[BUG] No irqchip created after commit 11bc4a13d1f4 ("kvm: convert "-machine kernel_irqchip" to an accelerator property")

[Vitaly Kuznetsov]

I apologize if this was already reported,

I just noticed that with the latest updates QEMU doesn't start with the
following configuration:

qemu-system-x86_64 -name guest=win10 -machine pc,accel=kvm -cpu 
host,hv_vpindex,hv_synic ...

qemu-system-x86_64: failed to turn on HyperV SynIC in KVM: Invalid argument
qemu-system-x86_64: kvm_init_vcpu failed: Invalid argument

If I add 'kernel-irqchip=split' or ',kernel-irqchip=on' it starts as
usual. I bisected this to the following commit:

commit 11bc4a13d1f4b07dafbd1dda4d4bf0fdd7ad65f2 (HEAD, refs/bisect/bad)
Author: Paolo Bonzini <address@hidden>
Date:   Wed Nov 13 10:56:53 2019 +0100

    kvm: convert "-machine kernel_irqchip" to an accelerator property
    
so aparently we now default to 'kernel_irqchip=off'. Is this the desired
behavior?

-- 
Vitaly