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>

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index c0cbfa1116c0829dd4b37ca3a1454d394ed13777..8c4791f17ec1ee9c943e087fd47a3822901be0a3 100644 (file)
--- 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));