Hi Jacob,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   931294922e65a23e1aad6398b9ae02df74044679
commit: f68c7f539b6e9712e941212ab95a1feb5a0bf3b3 [4254/7588] iommu/vt-d: Enable write protect for supervisor SVM
config: ia64-allmodconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=f68c7f539b6e9712e941212ab95a1feb5a0bf3b3
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout f68c7f539b6e9712e941212ab95a1feb5a0bf3b3
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

   drivers/iommu/intel/pasid.c: In function 'pasid_enable_wpe':

quoted

drivers/iommu/intel/pasid.c:536:22: error: implicit declaration of function 'read_cr0' [-Werror=implicit-function-declaration]

     536 |  unsigned long cr0 = read_cr0();
         |                      ^~~~~~~~
   In file included from include/linux/build_bug.h:5,
                    from include/linux/bits.h:22,
                    from include/linux/bitops.h:6,
                    from drivers/iommu/intel/pasid.c:12:

quoted

drivers/iommu/intel/pasid.c:539:23: error: 'X86_CR0_WP' undeclared (first use in this function)

     539 |  if (unlikely(!(cr0 & X86_CR0_WP))) {
         |                       ^~~~~~~~~~
   include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
      78 | # define unlikely(x) __builtin_expect(!!(x), 0)
         |                                          ^
   drivers/iommu/intel/pasid.c:539:23: note: each undeclared identifier is reported only once for each function it appears in
     539 |  if (unlikely(!(cr0 & X86_CR0_WP))) {
         |                       ^~~~~~~~~~
   include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
      78 | # define unlikely(x) __builtin_expect(!!(x), 0)
         |                                          ^
   cc1: some warnings being treated as errors

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for FRAME_POINTER
   Depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
   Selected by
   - FAULT_INJECTION_STACKTRACE_FILTER && FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT && !X86_64 && !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86


vim +/read_cr0 +536 drivers/iommu/intel/pasid.c

   533	
   534	static inline int pasid_enable_wpe(struct pasid_entry *pte)
   535	{
 > 536		unsigned long cr0 = read_cr0();
   537	
   538		/* CR0.WP is normally set but just to be sure */
 > 539		if (unlikely(!(cr0 & X86_CR0_WP))) {
   540			pr_err_ratelimited("No CPU write protect!\n");
   541			return -EINVAL;
   542		}
   543		pasid_set_wpe(pte);
   544	
   545		return 0;
   546	};
   547	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org