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Subject[intel-tdx:guest-hardening-rebased 13/23] kernel/dma/swiotlb.c:531:75: warning: suggest parentheses around '-' in operand of '&'
tree:   https://github.com/intel/tdx.git guest-hardening-rebased
head: c170462888e1dab8e3e80c1c6e3708dd473ad1ed
commit: 294874a30f655fe082a24e1ca1aa3cafe41d00fd [13/23] swiotlb: Allocate memory in a cache-friendly way
config: x86_64-defconfig (https://download.01.org/0day-ci/archive/20220717/202207170722.7onSclOe-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel/tdx/commit/294874a30f655fe082a24e1ca1aa3cafe41d00fd
git remote add intel-tdx https://github.com/intel/tdx.git
git fetch --no-tags intel-tdx guest-hardening-rebased
git checkout 294874a30f655fe082a24e1ca1aa3cafe41d00fd
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/dma/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

kernel/dma/swiotlb.c: In function 'swiotlb_find_slots':
>> kernel/dma/swiotlb.c:531:75: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
531 | if (alloc_align_mask && (slot_dma_addr & alloc_align_mask - 1))
| ~~~~~~~~~~~~~~~~~^~~


vim +531 kernel/dma/swiotlb.c

487
488 /*
489 * Find a suitable number of IO TLB entries size that will fit this request and
490 * allocate a buffer from that IO TLB pool.
491 */
492 static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
493 size_t alloc_size, unsigned int alloc_align_mask)
494 {
495 struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
496 struct io_tlb_slot *slot, *tmp;
497 unsigned long boundary_mask = dma_get_seg_boundary(dev);
498 dma_addr_t tbl_dma_addr =
499 phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
500 dma_addr_t slot_dma_addr;
501 unsigned long max_slots = get_max_slots(boundary_mask);
502 unsigned int iotlb_align_mask =
503 dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);
504 unsigned int nslots = nr_slots(alloc_size);
505 unsigned int index, i;
506 unsigned int offset = swiotlb_align_offset(dev, orig_addr);
507 unsigned long flags;
508
509 BUG_ON(!nslots);
510
511 spin_lock_irqsave(&mem->lock, flags);
512 if (unlikely(nslots > mem->nslabs - mem->used))
513 goto not_found;
514
515 list_for_each_entry_safe(slot, tmp, &mem->free_slots, node) {
516 index = slot - mem->slots;
517 slot_dma_addr = slot_addr(tbl_dma_addr, index);
518 if (orig_addr &&
519 (slot_dma_addr & iotlb_align_mask) !=
520 (orig_addr & iotlb_align_mask)) {
521 continue;
522 }
523 /*
524 * If requested size is larger than a page, ensure allocated
525 * memory to be page aligned.
526 */
527 if (alloc_size >= PAGE_SIZE && (slot_dma_addr & ~PAGE_MASK))
528 continue;
529
530 /* Ensure requested alignment is met */
> 531 if (alloc_align_mask && (slot_dma_addr & alloc_align_mask - 1))
532 continue;
533
534 if (io_tlb_offset(index) + nslots > IO_TLB_SEGSIZE)
535 continue;
536
537 /*
538 * If we find a slot that indicates we have 'nslots' number of
539 * contiguous buffers, we allocate the buffers from that slot
540 * and mark the entries as '0' indicating unavailable.
541 */
542 if (!iommu_is_span_boundary(index, nslots,
543 nr_slots(tbl_dma_addr),
544 max_slots)) {
545 if (find_next_zero_bit(mem->bitmap, index + nslots, index) ==
546 index + nslots)
547 goto found;
548 }
549 }
550
551 not_found:
552 spin_unlock_irqrestore(&mem->lock, flags);
553 return -1;
554
555 found:
556 for (i = index; i < index + nslots; i++) {
557 __clear_bit(i, mem->bitmap);
558 mem->slots[i].alloc_size =
559 alloc_size - (offset + ((i - index) << IO_TLB_SHIFT));
560 list_del(&mem->slots[i].node);
561 }
562
563 mem->used += nslots;
564
565 spin_unlock_irqrestore(&mem->lock, flags);
566 return index;
567 }
568

--
0-DAY CI Kernel Test Service
https://01.org/lkp

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