile-tested only.
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20240304205005.10078-4-W_Armin@gmx.deReviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/amd/pmf/pmf.h

@@ -17,7 +17,11 @@
 #define POLICY_BUF_MAX_SZ		0x4b000
 #define POLICY_SIGN_COOKIE		0x31535024
 #define POLICY_COOKIE_OFFSET		0x10
-#define POLICY_COOKIE_LEN		0x14
+
+struct cookie_header {
+	u32 sign;
+	u32 length;
+} __packed;
 
 /* APMF Functions */
 #define APMF_FUNC_VERIFY_INTERFACE			0

drivers/platform/x86/amd/pmf/tee-if.c

@@ -246,17 +246,16 @@ static void amd_pmf_invoke_cmd(struct work_struct *work)
 
 static int amd_pmf_start_policy_engine(struct amd_pmf_dev *dev)
 {
-	u32 cookie, length;
+	struct cookie_header *header;
 	int res;
 
-	cookie = *(u32 *)(dev->policy_buf + POLICY_COOKIE_OFFSET);
-	length = *(u32 *)(dev->policy_buf + POLICY_COOKIE_LEN);
+	header = (struct cookie_header *)(dev->policy_buf + POLICY_COOKIE_OFFSET);
 
-	if (cookie != POLICY_SIGN_COOKIE || !length)
+	if (header->sign != POLICY_SIGN_COOKIE || !header->length)
 		return -EINVAL;
 
 	/* Update the actual length */
-	dev->policy_sz = length + 512;
+	dev->policy_sz = header->length + 512;
 	res = amd_pmf_invoke_cmd_init(dev);
 	if (res == TA_PMF_TYPE_SUCCESS) {
 		/* Now its safe to announce that smart pc is enabled */