Re: [PATCH v2 1/5] KVM: Add arch specific interfaces for sampling guest callchains

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

Hi Tianyi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 8a749fd1a8720d4619c91c8b6e7528c0a355c0aa]

url:    https://github.com/intel-lab-lkp/linux/commits/Tianyi-Liu/KVM-Add-arch-specific-interfaces-for-sampling-guest-callchains/20231008-230042
base:   8a749fd1a8720d4619c91c8b6e7528c0a355c0aa
patch link:    https://lore.kernel.org/r/SY4P282MB10840154D4F09917D6528BC69DCFA%40SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM
patch subject: [PATCH v2 1/5] KVM: Add arch specific interfaces for sampling guest callchains
config: arm64-randconfig-003-20231009 (https://download.01.org/0day-ci/archive/20231009/202310090448.ffbVfkHi-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231009/202310090448.ffbVfkHi-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310090448.ffbVfkHi-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/uapi/linux/posix_types.h:5,
                    from include/uapi/linux/types.h:14,
                    from include/linux/types.h:6,
                    from include/linux/kasan-checks.h:5,
                    from include/asm-generic/rwonce.h:26,
                    from arch/arm64/include/asm/rwonce.h:71,
                    from include/linux/compiler.h:246,
                    from include/asm-generic/bug.h:5,
                    from arch/arm64/include/asm/bug.h:26,
                    from include/linux/bug.h:5,
                    from arch/arm64/kvm/arm.c:7:
   arch/arm64/kvm/arm.c: In function 'kvm_arch_vcpu_get_frame_pointer':
>> include/linux/stddef.h:8:14: warning: returning 'void *' from a function with return type 'long unsigned int' makes integer from pointer without a cast [-Wint-conversion]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/arm.c:578:16: note: in expansion of macro 'NULL'
     578 |         return NULL;
         |                ^~~~


vim +8 include/linux/stddef.h

^1da177e4c3f41 Linus Torvalds   2005-04-16  6  
^1da177e4c3f41 Linus Torvalds   2005-04-16  7  #undef NULL
^1da177e4c3f41 Linus Torvalds   2005-04-16 @8  #define NULL ((void *)0)
6e218287432472 Richard Knutsson 2006-09-30  9  

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https://github.com/intel/lkp-tests/wiki