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

From: Konrad Rzeszutek Wilk <[email-masked]>
Date: Thu, 24 Jun 2021 11:55:19 -0400

On Thu, Jun 24, 2021 at 10:10:51AM -0400, Qian Cai wrote:
> 
> 
> 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.

Cool. Let me squash this patch in #6 and rebase the rest of them.

Claire, could you check the devel/for-linus-5.14 say by end of today to
double check that I didn't mess anything up please?

Will,

Thank you for generating the fix! I am going to run it on x86 and Xen
to make sure all is good (granted last time I ran devel/for-linus-5.14
on that setup I didn't see any errors so I need to double check
I didn't do something silly like run a wrong kernel).

> 
> > 
> > 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 &&
> >