[PATCH v4 14/17] x86/VPMU: Save VPMU state for PV guests during context switch

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

Save VPMU state during context switch for both HVM and PV guests unless we
are in PMU privileged mode (i.e. dom0 is doing all profiling) and the switched
out domain is not the control domain. The latter condition is needed because
me may have just turned the privileged PMU mode on and thus need to save last
domain.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 xen/arch/x86/domain.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 25572d5..124c0e7 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1444,17 +1444,16 @@ void context_switch(struct vcpu *prev, struct vcpu *next)
     }
 
     if (prev != next)
-        update_runstate_area(prev);
-
-    if ( is_hvm_vcpu(prev) )
     {
-        if (prev != next)
+        update_runstate_area(prev);
+        if ( !(vpmu_mode & XENPMU_MODE_PRIV) ||
+             !is_control_domain(prev->domain) )
             vpmu_save(prev);
-
-        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);
@@ -1491,7 +1490,7 @@ void context_switch(struct vcpu *prev, struct vcpu *next)
                            (next->domain->domain_id != 0));
     }
 
-    if (is_hvm_vcpu(next) && (prev != next) )
+    if ( (prev != next) && !(vpmu_mode & XENPMU_MODE_PRIV) )
         /* Must be done with interrupts enabled */
         vpmu_load(next);
 
-- 
1.8.1.4