X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=blobdiff_plain;f=palacios%2Fsrc%2Fpalacios%2Fvmm_barrier.c;h=a94e40f157eb5d82c2b370886ce2022eb2d73d85;hb=4e43946f01f687361197dc9571b7df02ae20de30;hp=f7b863da01e1d9e43f19d9d00598ce7a69e18999;hpb=5f957c3aeebed4a07a0862cb5fbf595aa4436e81;p=palacios.git

diff --git a/palacios/src/palacios/vmm_barrier.c b/palacios/src/palacios/vmm_barrier.c
index f7b863d..a94e40f 100644
--- a/palacios/src/palacios/vmm_barrier.c
+++ b/palacios/src/palacios/vmm_barrier.c
@@ -41,28 +41,14 @@ int v3_deinit_barrier(struct v3_vm_info * vm_info) {
     return 0;
 }
 
-
-/* Barrier synchronization primitive
- *   -- This call will block until all the guest cores are waiting at a common synchronization point
- *      in a yield loop. The core will block at the sync point until the barrier is lowered.
- * 
- *   ARGUMENTS: 
- *       vm_info -- The VM for which the barrier is being activated
- *       local_core -- The core whose thread this function is being called from, or NULL 
- *                     if the calling thread is not associated with a VM's core context
- */
-
-int v3_raise_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core) {
+int v3_raise_barrier_nowait(struct v3_vm_info * vm_info, struct guest_info * local_core) {
     struct v3_barrier * barrier = &(vm_info->barrier);
     addr_t flag;
     int acquired = 0;
-    int all_blocked = 0;
 
     int local_vcpu = -1;
     int i = 0;
 
-
-
     flag = v3_lock_irqsave(barrier->lock);
 
     if (barrier->active == 0) {
@@ -99,6 +85,18 @@ int v3_raise_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core
 	}
     }
 
+    return 0;
+}
+
+int v3_wait_for_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core) {
+    struct v3_barrier * barrier = &(vm_info->barrier);
+    int all_blocked = 0;
+    int i = 0;
+
+    if (barrier->active == 0) {
+	return -1;
+    }
+
     // wait for barrier catch on all cores
     while (all_blocked == 0) {
 	all_blocked = 1;
@@ -122,15 +120,45 @@ int v3_raise_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core
 	    break;
 	}
 
-	v3_yield(local_core);
+        // return immediately and spin if there is no one to yield to 
+	v3_yield(local_core,-1);
     }
 
-
     return 0;
 }
 
 
 
+/* Barrier synchronization primitive
+ *   -- This call will block until all the guest cores are waiting at a common synchronization point
+ *      in a yield loop. The core will block at the sync point until the barrier is lowered.
+ * 
+ *   ARGUMENTS: 
+ *       vm_info -- The VM for which the barrier is being activated
+ *       local_core -- The core whose thread this function is being called from, or NULL 
+ *                     if the calling thread is not associated with a VM's core context
+ */
+
+int v3_raise_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core) {
+    int ret = 0;
+
+
+    if ((vm_info->run_state != VM_RUNNING) && 
+	(vm_info->run_state != VM_SIMULATING)) {
+	return 0;
+    }
+
+    ret = v3_raise_barrier_nowait(vm_info, local_core);
+
+    if (ret != 0) {
+	return ret;
+    }
+
+    return v3_wait_for_barrier(vm_info, local_core);
+}
+
+
+
 /* Lowers a barrier that has already been raised
  *    guest cores will automatically resume execution 
  *    once this has been called
@@ -141,6 +169,12 @@ int v3_raise_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core
 int v3_lower_barrier(struct v3_vm_info * vm_info) {
     struct v3_barrier * barrier = &(vm_info->barrier);
 
+    
+    if ((vm_info->run_state != VM_RUNNING) && 
+	(vm_info->run_state != VM_SIMULATING)) {
+	return 0;
+    }
+
     // Clear the active flag, so cores won't wait 
     barrier->active = 0;
 
@@ -164,8 +198,15 @@ int v3_wait_at_barrier(struct guest_info * core) {
     if (barrier->active == 0) {
 	return 0;
     }
+#ifndef V3_CONFIG_FP_SWITCH
+    v3_get_fp_state(core); // snapshot FP state now
+#else
+#   ifdef V3_CONFIG_LAZY_FP_SWITCH
+    v3_get_fp_state(core); // snapshot FP state now regardless of lazy eval
+#   endif
+#endif
 
-    V3_Print("Core %d waiting at barrier\n", core->vcpu_id);
+    V3_Print(core->vm_info, core, "Core %d waiting at barrier\n", core->vcpu_id);
 
     /*  Barrier has been activated. 
      *  Wait here until it's lowered
@@ -174,12 +215,21 @@ int v3_wait_at_barrier(struct guest_info * core) {
     
     // set cpu bit in barrier bitmap
     v3_bitmap_set(&(barrier->cpu_map), core->vcpu_id);
-    V3_Print("Core %d bit set as waiting\n", core->vcpu_id);
+    V3_Print(core->vm_info, core, "Core %d bit set as waiting\n", core->vcpu_id);
 
     // wait for cpu bit to clear
     while (v3_bitmap_check(&(barrier->cpu_map), core->vcpu_id)) {
-	v3_yield(core);
+        // Barrier wait will spin if there is no competing work
+	v3_yield(core,-1);
     }
 
+#ifndef V3_CONFIG_FP_SWITCH    
+    core->fp_state.need_restore=1;  // restore FP on next entry
+#else
+#   ifdef V3_CONFIG_LAZY_FP_SWITCH
+    core->fp_state.need_restore=1;  // restore FP on next entry
+#   endif
+#endif
+
     return 0;
 }