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Re: [Xen-devel] [PATCH 3/7] vm-event: introduce vm_event_vcpu_enter



Hello,

On 17/06/16 12:40, Corneliu ZUZU wrote:
On 6/17/2016 11:55 AM, Julien Grall wrote:
On 16/06/16 15:08, Corneliu ZUZU wrote:
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index d31f821..ba248c8 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -19,6 +19,7 @@
  #include <xen/errno.h>
  #include <xen/bitops.h>
  #include <xen/grant_table.h>
+#include <xen/vm_event.h>

  #include <asm/current.h>
  #include <asm/event.h>
@@ -251,6 +252,8 @@ static void schedule_tail(struct vcpu *prev)

      ctxt_switch_to(current);

+    vm_event_vcpu_enter(current);
+
      local_irq_enable();

      context_saved(prev);
@@ -296,7 +299,7 @@ void context_switch(struct vcpu *prev, struct
vcpu *next)

  void continue_running(struct vcpu *same)
  {
-    /* Nothing to do */
+    vm_event_vcpu_enter(same);
  }

  void sync_local_execstate(void)

From my understanding of the commit message, vm_event_vcpu_enter
should be called before returning to the guest. The scheduling
functions are not called every-time Xen is returning to the guest. So
if you want to do every time Xen is re-entering to the guest, then
this should be done in leave_hypervisor_tail.

Regards,


Which is also done, vm_event_vcpu_enter is called from
leave_hypervisor_tail as well.

Sorry I did not spot this one.

Are you saying that calling from leave_hypervisor_tail is enough and
that the schedule_tail call is not necessary?

leave_hypervisor_tail will always be called before returning to the guest. So a call to vm_event_vcpu_enter in this function will be sufficient.

Regards,

--
Julien Grall

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