Re: [Xen-devel] [PATCH v2 21/45] ARM: new VGIC: Implement vgic_vcpu_pending_irq

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 03/15/2018 08:30 PM, Andre Przywara wrote:
> Tell Xen whether a particular VCPU has an IRQ that needs handling
> in the guest. This is used to decide whether a VCPU is runnable or
> if a hypercall should be preempted to let the guest handle the IRQ.
>
> This is based on Linux commit 90eee56c5f90, written by Eric Auger.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> ---
> Changelog v1 ... v2:
> - adjust to new vgic_vcpu_pending_irq() prototype, drop wrapper
>
>   xen/arch/arm/vgic/vgic.c | 37 +++++++++++++++++++++++++++++++++++++
>   1 file changed, 37 insertions(+)
>
> diff --git a/xen/arch/arm/vgic/vgic.c b/xen/arch/arm/vgic/vgic.c
> index 035c8c8f74..a1556e53e8 100644
> --- a/xen/arch/arm/vgic/vgic.c
> +++ b/xen/arch/arm/vgic/vgic.c
> @@ -637,6 +637,43 @@ void vgic_sync_to_lrs(void)
>       gic_hw_ops->update_hcr_status(GICH_HCR_EN, 1);
>   }
>   
> +/**
> + * vgic_vcpu_pending_irq() - determine if interrupts need to be injected
> + * @vcpu: The vCPU on which to check for interrupts.
> + *
> + * Checks whether there is an interrupt on the given VCPU which needs
> + * handling in the guest. This requires at least one IRQ to be pending
> + * and enabled.
> + *
> + * Returns: 1 if the guest should run to handle interrupts, 0 otherwise.
This does not match with the current implementation as you return bool.

> + */
> +int vgic_vcpu_pending_irq(struct vcpu *vcpu)
> +{
> +    struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic;
> +    struct vgic_irq *irq;
> +    bool pending = false;
> +    unsigned long flags;
> +
> +    if ( !vcpu->domain->arch.vgic.enabled )
> +        return false;
Please don't mix bool and int. Ideally the interface should return a 
bool and not an int.
> +
> +    spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
> +
> +    list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list)
> +    {
> +        spin_lock(&irq->irq_lock);
> +        pending = irq_is_pending(irq) && irq->enabled;
> +        spin_unlock(&irq->irq_lock);
> +
> +        if ( pending )
> +            break;
> +    }
> +
> +    spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
> +
> +    return pending;
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
Cheers,

--
Julien Grall

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