Re: [PATCH RFC] x86/kvm/lapic: always disable MMIO interface in x2APIC mode

From: Paolo Bonzini
Date: Fri Jul 27 2018 - 13:00:43 EST

On 27/07/2018 18:48, Jim Mattson wrote:
> On a physical machine, I would expect the default local APIC page to
> fall in the PCI hole, so it would be correct to sink writes and to
> return all ones for reads. Does qemu implement a PCI hole, and does
> this address fall into it?

It does implement a PCI hole, but when using the kernel LAPIC it expects
that only devices write to that range; therefore that address doesn't
fall into the PCI hole, and instead it generates an MSIs.