Re: [Xen-devel] [PATCH v25 07/15] x86/VPMU: Save VPMU state for PV guests during context switch

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>]

Am Freitag 19 Juni 2015, 14:44:38 schrieb Boris Ostrovsky:
> 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>
> 
> ---
> Changes in v25:
> * Replaced is_hvm_vcpu with is_hvm_domain to be consistent with recent changes
>  to context_switch()

Reviewed-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>

> 
>  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 b699f68..11197e4 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -1543,17 +1543,14 @@ void context_switch(struct vcpu *prev, struct vcpu 
> *next)
>      }
>  
>      if ( prev != next )
> -        _update_runstate_area(prev);
> -
> -    if ( is_hvm_domain(prevd) )
>      {
> -        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_domain(prevd) && !list_empty(&prev->arch.hvm_vcpu.tm_list) )
> +        pt_save_timer(prev);
> +
>      local_irq_disable();
>  
>      set_current(next);
> @@ -1591,15 +1588,16 @@ void context_switch(struct vcpu *prev, struct vcpu 
> *next)
>                             !is_hardware_domain(nextd));
>      }
>  
> -    if (is_hvm_domain(nextd) && (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);
>  
> 

-- 
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