Hi Dor,
  Please find a patch attached for your review which adds support for dynamic substitution of the PIC/APIC code to QEMU. This will allow us to selectively chose the KVM in-kernel apic emulation vs the QEMU user-space apic emulation.  Support for both is key to allow "--no-kvm" type operation to continue working even after the in-kernel code is deployed.

Note that this is only the part the allows indirection.  The code that actually fills in the "slim apic" in QEMU, as well as the kernel side changes applied to git are not included here.  Note also that this patch can stand alone.  I have confirmed that I can boot a guest with no discernible difference in behavior/performance both before and after this patch. YMMV as my test cases are limited.

Note that this patch only touches the KVM specific portions of QEMU (namely, x86/i8259/apic support).  If we decide that this should be pushed to QEMU upstream, there is still work to be done to convert the other PIC implementations (e.g. arm_pic, etc) to use the new interface.

I will continue to work on the kernel/slim-apic side while I await your feedback.  (BTW: Thanks for pointing me towards your branch...it has been most helpful rather than starting from scratch.  I already have most of the kernel-side code ported already in a separate queue which I will share once I get a baseline).  

Thanks!

-Greg