Adding sender field to memory region descriptor.

This was added in the latest SPCI specification beta.

Bug: 132420445
Change-Id: I75b6e08e95bb257f362cc912c0fd946a7171a417
diff --git a/src/spci_architected_message.c b/src/spci_architected_message.c
index c17daf4..06106d5 100644
--- a/src/spci_architected_message.c
+++ b/src/spci_architected_message.c
@@ -588,6 +588,11 @@
 		return spci_error(SPCI_INVALID_PARAMETERS);
 	}
 
+	/* The sender must match the message sender. */
+	if (memory_region->sender != from_locked.vm->id) {
+		return spci_error(SPCI_INVALID_PARAMETERS);
+	}
+
 	/* We only support a single recipient. */
 	if (memory_region->attribute_count != 1) {
 		return spci_error(SPCI_INVALID_PARAMETERS);