linux-kernel - Re: [PATCH] x86/tdx: Optimize try_accept_memory() to reduce 1GB page accepted failed times

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Message-ID: <202401100620.TjY1Uq2O-lkp@intel.com>
Date: Wed, 10 Jan 2024 07:05:43 +0800
From: kernel test robot <lkp@...el.com>
To: Jun Miao <jun.miao@...el.com>, kirill.shutemov@...ux.intel.com,
	dave.hansen@...ux.intel.com
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev, jun.miao@...el.com,
	x86@...nel.org, linux-coco@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/tdx: Optimize try_accept_memory() to reduce 1GB page
 accepted failed times

Hi Jun,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/x86/tdx]
[also build test WARNING on next-20240109]
[cannot apply to linus/master v6.7]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jun-Miao/x86-tdx-Optimize-try_accept_memory-to-reduce-1GB-page-accepted-failed-times/20240109-134908
base:   tip/x86/tdx
patch link:    https://lore.kernel.org/r/20240109054824.9023-1-jun.miao%40intel.com
patch subject: [PATCH] x86/tdx: Optimize try_accept_memory() to reduce 1GB page accepted failed times
config: x86_64-allmodconfig (https://download.01.org/0day-ci/archive/20240110/202401100620.TjY1Uq2O-lkp@intel.com/config)
compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240110/202401100620.TjY1Uq2O-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401100620.TjY1Uq2O-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/x86/coco/tdx/tdx-shared.c:62:3: warning: '/*' within block comment [-Wcomment]
      62 |                 /* The 4KB page case or accept 2MB page failed case. */
         |                 ^
>> arch/x86/coco/tdx/tdx-shared.c:63:8: warning: variable 'accept_size' is uninitialized when used here [-Wuninitialized]
      63 |                 if (!accept_size)
         |                      ^~~~~~~~~~~
   arch/x86/coco/tdx/tdx-shared.c:49:28: note: initialize the variable 'accept_size' to silence this warning
      49 |                 unsigned long accept_size;
         |                                          ^
         |                                           = 0
   2 warnings generated.


vim +62 arch/x86/coco/tdx/tdx-shared.c

    40	
    41	bool tdx_accept_memory(phys_addr_t start, phys_addr_t end)
    42	{
    43		/*
    44		 * For shared->private conversion, accept the page using
    45		 * TDG_MEM_PAGE_ACCEPT TDX module call.
    46		 */
    47		while (start < end) {
    48			unsigned long len = end - start;
    49			unsigned long accept_size;
    50	
    51			/*
    52			 * Try larger accepts first. It gives chance to VMM to keep
    53			 * 1G/2M Secure EPT entries where possible and speeds up
    54			 * process by cutting number of hypercalls (if successful).
    55			 * Since per current TDX spec, only support for adding 4KB or
    56			 * 2MB page dynamically.
    57			 * /
    58	
    59			if (IS_ALIGNED(start, PMD_SIZE) && len >= PMD_SIZE)
    60				accept_size = try_accept_one(start, len, PG_LEVEL_2M);
    61	
  > 62			/* The 4KB page case or accept 2MB page failed case. */
  > 63			if (!accept_size)
    64				accept_size = try_accept_one(start, len, PG_LEVEL_4K);
    65			if (!accept_size)
    66				return false;
    67			start += accept_size;
    68		}
    69	
    70		return true;
    71	}
    72	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki