arch/x86/guest/nested.c, where nested_vmexit_handler() is defined, is
only compiled when CONFIG_NVMX_ENABLED is enabled. Define a dummy
function in include/arch/x86/asm/guest/nested.h to fix the undefined
reference linker error.
Tracked-On: #8465
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>