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

On 6/24/2021 7:48 AM, Will Deacon wrote:

quoted

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).

quoted

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 &&