Re: [Qemu-devel] [RFC PATCH v2] kvm: x86: ignore ioapic polarity

[Gabriel L. Somlo]

On Thu, Mar 13, 2014 at 11:53:04AM +0100, Paolo Bonzini wrote:
> Instead of this, I'm adding the following to the KVM_IRQ_LINE ioctl:
> 
> +On real hardware, interrupt pins can be active-low or active-high.  This
> +does not matter for the level field of struct kvm_irq_level: 1 always
> +means active (asserted), 0 means inactive (deasserted).
> +
> +x86 allows the operating system to program the interrupt polarity
> +(active-low/active-high) for level-triggered interrupts, and KVM used
> +to consider the polarity.  However, due to bitrot in the handling of
> +active-low interrupts, the above convention is now valid on x86 too.
> +This is signaled by KVM_CAP_X86_IOAPIC_POLARITY_IGNORED.  Userspace
> +should not present interrupts to the guest as active-low unless this
> +capability is present (or unless it is not using the in-kernel irqchip,
> +of course).
> 
> and applying the patch to kvm/queue.

Sounds great to me, thanks !

--Gabriel