Hi Paolo, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: d15be546031cf65a0fc34879beca02fd90fe7ac7 commit: c50d8ae3a1274f32c9033bbb0e1c5b3115da2112 KVM: x86: create mmu/ subdirectory date: 8 months ago config: i386-randconfig-s002-20200724 (attached as .config) compiler: gcc-9 (Debian 9.3.0-14) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.2-93-g4c6cbe55-dirty git checkout c50d8ae3a1274f32c9033bbb0e1c5b3115da2112 # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) arch/x86/kvm/mmu/mmu.c:705:18: sparse: sparse: cast to non-scalar arch/x86/kvm/mmu/mmu.c:724:18: sparse: sparse: cast to non-scalar arch/x86/kvm/mmu/mmu.c:4759:57: sparse: sparse: cast truncates bits from constant value (ffffff33 becomes 33) arch/x86/kvm/mmu/mmu.c:4761:56: sparse: sparse: cast truncates bits from constant value (ffffff0f becomes f) arch/x86/kvm/mmu/mmu.c:4763:57: sparse: sparse: cast truncates bits from constant value (ffffff55 becomes 55) vim +686 arch/x86/kvm/mmu/mmu.c c2a2ac2b563ccc3 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 680 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 681 static void __set_spte(u64 *sptep, u64 spte) 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 682 { 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 683 union split_spte *ssptep, sspte; a9221dd5ec125fb arch/x86/kvm/mmu.c Avi Kivity 2010-06-06 684 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 685 ssptep = (union split_spte *)sptep; 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 @686 sspte = (union split_spte)spte; 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 687 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 688 ssptep->spte_high = sspte.spte_high; 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 689 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 690 /* 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 691 * If we map the spte from nonpresent to present, We should store 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 692 * the high bits firstly, then set present bit, so cpu can not 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 693 * fetch this spte while we are setting the spte. 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 694 */ 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 695 smp_wmb(); 603e0651cfc8562 arch/x86/kvm/mmu.c Xiao Guangrong 2011-07-12 696 b19ee2ff3b287fe arch/x86/kvm/mmu.c Nadav Amit 2016-05-11 697 WRITE_ONCE(ssptep->spte_low, sspte.spte_low); a9221dd5ec125fb arch/x86/kvm/mmu.c Avi Kivity 2010-06-06 698 } a9221dd5ec125fb arch/x86/kvm/mmu.c Avi Kivity 2010-06-06 699 :::::: The code at line 686 was first introduced by commit :::::: 603e0651cfc8562b103454d7ded71f3ad1eb3a37 KVM: MMU: do not need atomicly to set/clear spte :::::: TO: Xiao Guangrong <xiaoguangrong(a)cn.fujitsu.com&gt; :::::: CC: Avi Kivity <avi(a)redhat.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org