[Xen-devel] [PATCH v10 18/20] 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.

Since it is now possible for vpmu_switch_to() to call 
vmx_vmcs_try_enter()->vcpu_pause()
which needs is_running to be correctly set/cleared we call context_saved() 
before
vpmu_switch_to() is executed.

Also, because we are calling both VPMU context switch routines from under the
'if (prev != next)' check we can drop this check from inline definitions.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 xen/arch/x86/domain.c          | 19 +++++++++----------
 xen/include/asm-x86/hvm/vpmu.h |  4 ++--
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index ecbb3df..18ec530 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1495,16 +1495,14 @@ void context_switch(struct vcpu *prev, struct vcpu 
*next)
     }
 
     if ( prev != next )
-        _update_runstate_area(prev);
-
-    if ( is_hvm_vcpu(prev) )
     {
+        _update_runstate_area(prev);
         vpmu_switch_from(prev, next);
-
-        if ( !list_empty(&prev->arch.hvm_vcpu.tm_list) )
-            pt_save_timer(prev);
     }
 
+    if ( is_hvm_vcpu(prev) && !list_empty(&prev->arch.hvm_vcpu.tm_list) )
+        pt_save_timer(prev);
+
     local_irq_disable();
 
     set_current(next);
@@ -1542,15 +1540,16 @@ void context_switch(struct vcpu *prev, struct vcpu 
*next)
                            !is_hardware_domain(next->domain));
     }
 
-    if ( is_hvm_vcpu(prev) )
-        /* 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);
 
diff --git a/xen/include/asm-x86/hvm/vpmu.h b/xen/include/asm-x86/hvm/vpmu.h
index 977a44c..ad86390 100644
--- a/xen/include/asm-x86/hvm/vpmu.h
+++ b/xen/include/asm-x86/hvm/vpmu.h
@@ -119,13 +119,13 @@ extern uint64_t vpmu_features;
 /* Context switch */
 inline void vpmu_switch_from(struct vcpu *prev, struct vcpu *next)
 {
-    if ( (prev != next) && (vpmu_mode & XENPMU_MODE_SELF) )
+    if ( vpmu_mode & XENPMU_MODE_SELF )
         vpmu_save(prev);
 }
 
 inline void vpmu_switch_to(struct vcpu *prev, struct vcpu *next)
 {
-    if ( (prev != next) && (vpmu_mode & XENPMU_MODE_SELF) )
+    if ( vpmu_mode & XENPMU_MODE_SELF )
         vpmu_load(next);
 }
 
-- 
1.8.1.4


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