Re: [Xen-devel] [PATCH] VMX: don't unintentionally leave x2APIC MSR intercepts disabled

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Monday, September 15, 2014 9:10 AM
> 
> These should be re-enabled in particular when the virtualized APIC
> transitions to HW-disabled state.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

> 
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -2167,6 +2167,7 @@ void vmx_vlapic_msr_changed(struct vcpu
>  {
>      int virtualize_x2apic_mode;
>      struct vlapic *vlapic = vcpu_vlapic(v);
> +    unsigned int msr;
> 
>      virtualize_x2apic_mode = ( (cpu_has_vmx_apic_reg_virt ||
>                                  cpu_has_vmx_virtual_intr_delivery)
> &&
> @@ -2183,8 +2184,6 @@ void vmx_vlapic_msr_changed(struct vcpu
>      if ( !vlapic_hw_disabled(vlapic) &&
>           (vlapic_base_address(vlapic) == APIC_DEFAULT_PHYS_BASE) )
>      {
> -        unsigned int msr;
> -
>          if ( virtualize_x2apic_mode && vlapic_x2apic_mode(vlapic) )
>          {
>              v->arch.hvm_vmx.secondary_exec_control |=
> @@ -2213,15 +2212,15 @@ void vmx_vlapic_msr_changed(struct vcpu
>              }
>          }
>          else
> -        {
>              v->arch.hvm_vmx.secondary_exec_control |=
>                  SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
> -            for ( msr = MSR_IA32_APICBASE_MSR;
> -                  msr <= MSR_IA32_APICBASE_MSR + 0xff; msr++ )
> -                vmx_enable_intercept_for_msr(v, msr,
> -                                             MSR_TYPE_R |
> MSR_TYPE_W);
> -        }
>      }
> +    if ( !(v->arch.hvm_vmx.secondary_exec_control &
> +           SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE) )
> +        for ( msr = MSR_IA32_APICBASE_MSR;
> +              msr <= MSR_IA32_APICBASE_MSR + 0xff; msr++ )
> +            vmx_enable_intercept_for_msr(v, msr, MSR_TYPE_R |
> MSR_TYPE_W);
> +
>      vmx_update_secondary_exec_control(v);
>      vmx_vmcs_exit(v);
>  }
> 
> 


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