Enhancements to VNET and to halting:

[palacios.git] / palacios / src / palacios / vmm_halt.c

diff --git a/palacios/src/palacios/vmm_halt.c b/palacios/src/palacios/vmm_halt.c
index bb4a46a..604d06b 100644 (file)
--- a/palacios/src/palacios/vmm_halt.c
+++ b/palacios/src/palacios/vmm_halt.c
@@ -28,27 +28,51 @@
 #endif
 
 
+#define NO_PROGRESS_CYCLE_LIMIT  4000000ULL   // 4 million cycles, about 1ms on a 4 GHz machine
+
+#define YIELD_TIME_USEC    1000
+
 
 //
 // This should trigger a #GP if cpl != 0, otherwise, yield to host
 //
 
-int v3_handle_halt(struct guest_info * info) {
-
+int v3_handle_halt(struct guest_info * info) 
+{
+    
     if (info->cpl != 0) { 
        v3_raise_exception(info, GPF_EXCEPTION);
     } else {
+       uint64_t total_cycles;
+       
+
        PrintDebug("CPU Yield\n");
 
-       while (!v3_intr_pending(info)) {
-           /* Since we're in an exit, time is already paused here, so no need to pause again. */
-         //        V3_Print("palacios: halt->yield\n");
+       total_cycles = 0;
+
+       while (!v3_intr_pending(info) && (info->vm_info->run_state == VM_RUNNING)) {
+            uint64_t t, cycles;
+           /* Yield, allowing time to pass while yielded */
+           t = v3_get_host_time(&info->time_state);
+
+           // adaptively select the best yield option
+           if (total_cycles > NO_PROGRESS_CYCLE_LIMIT) { 
+               // Slow yield - will take at least YIELD_TIME_USEC to come back
+               v3_yield(info,YIELD_TIME_USEC);
+           } else {
+               // Fast yield - may come back immediately
+               v3_yield(info,-1);
+           }
+
+           cycles = v3_get_host_time(&info->time_state) - t;
+
+           if ((total_cycles + cycles) > total_cycles) { 
+               total_cycles += cycles;
+           }
+
+           v3_advance_time(info, &cycles);
 
-           v3_yield(info);
-           
-           v3_disable_ints();
            v3_update_timers(info);
-           v3_enable_ints();
            
            /* At this point, we either have some combination of 
               interrupts, including perhaps a timer interrupt, or 
@@ -58,6 +82,7 @@ int v3_handle_halt(struct guest_info * info) {
                /* if no interrupt, then we do halt */
                /* asm("hlt"); */
            }
+
        }
 
        /* V3_Print("palacios: done with halt\n"); */