Re: [PATCH for-6.1 v2] i386: do not call cpudef-only models functions for max, host, base

[David Woodhouse]

On Mon, 2021-11-29 at 20:10 +0100, Claudio Fontana wrote:
> 
> Hmm I thought what you actually care for, for cpu "host", is just the 
> kvm_enable_x2apic() call, not the kvm_default_props.
> 
> 
> 
> Do you also expect the kvm_default_prop "kvm-msi-ext-dest-id" to be switch to 
> "on" and applied?

It's already on today. It just isn't *true* because QEMU never called
kvm_enable_x2apic().

So what I care about (in case ∃ APIC IDs >= 255) is two things:

 1. Qemu needs to call kvm_enable_x2apic().
 2. If that *fails* qemu needs to *stop* advertising X2APIC and ext-dest-id.


That last patch snippet in pc_machine_done() should suffice to achieve
that, I think. Because if kvm_enable_x2apic() fails and qemu has been
asked for that many CPUs, it aborts completely. Which seems right.

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