Dong, Eddie wrote:
x2apic has the following benefit:

- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one ICR write instead of two
- potential to support large guests once we add interrupt remapping
- shared code with the Hyper-V paravirt interface

Is there any plan to implement an PV irqchip such as Xenirqchip for KVM?

No.  PV irqchips (and PV in general) have the following drawbacks:

- need to define and maintain an ABI
- only works on newer Linux guests
- obsoleted when hardware improves
- increase code size and maintenance effort
- have problems during transitions (boot, kexec)
- don't integrate well with device assignment
- require effort outside the kvm codebase

If a significant performance benefit can be demonstrated, I'll consider it, but until then my preference is full virtualization augmented by optional, targeted pv assists (like the TPR patching).

--
error compiling committee.c: too many arguments to function

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