CC: [email protected]
In-Reply-To: <[email protected]>
References: <[email protected]>
TO: Balbir Singh <[email protected]>
CC: [email protected], [email protected]

Hi Balbir,

I love your patch! Perhaps something to improve:

[auto build test WARNING on kvm/linux-next]
[also build test WARNING on linus/master v5.7-rc1 next-20200413]
[cannot apply to tip/auto-latest tip/x86/mm tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    
https://github.com/0day-ci/linux/commits/Balbir-Singh/Optionally-flush-L1D-on-context-switch/20200408-192153
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
:::::: branch date: 5 days ago
:::::: commit date: 5 days ago

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <[email protected]>


cppcheck warnings: (new ones prefixed by >>)

>> arch/x86/kernel/l1d_flush.c:25:26: warning: 'l1d_flush_pages' is of type 
>> 'void *'. When using void pointers in calculations, the behaviour is 
>> undefined. [arithOperationsOnVoidPointer]
     memset(l1d_flush_pages + i * PAGE_SIZE, i + 1,
                            ^

# 
https://github.com/0day-ci/linux/commit/01f030960171a1eb6e3183aa69d002464fdb4194
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 01f030960171a1eb6e3183aa69d002464fdb4194
vim +25 arch/x86/kernel/l1d_flush.c

01f030960171a1 Balbir Singh 2020-04-08   3  
01f030960171a1 Balbir Singh 2020-04-08   4  void *alloc_l1d_flush_pages(void)
01f030960171a1 Balbir Singh 2020-04-08   5  {
01f030960171a1 Balbir Singh 2020-04-08   6      struct page *page;
01f030960171a1 Balbir Singh 2020-04-08   7      void *l1d_flush_pages = NULL;
01f030960171a1 Balbir Singh 2020-04-08   8      int i;
01f030960171a1 Balbir Singh 2020-04-08   9  
01f030960171a1 Balbir Singh 2020-04-08  10      /*
01f030960171a1 Balbir Singh 2020-04-08  11       * This allocation for 
l1d_flush_pages is not tied to a VM/task's
01f030960171a1 Balbir Singh 2020-04-08  12       * lifetime and so should not 
be charged to a memcg.
01f030960171a1 Balbir Singh 2020-04-08  13       */
01f030960171a1 Balbir Singh 2020-04-08  14      page = alloc_pages(GFP_KERNEL, 
L1D_CACHE_ORDER);
01f030960171a1 Balbir Singh 2020-04-08  15      if (!page)
01f030960171a1 Balbir Singh 2020-04-08  16              return NULL;
01f030960171a1 Balbir Singh 2020-04-08  17      l1d_flush_pages = 
page_address(page);
01f030960171a1 Balbir Singh 2020-04-08  18  
01f030960171a1 Balbir Singh 2020-04-08  19      /*
01f030960171a1 Balbir Singh 2020-04-08  20       * Initialize each page with a 
different pattern in
01f030960171a1 Balbir Singh 2020-04-08  21       * order to protect against KSM 
in the nested
01f030960171a1 Balbir Singh 2020-04-08  22       * virtualization case.
01f030960171a1 Balbir Singh 2020-04-08  23       */
01f030960171a1 Balbir Singh 2020-04-08  24      for (i = 0; i < 1u << 
L1D_CACHE_ORDER; ++i) {
01f030960171a1 Balbir Singh 2020-04-08 @25              memset(l1d_flush_pages 
+ i * PAGE_SIZE, i + 1,
01f030960171a1 Balbir Singh 2020-04-08  26                              
PAGE_SIZE);
01f030960171a1 Balbir Singh 2020-04-08  27      }
01f030960171a1 Balbir Singh 2020-04-08  28      return l1d_flush_pages;
01f030960171a1 Balbir Singh 2020-04-08  29  }
01f030960171a1 Balbir Singh 2020-04-08  30  
EXPORT_SYMBOL_GPL(alloc_l1d_flush_pages);
01f030960171a1 Balbir Singh 2020-04-08  31  

---
0-DAY CI Kernel Test Service, Intel Corporation
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