Hi David, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on vhost/linux-next] [also build test WARNING on v5.10-rc7] [cannot apply to xen-tip/linux-next kvm/linux-next next-20201210] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/David-Woodhouse/KVM-Add-Xen-hype... base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next config: x86_64-randconfig-s021-20201210 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce: # apt-get install sparse # sparse version: v0.6.3-179-ga00755aa-dirty # https://github.com/0day-ci/linux/commit/ac2b425f8c484a711fe7b2a01e875fd95... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review David-Woodhouse/KVM-Add-Xen-hypercall-and-shared-info-pages/20201206-190926 git checkout ac2b425f8c484a711fe7b2a01e875fd95248ac20 # save the attached .config to linux build tree make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 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/xen.c:67:46: sparse: expected void const [noderef] __user * arch/x86/kvm/xen.c:67:46: sparse: got unsigned char [usertype] * vim +67 arch/x86/kvm/xen.c 17 18 int kvm_xen_hvm_config(struct kvm_vcpu *vcpu, u64 data) 19 { 20 struct kvm *kvm = vcpu->kvm; 21 u32 page_num = data & ~PAGE_MASK; 22 u64 page_addr = data & PAGE_MASK; 23 24 /* 25 * If Xen hypercall intercept is enabled, fill the hypercall 26 * page with VMCALL/VMMCALL instructions since that's what 27 * we catch. Else the VMM has provided the hypercall pages 28 * with instructions of its own choosing, so use those. 29 */ 30 if (kvm_xen_hypercall_enabled(kvm)) { 31 u8 instructions[32]; 32 int i; 33 34 if (page_num) 35 return 1; 36 37 /* mov imm32, %eax */ 38 instructions[0] = 0xb8; 39 40 /* vmcall / vmmcall */ 41 kvm_x86_ops.patch_hypercall(vcpu, instructions + 5); 42 43 /* ret */ 44 instructions[8] = 0xc3; 45 46 /* int3 to pad */ 47 memset(instructions + 9, 0xcc, sizeof(instructions) - 9); 48 49 for (i = 0; i < PAGE_SIZE / sizeof(instructions); i++) { 50 *(u32 *)&instructions[1] = i; 51 if (kvm_vcpu_write_guest(vcpu, 52 page_addr + (i * sizeof(instructions)), 53 instructions, sizeof(instructions))) 54 return 1; 55 } 56 } else { 57 int lm = is_long_mode(vcpu); 58 u8 *blob_addr = lm ? (u8 *)(long)kvm->arch.xen_hvm_config.blob_addr_64 59 : (u8 *)(long)kvm->arch.xen_hvm_config.blob_addr_32; 60 u8 blob_size = lm ? kvm->arch.xen_hvm_config.blob_size_64 61 : kvm->arch.xen_hvm_config.blob_size_32; 62 u8 *page; 63 64 if (page_num >= blob_size) 65 return 1; 66 68 if (IS_ERR(page)) 69 return PTR_ERR(page); 70 71 if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE)) { 72 kfree(page); 73 return 1; 74 } 75 } 76 return 0; 77 } 78 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org