linux-kernel - Undefined reference to `l1tf_vmx_mitigation' without CONFIG_KVM

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Date:   Wed, 15 Aug 2018 11:42:00 +0300
From:   Dmitrii Tcvetkov <demfloro@...floro.ru>
To:     linux-kernel@...r.kernel.org
Subject: Undefined reference to `l1tf_vmx_mitigation' without
 CONFIG_KVM_INTEL

By build testing 4.18.1-rc2 from
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.18.y
with my custom kernel config I got build error:
  CHK     include/generated/autoksyms.h
  GEN     .version
  CHK     include/generated/compile.h
  AR      built-in.a
  LD      vmlinux.o
  MODPOST vmlinux.o
ld: arch/x86/kvm/x86.o: in function `kvm_get_arch_capabilities':
x86.c:(.text+0x46f2): undefined reference to `l1tf_vmx_mitigation'
make[1]: *** [Makefile:1010: vmlinux] Error 1
make: *** [Makefile:979: autoksyms_recursive] Error 2

Build is successful with
CONFIG_KVM=y
CONFIG_KVM_INTEL=y
CONFIG_KVM_AMD=y
but fails if only
CONFIG_KVM=y
CONFIG_KVM_AMD=y
are selected.

The issue also reproduces on current mainline master (31130a16d459de) with the same error.

View attachment "kern.config" of type "text/plain" (108171 bytes)