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Subject[PATCH v2 1/7] swiotlb: Make io_tlb_end a physical address instead of a virtual one
Date
This change replaces all references to the virtual address for io_tlb_end
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>
---

lib/swiotlb.c | 24 +++++++++++++-----------
1 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index f114bf6..19aac9f 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -57,7 +57,8 @@ int swiotlb_force;
* swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
* API.
*/
-static char *io_tlb_start, *io_tlb_end;
+static char *io_tlb_start;
+phys_addr_t io_tlb_end;

/*
* The number of IO TLB blocks (in groups of 64) between io_tlb_start and
@@ -125,14 +126,16 @@ 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;
+ phys_addr_t pstart;
+ unsigned char *vend;

pstart = virt_to_phys(io_tlb_start);
- pend = virt_to_phys(io_tlb_end);
+ 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)pend - 1,
- bytes >> 20, io_tlb_start, io_tlb_end - 1);
+ (unsigned long long)pstart,
+ (unsigned long long)io_tlb_end,
+ bytes >> 20, io_tlb_start, vend - 1);
}

void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
@@ -143,7 +146,7 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)

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

/*
* Allocate and initialize the free list array. This array is used
@@ -254,7 +257,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)

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

memset(io_tlb_start, 0, bytes);

@@ -304,7 +307,7 @@ cleanup3:
sizeof(int)));
io_tlb_list = NULL;
cleanup2:
- io_tlb_end = NULL;
+ io_tlb_end = 0;
io_tlb_start = NULL;
io_tlb_nslabs = 0;
return -ENOMEM;
@@ -339,8 +342,7 @@ void __init swiotlb_free(void)

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

/*
@@ -938,6 +940,6 @@ EXPORT_SYMBOL(swiotlb_dma_mapping_error);
int
swiotlb_dma_supported(struct device *hwdev, u64 mask)
{
- return swiotlb_virt_to_bus(hwdev, io_tlb_end - 1) <= mask;
+ return phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
}
EXPORT_SYMBOL(swiotlb_dma_supported);


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