Re: [PATCH] KVM: nVMX: Properly handle userspace interrupt window request

[Paolo Bonzini]

On 03/03/20 07:27, Sean Christopherson wrote:
> Odds are good that this doesn't solve all the problems with running nested
> VMX and a userspace LAPIC, but I'm at least able to boot a kernel and run
> unit tests, i.e. it's less broken than before.  Not that it matters, I'm
> guessing no one actually uses this configuration, e.g. running a SMP
> guest with the current KVM+kernel hangs during boot because Qemu
> advertises PV IPIs to the guest, which require an in-kernel LAPIC.  I
> stumbled on this disaster when disabling the in-kernel LAPIC for a
> completely unrelated test.  I'm happy even if it does nothing more than
> get rid of the awful logic vmx_check_nested_events().

Yes, userspace LAPIC is more or less constantly broken.  I think it
should be deprecated in QEMU.

Paolo