Re: [PATCH v5 02/16] KVM: x86/xen: intercept xen hypercalls if enabled

[kernel test robot <lkp@intel.com>]

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Hi David,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on v5.11-rc3]
[also build test WARNING on next-20210111]
[cannot apply to kvm/linux-next xen-tip/linux-next vhost/linux-next]
[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-minimal-support-for-Xen-HVM-guests/20210112-040054
base:    7c53f6b671f4aba70ff15e1b05148b10d58c2837
config: x86_64-randconfig-s022-20210111 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-208-g46a52ca4-dirty
        # https://github.com/0day-ci/linux/commit/9e109a13c92b207e4edbaf4b8ccb22a32ffcb587
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Woodhouse/KVM-Add-minimal-support-for-Xen-HVM-guests/20210112-040054
        git checkout 9e109a13c92b207e4edbaf4b8ccb22a32ffcb587
        # 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@intel.com>


"sparse warnings: (new ones prefixed by >>)"
>> arch/x86/kvm/xen.c:67:46: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const [noderef] __user * @@     got unsigned char [usertype] * @@
   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	
  > 67			page = memdup_user(blob_addr + (page_num * PAGE_SIZE), PAGE_SIZE);
    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

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