From: Bumyong Lee <bumyong.lee@xxxxxxxxxxx> commit 5f89468e2f060031cd89fd4287298e0eaf246bf6 upstream. (Backported as different form due to absence of below patch series https://lore.kernel.org/linux-iommu/20210301074436.919889-1-hch@xxxxxx/) in case of driver wants to sync part of ranges with offset, swiotlb_tbl_sync_single() copies from orig_addr base to tlb_addr with offset and ends up with data mismatch. It was removed from "swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single", but said logic has to be added back in. >From Linus's email: "That commit which the removed the offset calculation entirely, because the old (unsigned long)tlb_addr & (IO_TLB_SIZE - 1) was wrong, but instead of removing it, I think it should have just fixed it to be (tlb_addr - mem->start) & (IO_TLB_SIZE - 1); instead. That way the slot offset always matches the slot index calculation." (Unfortunatly that broke NVMe). The use-case that drivers are hitting is as follow: 1. Get dma_addr_t from dma_map_single() dma_addr_t tlb_addr = dma_map_single(dev, vaddr, vsize, DMA_TO_DEVICE); |<---------------vsize------------->| +-----------------------------------+ | | original buffer +-----------------------------------+ vaddr swiotlb_align_offset |<----->|<---------------vsize------------->| +-------+-----------------------------------+ | | | swiotlb buffer +-------+-----------------------------------+ tlb_addr 2. Do something 3. Sync dma_addr_t through dma_sync_single_for_device(..) dma_sync_single_for_device(dev, tlb_addr + offset, size, DMA_TO_DEVICE); Error case. Copy data to original buffer but it is from base addr (instead of base addr + offset) in original buffer: swiotlb_align_offset |<----->|<- offset ->|<- size ->| +-------+-----------------------------------+ | | |##########| | swiotlb buffer +-------+-----------------------------------+ tlb_addr |<- size ->| +-----------------------------------+ |##########| | original buffer +-----------------------------------+ vaddr The fix is to copy the data to the original buffer and take into account the offset, like so: swiotlb_align_offset |<----->|<- offset ->|<- size ->| +-------+-----------------------------------+ | | |##########| | swiotlb buffer +-------+-----------------------------------+ tlb_addr |<- offset ->|<- size ->| +-----------------------------------+ | |##########| | original buffer +-----------------------------------+ vaddr [One fix which was Linus's that made more sense to as it created a symmetry would break NVMe. The reason for that is the: unsigned int offset = (tlb_addr - mem->start) & (IO_TLB_SIZE - 1); would come up with the proper offset, but it would lose the alignment (which this patch contains).] Fixes: 16fc3cef33a0 ("swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single") Signed-off-by: Bumyong Lee <bumyong.lee@xxxxxxxxxxx> Signed-off-by: Chanho Park <chanho61.park@xxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reported-by: Dominique MARTINET <dominique.martinet@xxxxxxxxxxxxxxxxx> Reported-by: Horia Geantă <horia.geanta@xxxxxxx> Tested-by: Horia Geantă <horia.geanta@xxxxxxx> CC: stable@xxxxxxxxxxxxxxx Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> --- kernel/dma/swiotlb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 0f61b14b0099..0ed0e1f215c7 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -667,6 +667,9 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr, if (orig_addr == INVALID_PHYS_ADDR) return; + orig_addr += (tlb_addr & (IO_TLB_SIZE - 1)) - + swiotlb_align_offset(hwdev, orig_addr); + switch (target) { case SYNC_FOR_CPU: if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)) -- 2.32.0
