Hello Alex Williamson,
The patch edad96db58d2: "iommu/vt-d: Fix unmap_pages support" from
Nov 22, 2021, leads to the following Smatch static checker warning:
drivers/iommu/intel/iommu.c:1369 dma_pte_clear_level()
error: uninitialized symbol 'level_pfn'.
drivers/iommu/intel/iommu.c
1330 static struct page *dma_pte_clear_level(struct dmar_domain *domain,
int level,
1331 struct dma_pte *pte, unsigned
long pfn,
1332 unsigned long start_pfn,
1333 unsigned long last_pfn,
1334 struct page *freelist)
1335 {
1336 struct dma_pte *first_pte = NULL, *last_pte = NULL;
1337
1338 pfn = max(start_pfn, pfn);
1339 pte = &pte[pfn_level_offset(pfn, level)];
1340
1341 do {
1342 unsigned long level_pfn;
1343
1344 if (!dma_pte_present(pte))
1345 goto next;
^^^^^^^^^^
If we ever hit this goto then there is going to be a bug.
1346
1347 level_pfn = pfn & level_mask(level);
1348
1349 /* If range covers entire pagetable, free it */
1350 if (start_pfn <= level_pfn &&
1351 last_pfn >= level_pfn + level_size(level) - 1) {
1352 /* These suborbinate page tables are going
away entirely. Don't
1353 bother to clear them; we're just going to
*free* them. */
1354 if (level > 1 && !dma_pte_superpage(pte))
1355 freelist =
dma_pte_list_pagetables(domain, level - 1, pte, freelist);
1356
1357 dma_clear_pte(pte);
1358 if (!first_pte)
1359 first_pte = pte;
1360 last_pte = pte;
1361 } else if (level > 1) {
1362 /* Recurse down into a level that isn't
*entirely* obsolete */
1363 freelist = dma_pte_clear_level(domain, level -
1,
1364
phys_to_virt(dma_pte_addr(pte)),
1365 level_pfn,
start_pfn, last_pfn,
1366 freelist);
1367 }
1368 next:
--> 1369 pfn = level_pfn + level_size(level);
^^^^^^^^^
1370 } while (!first_pte_in_page(++pte) && pfn <= last_pfn);
1371
1372 if (first_pte)
1373 domain_flush_cache(domain, first_pte,
1374 (void *)++last_pte - (void
*)first_pte);
1375
1376 return freelist;
1377 }
regards,
dan carpenter
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