[tlul] Clarify unselected bytes integrity
- clarify the point raised in #11576
- The original intent of the integrity generation / checker was to
check even if the source data is garbage in byte lanes that were
not selected. This broadens the surface of "detection". Meaning
even if someone were to attack lanes that we do not care about,
we still flag as it is an attack on the system.
- By removing the byte lane masking in this PR however, we also make
it a requirement that DV ever only drive "random" data on unselected
byte lanes, not "don't care" data. This is also more reflective
of real silicon, since x is not a realy value. No matter if the value
is 0/1, we generate integrity on it and expect it to be kept throughout
the transaction.
Signed-off-by: Timothy Chen <timothytim@google.com>
diff --git a/hw/ip/tlul/rtl/tlul_cmd_intg_gen.sv b/hw/ip/tlul/rtl/tlul_cmd_intg_gen.sv
index 278625e..43adb97 100644
--- a/hw/ip/tlul/rtl/tlul_cmd_intg_gen.sv
+++ b/hw/ip/tlul/rtl/tlul_cmd_intg_gen.sv
@@ -32,9 +32,7 @@
logic [DataIntgWidth-1:0] data_intg;
if (EnableDataIntgGen) begin : gen_data_intg
- for (genvar i = 0; i < top_pkg::TL_DBW; i++) begin : gen_data_fill
- assign data_final[i*8 +: 8] = tl_i.a_mask[i] ? tl_i.a_data[i*8 +: 8] : '0;
- end
+ assign data_final = tl_i.a_data;
logic [DataMaxWidth-1:0] unused_data;
prim_secded_inv_39_32_enc u_data_gen (
