Re: [PATCH v14 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing

[Qian Cai]

On 6/24/2021 7:48 AM, Will Deacon wrote:
> Ok, diff below which attempts to tackle the offset issue I mentioned as
> well. Qian Cai -- please can you try with these changes?

This works fine.

> 
> Will
> 
> --->8
> 
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index 175b6c113ed8..39284ff2a6cd 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -116,7 +116,9 @@ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
>  
>  static inline bool is_swiotlb_force_bounce(struct device *dev)
>  {
> -       return dev->dma_io_tlb_mem->force_bounce;
> +       struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
> +
> +       return mem && mem->force_bounce;
>  }
>  
>  void __init swiotlb_exit(void);
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 44be8258e27b..0ffbaae9fba2 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -449,6 +449,7 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
>                 dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);
>         unsigned int nslots = nr_slots(alloc_size), stride;
>         unsigned int index, wrap, count = 0, i;
> +       unsigned int offset = swiotlb_align_offset(dev, orig_addr);
>         unsigned long flags;
>  
>         BUG_ON(!nslots);
> @@ -497,7 +498,7 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
>         for (i = index; i < index + nslots; i++) {
>                 mem->slots[i].list = 0;
>                 mem->slots[i].alloc_size =
> -                       alloc_size - ((i - index) << IO_TLB_SHIFT);
> +                       alloc_size - (offset + ((i - index) << IO_TLB_SHIFT));
>         }
>         for (i = index - 1;
>              io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
>