[openeuler:openEuler-1.0-LTS 21050/21544] arch/x86/include/asm/msr.h:272:9: warning: 'mcu_ctrl' may be used uninitialized

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

tree:   https://gitee.com/openeuler/kernel.git openEuler-1.0-LTS
head:   1f0983450549eeea71fb9333517330947a779262
commit: 99dec2700cf36e58d3fdb295e1fed7e9d04a916c [21050/21544] x86/speculation: Add Gather Data Sampling mitigation
config: x86_64-allnoconfig (https://download.01.org/0day-ci/archive/20240113/202401130830.UR68iRGU-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240113/202401130830.UR68iRGU-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/202401130830.UR68iRGU-lkp@intel.com/

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   In file included from arch/x86/include/asm/processor.h:21,
                    from arch/x86/include/asm/cpufeature.h:5,
                    from arch/x86/include/asm/thread_info.h:53,
                    from include/linux/thread_bits.h:22,
                    from include/linux/thread_info.h:14,
                    from arch/x86/include/asm/preempt.h:7,
                    from include/linux/preempt.h:81,
                    from include/linux/rcupdate.h:40,
                    from include/linux/rculist.h:11,
                    from include/linux/pid.h:5,
                    from include/linux/sched.h:14,
                    from include/linux/utsname.h:6,
                    from arch/x86/kernel/cpu/bugs.c:12:
   In function 'wrmsrl',
       inlined from 'update_gds_msr' at arch/x86/kernel/cpu/bugs.c:689:2:
>> arch/x86/include/asm/msr.h:272:9: warning: 'mcu_ctrl' may be used uninitialized [-Wmaybe-uninitialized]
     272 |         native_write_msr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32));
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/x86/kernel/cpu/bugs.c: In function 'update_gds_msr':
   arch/x86/kernel/cpu/bugs.c:667:13: note: 'mcu_ctrl' was declared here
     667 |         u64 mcu_ctrl;
         |             ^~~~~~~~


vim +/mcu_ctrl +272 arch/x86/include/asm/msr.h

be7baf80a69964 include/asm-x86/msr.h      Thomas Gleixner 2007-10-23  266  
be7baf80a69964 include/asm-x86/msr.h      Thomas Gleixner 2007-10-23  267  #define rdmsrl(msr, val)			\
abb0ade013507c include/asm-x86/msr.h      Joe Perches     2008-03-23  268  	((val) = native_read_msr((msr)))
be7baf80a69964 include/asm-x86/msr.h      Thomas Gleixner 2007-10-23  269  
5d07c2cc1962fa arch/x86/include/asm/msr.h Borislav Petkov 2016-11-02  270  static inline void wrmsrl(unsigned int msr, u64 val)
47edb65178cb70 arch/x86/include/asm/msr.h Andy Lutomirski 2015-07-23  271  {
679bcea857d728 arch/x86/include/asm/msr.h Borislav Petkov 2015-11-23 @272  	native_write_msr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32));
47edb65178cb70 arch/x86/include/asm/msr.h Andy Lutomirski 2015-07-23  273  }
be7baf80a69964 include/asm-x86/msr.h      Thomas Gleixner 2007-10-23  274  

:::::: The code at line 272 was first introduced by commit
:::::: 679bcea857d72868e3431dde3a0e158bf0ed9119 x86/MSR: Chop off lower 32-bit value

:::::: TO: Borislav Petkov <bp@suse.de>
:::::: CC: Ingo Molnar <mingo@kernel.org>

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