[gentoo-user] x86.c:(.text+0xb2): undefined reference to `l1tf_vmx_mitigation' with linux kernel 4.18.1

Hi,

CPU bugs seem to be more and more common:
https://www.heise.de/security/meldung/Linux-Kernel-und-Distributionen-schuetzen-vor-Prozessorluecke-Foreshadow-L1TF-4137264.html
https://www.heise.de/security/meldung/Spectre-NG-Foreshadow-gefaehrdet-Intel-Prozessoren-4137209.html
(sorry, I only know of this german spoken references...)

With Linux kernel 4.18.1 Linus has introduced a fix (aka workaround)
of the  Foreshadow bug.

Unfortunately compiling that kernel (as downloaded from
https://mirrors.edge.kernel.org/pub/linux/kernel/v4.x/ )

gives me this bug:


...
  AR      arch/x86/lib/built-in.a
  CC      virt/lib/irqbypass.o
  AR      virt/lib/built-in.a
  AR      virt/built-in.a
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  AR      init/built-in.a
  AR      built-in.a
  LD      vmlinux.o
  MODPOST vmlinux.o
arch/x86/kvm/x86.o: In function `kvm_get_arch_capabilities':
x86.c:(.text+0xb2): undefined reference to `l1tf_vmx_mitigation'
make[1]: *** [Makefile:1010: vmlinux] Error 1
make: *** [Makefile:273: __build_one_by_one] Error 2
[1]    25144 exit 2     make clean all


I am alone or is this known (a quick search on startpage.com does not
give me any useful) or ... ?
Is there a way around it?

Cheers!
Meino