swiotlb: Make io_tlb_start a physical address instead of a virtual one

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>

1 files changed, 29 insertions, 29 deletions

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index c0cbfa1116c0..8c4791f17ec1 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -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
@@ -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)
@@ -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
@@ -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) {
@@ -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
@@ -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;
 
@@ -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;
         }
@@ -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;
 }
 
@@ -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
@@ -308,7 +308,7 @@ cleanup3:
         io_tlb_list = NULL;
 cleanup2:
         io_tlb_end = 0;
-        io_tlb_start = NULL;
+        io_tlb_start = 0;
         io_tlb_nslabs = 0;
         return -ENOMEM;
 }
@@ -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),
@@ -334,7 +334,7 @@ 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;
@@ -342,7 +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 < io_tlb_end;
+        return paddr >= io_tlb_start && paddr < io_tlb_end;
 }
 
 /*
@@ -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
@@ -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);
 }
@@ -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];
 
         /*
@@ -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));