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SubjectRe: [PATCH v6 2/6] x86/mce: relocate set{clear}_mce_nospec() functions
Hi Jane,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on nvdimm/libnvdimm-for-next]
[also build test WARNING on device-mapper-dm/for-next linus/master v5.17-rc8 next-20220318]
[cannot apply to tip/x86/mm]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Jane-Chu/DAX-poison-recovery/20220319-143144
base: https://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm.git libnvdimm-for-next
config: x86_64-randconfig-a012 (https://download.01.org/0day-ci/archive/20220319/202203191603.mQUQZZV5-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project a6e70e4056dff962ec634c5bd4f2f4105a0bef71)
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://github.com/0day-ci/linux/commit/71b9b09529b207ce15667c1f5fba4b727b6754e6
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Jane-Chu/DAX-poison-recovery/20220319-143144
git checkout 71b9b09529b207ce15667c1f5fba4b727b6754e6
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/mm/pat/ fs/fuse/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> arch/x86/mm/pat/set_memory.c:1935:5: warning: no previous prototype for function 'set_mce_nospec' [-Wmissing-prototypes]
int set_mce_nospec(unsigned long pfn, bool unmap)
^
arch/x86/mm/pat/set_memory.c:1935:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
int set_mce_nospec(unsigned long pfn, bool unmap)
^
static
>> arch/x86/mm/pat/set_memory.c:1968:5: warning: no previous prototype for function 'clear_mce_nospec' [-Wmissing-prototypes]
int clear_mce_nospec(unsigned long pfn)
^
arch/x86/mm/pat/set_memory.c:1968:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
int clear_mce_nospec(unsigned long pfn)
^
static
2 warnings generated.


vim +/set_mce_nospec +1935 arch/x86/mm/pat/set_memory.c

1927
1928 #ifdef CONFIG_X86_64
1929 /*
1930 * Prevent speculative access to the page by either unmapping
1931 * it (if we do not require access to any part of the page) or
1932 * marking it uncacheable (if we want to try to retrieve data
1933 * from non-poisoned lines in the page).
1934 */
> 1935 int set_mce_nospec(unsigned long pfn, bool unmap)
1936 {
1937 unsigned long decoy_addr;
1938 int rc;
1939
1940 /* SGX pages are not in the 1:1 map */
1941 if (arch_is_platform_page(pfn << PAGE_SHIFT))
1942 return 0;
1943 /*
1944 * We would like to just call:
1945 * set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
1946 * but doing that would radically increase the odds of a
1947 * speculative access to the poison page because we'd have
1948 * the virtual address of the kernel 1:1 mapping sitting
1949 * around in registers.
1950 * Instead we get tricky. We create a non-canonical address
1951 * that looks just like the one we want, but has bit 63 flipped.
1952 * This relies on set_memory_XX() properly sanitizing any __pa()
1953 * results with __PHYSICAL_MASK or PTE_PFN_MASK.
1954 */
1955 decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63));
1956
1957 if (unmap)
1958 rc = set_memory_np(decoy_addr, 1);
1959 else
1960 rc = set_memory_uc(decoy_addr, 1);
1961 if (rc)
1962 pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
1963 return rc;
1964 }
1965 EXPORT_SYMBOL(set_mce_nospec);
1966
1967 /* Restore full speculative operation to the pfn. */
> 1968 int clear_mce_nospec(unsigned long pfn)
1969 {
1970 return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1);
1971 }
1972 EXPORT_SYMBOL(clear_mce_nospec);
1973

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

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