Re: [PATCH RFC 2/2] cpu/bugs: cgroup: Add a cgroup knob to bypass CPU mitigations

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

Hi Pawan,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build errors:

[auto build test ERROR on 98f7e32f20d28ec452afb208f9cffc08448a2652]

url:    https://github.com/intel-lab-lkp/linux/commits/Pawan-Gupta/x86-entry_64-Add-a-separate-unmitigated-entry-exit-path/20240920-055414
base:   98f7e32f20d28ec452afb208f9cffc08448a2652
patch link:    https://lore.kernel.org/r/20240919-selective-mitigation-v1-2-1846cf41895e%40linux.intel.com
patch subject: [PATCH RFC 2/2] cpu/bugs: cgroup: Add a cgroup knob to bypass CPU mitigations
config: i386-allnoconfig (https://download.01.org/0day-ci/archive/20240921/202409211416.LSaNCLbs-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/20240921/202409211416.LSaNCLbs-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/202409211416.LSaNCLbs-lkp@intel.com/

All errors (new ones prefixed by >>):

   arch/x86/kernel/cpu/bugs.c: In function 'cpu_mitigation_skip':
>> arch/x86/kernel/cpu/bugs.c:137:29: error: implicit declaration of function 'task_dfl_cgroup'; did you mean 'task_get_cgroup1'? [-Werror=implicit-function-declaration]
     137 |                 prev_skip = task_dfl_cgroup(prev)->cpu_skip_mitigation;
         |                             ^~~~~~~~~~~~~~~
         |                             task_get_cgroup1
>> arch/x86/kernel/cpu/bugs.c:137:50: error: invalid type argument of '->' (have 'int')
     137 |                 prev_skip = task_dfl_cgroup(prev)->cpu_skip_mitigation;
         |                                                  ^~
   arch/x86/kernel/cpu/bugs.c:139:50: error: invalid type argument of '->' (have 'int')
     139 |                 next_skip = task_dfl_cgroup(next)->cpu_skip_mitigation;
         |                                                  ^~
   arch/x86/kernel/cpu/bugs.c:147:50: error: 'entry_SYSCALL_64_unmitigated' undeclared (first use in this function)
     147 |                 wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64_unmitigated);
         |                                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/x86/kernel/cpu/bugs.c:147:50: note: each undeclared identifier is reported only once for each function it appears in
   arch/x86/kernel/cpu/bugs.c:149:50: error: 'entry_SYSCALL_64_mitigated' undeclared (first use in this function); did you mean 'entry_SYSCALL_compat'?
     149 |                 wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64_mitigated);
         |                                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~
         |                                                  entry_SYSCALL_compat
   cc1: some warnings being treated as errors


vim +137 arch/x86/kernel/cpu/bugs.c

   130	
   131	inline void cpu_mitigation_skip(struct task_struct *prev,
   132					struct task_struct *next)
   133	{
   134		bool prev_skip = false, next_skip = false;
   135	
   136		if (prev->mm)
 > 137			prev_skip = task_dfl_cgroup(prev)->cpu_skip_mitigation;
   138		if (next->mm)
   139			next_skip = task_dfl_cgroup(next)->cpu_skip_mitigation;
   140	
   141		if (!prev_skip && !next_skip)
   142			return;
   143		if (prev_skip == next_skip)
   144			return;
   145	
   146		if (next_skip)
   147			wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64_unmitigated);
   148		else
   149			wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64_mitigated);
   150	}
   151	

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