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: 682f732ecf73 ("KVM: x86: bump MAX_VCPUS to 288")
Reviewed-by: David Hildenbrand <[email protected]>
Signed-off-by: Radim Krčmář <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

0 files changed, 0 insertions, 0 deletions