[RFC PATCH 2/7] swiotlb: Make io_tlb_start a physical address instead of a virtual address
Alexander Duyck
alexander.h.duyck at intel.com
Thu Oct 4 00:38:53 UTC 2012
This change makes it so that io_tlb_start contains a physical address instead
of a virtual address. The advantage to this is that we can avoid costly
translations between virtual and physical addresses when comparing the
io_tlb_start against DMA addresses.
Signed-off-by: Alexander Duyck <alexander.h.duyck at intel.com>
---
lib/swiotlb.c | 61 +++++++++++++++++++++++++++++----------------------------
1 files changed, 31 insertions(+), 30 deletions(-)
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 5cc4d4e..02abb72 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -57,7 +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;
+phys_addr_t io_tlb_start;
/*
* The number of IO TLB blocks (in groups of 64).
@@ -125,14 +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, pend;
+ unsigned char *vstart, *vend;
- pstart = virt_to_phys(io_tlb_start);
- pend = pstart + bytes;
+ vstart = phys_to_virt(io_tlb_start);
+ vend = vstart + bytes;
printk(KERN_INFO "software IO TLB [mem %#010llx-%#010llx] (%luMB) mapped at [%p-%p]\n",
- (unsigned long long)pstart, (unsigned long long)pend - 1,
- bytes >> 20, io_tlb_start, io_tlb_start + bytes - 1);
+ (unsigned long long)io_tlb_start,
+ (unsigned long long)io_tlb_start + bytes - 1,
+ bytes >> 20, vstart, vend - 1);
}
void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
@@ -142,7 +143,7 @@ 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_start = __pa(tlb);
/*
* Allocate and initialize the free list array. This array is used
@@ -171,6 +172,7 @@ 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) {
@@ -183,11 +185,11 @@ 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
@@ -205,6 +207,7 @@ 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;
@@ -221,14 +224,14 @@ 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;
}
@@ -237,9 +240,9 @@ 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;
}
@@ -251,9 +254,9 @@ 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_start = virt_to_phys(tlb);
- memset(io_tlb_start, 0, bytes);
+ memset(tlb, 0, bytes);
/*
* Allocate and initialize the free list array. This array is used
@@ -300,7 +303,7 @@ cleanup3:
sizeof(int)));
io_tlb_list = NULL;
cleanup2:
- io_tlb_start = NULL;
+ io_tlb_start = 0;
io_tlb_nslabs = 0;
return -ENOMEM;
}
@@ -317,7 +320,7 @@ 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),
@@ -326,7 +329,7 @@ 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;
@@ -334,10 +337,8 @@ void __init swiotlb_free(void)
static int is_swiotlb_buffer(phys_addr_t paddr)
{
- phys_addr_t swiotlb_start = virt_to_phys(io_tlb_start);
-
- return paddr >= swiotlb_start &&
- paddr < (swiotlb_start + (io_tlb_nslabs << IO_TLB_SHIFT));
+ return paddr >= io_tlb_start &&
+ paddr < (io_tlb_start + (io_tlb_nslabs << IO_TLB_SHIFT));
}
/*
@@ -450,7 +451,7 @@ 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
@@ -494,7 +495,7 @@ 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);
}
@@ -508,7 +509,7 @@ 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];
/*
@@ -549,7 +550,7 @@ 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));
@@ -937,6 +938,6 @@ swiotlb_dma_supported(struct device *hwdev, u64 mask)
{
unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
- return swiotlb_virt_to_bus(hwdev, io_tlb_start + bytes - 1) <= mask;
+ return phys_to_dma(hwdev, io_tlb_start + bytes - 1) <= mask;
}
EXPORT_SYMBOL(swiotlb_dma_supported);
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