[Xen-devel] [PATCH v20 07/13] x86/VPMU: Save VPMU state for PV guests during context switch

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

Save VPMU state during context switch for both HVM and PV(H) guests.

A subsequent patch ("x86/VPMU: NMI-based VPMU support") will make it possible
for vpmu_switch_to() to call vmx_vmcs_try_enter()->vcpu_pause() which needs
is_running to be correctly set/cleared. To prepare for that, call 
context_saved()
before vpmu_switch_to() is executed. (Note that while this change could have
been dalayed until that later patch, the changes are harmless to existing code
and so we do it here)

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/domain.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index dd10223..03bcbd3 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1534,17 +1534,14 @@ void context_switch(struct vcpu *prev, struct vcpu 
*next)
     }
 
     if ( prev != next )
-        _update_runstate_area(prev);
-
-    if ( is_hvm_vcpu(prev) )
     {
-        if (prev != next)
-            vpmu_switch_from(prev);
-
-        if ( !list_empty(&prev->arch.hvm_vcpu.tm_list) )
-            pt_save_timer(prev);
+        _update_runstate_area(prev);
+        vpmu_switch_from(prev);
     }
 
+    if ( is_hvm_vcpu(prev) && !list_empty(&prev->arch.hvm_vcpu.tm_list) )
+        pt_save_timer(prev);
+
     local_irq_disable();
 
     set_current(next);
@@ -1582,15 +1579,16 @@ void context_switch(struct vcpu *prev, struct vcpu 
*next)
                            !is_hardware_domain(next->domain));
     }
 
-    if (is_hvm_vcpu(next) && (prev != next) )
-        /* Must be done with interrupts enabled */
-        vpmu_switch_to(next);
-
     context_saved(prev);
 
     if ( prev != next )
+    {
         _update_runstate_area(next);
 
+        /* Must be done with interrupts enabled */
+        vpmu_switch_to(next);
+    }
+
     /* Ensure that the vcpu has an up-to-date time base. */
     update_vcpu_system_time(next);
 
-- 
1.8.1.4


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