[Xen-devel] [PATCH 11/12] Allow vcpu to pause self

Tian, Kevin
2007-05-15T14:22:59Z

Add self pause ability, which is required by vcpu0/dom0 when
running on a AP. This can''t be satisfied by existing interface,
since the new flag also serves as a sync point.

Signed-off-by Kevin Tian <kevin.tian@intel.com>

diff -r d5315422dbc8 xen/common/domain.c
--- a/xen/common/domain.c	Mon May 14 18:35:31 2007 -0400
+++ b/xen/common/domain.c	Mon May 14 20:21:04 2007 -0400
@@ -530,6 +530,17 @@ void vcpu_pause_nosync(struct vcpu *v)
     vcpu_sleep_nosync(v);
 }

+/* _VPF_need_sync serves not only as flag for sync pause, but also
+ * as hint for other cpu waiting for this pause.
+ */
+void vcpu_pause_self(void)
+{
+    struct vcpu *v = current;
+
+    set_bit(_VPF_need_sync, &v->pause_flags);
+    vcpu_pause_nosync(v);
+}
+
 void vcpu_unpause(struct vcpu *v)
 {
     if ( atomic_dec_and_test(&v->pause_count) )
diff -r d5315422dbc8 xen/common/schedule.c
--- a/xen/common/schedule.c	Mon May 14 18:35:31 2007 -0400
+++ b/xen/common/schedule.c	Mon May 14 18:54:28 2007 -0400
@@ -691,6 +691,13 @@ void context_saved(struct vcpu *prev)

     if ( unlikely(test_bit(_VPF_migrating, &prev->pause_flags)) )
         vcpu_migrate(prev);
+
+    if ( unlikely(test_bit(_VPF_need_sync, &prev->pause_flags)) )
+    {
+        sync_vcpu_execstate(prev);
+        /* test and clear can be split, since here is the only clear
point */
+        clear_bit(_VPF_need_sync, &prev->pause_flags);
+    }
 }

 /* The scheduler timer: force a run through the scheduler */
diff -r d5315422dbc8 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h	Mon May 14 18:35:31 2007 -0400
+++ b/xen/include/xen/sched.h	Mon May 14 20:21:30 2007 -0400
@@ -457,6 +457,9 @@ extern struct domain *domain_list;
  /* VCPU affinity has changed: migrating to a new CPU. */
 #define _VPF_migrating       3
 #define VPF_migrating        (1UL<<_VPF_migrating)
+ /* VCPU needs full context sync once switched out */
+#define _VPF_need_sync       4
+#define VPF_need_sync        (1UL<<_VPF_need_sync)

 static inline int vcpu_runnable(struct vcpu *v)
 {
@@ -467,6 +470,7 @@ static inline int vcpu_runnable(struct v

 void vcpu_pause(struct vcpu *v);
 void vcpu_pause_nosync(struct vcpu *v);
+void vcpu_pause_self(void);
 void domain_pause(struct domain *d);
 void vcpu_unpause(struct vcpu *v);
 void domain_unpause(struct domain *d);


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