Re: [Xen-devel] [PATCH] xen/arm: Save/Restore GICH_APR register

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 4 Apr 2013, Julien Grall wrote:
> Linux uses GICC_CTLR.EOImodeNS set to 0, which means both priority drop
> and deactivate interrupt functionality are made when something is
> written in GICC_EOIR.
> 
> As the ARM manual specifies: "having an active interrupt in the List registers
> with a priority that is not set in the corresponding Active Priorities 
> register"
> when GICV_CTLR.EOImode (ie GICC_CTLR.EOImodeNS in the guest context) result
> in unpredicable behavior, we need to save/restore GICH_APR.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Nice catch!!

Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


>  xen/arch/arm/gic.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> index 41abdfb..ccb90e5 100644
> --- a/xen/arch/arm/gic.c
> +++ b/xen/arch/arm/gic.c
> @@ -70,6 +70,7 @@ void gic_save_state(struct vcpu *v)
>          v->arch.gic_lr[i] = GICH[GICH_LR + i];
>      v->arch.lr_mask = this_cpu(lr_mask);
>      spin_unlock_irq(&gic.lock);
> +    v->arch.gic_apr = GICH[GICH_APR];
>      /* Disable until next VCPU scheduled */
>      GICH[GICH_HCR] = 0;
>      isb();
> @@ -87,6 +88,7 @@ void gic_restore_state(struct vcpu *v)
>      for ( i=0; i<nr_lrs; i++)
>          GICH[GICH_LR + i] = v->arch.gic_lr[i];
>      spin_unlock_irq(&gic.lock);
> +    GICH[GICH_APR] = v->arch.gic_apr;
>      GICH[GICH_HCR] = GICH_HCR_EN;
>      isb();
>  
> -- 
> 1.7.10.4
> 

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