Re: [Xen-devel] [PATCH 03/10] xen/arm: vgic-v3: Correctly handle GICD_CTLR

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2015-01-19 at 16:29 +0000, Julien Grall wrote:
> As backward GICv2 compatibility is not supported in the VGICv3 driver,
> the bit ARE_NS should be set at any time.

Looking at the docs, I think you mean it is RAO/WI if GICv2 compat is
absent (rather than imply the guest should set it).

> 
> Futhermore, when ARE_NS is set, the guest can only modify EnableGrp1A.

"Furthermore"

> At same time take the vgic_lock to write into domain.arch.vgic.ctrl. It
> was already taken during read.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>  xen/arch/arm/vgic-v3.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index 406ea93..1aa2f58 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -45,6 +45,12 @@
>  #define GICV3_GICR_PIDR2  GICV3_GICD_PIDR2
>  #define GICV3_GICR_PIDR4  GICV3_GICD_PIDR4
>  
> +/*
> + * GICD_CTLR default value:
> + *      - No GICv2 compatibility => ARE = 1
> + */
> +#define VGICD_CTLR_DEFAULT  (GICD_CTLR_ARE_NS)
> +
>  static struct vcpu *vgic_v3_irouter_to_vcpu(struct vcpu *v, uint64_t irouter)
>  {
>      irouter &= ~(GICD_IROUTER_SPI_MODE_ANY);
> @@ -834,8 +840,15 @@ static int vgic_v3_distr_mmio_write(struct vcpu *v, 
> mmio_info_t *info)
>      {
>      case GICD_CTLR:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        /* Ignore all but the enable bit */
> -        v->domain->arch.vgic.ctlr = (*r) & GICD_CTL_ENABLE;
> +
> +        vgic_lock(v);
> +        /* Only EnableGrp1A can be changed */
> +        if ( *r & GICD_CTLR_ENABLE_G1A )
> +            v->domain->arch.vgic.ctlr |= GICD_CTLR_ENABLE_G1A;
> +        else
> +            v->domain->arch.vgic.ctlr &= ~GICD_CTLR_ENABLE_G1A;
> +        vgic_unlock(v);
> +
>          return 1;
>      case GICD_TYPER:
>          /* RO -- write ignored */
> @@ -1092,6 +1105,8 @@ static int vgic_v3_domain_init(struct domain *d)
>          register_mmio_handler(d, &vgic_rdistr_mmio_handler,
>              d->arch.vgic.rbase[i], d->arch.vgic.rbase_size[i]);
>  
> +    d->arch.vgic.ctlr = VGICD_CTLR_DEFAULT;
> +
>      return 0;
>  }
>  



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