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Re: [Xen-devel] [PATCH v2 06/45] xen/arm: gic: Split the field state in gic_lr in 2 fields active and pending



On Thu, 15 Mar 2018, Andre Przywara wrote:
> From: Julien Grall <julien.grall@xxxxxxx>
> 
> Mostly making the code nicer to read.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> Changes:
> - Use 1ULL
> - Remove pointless == *_STATE_*
> 
>  xen/arch/arm/gic-v2.c             | 15 +++++++++++----
>  xen/arch/arm/gic-v3.c             | 12 +++++++++---
>  xen/arch/arm/gic-vgic.c           |  6 +++---
>  xen/include/asm-arm/gic.h         |  3 ++-
>  xen/include/asm-arm/gic_v3_defs.h |  2 ++
>  5 files changed, 27 insertions(+), 11 deletions(-)
> 
> diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
> index 9d589115bd..6dae5c1e55 100644
> --- a/xen/arch/arm/gic-v2.c
> +++ b/xen/arch/arm/gic-v2.c
> @@ -51,6 +51,8 @@
>  #define GICH_V2_LR_PHYSICAL_SHIFT  10
>  #define GICH_V2_LR_STATE_MASK      0x3
>  #define GICH_V2_LR_STATE_SHIFT     28
> +#define GICH_V2_LR_PENDING         (1U << 28)
> +#define GICH_V2_LR_ACTIVE          (1U << 29)
>  #define GICH_V2_LR_PRIORITY_SHIFT  23
>  #define GICH_V2_LR_PRIORITY_MASK   0x1f
>  #define GICH_V2_LR_HW_SHIFT        31
> @@ -467,7 +469,8 @@ static void gicv2_read_lr(int lr, struct gic_lr *lr_reg)
>      lr_reg->pirq = (lrv >> GICH_V2_LR_PHYSICAL_SHIFT) & 
> GICH_V2_LR_PHYSICAL_MASK;
>      lr_reg->virq = (lrv >> GICH_V2_LR_VIRTUAL_SHIFT) & 
> GICH_V2_LR_VIRTUAL_MASK;
>      lr_reg->priority = (lrv >> GICH_V2_LR_PRIORITY_SHIFT) & 
> GICH_V2_LR_PRIORITY_MASK;
> -    lr_reg->state     = (lrv >> GICH_V2_LR_STATE_SHIFT) & 
> GICH_V2_LR_STATE_MASK;
> +    lr_reg->pending = lrv & GICH_V2_LR_PENDING;
> +    lr_reg->active = lrv & GICH_V2_LR_ACTIVE;
>      lr_reg->hw_status = lrv & GICH_V2_LR_HW;
>  }
>  
> @@ -478,9 +481,13 @@ static void gicv2_write_lr(int lr, const struct gic_lr 
> *lr_reg)
>      lrv = ( ((lr_reg->pirq & GICH_V2_LR_PHYSICAL_MASK) << 
> GICH_V2_LR_PHYSICAL_SHIFT) |
>            ((lr_reg->virq & GICH_V2_LR_VIRTUAL_MASK) << 
> GICH_V2_LR_VIRTUAL_SHIFT)   |
>            ((uint32_t)(lr_reg->priority & GICH_V2_LR_PRIORITY_MASK)
> -                                      << GICH_V2_LR_PRIORITY_SHIFT) |
> -          ((uint32_t)(lr_reg->state & GICH_V2_LR_STATE_MASK)
> -                                   << GICH_V2_LR_STATE_SHIFT) );
> +                                      << GICH_V2_LR_PRIORITY_SHIFT) );
> +
> +    if ( lr_reg->active )
> +        lrv |= GICH_V2_LR_ACTIVE;
> +
> +    if ( lr_reg->pending )
> +        lrv |= GICH_V2_LR_PENDING;
>  
>      if ( lr_reg->hw_status )
>          lrv |= GICH_V2_LR_HW;
> diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
> index f761ae60d6..6547b5eb0d 100644
> --- a/xen/arch/arm/gic-v3.c
> +++ b/xen/arch/arm/gic-v3.c
> @@ -1010,7 +1010,8 @@ static void gicv3_read_lr(int lr, struct gic_lr *lr_reg)
>      lr_reg->virq = (lrv >> ICH_LR_VIRTUAL_SHIFT) & ICH_LR_VIRTUAL_MASK;
>  
>      lr_reg->priority  = (lrv >> ICH_LR_PRIORITY_SHIFT) & 
> ICH_LR_PRIORITY_MASK;
> -    lr_reg->state     = (lrv >> ICH_LR_STATE_SHIFT) & ICH_LR_STATE_MASK;
> +    lr_reg->pending   = lrv & ICH_LR_STATE_PENDING;
> +    lr_reg->active    = lrv & ICH_LR_STATE_ACTIVE;
>      lr_reg->hw_status = lrv & ICH_LR_HW;
>  }
>  
> @@ -1020,8 +1021,13 @@ static void gicv3_write_lr(int lr_reg, const struct 
> gic_lr *lr)
>  
>      lrv = ( ((u64)(lr->pirq & ICH_LR_PHYSICAL_MASK) << 
> ICH_LR_PHYSICAL_SHIFT)|
>          ((u64)(lr->virq & ICH_LR_VIRTUAL_MASK)  << ICH_LR_VIRTUAL_SHIFT) |
> -        ((u64)(lr->priority & ICH_LR_PRIORITY_MASK) << 
> ICH_LR_PRIORITY_SHIFT)|
> -        ((u64)(lr->state & ICH_LR_STATE_MASK) << ICH_LR_STATE_SHIFT) );
> +        ((u64)(lr->priority & ICH_LR_PRIORITY_MASK) << 
> ICH_LR_PRIORITY_SHIFT) );
> +
> +    if ( lr->active )
> +        lrv |= ICH_LR_STATE_ACTIVE;
> +
> +    if ( lr->pending )
> +        lrv |= ICH_LR_STATE_PENDING;
>  
>      if ( lr->hw_status )
>          lrv |= ICH_LR_HW;
> diff --git a/xen/arch/arm/gic-vgic.c b/xen/arch/arm/gic-vgic.c
> index e3cb47e80e..d831b35525 100644
> --- a/xen/arch/arm/gic-vgic.c
> +++ b/xen/arch/arm/gic-vgic.c
> @@ -189,7 +189,7 @@ static void gic_update_one_lr(struct vcpu *v, int i)
>          return;
>      }
>  
> -    if ( lr_val.state & GICH_LR_ACTIVE )
> +    if ( lr_val.active )
>      {
>          set_bit(GIC_IRQ_GUEST_ACTIVE, &p->status);
>          if ( test_bit(GIC_IRQ_GUEST_ENABLED, &p->status) &&
> @@ -197,7 +197,7 @@ static void gic_update_one_lr(struct vcpu *v, int i)
>          {
>              if ( p->desc == NULL )
>              {
> -                lr_val.state |= GICH_LR_PENDING;
> +                lr_val.pending = true;
>                  gic_hw_ops->write_lr(i, &lr_val);
>              }
>              else
> @@ -205,7 +205,7 @@ static void gic_update_one_lr(struct vcpu *v, int i)
>                           irq, v->domain->domain_id, v->vcpu_id, i);
>          }
>      }
> -    else if ( lr_val.state & GICH_LR_PENDING )
> +    else if ( lr_val.pending )
>      {
>          int q __attribute__ ((unused)) = 
> test_and_clear_bit(GIC_IRQ_GUEST_QUEUED, &p->status);
>  #ifdef GIC_DEBUG
> diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
> index daec51499c..c32861d4fa 100644
> --- a/xen/include/asm-arm/gic.h
> +++ b/xen/include/asm-arm/gic.h
> @@ -209,7 +209,8 @@ struct gic_lr {
>     /* Virtual IRQ */
>     uint32_t virq;
>     uint8_t priority;
> -   uint8_t state;
> +   bool active;
> +   bool pending;
>     bool hw_status;
>  };

I like the readability but dislike the increase memory usage. I would
have kept a single uint8_t and I would have used status flags as an
approach, maybe I would have improved on those flags.

That said, it doesn't bother me enough to nack the patch :-)


> diff --git a/xen/include/asm-arm/gic_v3_defs.h 
> b/xen/include/asm-arm/gic_v3_defs.h
> index ccb72cf0f1..d9827bd84c 100644
> --- a/xen/include/asm-arm/gic_v3_defs.h
> +++ b/xen/include/asm-arm/gic_v3_defs.h
> @@ -171,6 +171,8 @@
>  #define ICH_LR_PHYSICAL_SHIFT        32
>  #define ICH_LR_STATE_MASK            0x3
>  #define ICH_LR_STATE_SHIFT           62
> +#define ICH_LR_STATE_PENDING         (1ULL << 62)
> +#define ICH_LR_STATE_ACTIVE          (1ULL << 63)
>  #define ICH_LR_PRIORITY_MASK         0xff
>  #define ICH_LR_PRIORITY_SHIFT        48
>  #define ICH_LR_HW_MASK               0x1
> -- 
> 2.14.1
> 

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