[PATCH v4 09/14] swiotlb: Refactor swiotlb_tbl_{map,unmap}_single

Claire Chang
2021-02-09T06:28:00Z

Refactor swiotlb_tbl_{map,unmap}_single to make the code reusable for
dev_swiotlb_{alloc,free}.

Signed-off-by: Claire Chang <tientzu@chromium.org>
---
kernel/dma/swiotlb.c | 116 ++++++++++++++++++++++++++-----------------
1 file changed, 71 insertions(+), 45 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 6fdebde8fb1f..f64cbe6e84cc 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -509,14 +509,12 @@ 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)
+static int swiotlb_tbl_find_free_region(struct device *hwdev,
+ dma_addr_t tbl_dma_addr,
+ size_t alloc_size, unsigned long attrs)
{
struct swiotlb *swiotlb = get_swiotlb(hwdev);
- dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, swiotlb->start);
unsigned long flags;
- phys_addr_t tlb_addr;
unsigned int nslots, stride, index, wrap;
int i;
unsigned long mask;
@@ -531,15 +529,6 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
#endif
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;
@@ -601,7 +590,6 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
swiotlb->list[i] = 0;
for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && swiotlb->list[i]; i--)
swiotlb->list[i] = ++count;
- tlb_addr = swiotlb->start + (index << IO_TLB_SHIFT);

/*
* Update the indices to avoid searching in the next
@@ -624,45 +612,20 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
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, swiotlb->nslabs, tmp_io_tlb_used);
- return (phys_addr_t)DMA_MAPPING_ERROR;
+ return -ENOMEM;
+
found:
swiotlb->used += nslots;
spin_unlock_irqrestore(&swiotlb->lock, flags);

- /*
- * 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++)
- swiotlb->orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
- 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;
+ return index;
}

-/*
- * tlb_addr is the physical address of the bounce buffer to unmap.
- */
-void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
- size_t mapping_size, size_t alloc_size,
- enum dma_data_direction dir, unsigned long attrs)
+static void swiotlb_tbl_release_region(struct device *hwdev, int index, size_t size)
{
struct swiotlb *swiotlb = get_swiotlb(hwdev);
unsigned long flags;
- int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
- int index = (tlb_addr - swiotlb->start) >> IO_TLB_SHIFT;
- phys_addr_t orig_addr = swiotlb->orig_addr[index];
-
- /*
- * First, sync the memory before unmapping the entry
- */
- if (orig_addr != INVALID_PHYS_ADDR &&
- !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
- ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
- swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
+ int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;

/*
* Return the buffer to the free list by setting the corresponding
@@ -694,6 +657,69 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
spin_unlock_irqrestore(&swiotlb->lock, flags);
}

+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)
+{
+ struct swiotlb *swiotlb = get_swiotlb(hwdev);
+ dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, swiotlb->start);
+ phys_addr_t tlb_addr;
+ unsigned int nslots, index;
+ int i;
+
+ 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;
+ }
+
+ index = swiotlb_tbl_find_free_region(hwdev, tbl_dma_addr, alloc_size, attrs);
+ if (index < 0)
+ return (phys_addr_t)DMA_MAPPING_ERROR;
+
+ tlb_addr = swiotlb->start + (index << IO_TLB_SHIFT);
+
+ /*
+ * 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.
+ */
+ nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+ for (i = 0; i < nslots; i++)
+ swiotlb->orig_addr[index + i] = orig_addr + (i << IO_TLB_SHIFT);
+ 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;
+}
+
+/*
+ * tlb_addr is the physical address of the bounce buffer to unmap.
+ */
+void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
+ size_t mapping_size, size_t alloc_size,
+ enum dma_data_direction dir, unsigned long attrs)
+{
+ struct swiotlb *swiotlb = get_swiotlb(hwdev);
+ int index = (tlb_addr - swiotlb->start) >> IO_TLB_SHIFT;
+ phys_addr_t orig_addr = swiotlb->orig_addr[index];
+
+ /*
+ * First, sync the memory before unmapping the entry
+ */
+ if (orig_addr != INVALID_PHYS_ADDR &&
+ !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+ ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
+ swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
+
+ swiotlb_tbl_release_region(hwdev, index, alloc_size);
+}
+
void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
size_t size, enum dma_data_direction dir,
enum dma_sync_target target)
--
2.30.0.478.g8a0d178c01-goog