[PATCH v2 RESEND 2/7] swiotlb: Move code around in preparation for dynamic bounce buffers
Petr Tesarik
petrtesarik at huaweicloud.com
Tue May 9 09:18:14 UTC 2023
From: Petr Tesarik <petr.tesarik.ext at huawei.com>
To prepare for the introduction of dynamically allocated bounce
buffers, separate out common code and code which handles non-dynamic
(aka fixed) bounce buffers.
No functional change, but this commit should make the addition of
dynamic allocations easier to review.
Signed-off-by: Petr Tesarik <petr.tesarik.ext at huawei.com>
---
include/linux/swiotlb.h | 31 ++++++++++-
kernel/dma/swiotlb.c | 110 +++++++++++++++++++++++++++++++++-------
2 files changed, 122 insertions(+), 19 deletions(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index d851dbce1143..281ecc6b9bcc 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -114,11 +114,40 @@ struct io_tlb_mem {
};
extern struct io_tlb_mem io_tlb_default_mem;
+/**
+ * is_swiotlb_fixed() - check if a physical address belongs to a swiotlb slot
+ * @mem: relevant swiotlb pool
+ * @paddr: physical address within the DMA buffer
+ *
+ * Check if @paddr points into a fixed bounce buffer slot.
+ * This check should be as fast as possible.
+ *
+ * Return:
+ * * %true if @paddr points into a @mem fixed slot
+ * * %false otherwise
+ */
+static inline bool is_swiotlb_fixed(struct io_tlb_mem *mem, phys_addr_t paddr)
+{
+ return paddr >= mem->start && paddr < mem->end;
+}
+
+/**
+ * is_swiotlb_buffer() - check if a physical address is allocated from the
+ * swiotlb pool
+ * @dev: device which has mapped the buffer
+ * @paddr: physical address within the DMA buffer
+ *
+ * Check if @paddr points into a bounce buffer.
+ *
+ * Return:
+ * * %true if @paddr points into a bounce buffer
+ * * %false otherwise
+ */
static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
{
struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
- return mem && paddr >= mem->start && paddr < mem->end;
+ return mem && is_swiotlb_fixed(mem, paddr);
}
static inline bool is_swiotlb_force_bounce(struct device *dev)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index af2e304c672c..96ba93be6772 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -76,6 +76,10 @@ struct io_tlb_mem io_tlb_default_mem;
static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT;
static unsigned long default_nareas;
+static void swiotlb_copy(struct device *dev, phys_addr_t orig_addr,
+ unsigned char *vaddr, size_t size, size_t alloc_size,
+ unsigned int tlb_offset, enum dma_data_direction dir);
+
/**
* struct io_tlb_area - IO TLB memory area descriptor
*
@@ -480,7 +484,6 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
phys_addr_t orig_addr = mem->slots[index].orig_addr;
size_t alloc_size = mem->slots[index].alloc_size;
- unsigned long pfn = PFN_DOWN(orig_addr);
unsigned char *vaddr = mem->vaddr + tlb_addr - mem->start;
unsigned int tlb_offset, orig_addr_offset;
@@ -497,6 +500,34 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
}
tlb_offset -= orig_addr_offset;
+ swiotlb_copy(dev, orig_addr, vaddr, size, alloc_size, tlb_offset, dir);
+}
+
+/**
+ * swiotlb_copy() - copy swiotlb buffer content, checking for overflows.
+ * @dev: device which has mapped the bounce buffer
+ * @orig_addr: physical address of the original buffer
+ * @vaddr: virtual address inside the bounce buffer
+ * @size: number of bytes to copy
+ * @alloc_size: total allocated size of the bounce buffer
+ * @tlb_offset: offset within the bounce buffer
+ * @dir: direction of the data transfer
+ *
+ * If @dir is %DMA_TO_DEVICE, copy data from the original buffer to the
+ * bounce buffer, otherwise copy from the bounce buffer to the original
+ * buffer.
+ *
+ * The original buffer may be in high memory; that's why @orig_addr is
+ * a physical address. Note that this is the address of the beginning
+ * of the bounce buffer. Copying starts at offset @tlb_offset. This is
+ * needed to check accesses beyond the allocated size.
+ */
+static void swiotlb_copy(struct device *dev, phys_addr_t orig_addr,
+ unsigned char *vaddr, size_t size, size_t alloc_size,
+ unsigned int tlb_offset, enum dma_data_direction dir)
+{
+ unsigned long pfn = PFN_DOWN(orig_addr);
+
if (tlb_offset > alloc_size) {
dev_WARN_ONCE(dev, 1,
"Buffer overflow detected. Allocation size: %zu. Mapping size: %zu+%u.\n",
@@ -727,15 +758,65 @@ static unsigned long mem_used(struct io_tlb_mem *mem)
return used;
}
+/**
+ * swiotlb_fixed_map() - allocate a bounce buffer from fixed slots
+ * @dev: device which maps the buffer
+ * @orig_addr: address of the original buffer
+ * @alloc_size: total size of the original buffer
+ * @alloc_align_mask:
+ * required physical alignment of the I/O buffer
+ * @attrs: optional DMA attributes for the map operation
+ *
+ * Search for a suitable slot or sequence of slots and initialize them
+ * for use with the original buffer.
+ *
+ * Return: Physical address of the bounce buffer, or %DMA_MAPPING_ERROR.
+ */
+static phys_addr_t swiotlb_fixed_map(struct device *dev, phys_addr_t orig_addr,
+ size_t alloc_size, unsigned int alloc_align_mask,
+ unsigned long attrs)
+{
+ struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+ unsigned int offset = swiotlb_align_offset(dev, orig_addr);
+ int index = swiotlb_find_slots(dev, orig_addr,
+ alloc_size + offset, alloc_align_mask);
+ unsigned int i;
+
+ if (index == -1)
+ 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 < nr_slots(alloc_size + offset); i++)
+ mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);
+ return slot_addr(mem->start, index) + offset;
+}
+
+/**
+ * swiotlb_tbl_map_single() - map DMA buffer to a bounce buffer
+ * @dev: device which maps the buffer
+ * @orig_addr: address of the original buffer
+ * @mapping_size: size of the original buffer to be synced now
+ * @alloc_size: total size of the original buffer
+ * @alloc_align_mask:
+ * required physical alignment of the I/O buffer
+ * @dir: direction of the data transfer
+ * @attrs: optional DMA attributes for the map operation
+ *
+ * Create a mapping of the DMA buffer into a bounce buffer and copy the
+ * original data.
+ *
+ * Return: Physical address of the bounce buffer, or %DMA_MAPPING_ERROR.
+ */
phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
size_t mapping_size, size_t alloc_size,
unsigned int alloc_align_mask, enum dma_data_direction dir,
unsigned long attrs)
{
struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
- unsigned int offset = swiotlb_align_offset(dev, orig_addr);
- unsigned int i;
- int index;
phys_addr_t tlb_addr;
if (!mem || !mem->nslabs) {
@@ -753,24 +834,17 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
return (phys_addr_t)DMA_MAPPING_ERROR;
}
- index = swiotlb_find_slots(dev, orig_addr,
- alloc_size + offset, alloc_align_mask);
- if (index == -1) {
+ tlb_addr = swiotlb_fixed_map(dev, orig_addr, alloc_size,
+ alloc_align_mask, attrs);
+
+ if (tlb_addr == (phys_addr_t)DMA_MAPPING_ERROR) {
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, mem->nslabs, mem_used(mem));
- return (phys_addr_t)DMA_MAPPING_ERROR;
+ "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
+ alloc_size, mem->nslabs, mem_used(mem));
+ return tlb_addr;
}
- /*
- * 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 < nr_slots(alloc_size + offset); i++)
- mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);
- tlb_addr = slot_addr(mem->start, index) + offset;
/*
* When dir == DMA_FROM_DEVICE we could omit the copy from the orig
* to the tlb buffer, if we knew for sure the device will
--
2.25.1
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