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Mon, 06 Oct 2025 00:33:18 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-46e619b8507sm243679325e9.3.2025.10.06.00.33.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Oct 2025 00:33:17 -0700 (PDT) Date: Mon, 6 Oct 2025 10:33:13 +0300 From: Dan Carpenter To: oe-kbuild@lists.linux.dev, James Houghton , Paolo Bonzini , Sean Christopherson Cc: lkp@intel.com, oe-kbuild-all@lists.linux.dev, James Houghton , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] KVM: For manual-protect GET_DIRTY_LOG, do not hold slots lock Message-ID: <202510041919.LaZWBcDN-lkp@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250930172850.598938-1-jthoughton@google.com> Hi James, kernel test robot noticed the following build warnings: url: https://github.com/intel-lab-lkp/linux/commits/James-Houghton/KVM-selftests-Add-parallel-KVM_GET_DIRTY_LOG-to-dirty_log_perf_test/20251001-013306 base: a6ad54137af92535cfe32e19e5f3bc1bb7dbd383 patch link: https://lore.kernel.org/r/20250930172850.598938-1-jthoughton%40google.com patch subject: [PATCH 1/2] KVM: For manual-protect GET_DIRTY_LOG, do not hold slots lock config: x86_64-randconfig-161-20251004 (https://download.01.org/0day-ci/archive/20251004/202510041919.LaZWBcDN-lkp@intel.com/config) compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261) 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 | Reported-by: Dan Carpenter | Closes: https://lore.kernel.org/r/202510041919.LaZWBcDN-lkp@intel.com/ New smatch warnings: arch/x86/kvm/../../../virt/kvm/kvm_main.c:2290 kvm_get_dirty_log_protect() error: uninitialized symbol 'flush'. vim +/flush +2290 arch/x86/kvm/../../../virt/kvm/kvm_main.c ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2255 n = kvm_dirty_bitmap_bytes(memslot); 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2256 if (!protect) { 2a31b9db153530d virt/kvm/kvm_main.c Paolo Bonzini 2018-10-23 2257 /* 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2258 * Unlike kvm_get_dirty_log, we never flush, because no flush is 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2259 * needed until KVM_CLEAR_DIRTY_LOG. There is some code 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2260 * duplication between this function and kvm_get_dirty_log, but 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2261 * hopefully all architecture transition to 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2262 * kvm_get_dirty_log_protect and kvm_get_dirty_log can be 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2263 * eliminated. 2a31b9db153530d virt/kvm/kvm_main.c Paolo Bonzini 2018-10-23 2264 */ 2a31b9db153530d virt/kvm/kvm_main.c Paolo Bonzini 2018-10-23 2265 dirty_bitmap_buffer = dirty_bitmap; 2a31b9db153530d virt/kvm/kvm_main.c Paolo Bonzini 2018-10-23 2266 } else { 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2267 bool flush; flush needs to be initialized to false. 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2268 03133347b4452ef virt/kvm/kvm_main.c Claudio Imbrenda 2018-04-30 2269 dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot); ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2270 memset(dirty_bitmap_buffer, 0, n); ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2271 531810caa9f4bc9 virt/kvm/kvm_main.c Ben Gardon 2021-02-02 2272 KVM_MMU_LOCK(kvm); ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2273 for (i = 0; i < n / sizeof(long); i++) { ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2274 unsigned long mask; ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2275 gfn_t offset; ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2276 ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2277 if (!dirty_bitmap[i]) ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2278 continue; ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2279 0dff084607bd555 virt/kvm/kvm_main.c Sean Christopherson 2020-02-18 2280 flush = true; ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2281 mask = xchg(&dirty_bitmap[i], 0); ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2282 dirty_bitmap_buffer[i] = mask; ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2283 ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2284 offset = i * BITS_PER_LONG; 58d2930f4ee335a virt/kvm/kvm_main.c Takuya Yoshikawa 2015-03-17 2285 kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, 58d2930f4ee335a virt/kvm/kvm_main.c Takuya Yoshikawa 2015-03-17 2286 offset, mask); 58d2930f4ee335a virt/kvm/kvm_main.c Takuya Yoshikawa 2015-03-17 2287 } 531810caa9f4bc9 virt/kvm/kvm_main.c Ben Gardon 2021-02-02 2288 KVM_MMU_UNLOCK(kvm); 2a31b9db153530d virt/kvm/kvm_main.c Paolo Bonzini 2018-10-23 2289 0dff084607bd555 virt/kvm/kvm_main.c Sean Christopherson 2020-02-18 @2290 if (flush) Either uninitialized or true. Never false. 619b5072443c05c virt/kvm/kvm_main.c David Matlack 2023-08-11 2291 kvm_flush_remote_tlbs_memslot(kvm, memslot); 82fb1294f7ad3ee virt/kvm/kvm_main.c James Houghton 2025-09-30 2292 } 0dff084607bd555 virt/kvm/kvm_main.c Sean Christopherson 2020-02-18 2293 ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2294 if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n)) 58d6db349172786 virt/kvm/kvm_main.c Markus Elfring 2017-01-22 2295 return -EFAULT; 58d6db349172786 virt/kvm/kvm_main.c Markus Elfring 2017-01-22 2296 return 0; ba0513b5b8ffbcb virt/kvm/kvm_main.c Mario Smarduch 2015-01-15 2297 } -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki