[Xen-devel] [PATCH v15 14/21] 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>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reviewed-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
Tested-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
---
 xen/arch/x86/domain.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index ce1d187..0de8a20 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1541,16 +1541,13 @@ 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, next);
+        _update_runstate_area(prev);
+        vpmu_switch_from(prev, next);
+    }
 
-        if ( !list_empty(&prev->arch.hvm_vcpu.tm_list) )
+    if ( is_hvm_vcpu(prev) && !list_empty(&prev->arch.hvm_vcpu.tm_list) )
             pt_save_timer(prev);
-    }
 
     local_irq_disable();
 
@@ -1589,15 +1586,16 @@ void context_switch(struct vcpu *prev, struct vcpu 
*next)
                            !is_hardware_domain(next->domain));
     }
 
-    if ( is_hvm_vcpu(prev) && (prev != next) )
-        /* Must be done with interrupts enabled */
-        vpmu_switch_to(prev, next);
-
     context_saved(prev);
 
     if ( prev != next )
+    {
         _update_runstate_area(next);
 
+        /* Must be done with interrupts enabled */
+        vpmu_switch_to(prev, 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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