From 2ae332cce8293ff46667fcc86745741d81beac47 Mon Sep 17 00:00:00 2001
From: Stanislav Shwartsman <sshwarts@users.sourceforge.net>
Date: Fri, 9 Aug 2019 19:57:13 +0000
Subject: [PATCH] patch by Luigu.B - significantly speedup multi-threaded guest
 simulation

---
 bochs/cpu/cpu.cc |  8 ++------
 bochs/cpu/cpu.h  |  2 +-
 bochs/main.cc    | 16 +++++++++++++---
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/bochs/cpu/cpu.cc b/bochs/cpu/cpu.cc
index a9b24688d..7fd48c4c5 100644
--- a/bochs/cpu/cpu.cc
+++ b/bochs/cpu/cpu.cc
@@ -26,6 +26,8 @@
 
 #include "cpustats.h"
 
+jmp_buf BX_CPU_C::jmp_buf_env;
+
 void BX_CPU_C::cpu_loop(void)
 {
 #if BX_DEBUGGER
@@ -134,12 +136,6 @@ void BX_CPU_C::cpu_loop(void)
 
 void BX_CPU_C::cpu_run_trace(void)
 {
-  if (setjmp(BX_CPU_THIS_PTR jmp_buf_env)) {
-    // can get here only from exception function or VMEXIT
-    BX_CPU_THIS_PTR icount++;
-    return;
-  }
-
   // check on events which occurred for previous instructions (traps)
   // and ones which are asynchronous to the CPU (hardware interrupts)
   if (BX_CPU_THIS_PTR async_event) {
diff --git a/bochs/cpu/cpu.h b/bochs/cpu/cpu.h
index 404ace882..5ab485a86 100644
--- a/bochs/cpu/cpu.h
+++ b/bochs/cpu/cpu.h
@@ -1216,7 +1216,7 @@ public: // for now...
 #endif
 
   // for exceptions
-  jmp_buf jmp_buf_env;
+  static jmp_buf jmp_buf_env;
   unsigned last_exception_type;
 
   // Boundaries of current code page, based on EIP
diff --git a/bochs/main.cc b/bochs/main.cc
index 088ce5860..18c01d54f 100644
--- a/bochs/main.cc
+++ b/bochs/main.cc
@@ -1060,14 +1060,22 @@ int bx_begin_simulation(int argc, char *argv[])
 
       static int quantum = SIM->get_param_num(BXPN_SMP_QUANTUM)->get();
       Bit32u executed = 0, processor = 0;
+      bool run = true;
 
+      if (setjmp(BX_CPU_C::jmp_buf_env)) {
+        // can get here only from exception function or VMEXIT
+        BX_CPU(processor)->icount++;
+        run = false;
+      }
       while (1) {
          // do some instructions in each processor
-         Bit64u icount = BX_CPU(processor)->icount_last_sync = BX_CPU(processor)->get_icount();
-         BX_CPU(processor)->cpu_run_trace();
+        if (run)
+          BX_CPU(processor)->cpu_run_trace();
+        else
+          run = true;
 
          // see how many instruction it was able to run
-         Bit32u n = (Bit32u)(BX_CPU(processor)->get_icount() - icount);
+         Bit32u n = (Bit32u)(BX_CPU(processor)->get_icount() - BX_CPU(processor)->icount_last_sync);
          if (n == 0) n = quantum; // the CPU was halted
          executed += n;
 
@@ -1077,6 +1085,8 @@ int bx_begin_simulation(int argc, char *argv[])
            executed %= BX_SMP_PROCESSORS;
          }
 
+         BX_CPU(processor)->icount_last_sync = BX_CPU(processor)->get_icount();
+
          if (bx_pc_system.kill_bochs_request)
            break;
       }