From: Christoph Hellwig hch@lst.de
'commit 26a7e094783d ("swiotlb: refactor swiotlb_tbl_map_single")'
Split out a bunch of a self-contained helpers to make the function easier to follow.
Signed-off-by: Christoph Hellwig hch@lst.de Acked-by: Jianxiong Gao jxgao@google.com Tested-by: Jianxiong Gao jxgao@google.com Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Jianxiong Gao jxgao@google.com --- kernel/dma/swiotlb.c | 177 +++++++++++++++++++++---------------------- 1 file changed, 86 insertions(+), 91 deletions(-)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 47d5dfeffd0a..a3c0ccc53b8d 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -452,134 +452,129 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr, } }
-phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr, - size_t mapping_size, size_t alloc_size, - enum dma_data_direction dir, unsigned long attrs) +#define slot_addr(start, idx) ((start) + ((idx) << IO_TLB_SHIFT)) +/* + * Carefully handle integer overflow which can occur when boundary_mask == ~0UL. + */ +static inline unsigned long get_max_slots(unsigned long boundary_mask) { - dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, io_tlb_start); - unsigned long flags; - phys_addr_t tlb_addr; - unsigned int nslots, stride, index, wrap; - int i; - unsigned long mask; - unsigned long offset_slots; - unsigned long max_slots; - unsigned long tmp_io_tlb_used; - - if (no_iotlb_memory) - panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer"); - - if (mem_encrypt_active()) - pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n"); - - if (mapping_size > alloc_size) { - dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)", - mapping_size, alloc_size); - return (phys_addr_t)DMA_MAPPING_ERROR; - } - - mask = dma_get_seg_boundary(hwdev); - - tbl_dma_addr &= mask; + if (boundary_mask == ~0UL) + return 1UL << (BITS_PER_LONG - IO_TLB_SHIFT); + return nr_slots(boundary_mask + 1); +}
- offset_slots = nr_slots(tbl_dma_addr); +static unsigned int wrap_index(unsigned int index) +{ + if (index >= io_tlb_nslabs) + return 0; + return index; +}
- /* - * Carefully handle integer overflow which can occur when mask == ~0UL. - */ - max_slots = mask + 1 - ? nr_slots(mask + 1) - : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT); +/* + * Find a suitable number of IO TLB entries size that will fit this request and + * allocate a buffer from that IO TLB pool. + */ +static int find_slots(struct device *dev, size_t alloc_size) +{ + unsigned long boundary_mask = dma_get_seg_boundary(dev); + dma_addr_t tbl_dma_addr = + phys_to_dma_unencrypted(dev, io_tlb_start) & boundary_mask; + unsigned long max_slots = get_max_slots(boundary_mask); + unsigned int nslots = nr_slots(alloc_size), stride = 1; + unsigned int index, wrap, count = 0, i; + unsigned long flags; + BUG_ON(!nslots);
/* * For mappings greater than or equal to a page, we limit the stride * (and hence alignment) to a page size. */ - nslots = nr_slots(alloc_size); if (alloc_size >= PAGE_SIZE) - stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT)); - else - stride = 1; + stride <<= (PAGE_SHIFT - IO_TLB_SHIFT);
- BUG_ON(!nslots); - - /* - * Find suitable number of IO TLB entries size that will fit this - * request and allocate a buffer from that IO TLB pool. - */ spin_lock_irqsave(&io_tlb_lock, flags); - if (unlikely(nslots > io_tlb_nslabs - io_tlb_used)) goto not_found;
- index = ALIGN(io_tlb_index, stride); - if (index >= io_tlb_nslabs) - index = 0; - wrap = index; - + index = wrap = wrap_index(ALIGN(io_tlb_index, stride)); do { - while (iommu_is_span_boundary(index, nslots, offset_slots, - max_slots)) { - index += stride; - if (index >= io_tlb_nslabs) - index = 0; - if (index == wrap) - goto not_found; - } - /* * If we find a slot that indicates we have 'nslots' number of * contiguous buffers, we allocate the buffers from that slot * and mark the entries as '0' indicating unavailable. */ - if (io_tlb_list[index] >= nslots) { - int count = 0; - - for (i = index; i < (int) (index + nslots); i++) - io_tlb_list[i] = 0; - for (i = index - 1; - io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 && - io_tlb_list[i]; i--) - io_tlb_list[i] = ++count; - tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT); - - /* - * Update the indices to avoid searching in the next - * round. - */ - io_tlb_index = ((index + nslots) < io_tlb_nslabs - ? (index + nslots) : 0); - - goto found; + if (!iommu_is_span_boundary(index, nslots, + nr_slots(tbl_dma_addr), + max_slots)) { + if (io_tlb_list[index] >= nslots) + goto found; } - index += stride; - if (index >= io_tlb_nslabs) - index = 0; + index = wrap_index(index + stride); } while (index != wrap);
not_found: - tmp_io_tlb_used = io_tlb_used; - spin_unlock_irqrestore(&io_tlb_lock, flags); - if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit()) - dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n", - alloc_size, io_tlb_nslabs, tmp_io_tlb_used); - return (phys_addr_t)DMA_MAPPING_ERROR; + return -1; found: + for (i = index; i < index + nslots; i++) + io_tlb_list[i] = 0; + for (i = index - 1; + io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 && + io_tlb_list[i]; i--) + io_tlb_list[i] = ++count; + + /* + * Update the indices to avoid searching in the next round. + */ + if (index + nslots < io_tlb_nslabs) + io_tlb_index = index + nslots; + else + io_tlb_index = 0; io_tlb_used += nslots; + spin_unlock_irqrestore(&io_tlb_lock, flags); + return index; +}
+phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, + size_t mapping_size, size_t alloc_size, + enum dma_data_direction dir, unsigned long attrs) +{ + unsigned int index, i; + phys_addr_t tlb_addr; + + if (no_iotlb_memory) + panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer"); + + if (mem_encrypt_active()) + pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n"); + + if (mapping_size > alloc_size) { + dev_warn_once(dev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)", + mapping_size, alloc_size); + return (phys_addr_t)DMA_MAPPING_ERROR; + } + + index = find_slots(dev, alloc_size); + if (index == -1) { + if (!(attrs & DMA_ATTR_NO_WARN)) + dev_warn_ratelimited(dev, + "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n", + alloc_size, io_tlb_nslabs, io_tlb_used); + return (phys_addr_t)DMA_MAPPING_ERROR; + } /* * Save away the mapping from the original address to the DMA address. * This is needed when we sync the memory. Then we sync the buffer if * needed. */ - for (i = 0; i < nslots; i++) - io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); + for (i = 0; i < nr_slots(alloc_size); i++) + io_tlb_orig_addr[index + i] = slot_addr(orig_addr, i); + + tlb_addr = slot_addr(io_tlb_start, index); if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE); - return tlb_addr; }