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swiotlb: Make io_tlb_start a physical address instead of a virtual one
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This change replaces all references to the virtual address for io_tlb_start
with references to the physical address io_tlb_end.  The main advantage of
replacing the virtual address with a physical address is that we can avoid
having to do multiple translations from the virtual address to the physical
one needed for testing an existing DMA address.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Alexander Duyck authored and Konrad Rzeszutek Wilk committed Oct 30, 2012
1 parent c40dba0 commit ff7204a
Showing 1 changed file with 29 additions and 29 deletions.
58 changes: 29 additions & 29 deletions lib/swiotlb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,8 +57,7 @@ int swiotlb_force;
* swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
* API.
*/
static char *io_tlb_start;
static phys_addr_t io_tlb_end;
static phys_addr_t io_tlb_start, io_tlb_end;

/*
* The number of IO TLB blocks (in groups of 64) between io_tlb_start and
Expand Down Expand Up @@ -126,16 +125,15 @@ static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
void swiotlb_print_info(void)
{
unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
phys_addr_t pstart;
unsigned char *vend;
unsigned char *vstart, *vend;

pstart = virt_to_phys(io_tlb_start);
vstart = phys_to_virt(io_tlb_start);
vend = phys_to_virt(io_tlb_end);

printk(KERN_INFO "software IO TLB [mem %#010llx-%#010llx] (%luMB) mapped at [%p-%p]\n",
(unsigned long long)pstart,
(unsigned long long)io_tlb_start,
(unsigned long long)io_tlb_end,
bytes >> 20, io_tlb_start, vend - 1);
bytes >> 20, vstart, vend - 1);
}

void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
Expand All @@ -145,8 +143,8 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
bytes = nslabs << IO_TLB_SHIFT;

io_tlb_nslabs = nslabs;
io_tlb_start = tlb;
io_tlb_end = __pa(io_tlb_start) + bytes;
io_tlb_start = __pa(tlb);
io_tlb_end = io_tlb_start + bytes;

/*
* Allocate and initialize the free list array. This array is used
Expand Down Expand Up @@ -176,6 +174,7 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
static void __init
swiotlb_init_with_default_size(size_t default_size, int verbose)
{
unsigned char *vstart;
unsigned long bytes;

if (!io_tlb_nslabs) {
Expand All @@ -188,11 +187,11 @@ swiotlb_init_with_default_size(size_t default_size, int verbose)
/*
* Get IO TLB memory from the low pages
*/
io_tlb_start = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
if (!io_tlb_start)
vstart = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
if (!vstart)
panic("Cannot allocate SWIOTLB buffer");

swiotlb_init_with_tbl(io_tlb_start, io_tlb_nslabs, verbose);
swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose);
}

void __init
Expand All @@ -210,6 +209,7 @@ int
swiotlb_late_init_with_default_size(size_t default_size)
{
unsigned long bytes, req_nslabs = io_tlb_nslabs;
unsigned char *vstart = NULL;
unsigned int order;
int rc = 0;

Expand All @@ -226,14 +226,14 @@ swiotlb_late_init_with_default_size(size_t default_size)
bytes = io_tlb_nslabs << IO_TLB_SHIFT;

while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
io_tlb_start = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
order);
if (io_tlb_start)
vstart = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
order);
if (vstart)
break;
order--;
}

if (!io_tlb_start) {
if (!vstart) {
io_tlb_nslabs = req_nslabs;
return -ENOMEM;
}
Expand All @@ -242,9 +242,9 @@ swiotlb_late_init_with_default_size(size_t default_size)
"for software IO TLB\n", (PAGE_SIZE << order) >> 20);
io_tlb_nslabs = SLABS_PER_PAGE << order;
}
rc = swiotlb_late_init_with_tbl(io_tlb_start, io_tlb_nslabs);
rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);
if (rc)
free_pages((unsigned long)io_tlb_start, order);
free_pages((unsigned long)vstart, order);
return rc;
}

Expand All @@ -256,10 +256,10 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
bytes = nslabs << IO_TLB_SHIFT;

io_tlb_nslabs = nslabs;
io_tlb_start = tlb;
io_tlb_end = virt_to_phys(io_tlb_start) + bytes;
io_tlb_start = virt_to_phys(tlb);
io_tlb_end = io_tlb_start + bytes;

memset(io_tlb_start, 0, bytes);
memset(tlb, 0, bytes);

/*
* Allocate and initialize the free list array. This array is used
Expand Down Expand Up @@ -308,7 +308,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
io_tlb_list = NULL;
cleanup2:
io_tlb_end = 0;
io_tlb_start = NULL;
io_tlb_start = 0;
io_tlb_nslabs = 0;
return -ENOMEM;
}
Expand All @@ -325,7 +325,7 @@ void __init swiotlb_free(void)
get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
sizeof(int)));
free_pages((unsigned long)io_tlb_start,
free_pages((unsigned long)phys_to_virt(io_tlb_start),
get_order(io_tlb_nslabs << IO_TLB_SHIFT));
} else {
free_bootmem_late(__pa(io_tlb_overflow_buffer),
Expand All @@ -334,15 +334,15 @@ void __init swiotlb_free(void)
PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
free_bootmem_late(__pa(io_tlb_list),
PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
free_bootmem_late(__pa(io_tlb_start),
free_bootmem_late(io_tlb_start,
PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
}
io_tlb_nslabs = 0;
}

static int is_swiotlb_buffer(phys_addr_t paddr)
{
return paddr >= virt_to_phys(io_tlb_start) && paddr < io_tlb_end;
return paddr >= io_tlb_start && paddr < io_tlb_end;
}

/*
Expand Down Expand Up @@ -455,7 +455,7 @@ void *swiotlb_tbl_map_single(struct device *hwdev, dma_addr_t tbl_dma_addr,
io_tlb_list[i] = 0;
for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
io_tlb_list[i] = ++count;
dma_addr = io_tlb_start + (index << IO_TLB_SHIFT);
dma_addr = (char *)phys_to_virt(io_tlb_start) + (index << IO_TLB_SHIFT);

/*
* Update the indices to avoid searching in the next
Expand Down Expand Up @@ -499,7 +499,7 @@ static void *
map_single(struct device *hwdev, phys_addr_t phys, size_t size,
enum dma_data_direction dir)
{
dma_addr_t start_dma_addr = swiotlb_virt_to_bus(hwdev, io_tlb_start);
dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start);

return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir);
}
Expand All @@ -513,7 +513,7 @@ swiotlb_tbl_unmap_single(struct device *hwdev, char *dma_addr, size_t size,
{
unsigned long flags;
int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
int index = (dma_addr - (char *)phys_to_virt(io_tlb_start)) >> IO_TLB_SHIFT;
phys_addr_t phys = io_tlb_orig_addr[index];

/*
Expand Down Expand Up @@ -554,7 +554,7 @@ swiotlb_tbl_sync_single(struct device *hwdev, char *dma_addr, size_t size,
enum dma_data_direction dir,
enum dma_sync_target target)
{
int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
int index = (dma_addr - (char *)phys_to_virt(io_tlb_start)) >> IO_TLB_SHIFT;
phys_addr_t phys = io_tlb_orig_addr[index];

phys += ((unsigned long)dma_addr & ((1 << IO_TLB_SHIFT) - 1));
Expand Down

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