On 18/06/21 18:47, David Matlack wrote:
> On Fri, Jun 18, 2021 at 12:42:56PM +0200, Paolo Bonzini wrote:
>> On 18/06/21 09:17, kernel test robot wrote:
>>>      ld: arch/x86/kvm/mmu/mmu.o: in function `get_mmio_spte':
>>>>> arch/x86/kvm/mmu/mmu.c:3612: undefined reference to `kvm_tdp_mmu_get_walk'
>>>      ld: arch/x86/kvm/mmu/mmu.o: in function `direct_page_fault':
>>>>> arch/x86/kvm/mmu/mmu.c:3830: undefined reference to `kvm_tdp_mmu_map'
>>
>> Turns out sometimes is_tdp_mmu_root is not inlined after this patch.
>> Fixed thusly:
> 
> Thanks for the fix. I guess after I removed the is_tdp_mmu_enabled()
> check the compiler couldn't determine what is_tdp_mmu_root() would
> return on 32-bit builds anymore.

It still could, but only as long as is_tdp_mmu_root was inlined.  Your 
patch caused the final "return false" to only appear after a few WARN_ON 
checks that obviously can't be removed, and therefore tipped the balance 
towards not inlining it!

Paolo