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Fri, 02 May 2025 06:06:37 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-3a099ae0c25sm2154140f8f.17.2025.05.02.06.06.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 May 2025 06:06:37 -0700 (PDT) Date: Fri, 2 May 2025 16:06:34 +0300 From: Dan Carpenter To: Nadav Amit Cc: kvm@vger.kernel.org Subject: [bug report] x86: vmx: Comprehensive max VMCS field search Message-ID: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hello Nadav Amit, Commit 2b0418e4adf6 ("x86: vmx: Comprehensive max VMCS field search") from Dec 19, 2019 (linux-next), leads to the following Smatch static checker warning: x86/vmx.c:346 find_vmcs_max_index() warn: always true condition '(idx >= 0) => (0-u32max >= 0)' x86/vmx.c 339 static u32 find_vmcs_max_index(void) 340 { 341 u32 idx, width, type, enc; 342 u64 actual; 343 int ret; 344 345 /* scan backwards and stop when found */ --> 346 for (idx = (1 << 9) - 1; idx >= 0; idx--) { ^^^^^^^^ idx is u32 so this is an endless loop. 347 348 /* try all combinations of width and type */ 349 for (type = 0; type < (1 << 2); type++) { 350 for (width = 0; width < (1 << 2) ; width++) { 351 enc = (idx << VMCS_FIELD_INDEX_SHIFT) | 352 (type << VMCS_FIELD_TYPE_SHIFT) | 353 (width << VMCS_FIELD_WIDTH_SHIFT); 354 355 ret = vmcs_read_safe(enc, &actual); 356 assert(!(ret & X86_EFLAGS_CF)); 357 if (!(ret & X86_EFLAGS_ZF)) 358 return idx; 359 } 360 } 361 } 362 /* some VMCS fields should exist */ 363 assert(0); 364 return 0; 365 } regards, dan carpenter