[Kernel] Deny non-zero users for some XAM exports.

src/xenia/kernel/xam/xam_user.cc

@@ -379,6 +379,16 @@ SHIM_CALL XamUserCheckPrivilege_shim(PPCContext* ppc_context,
   XELOGD("XamUserCheckPrivilege(%d, %.8X, %.8X)", user_index, mask,
          out_value_ptr);
 
+  if ((user_index & 0xFF) == 0xFF) {
+    // Always pin user to 0.
+    user_index = 0;
+  }
+
+  if (user_index) {
+    SHIM_SET_RETURN_32(X_ERROR_NO_SUCH_USER);
+    return;
+  }
+
   // If we deny everything, games should hopefully not try to do stuff.
   SHIM_SET_MEM_32(out_value_ptr, 0);
 
@@ -393,6 +403,16 @@ SHIM_CALL XamUserContentRestrictionGetFlags_shim(PPCContext* ppc_context,
   XELOGD("XamUserContentRestrictionGetFlags(%d, %.8X)", user_index,
          out_flags_ptr);
 
+  if ((user_index & 0xFF) == 0xFF) {
+    // Always pin user to 0.
+    user_index = 0;
+  }
+
+  if (user_index) {
+    SHIM_SET_RETURN_32(X_ERROR_NO_SUCH_USER);
+    return;
+  }
+
   // No restrictions?
   SHIM_SET_MEM_32(out_flags_ptr, 0);
 
@@ -409,6 +429,16 @@ SHIM_CALL XamUserContentRestrictionGetRating_shim(PPCContext* ppc_context,
   XELOGD("XamUserContentRestrictionGetRating(%d, %.8X, %.8X, %.8X)", user_index,
          unk1, out_unk2_ptr, out_unk3_ptr);
 
+  if ((user_index & 0xFF) == 0xFF) {
+    // Always pin user to 0.
+    user_index = 0;
+  }
+
+  if (user_index) {
+    SHIM_SET_RETURN_32(X_ERROR_NO_SUCH_USER);
+    return;
+  }
+
   // Some games have special case paths for 3F that differ from the failure
   // path, so my guess is that's 'don't care'.
   SHIM_SET_MEM_32(out_unk2_ptr, 0x3F);
@@ -453,7 +483,8 @@ SHIM_CALL XamUserAreUsersFriends_shim(PPCContext* ppc_context,
   XELOGD("XamUserAreUsersFriends(%d, %.8X, %.8X, %.8X, %.8X)", user_index, unk1,
          unk2, out_value_ptr, overlapped_ptr);
 
-  if (user_index == 255) {
+  if ((user_index & 0xFF) == 0xFF) {
+    // Always pin user to 0.
     user_index = 0;
   }