Protect fapi rc between processor and async thread

Since we share a global fapi rc betweeen threads,
to avoid corruption, following approach -
1. Run processor thread at higher priority than async thread
2. Once async thread is unlocked, make it non pre-emptable

Change-Id: I873affbc15d99c8020c3d074e58aae1165e7ae12
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/61355
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Sachin Gupta <sgupta2m@in.ibm.com>
(cherry picked from commit bcd84270938b75c83cc364ff2c75133638cddb6e)
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/61461

src/sbefw/core/sbecmdprocessor.C

@@ -455,6 +455,11 @@ void sbeAsyncCommandProcessor_routine(void *arg)
 
         ReturnCode rc = FAPI2_RC_SUCCESS;
         Target<TARGET_TYPE_PROC_CHIP > proc = plat_getChipTarget();
+
+        // Run the procedure atomically
+        PkMachineContext  ctx;
+        pk_critical_section_enter(&ctx);
+
         SBE_EXEC_HWP(rc, p9_sbe_io_eol_toggle, proc)
         if (rc != FAPI2_RC_SUCCESS)
         {
@@ -463,6 +468,8 @@ void sbeAsyncCommandProcessor_routine(void *arg)
             captureAsyncFFDC(SBE_PRI_GENERIC_EXECUTION_FAILURE,
                              SBE_SEC_PERIODIC_IO_TOGGLE_FAILED);
         }
+
+        pk_critical_section_exit(&ctx);
     } while(1);
     #endif // PERIODIC_IO_TOGGLE_SUPPORTED
     #undef SBE_FUNC

src/sbefw/core/sbemain.C

@@ -226,7 +226,7 @@ int sbeInitThreads(void)
                             (void *)0,
                             (PkAddress)sbeSyncCommandProcessor_stack,
                             SBE_THREAD_SYNC_CMD_PROC_STACK_SIZE,
-                            THREAD_PRIORITY_7);
+                            THREAD_PRIORITY_6);
         if (l_rc)
         {
             break;
@@ -238,7 +238,7 @@ int sbeInitThreads(void)
                             (void *)0,
                             (PkAddress)sbeAsyncCommandProcessor_stack,
                             SBE_THREAD_ASYNC_CMD_PROC_STACK_SIZE,
-                            THREAD_PRIORITY_6);
+                            THREAD_PRIORITY_7);
         if (l_rc)
         {
             break;