Re: [RFC 0/6] KVM: arm/arm64: gsi routing support

[Eric Auger <eric.auger@linaro.org>]

Hi Favel,
On 06/23/2015 10:50 AM, Pavel Fedin wrote:
>  Hello!
> 
>> I was talking about what
>> is done without this "gsi direct mapping" feature. In that case the low
>> GSI numbers are used by irqchip routing entries. So kvm_irqchip_get_virq
>> returns a gsi beyond the irqchip routed gsi's.
> 
>  But aren't these low numbers just routed by the qemu too? I don't see qemu getting any predefined
> routing from the kernel. 

(some) iqrchip routing is set through kvm_irqchip_add_irq_route.
hw/i386/kvm/ioapic.c
hw/intc/openpic_kvm.c

kvm_irqchip_add_irq_route uses kvm_add_routing_entry and this is this
latter that uses set_gsis which books gsi's.

there is also a default gsi routing table set in kvm archi specific code.

Best Regards

Eric

kvm_init_irq_routing() allocates used_gsi_bitmap as all zeros, and
> kvm_irqchip_get_virq() just starts to give those free numbers, starting from zero. I believe during
> machine init we allocate virq's and route them to irqchip explicitly, don't we ?
>  Sorry for being perhaps ignorant, i haven't studied x86 qemu code too much.

> 
> Kind regards,
> Pavel Fedin
> Expert Engineer
> Samsung Electronics Research center Russia
> 
>