linux-kernel - include/uapi/linux/vbox_vmmdev_types.h:239:4: warning: field u within 'struct vmmdev_hgcm_function_parameter32' is less aligned than 'union (unnamed union at include/uapi/linux/vbox_vmmdev_types.h:223:2)' and is usually due to 'struct vmmdev_hgcm

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Message-ID: <202507240731.jgaW3v2n-lkp@intel.com>
Date: Thu, 24 Jul 2025 07:44:26 +0800
From: kernel test robot <lkp@...el.com>
To: Arnd Bergmann <arnd@...db.de>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Hans de Goede <hdegoede@...hat.com>
Subject: include/uapi/linux/vbox_vmmdev_types.h:239:4: warning: field u
 within 'struct vmmdev_hgcm_function_parameter32' is less aligned than 'union
 (unnamed union at include/uapi/linux/vbox_vmmdev_types.h:223:2)' and is
 usually due to 'struct vmmdev_hgcm_function...

Hi Arnd,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   01a412d06bc5786eb4e44a6c8f0f4659bd4c9864
commit: c99e1e1d0850ff157f1bc16871acd2dff5a9bcc3 vbox: add HAS_IOPORT dependency
date:   5 months ago
config: arm-randconfig-r122-20250724 (https://download.01.org/0day-ci/archive/20250724/202507240731.jgaW3v2n-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 853c343b45b3e83cc5eeef5a52fc8cc9d8a09252)
reproduce: (https://download.01.org/0day-ci/archive/20250724/202507240731.jgaW3v2n-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507240731.jgaW3v2n-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/virt/vboxguest/vboxguest_linux.c:15:
   In file included from include/linux/vbox_utils.h:8:
>> include/uapi/linux/vbox_vmmdev_types.h:239:4: warning: field u within 'struct vmmdev_hgcm_function_parameter32' is less aligned than 'union (unnamed union at include/uapi/linux/vbox_vmmdev_types.h:223:2)' and is usually due to 'struct vmmdev_hgcm_function_parameter32' being packed, which can lead to unaligned accesses [-Wunaligned-access]
     239 |         } u;
         |           ^
>> include/uapi/linux/vbox_vmmdev_types.h:254:6: warning: field u within 'struct vmmdev_hgcm_function_parameter64::(unnamed at include/uapi/linux/vbox_vmmdev_types.h:249:3)' is less aligned than 'union (unnamed union at include/uapi/linux/vbox_vmmdev_types.h:251:4)' and is usually due to 'struct vmmdev_hgcm_function_parameter64::(unnamed at include/uapi/linux/vbox_vmmdev_types.h:249:3)' being packed, which can lead to unaligned accesses [-Wunaligned-access]
     254 |                         } u;
         |                           ^
   2 warnings generated.


vim +239 include/uapi/linux/vbox_vmmdev_types.h

f6ddd094f57934 Hans de Goede 2017-11-30  219  
f6ddd094f57934 Hans de Goede 2017-11-30  220  /** HGCM function parameter, 32-bit client. */
f6ddd094f57934 Hans de Goede 2017-11-30  221  struct vmmdev_hgcm_function_parameter32 {
f6ddd094f57934 Hans de Goede 2017-11-30  222  	enum vmmdev_hgcm_function_parameter_type type;
f6ddd094f57934 Hans de Goede 2017-11-30  223  	union {
f6ddd094f57934 Hans de Goede 2017-11-30  224  		__u32 value32;
f6ddd094f57934 Hans de Goede 2017-11-30  225  		__u64 value64;
f6ddd094f57934 Hans de Goede 2017-11-30  226  		struct {
f6ddd094f57934 Hans de Goede 2017-11-30  227  			__u32 size;
f6ddd094f57934 Hans de Goede 2017-11-30  228  			union {
f6ddd094f57934 Hans de Goede 2017-11-30  229  				__u32 phys_addr;
f6ddd094f57934 Hans de Goede 2017-11-30  230  				__u32 linear_addr;
f6ddd094f57934 Hans de Goede 2017-11-30  231  			} u;
f6ddd094f57934 Hans de Goede 2017-11-30  232  		} pointer;
f6ddd094f57934 Hans de Goede 2017-11-30  233  		struct {
f6ddd094f57934 Hans de Goede 2017-11-30  234  			/** Size of the buffer described by the page list. */
f6ddd094f57934 Hans de Goede 2017-11-30  235  			__u32 size;
f6ddd094f57934 Hans de Goede 2017-11-30  236  			/** Relative to the request header. */
f6ddd094f57934 Hans de Goede 2017-11-30  237  			__u32 offset;
f6ddd094f57934 Hans de Goede 2017-11-30  238  		} page_list;
f6ddd094f57934 Hans de Goede 2017-11-30 @239  	} u;
f6ddd094f57934 Hans de Goede 2017-11-30  240  } __packed;
f6ddd094f57934 Hans de Goede 2017-11-30  241  VMMDEV_ASSERT_SIZE(vmmdev_hgcm_function_parameter32, 4 + 8);
f6ddd094f57934 Hans de Goede 2017-11-30  242  
f6ddd094f57934 Hans de Goede 2017-11-30  243  /** HGCM function parameter, 64-bit client. */
f6ddd094f57934 Hans de Goede 2017-11-30  244  struct vmmdev_hgcm_function_parameter64 {
f6ddd094f57934 Hans de Goede 2017-11-30  245  	enum vmmdev_hgcm_function_parameter_type type;
f6ddd094f57934 Hans de Goede 2017-11-30  246  	union {
f6ddd094f57934 Hans de Goede 2017-11-30  247  		__u32 value32;
f6ddd094f57934 Hans de Goede 2017-11-30  248  		__u64 value64;
f6ddd094f57934 Hans de Goede 2017-11-30  249  		struct {
f6ddd094f57934 Hans de Goede 2017-11-30  250  			__u32 size;
f6ddd094f57934 Hans de Goede 2017-11-30  251  			union {
f6ddd094f57934 Hans de Goede 2017-11-30  252  				__u64 phys_addr;
f6ddd094f57934 Hans de Goede 2017-11-30  253  				__u64 linear_addr;
f6ddd094f57934 Hans de Goede 2017-11-30 @254  			} u;
f6ddd094f57934 Hans de Goede 2017-11-30  255  		} __packed pointer;
f6ddd094f57934 Hans de Goede 2017-11-30  256  		struct {
f6ddd094f57934 Hans de Goede 2017-11-30  257  			/** Size of the buffer described by the page list. */
f6ddd094f57934 Hans de Goede 2017-11-30  258  			__u32 size;
f6ddd094f57934 Hans de Goede 2017-11-30  259  			/** Relative to the request header. */
f6ddd094f57934 Hans de Goede 2017-11-30  260  			__u32 offset;
f6ddd094f57934 Hans de Goede 2017-11-30  261  		} page_list;
f6ddd094f57934 Hans de Goede 2017-11-30  262  	} __packed u;
f6ddd094f57934 Hans de Goede 2017-11-30  263  } __packed;
f6ddd094f57934 Hans de Goede 2017-11-30  264  VMMDEV_ASSERT_SIZE(vmmdev_hgcm_function_parameter64, 4 + 12);
f6ddd094f57934 Hans de Goede 2017-11-30  265  

:::::: The code at line 239 was first introduced by commit
:::::: f6ddd094f5793447d594aa9f42032a7aba12b4d2 virt: Add vboxguest driver for Virtual Box Guest integration UAPI

:::::: TO: Hans de Goede <hdegoede@...hat.com>
:::::: CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki