From ca4159f123e95137ce5faa880ce2d1f84813a2f1 Mon Sep 17 00:00:00 2001
From: pgardratzama <pierre.gardrat@zama.ai>
Date: Mon, 6 Oct 2025 17:17:55 +0200
Subject: [PATCH] fix(hpu): fix overflow flag of OVF_MUL & OVF_MULS, also
 update simulation HPU config

---
 .../config_store/sim/hpu_config.toml           | 18 +++++++++++++-----
 .../tfhe-hpu-backend/src/fw/fw_impl/ilp.rs     |  3 ++-
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/backends/tfhe-hpu-backend/config_store/sim/hpu_config.toml b/backends/tfhe-hpu-backend/config_store/sim/hpu_config.toml
index fa5f5ab8f..618d55bed 100644
--- a/backends/tfhe-hpu-backend/config_store/sim/hpu_config.toml
+++ b/backends/tfhe-hpu-backend/config_store/sim/hpu_config.toml
@@ -25,18 +25,26 @@
   lut_mem = 256
   lut_pc = {Hbm={pc=34}}
 
-  fw_size= 16777215 # i.e. 16 MiB
+  fw_size= 16777216 # i.e. 16 MiB
   fw_pc = {Ddr= {offset= 0x3900_0000}} # NB: Allocation must take place in the Discrete DDR
 
   bsk_pc = [
     {Hbm={pc=8}},
+    {Hbm={pc=10}},
     {Hbm={pc=12}},
+    {Hbm={pc=14}},
     {Hbm={pc=24}},
+    {Hbm={pc=26}},
     {Hbm={pc=28}},
+    {Hbm={pc=30}},
     {Hbm={pc=40}},
+    {Hbm={pc=42}},
     {Hbm={pc=44}},
+    {Hbm={pc=46}},
     {Hbm={pc=56}},
-    {Hbm={pc=60}}
+    {Hbm={pc=58}},
+    {Hbm={pc=60}},
+    {Hbm={pc=62}}
   ]
 
   ksk_pc = [
@@ -64,7 +72,7 @@
 [firmware]
   implementation = "Llt"
   integer_w=[2,4,6,8,10,12,14,16,32,64,128]
-  min_batch_size = 11
+  min_batch_size = 12
   kogge_cfg            = "${HPU_BACKEND_DIR}/config_store/${HPU_CONFIG}/kogge_cfg.toml"
   custom_iop.'IOP[0]'  = "${HPU_BACKEND_DIR}/config_store/${HPU_CONFIG}/custom_iop/cust_0.asm"
   custom_iop.'IOP[1]'  = "${HPU_BACKEND_DIR}/config_store/${HPU_CONFIG}/custom_iop/cust_1.asm"
@@ -80,8 +88,8 @@
   custom_iop.'IOP[21]' = "${HPU_BACKEND_DIR}/config_store/${HPU_CONFIG}/custom_iop/cust_21.asm"
 
 [firmware.op_cfg.default]
-  fill_batch_fifo = true
-  min_batch_size = false
+  fill_batch_fifo = false
+  min_batch_size = true
   use_tiers = false
   flush_behaviour = "Patient"
   flush = true
diff --git a/backends/tfhe-hpu-backend/src/fw/fw_impl/ilp.rs b/backends/tfhe-hpu-backend/src/fw/fw_impl/ilp.rs
index f978bf420..d2aa99adc 100644
--- a/backends/tfhe-hpu-backend/src/fw/fw_impl/ilp.rs
+++ b/backends/tfhe-hpu-backend/src/fw/fw_impl/ilp.rs
@@ -498,6 +498,7 @@ pub fn iop_mulx(
     // Wrapped required lookup table in MetaVar
     let pbs_msg = new_pbs!(prog, "MsgOnly");
     let pbs_carry = new_pbs!(prog, "CarryInMsg");
+    let pbs_carry_is_some = new_pbs!(prog, "CarryIsSome");
     let pbs_mul_lsb = new_pbs!(prog, "MultCarryMsgLsb");
     let pbs_mul_msb = new_pbs!(prog, "MultCarryMsgMsb");
     let pbs_mult_is_some = new_pbs!(prog, "MultCarryMsgIsSome");
@@ -691,7 +692,7 @@ pub fn iop_mulx(
                     pp_vars.push_back((w + 1, msb));
                 } else if flag.is_some() {
                     // Last carry must be extracted for overflow computation
-                    let ovf_lsb_nz = var.pbs(&pbs_mult_msb_is_some, false);
+                    let ovf_lsb_nz = var.pbs(&pbs_carry_is_some, false);
                     ovf_non_zero_vars.push(ovf_lsb_nz);
                 }
             }