Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for APIC ID register

Radim Krčmář
2016-07-01T15:53:55Z

2016-07-01 17:07+0200, Paolo Bonzini:
> On 01/07/2016 16:54, Radim Krčmář wrote:
>>> > (Hint: we
>>> > want kvm-unit-tests for this).
>> :) Something like this?
>>
>> enable_xapic()
>> id = apic_id()
>> set_apic_id(id+1) // ?
>> enable_x2apic()
>> id == apic_id() & 0xff
>> disable_apic()
>> enable_xapic()
>> id == apic_id()
>>
>
> Yes, plus checking that it "moves" appropriately between low and high bits.

x2APIC cannot use MMIO interface, so apic_id() already does the best we
can ... if KVM is shifting wrong somwhere, then the id should differ.