RE: [PATCH] x86/vmx: reorder code in vmx_deliver_posted_intr

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

> From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Sent: Thursday, July 30, 2020 10:03 PM
> 
> Remove the unneeded else branch, which allows to reduce the
> indentation of a larger block of code, while making the flow of the
> function more obvious.
> 
> No functional change intended.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

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

> ---
>  xen/arch/x86/hvm/vmx/vmx.c | 55 ++++++++++++++++++--------------------
>  1 file changed, 26 insertions(+), 29 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index eb54aadfba..7773dcae1b 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -2003,6 +2003,8 @@ static void __vmx_deliver_posted_interrupt(struct
> vcpu *v)
> 
>  static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
>  {
> +    struct pi_desc old, new, prev;
> +
>      if ( pi_test_and_set_pir(vector, &v->arch.hvm.vmx.pi_desc) )
>          return;
> 
> @@ -2014,41 +2016,36 @@ static void vmx_deliver_posted_intr(struct vcpu
> *v, u8 vector)
>           * VMEntry as it used to be.
>           */
>          pi_set_on(&v->arch.hvm.vmx.pi_desc);
> +        vcpu_kick(v);
> +        return;
>      }
> -    else
> -    {
> -        struct pi_desc old, new, prev;
> 
> -        prev.control = v->arch.hvm.vmx.pi_desc.control;
> +    prev.control = v->arch.hvm.vmx.pi_desc.control;
> 
> -        do {
> -            /*
> -             * Currently, we don't support urgent interrupt, all
> -             * interrupts are recognized as non-urgent interrupt,
> -             * Besides that, if 'ON' is already set, no need to
> -             * sent posted-interrupts notification event as well,
> -             * according to hardware behavior.
> -             */
> -            if ( pi_test_sn(&prev) || pi_test_on(&prev) )
> -            {
> -                vcpu_kick(v);
> -                return;
> -            }
> -
> -            old.control = v->arch.hvm.vmx.pi_desc.control &
> -                          ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
> -            new.control = v->arch.hvm.vmx.pi_desc.control |
> -                          (1 << POSTED_INTR_ON);
> +    do {
> +        /*
> +         * Currently, we don't support urgent interrupt, all
> +         * interrupts are recognized as non-urgent interrupt,
> +         * Besides that, if 'ON' is already set, no need to
> +         * sent posted-interrupts notification event as well,
> +         * according to hardware behavior.
> +         */
> +        if ( pi_test_sn(&prev) || pi_test_on(&prev) )
> +        {
> +            vcpu_kick(v);
> +            return;
> +        }
> 
> -            prev.control = cmpxchg(&v->arch.hvm.vmx.pi_desc.control,
> -                                   old.control, new.control);
> -        } while ( prev.control != old.control );
> +        old.control = v->arch.hvm.vmx.pi_desc.control &
> +                      ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
> +        new.control = v->arch.hvm.vmx.pi_desc.control |
> +                      (1 << POSTED_INTR_ON);
> 
> -        __vmx_deliver_posted_interrupt(v);
> -        return;
> -    }
> +        prev.control = cmpxchg(&v->arch.hvm.vmx.pi_desc.control,
> +                               old.control, new.control);
> +    } while ( prev.control != old.control );
> 
> -    vcpu_kick(v);
> +    __vmx_deliver_posted_interrupt(v);
>  }
> 
>  static void vmx_sync_pir_to_irr(struct vcpu *v)
> --
> 2.28.0