From: Petr Tesarik Date: Thu, 6 Apr 2023 14:35:39 +0000 (+0200) Subject: swiotlb: fix a braino in the alignment check fix X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bbb73a103fbbed6f63cb738d3783261c4241b4b2;p=linux.git swiotlb: fix a braino in the alignment check fix The alignment mask in swiotlb_do_find_slots() masks off the high bits which are not relevant for the alignment, so multiple requirements are combined with a bitwise OR rather than AND. In plain English, the stricter the alignment, the more bits must be set in iotlb_align_mask. Confusion may arise from the fact that the same variable is also used to mask off the offset within a swiotlb slot, which is achieved with a bitwise AND. Fixes: 0eee5ae10256 ("swiotlb: fix slot alignment checks") Reported-by: Dexuan Cui Link: https://lore.kernel.org/all/CAA42JLa1y9jJ7BgQvXeUYQh-K2mDNHd2BYZ4iZUz33r5zY7oAQ@mail.gmail.com/ Reported-by: Kelsey Steele Link: https://lore.kernel.org/all/20230405003549.GA21326@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net/ Signed-off-by: Petr Tesarik Tested-by: Dexuan Cui Signed-off-by: Christoph Hellwig --- diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 5b919ef832b6f..dac42a2ad5883 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -623,7 +623,7 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, phys_to_dma_unencrypted(dev, mem->start) & boundary_mask; unsigned long max_slots = get_max_slots(boundary_mask); unsigned int iotlb_align_mask = - dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1); + dma_get_min_align_mask(dev) | alloc_align_mask; unsigned int nslots = nr_slots(alloc_size), stride; unsigned int offset = swiotlb_align_offset(dev, orig_addr); unsigned int index, slots_checked, count = 0, i; @@ -639,8 +639,8 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, * allocations. */ if (alloc_size >= PAGE_SIZE) - iotlb_align_mask &= PAGE_MASK; - iotlb_align_mask &= alloc_align_mask; + iotlb_align_mask |= ~PAGE_MASK; + iotlb_align_mask &= ~(IO_TLB_SIZE - 1); /* * For mappings with an alignment requirement don't bother looping to