Hi Marc, FYI, the error/warning still remains. tree: https://android.googlesource.com/kernel/common android12-5.10 head: d0331b15e6abcacfccdc17a384f2de69c89b25fc commit: 1105b4d1cef4bc19ad20129a716194268c937eaf [6729/10755] BACKPORT: FROMGIT: KVM: arm64: Rework SVE host-save/guest-restore config: arm64-randconfig-r022-20210816 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 2c6448cdc2f68f8c28fd0bd9404182b81306e6e6) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install arm64 cross compiling tool for clang build # apt-get install binutils-aarch64-linux-gnu git remote add android-common https://android.googlesource.com/kernel/common git fetch --no-tags android-common android12-5.10 git checkout 1105b4d1cef4bc19ad20129a716194268c937eaf # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from arch/arm64/kvm/hyp/nvhe/switch.c:8: sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2); ^ arch/arm64/kvm/hyp/nvhe/switch.c:282:17: warning: no previous prototype for function 'kvm_unexpected_el2_exception' [-Wmissing-prototypes] asmlinkage void kvm_unexpected_el2_exception(void) ^ arch/arm64/kvm/hyp/nvhe/switch.c:282:12: note: declare 'static' if the function is not intended to be used outside of this translation unit asmlinkage void kvm_unexpected_el2_exception(void) ^ static 1 warning and 1 error generated. -- In file included from arch/arm64/kvm/hyp/nvhe/hyp-main.c:7: sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2); ^ arch/arm64/kvm/hyp/nvhe/hyp-main.c:233:6: warning: no previous prototype for function 'handle_trap' [-Wmissing-prototypes] void handle_trap(struct kvm_cpu_context *host_ctxt) ^ arch/arm64/kvm/hyp/nvhe/hyp-main.c:233:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void handle_trap(struct kvm_cpu_context *host_ctxt) ^ static 1 warning and 1 error generated. -- In file included from arch/arm64/kvm/hyp/nvhe/mem_protect.c:15: sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2); ^ 1 error generated. -- In file included from arch/arm64/kvm/hyp/vhe/switch.c:8: sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2); ^ arch/arm64/kvm/hyp/vhe/switch.c:227:17: warning: no previous prototype for function 'kvm_unexpected_el2_exception' [-Wmissing-prototypes] asmlinkage void kvm_unexpected_el2_exception(void) ^ arch/arm64/kvm/hyp/vhe/switch.c:227:12: note: declare 'static' if the function is not intended to be used outside of this translation unit asmlinkage void kvm_unexpected_el2_exception(void) ^ static 1 warning and 1 error generated. vim +/sve_cond_update_zcr_vq +216 arch/arm64/kvm/hyp/include/hyp/switch.h 213 214 static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu) 215 { 217 __sve_restore_state(vcpu_sve_pffr(vcpu), 218 &vcpu->arch.ctxt.fp_regs.fpsr); 219 write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR); 220 } 221 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org