Re: [PATCH v3 15/39] ARM: new VGIC: Implement vgic_vcpu_pending_irq

[Andre Przywara <andre.przywara@linaro.org>]

Hi,

On 22/03/18 03:52, Julien Grall wrote:
> Hi Andre,
> 
> On 03/21/2018 04:32 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@linaro.org>
>> ---
>> Changelog v2 ... v3:
>> - adjust vgic_vcpu_pending_irq() to return integers, not false/true
> 
> I would have preferred to have the return switch to bool instead. I
> guess this can be done on a follow-up. With one comment below:

I did that originally, but then you meanwhile merged that first patch
already. So I didn't want to add another patch to this series.
I am fine with changing this afterwards, probably as part of a fixup series.

> Reviewed-by: Julien Grall <julien.grall@arm.com>

Thanks!

Cheers,
Andre.

>>
>> 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 2fa595f4f7..925cda4580 100644
>> --- a/xen/arch/arm/vgic/vgic.c
>> +++ b/xen/arch/arm/vgic/vgic.c
>> @@ -647,6 +647,43 @@ 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.
> 
> NIT: Because of "ret = irq_is_pending(irq) && irq->enabled", you will
> return a non-zero value if the guest should run to handle interrupts.
> 
>> + */
>> +int vgic_vcpu_pending_irq(struct vcpu *vcpu)
>> +{
>> +    struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic;
>> +    struct vgic_irq *irq;
>> +    unsigned long flags;
>> +    int ret = 0;
>> +
>> +    if ( !vcpu->domain->arch.vgic.enabled )
>> +        return 0;
>> +
>> +    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);
>> +        ret = irq_is_pending(irq) && irq->enabled;
>> +        spin_unlock(&irq->irq_lock);
>> +
>> +        if ( ret )
>> +            break;
>> +    }
>> +
>> +    spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
>> +
>> +    return ret;
>> +}
>> +
>>   /*
>>    * Local variables:
>>    * mode: C
>>
> 
> Cheers,
> 

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