commit ec9ac73654ba02b7e806f390803ba872d9fde144
author Cindy Chen <chencindy@google.com> Fri Jun 05 17:44:08 2020 -0700
committer cindychip <cindy.chen0316@gmail.com> Mon Jun 08 09:00:07 2020 -0700
tree 8028e9779d15835b57e64a48816f3e2081ddd9f4
parent 384e6db70d8c9334818b6289b338acfa888f282f

[dv/hmac] Fix xcelium error

File in issue #2404. Xcelium detected an error happened when a race
condition between msg_q.delete() and hmac_process. This PR addresses
this issue by delete msg_q after hmac_process is detected in the forever
loop.

Signed-off-by: Cindy Chen <chencindy@google.com>

hw/ip/hmac/dv/env/hmac_scoreboard.sv

diff --git a/hw/ip/hmac/dv/env/hmac_scoreboard.sv b/hw/ip/hmac/dv/env/hmac_scoreboard.sv
index 8c6ea7e..07ff5c7 100644
--- a/hw/ip/hmac/dv/env/hmac_scoreboard.sv
+++ b/hw/ip/hmac/dv/env/hmac_scoreboard.sv
@@ -78,7 +78,6 @@
                 {hmac_process, hmac_start} = item.a_data[1:0];
                 // check if msg all streamed in, could happen during wr msg or trigger process
                 predict_digest(msg_q);
-                msg_q.delete();
               end else if (item.a_data[HashStart]) begin
                 {hmac_process, hmac_start} = item.a_data[1:0];
                 msg_q.delete(); // make sure did not include previous msg
@@ -244,6 +243,7 @@
 
   // hmac_wr_cnt was incremented every time when msg_q has 4 bytes streamed in
   // or when hash_process is triggered, and there are some remaining bytes
+  // this task will also clear the msg_q queue once hmac_process is set
   virtual task hmac_process_fifo_wr();
     fork
       begin : insolation_fork_process_fifo_wr
@@ -251,9 +251,13 @@
           wait(!cfg.under_reset);
           fork
             begin : increase_wr_cnt
-              wait(msg_q.size() >= (hmac_wr_cnt + 1) * 4 ||
-                  (hmac_process && msg_q.size() % 4 != 0));
-              if (sha_en) begin
+              bit has_unprocessed_msg = 1;
+              wait(msg_q.size() >= (hmac_wr_cnt + 1) * 4 || (hmac_process && msg_q.size() > 0));
+              if (hmac_process) begin
+                has_unprocessed_msg = msg_q.size() % 4 != 0;
+                msg_q.delete();
+              end
+              if (sha_en && has_unprocessed_msg) begin
                 // if fifo full, tlul will not write next data until fifo has space again
                 if ((hmac_wr_cnt - hmac_rd_cnt) == HMAC_MSG_FIFO_DEPTH) begin
                   wait((hmac_wr_cnt - hmac_rd_cnt) < HMAC_MSG_FIFO_DEPTH);