Make support for menvcfg.CBIE == 01 optional (#191)

* Make support for menvcfg.CBIE == 01 optional

* Added new parameter to generic_rv64 params.yaml

* Fix typo

Author: dhower-qc

arch/csr/menvcfg.yaml

@@ -246,7 +246,9 @@ menvcfg:
       definedBy: Zicbom
       type: RW-R
       sw_write(csr_value): |
-        if (csr_value.CBIE == 0 || csr_value.CBIE == 1 || csr_value.CBIE == 3) {
+        if ((csr_value.CBIE == 0) ||
+            (ALLOW_CBO_INVAL_UPGRADE_TO_FLUSH && (csr_value.CBIE == 1)) ||
+            (csr_value.CBIE == 3)) {
           return csr_value.CBIE;
         } else {
           return CSR[menvcfg].CBIE;

arch/ext/Zicbom.yaml

@@ -14,4 +14,13 @@ Zicbom:
         The observable size of a cache block, in bytes
       also_defined_in: [Zicboz, Zicbop]
       schema:
-        type: integer
+        type: integer
+    ALLOW_CBO_INVAL_UPGRADE_TO_FLUSH:
+      description: |
+        When true, an implementation can (when `menvcfg.CBIE` == `01`) upgrade a `cbo.inval`
+        instruction to a `cbo.flush`.
+
+        When false, an implementation does not support the upgrade, and the value '01' cannot be
+        written to `menvcfg.CBIE`.
+      schema:
+        type: boolean

cfgs/generic_rv64/params.yaml

@@ -514,3 +514,4 @@ params:
   MSTATUS_FS_WRITEABLE: true
   MSTATUS_TVM_IMPLEMENTED: true
   HW_MSTATUS_FS_DIRTY_UPDATE: precise
+  ALLOW_CBO_INVAL_UPGRADE_TO_FLUSH: true