On 07/08/2015 09:46, Wu, Feng wrote:
> If I understand it correctly, here you reserve the low part of the routing
> table, and insert entries with KVM_IRQ_ROUTING_MSI type in them,
> then you use this as a hint to KVM to set the EOI bit map. I have two
> concerns:
>
> - Currently, GSI 2 is used for MSI routing, I want to make sure after this
> patch, whether GSI 2 can still be used for _real_ MSI routing, if it can,
> does everything work correctly?
The patch has no effect if you use the in-kernel IOAPIC. If you use a
userspace IOAPIC you won't be able to use GSI 2 for MSI routing because
it falls in the reserved range.
> - Now, KVM_IRQ_ROUTING_MSI and KVM_IRQ_ROUTING_IRQCHIP
> type entries cannot share the same map[gsi] (pls refer to the following
> code), so where should be the IOAPIC entries exist in the map[] array?
With split irqchip, only KVM_IRQ_ROUTING_MSI is used. Does this answer
your question?
Paolo
> static int setup_routing_entry(struct kvm_irq_routing_table *rt,
> struct kvm_kernel_irq_routing_entry *e,
> const struct kvm_irq_routing_entry *ue)
> {
>
> ......
>
> /*
> * Do not allow GSI to be mapped to the same irqchip more than once.
> * Allow only one to one mapping between GSI and MSI.
> */
> hlist_for_each_entry(ei, &rt->map[ue->gsi], link)
> if (ei->type == KVM_IRQ_ROUTING_MSI ||
> ue->type == KVM_IRQ_ROUTING_MSI ||
> ue->u.irqchip.irqchip == ei->irqchip.irqchip)
> return r;
>
> ......
> }
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