KVM: x86: allow hotplug of VCPU with APIC ID over 0xff
LAPIC after reset is in xAPIC mode, which poses a problem for hotplug of VCPUs with high APIC ID, because reset VCPU is waiting for INIT/SIPI, but there is no way to uniquely address it using xAPIC. From many possible options, we chose the one that also works on real hardware: accepting interrupts addressed to LAPIC's x2APIC ID even in xAPIC mode. KVM intentionally differs from real hardware, because real hardware (Knights Landing) does just "x2apic_id & 0xff" to decide whether to accept the interrupt in xAPIC mode and it can deliver one interrupt to more than one physical destination, e.g. 0x123 to 0x123 and 0x23. Fixes: 682f732e ("KVM: x86: bump MAX_VCPUS to 288") Reviewed-by: NDavid Hildenbrand <david@redhat.com> Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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