From e141d9e4d0bf4d9845cf1ce8a5d955363219bb87 Mon Sep 17 00:00:00 2001
From: Minje Jun <minje.jun@samsung.com>
Date: Sun, 21 Jan 2024 16:14:53 +0900
Subject: [PATCH] mem-ruby: Writeback CHI UD_RU line at local evict

In Ruby CHI protocol UD_RU state means the line is in UD state in
the local cache and the upstream may have it in UD or UC state.
In the previous implementation UD_RU line was just dropped without
WriteBack which can cause loss of dirty data when the upstream has it
in UC state.
This commit fixes it by performing WriteBack when evciting UD_RU line.

Change-Id: I1db9b4f95cc576e71dcef38b01de24775df514ba
---
 src/mem/ruby/protocol/chi/CHI-cache-funcs.sm       |  8 ++++----
 src/mem/ruby/protocol/chi/CHI-cache-transitions.sm | 10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/mem/ruby/protocol/chi/CHI-cache-funcs.sm b/src/mem/ruby/protocol/chi/CHI-cache-funcs.sm
index fbafda61cd..ccef1d8deb 100644
--- a/src/mem/ruby/protocol/chi/CHI-cache-funcs.sm
+++ b/src/mem/ruby/protocol/chi/CHI-cache-funcs.sm
@@ -892,10 +892,10 @@ void copyCacheAndDir(CacheEntry cache_entry, DirEntry dir_entry,
   if (is_valid(cache_entry) &&
       ((initialState == State:UD) || (initialState == State:SD) ||
         (initialState == State:UC) || (initialState == State:SC) ||
-        (initialState == State:UD_RSC) || (initialState == State:SD_RSC) ||
-        (initialState == State:UC_RSC) || (initialState == State:SC_RSC) ||
-        (initialState == State:UD_RSD) || (initialState == State:SD_RSD) ||
-        (initialState == State:UD_T))) {
+        (initialState == State:UD_RU) || (initialState == State:UD_RSC) ||
+        (initialState == State:SD_RSC) || (initialState == State:UC_RSC) ||
+        (initialState == State:SC_RSC) || (initialState == State:UD_RSD) ||
+        (initialState == State:SD_RSD) || (initialState == State:UD_T))) {
     tbe.dataBlk := cache_entry.DataBlk;
     tbe.dataBlkValid.fillMask();
     tbe.dataValid := true;
diff --git a/src/mem/ruby/protocol/chi/CHI-cache-transitions.sm b/src/mem/ruby/protocol/chi/CHI-cache-transitions.sm
index 31b5b0914a..b2cb419833 100644
--- a/src/mem/ruby/protocol/chi/CHI-cache-transitions.sm
+++ b/src/mem/ruby/protocol/chi/CHI-cache-transitions.sm
@@ -710,10 +710,10 @@ transition({UD_RSC, UC_RSC, SC_RSC, SD_RSC, UD, RU, RSD, RUSD, RUSC, UD_RSD, SD_
 
 // Cache Replacement
 
-// When in UD_RU,UC_RU,UD_RSD,SD_RSD we also just drop the line since an upstream
+// When in UC_RU,UD_RSD,SD_RSD we also just drop the line since an upstream
 // cache has an up-to-data line that it will either WriteBack or WriteEvict
 transition({SC,UC,SC_RSC,UC_RSC,
-            UD_RU,UC_RU,UD_RSD,SD_RSD}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
+            UC_RU,UD_RSD,SD_RSD}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
   Initiate_Replacement;
   Initiate_Replacement_JustDrop;
   Profile_Eviction;
@@ -722,7 +722,7 @@ transition({SC,UC,SC_RSC,UC_RSC,
   ProcessNextState;
 }
 
-transition({UD,SD,UD_RSC,SD_RSC}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
+transition({UD,SD,UD_RU,UD_RSC,SD_RSC}, LocalHN_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
   Initiate_Replacement;
   Initiate_Replacement_WB;
   Profile_Eviction;
@@ -749,7 +749,7 @@ transition({UD,SD,UC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
   ProcessNextState;
 }
 
-transition({UD_RU,UC_RU,UD_RSD,SD_RSD,SC_RSC,UC_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
+transition({UC_RU,UD_RSD,SD_RSD,SC_RSC,UC_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
   Initiate_Replacement;
   Initiate_Replacement_JustDrop;
   Profile_Eviction;
@@ -758,7 +758,7 @@ transition({UD_RU,UC_RU,UD_RSD,SD_RSD,SC_RSC,UC_RSC}, Local_Eviction, BUSY_BLKD)
   ProcessNextState;
 }
 
-transition({UD_RSC,SD_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
+transition({UD_RU,UD_RSC,SD_RSC}, Local_Eviction, BUSY_BLKD) {ReplTBEAvailable} {
   Initiate_Replacement;
   Initiate_Replacement_WB;
   Profile_Eviction;