util/smmstoretool: Properly initialise the authenticated variable header

MonotonicCount is required, or UEFITool fails to parse the store.
TimeStamp is required for variables with authenticated attributes.

Change-Id: Iea933c9943ec18ea773700cdf1e3bede0e8ef292
Signed-off-by: Benjamin Doron <benjamin.doron00@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/88424
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/smmstoretool/fv.c

@@ -73,7 +73,6 @@ bool fv_init(struct mem_range_t fv)
 	++vol_hdr_dst->Checksum;
 
 	const VARIABLE_STORE_HEADER var_store_hdr = {
-		// Authentication-related fields will be filled with 0xff.
 		.Signature = EfiAuthenticatedVariableGuid,
 		// Actual size of the storage is block size, the rest is
 		// Fault Tolerant Write (FTW) space and the FTW spare space.

util/smmstoretool/vs.c

@@ -110,6 +110,10 @@ static void store_var(const struct var_t *var, bool is_auth_var_store, uint8_t *
 		hdr.NameSize = var->name_size;
 		hdr.DataSize = var->data_size;
 
+		hdr.MonotonicCount = 0;
+		memset(&hdr.TimeStamp, 0, sizeof(hdr.TimeStamp));
+		//hdr.PubKeyIndex = 0;
+
 		memcpy(data, &hdr, sizeof(hdr));
 		data += sizeof(hdr);
 	} else {