Re: [PATCH v4 09/14] swiotlb: Refactor swiotlb_tbl_{map, unmap}_single

[kernel test robot <lkp@intel.com>]

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Hi Claire,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.11-rc6 next-20210125]
[cannot apply to swiotlb/linux-next robh/for-next xen-tip/linux-next]
[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]

url:    https://github.com/0day-ci/linux/commits/Claire-Chang/Restricted-DMA/20210209-142608
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 61556703b610a104de324e4f061dc6cf7b218b46
config: x86_64-randconfig-m001-20210209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

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

smatch warnings:
kernel/dma/swiotlb.c:681 swiotlb_tbl_map_single() warn: unsigned 'index' is never less than zero.

vim +/index +681 kernel/dma/swiotlb.c

   659	
   660	phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
   661					   size_t mapping_size, size_t alloc_size,
   662					   enum dma_data_direction dir,
   663					   unsigned long attrs)
   664	{
   665		struct swiotlb *swiotlb = get_swiotlb(hwdev);
   666		dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, swiotlb->start);
   667		phys_addr_t tlb_addr;
   668		unsigned int nslots, index;
   669		int i;
   670	
   671		if (mem_encrypt_active())
   672			pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
   673	
   674		if (mapping_size > alloc_size) {
   675			dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
   676				      mapping_size, alloc_size);
   677			return (phys_addr_t)DMA_MAPPING_ERROR;
   678		}
   679	
   680		index = swiotlb_tbl_find_free_region(hwdev, tbl_dma_addr, alloc_size, attrs);
 > 681		if (index < 0)
   682			return (phys_addr_t)DMA_MAPPING_ERROR;
   683	
   684		tlb_addr = swiotlb->start + (index << IO_TLB_SHIFT);
   685	
   686		/*
   687		 * Save away the mapping from the original address to the DMA address.
   688		 * This is needed when we sync the memory.  Then we sync the buffer if
   689		 * needed.
   690		 */
   691		nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
   692		for (i = 0; i < nslots; i++)
   693			swiotlb->orig_addr[index + i] = orig_addr + (i << IO_TLB_SHIFT);
   694		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
   695		    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
   696			swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
   697	
   698		return tlb_addr;
   699	}
   700	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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