tree:   https://github.com/intel/tdx.git guest
head:   224dd4925275ef73ef78f1412d6f9d03564294eb
commit: 65aab3097498af2947a88010cc4354a2cd7edac1 [10/76] x86/tdx: Wire up KVM hypercalls
config: i386-randconfig-r032-20210616 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel/tdx/commit/65aab3097498af2947a88010cc4354a2cd7edac1
        git remote add intel-tdx https://github.com/intel/tdx.git
        git fetch --no-tags intel-tdx guest
        git checkout 65aab3097498af2947a88010cc4354a2cd7edac1
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from include/uapi/linux/kvm_para.h:36,
                    from include/linux/kvm_para.h:5,
                    from drivers/cpuidle/cpuidle-haltpoll.c:18:
   arch/x86/include/asm/kvm_para.h: In function 'kvm_hypercall0':
>> arch/x86/include/asm/kvm_para.h:38:10: error: implicit declaration of function 'tdx_kvm_hypercall'; did you mean 'kvm_hypercall0'? [-Werror=implicit-function-declaration]
      38 |   return tdx_kvm_hypercall(nr, 0, 0, 0, 0);
         |          ^~~~~~~~~~~~~~~~~
         |          kvm_hypercall0
   cc1: some warnings being treated as errors
--
   In file included from include/uapi/linux/kvm_para.h:36,
                    from include/linux/kvm_para.h:5,
                    from arch/x86/kernel/kvm.c:16:
   arch/x86/include/asm/kvm_para.h: In function 'kvm_hypercall0':
>> arch/x86/include/asm/kvm_para.h:38:10: error: implicit declaration of function 'tdx_kvm_hypercall'; did you mean 'kvm_hypercall0'? [-Werror=implicit-function-declaration]
      38 |   return tdx_kvm_hypercall(nr, 0, 0, 0, 0);
         |          ^~~~~~~~~~~~~~~~~
         |          kvm_hypercall0
   arch/x86/kernel/kvm.c: At top level:
   arch/x86/kernel/kvm.c:895:16: warning: no previous prototype for '__kvm_vcpu_is_preempted' [-Wmissing-prototypes]
     895 | __visible bool __kvm_vcpu_is_preempted(long cpu)
         |                ^~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +38 arch/x86/include/asm/kvm_para.h

    19	
    20	#define KVM_HYPERCALL \
    21	        ALTERNATIVE("vmcall", "vmmcall", X86_FEATURE_VMMCALL)
    22	
    23	/* For KVM hypercalls, a three-byte sequence of either the vmcall or the vmmcall
    24	 * instruction.  The hypervisor may replace it with something else but only the
    25	 * instructions are guaranteed to be supported.
    26	 *
    27	 * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
    28	 * The hypercall number should be placed in rax and the return value will be
    29	 * placed in rax.  No other registers will be clobbered unless explicitly
    30	 * noted by the particular hypercall.
    31	 */
    32	
    33	static inline long kvm_hypercall0(unsigned int nr)
    34	{
    35		long ret;
    36	
    37		if (prot_guest_has(PR_GUEST_TDX))
  > 38			return tdx_kvm_hypercall(nr, 0, 0, 0, 0);
    39	
    40		asm volatile(KVM_HYPERCALL
    41			     : "=a"(ret)
    42			     : "a"(nr)
    43			     : "memory");
    44		return ret;
    45	}
    46	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org