Hi Paolo, On Thu, Mar 10, 2022 at 05:05:41PM +0800, kernel test robot wrote: > tree: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue > head: ce41d078aaa9cf15cbbb4a42878cc6160d76525e > commit: ce41d078aaa9cf15cbbb4a42878cc6160d76525e [210/210] KVM: x86: synthesize CPUID leaf 0x80000021h if useful > config: x86_64-randconfig-a014 (https://download.01.org/0day-ci/archive/20220310/202203101604.2rV6WBqW-lkp@xxxxxxxxx/config) > compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 276ca87382b8f16a65bddac700202924228982f6) > 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 > # https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?id=ce41d078aaa9cf15cbbb4a42878cc6160d76525e > git remote add kvm https://git.kernel.org/pub/scm/virt/kvm/kvm.git > git fetch --no-tags kvm queue > git checkout ce41d078aaa9cf15cbbb4a42878cc6160d76525e > # save the config file to linux build tree > mkdir build_dir > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/kvm/ > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > All warnings (new ones prefixed by >>): > > >> arch/x86/kvm/cpuid.c:739:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough] > default: > ^ > arch/x86/kvm/cpuid.c:739:2: note: insert 'break;' to avoid fall-through > default: > ^ > break; > 1 warning generated. > > > vim +739 arch/x86/kvm/cpuid.c > > e53c95e8d41ef9 Sean Christopherson 2020-03-02 707 > e53c95e8d41ef9 Sean Christopherson 2020-03-02 708 static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array, > aa10a7dc8858f6 Sean Christopherson 2020-03-02 709 u32 function, u32 index) > 00b27a3efb1160 Avi Kivity 2011-11-23 710 { > e53c95e8d41ef9 Sean Christopherson 2020-03-02 711 struct kvm_cpuid_entry2 *entry; > e53c95e8d41ef9 Sean Christopherson 2020-03-02 712 > e53c95e8d41ef9 Sean Christopherson 2020-03-02 713 if (array->nent >= array->maxnent) > aa10a7dc8858f6 Sean Christopherson 2020-03-02 714 return NULL; > e53c95e8d41ef9 Sean Christopherson 2020-03-02 715 > e53c95e8d41ef9 Sean Christopherson 2020-03-02 716 entry = &array->entries[array->nent++]; > aa10a7dc8858f6 Sean Christopherson 2020-03-02 717 > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 718 memset(entry, 0, sizeof(*entry)); > 00b27a3efb1160 Avi Kivity 2011-11-23 719 entry->function = function; > 00b27a3efb1160 Avi Kivity 2011-11-23 720 entry->index = index; > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 721 switch (function & 0xC0000000) { > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 722 case 0x40000000: > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 723 /* Hypervisor leaves are always synthesized by __do_cpuid_func. */ > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 724 return entry; > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 725 > ce41d078aaa9cf Paolo Bonzini 2021-10-21 726 case 0x80000000: > ce41d078aaa9cf Paolo Bonzini 2021-10-21 727 /* > ce41d078aaa9cf Paolo Bonzini 2021-10-21 728 * 0x80000021 is sometimes synthesized by __do_cpuid_func, which > ce41d078aaa9cf Paolo Bonzini 2021-10-21 729 * would result in out-of-bounds calls to do_host_cpuid. > ce41d078aaa9cf Paolo Bonzini 2021-10-21 730 */ > ce41d078aaa9cf Paolo Bonzini 2021-10-21 731 { > ce41d078aaa9cf Paolo Bonzini 2021-10-21 732 static int max_cpuid_80000000; > ce41d078aaa9cf Paolo Bonzini 2021-10-21 733 if (!READ_ONCE(max_cpuid_80000000)) > ce41d078aaa9cf Paolo Bonzini 2021-10-21 734 WRITE_ONCE(max_cpuid_80000000, cpuid_eax(0x80000000)); > ce41d078aaa9cf Paolo Bonzini 2021-10-21 735 if (function > READ_ONCE(max_cpuid_80000000)) > ce41d078aaa9cf Paolo Bonzini 2021-10-21 736 return entry; > ce41d078aaa9cf Paolo Bonzini 2021-10-21 737 } > ce41d078aaa9cf Paolo Bonzini 2021-10-21 738 Please add a "break;" here to fix this clang warning. GCC does not warn when falling through to a case statement that just contains "break" or "return" but clang's verion of the warning does, which matches the kernel's guidance in Documentation/process/deprecated.rst for having all case statements end in either "break", "continue", "fallthrough", "goto", or "return". > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 @739 default: > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 740 break; > 2746a6b72ab9a9 Paolo Bonzini 2021-10-28 741 } > ab8bcf64971180 Paolo Bonzini 2019-06-24 742 > 00b27a3efb1160 Avi Kivity 2011-11-23 743 cpuid_count(entry->function, entry->index, > 00b27a3efb1160 Avi Kivity 2011-11-23 744 &entry->eax, &entry->ebx, &entry->ecx, &entry->edx); > d9aadaf689928b Paolo Bonzini 2019-07-04 745 > d9aadaf689928b Paolo Bonzini 2019-07-04 746 switch (function) { > d9aadaf689928b Paolo Bonzini 2019-07-04 747 case 4: > d9aadaf689928b Paolo Bonzini 2019-07-04 748 case 7: > d9aadaf689928b Paolo Bonzini 2019-07-04 749 case 0xb: > d9aadaf689928b Paolo Bonzini 2019-07-04 750 case 0xd: > a06dcd625d6181 Jim Mattson 2019-09-12 751 case 0xf: > a06dcd625d6181 Jim Mattson 2019-09-12 752 case 0x10: > a06dcd625d6181 Jim Mattson 2019-09-12 753 case 0x12: > d9aadaf689928b Paolo Bonzini 2019-07-04 754 case 0x14: > a06dcd625d6181 Jim Mattson 2019-09-12 755 case 0x17: > a06dcd625d6181 Jim Mattson 2019-09-12 756 case 0x18: > 690a757d610e50 Jing Liu 2022-01-05 757 case 0x1d: > 690a757d610e50 Jing Liu 2022-01-05 758 case 0x1e: > a06dcd625d6181 Jim Mattson 2019-09-12 759 case 0x1f: > d9aadaf689928b Paolo Bonzini 2019-07-04 760 case 0x8000001d: > d9aadaf689928b Paolo Bonzini 2019-07-04 761 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; > d9aadaf689928b Paolo Bonzini 2019-07-04 762 break; > d9aadaf689928b Paolo Bonzini 2019-07-04 763 } > aa10a7dc8858f6 Sean Christopherson 2020-03-02 764 > aa10a7dc8858f6 Sean Christopherson 2020-03-02 765 return entry; > 00b27a3efb1160 Avi Kivity 2011-11-23 766 } > 00b27a3efb1160 Avi Kivity 2011-11-23 767 > > :::::: The code at line 739 was first introduced by commit > :::::: 2746a6b72ab9a92bd188c4ac3e4122ee1c18f754 KVM: x86: skip host CPUID call for hypervisor leaves > > :::::: TO: Paolo Bonzini <pbonzini@xxxxxxxxxx> > :::::: CC: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cheers, Nathan
