arch/arm/xen/mm.c

   1 #include <linux/cpu.h>
   2 #include <linux/dma-mapping.h>
   3 #include <linux/bootmem.h>
   4 #include <linux/gfp.h>
   5 #include <linux/highmem.h>
   6 #include <linux/export.h>
   7 #include <linux/memblock.h>
   8 #include <linux/of_address.h>
   9 #include <linux/slab.h>
  10 #include <linux/types.h>
  11 #include <linux/dma-mapping.h>
  12 #include <linux/vmalloc.h>
  13 #include <linux/swiotlb.h>
  14
  15 #include <xen/xen.h>
  16 #include <xen/interface/grant_table.h>
  17 #include <xen/interface/memory.h>
  18 #include <xen/page.h>
  19 #include <xen/swiotlb-xen.h>
  20
  21 #include <asm/cacheflush.h>
  22 #include <asm/xen/hypercall.h>
  23 #include <asm/xen/interface.h>
  24
  25 unsigned long xen_get_swiotlb_free_pages(unsigned int order)
  26 {
  27         struct memblock_region *reg;
  28         gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM;
  29
  30         for_each_memblock(memory, reg) {
  31                 if (reg->base < (phys_addr_t)0xffffffff) {
  32                         flags |= __GFP_DMA;
  33                         break;
  34                 }
  35         }
  36         return __get_free_pages(flags, order);
  37 }
  38
  39 enum dma_cache_op {
  40        DMA_UNMAP,
  41        DMA_MAP,
  42 };
  43 static bool hypercall_cflush = false;
  44
  45 /* functions called by SWIOTLB */
  46
  47 static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
  48         size_t size, enum dma_data_direction dir, enum dma_cache_op op)
  49 {
  50         struct gnttab_cache_flush cflush;
  51         unsigned long xen_pfn;
  52         size_t left = size;
  53
  54         xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
  55         offset %= XEN_PAGE_SIZE;
  56
  57         do {
  58                 size_t len = left;
  59
  60                 /* buffers in highmem or foreign pages cannot cross page
  61                  * boundaries */
  62                 if (len + offset > XEN_PAGE_SIZE)
  63                         len = XEN_PAGE_SIZE - offset;
  64
  65                 cflush.op = 0;
  66                 cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
  67                 cflush.offset = offset;
  68                 cflush.length = len;
  69
  70                 if (op == DMA_UNMAP && dir != DMA_TO_DEVICE)
  71                         cflush.op = GNTTAB_CACHE_INVAL;
  72                 if (op == DMA_MAP) {
  73                         if (dir == DMA_FROM_DEVICE)
  74                                 cflush.op = GNTTAB_CACHE_INVAL;
  75                         else
  76                                 cflush.op = GNTTAB_CACHE_CLEAN;
  77                 }
  78                 if (cflush.op)
  79                         HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
  80
  81                 offset = 0;
  82                 xen_pfn++;
  83                 left -= len;
  84         } while (left);
  85 }
  86
  87 static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
  88                 size_t size, enum dma_data_direction dir)
  89 {
  90         dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
  91 }
  92
  93 static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
  94                 size_t size, enum dma_data_direction dir)
  95 {
  96         dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
  97 }
  98
  99 void __xen_dma_map_page(struct device *hwdev, struct page *page,
 100              dma_addr_t dev_addr, unsigned long offset, size_t size,
 101              enum dma_data_direction dir, unsigned long attrs)
 102 {
 103         if (is_device_dma_coherent(hwdev))
 104                 return;
 105         if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
 106                 return;
 107
 108         __xen_dma_page_cpu_to_dev(hwdev, dev_addr, size, dir);
 109 }
 110
 111 void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
 112                 size_t size, enum dma_data_direction dir,
 113                 unsigned long attrs)
 114
 115 {
 116         if (is_device_dma_coherent(hwdev))
 117                 return;
 118         if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
 119                 return;
 120
 121         __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
 122 }
 123
 124 void __xen_dma_sync_single_for_cpu(struct device *hwdev,
 125                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 126 {
 127         if (is_device_dma_coherent(hwdev))
 128                 return;
 129         __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
 130 }
 131
 132 void __xen_dma_sync_single_for_device(struct device *hwdev,
 133                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 134 {
 135         if (is_device_dma_coherent(hwdev))
 136                 return;
 137         __xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
 138 }
 139
 140 bool xen_arch_need_swiotlb(struct device *dev,
 141                            phys_addr_t phys,
 142                            dma_addr_t dev_addr)
 143 {
 144         unsigned int xen_pfn = XEN_PFN_DOWN(phys);
 145         unsigned int bfn = XEN_PFN_DOWN(dev_addr);
 146
 147         /*
 148          * The swiotlb buffer should be used if
 149          *      - Xen doesn't have the cache flush hypercall
 150          *      - The Linux page refers to foreign memory
 151          *      - The device doesn't support coherent DMA request
 152          *
 153          * The Linux page may be spanned acrros multiple Xen page, although
 154          * it's not possible to have a mix of local and foreign Xen page.
 155          * Furthermore, range_straddles_page_boundary is already checking
 156          * if buffer is physically contiguous in the host RAM.
 157          *
 158          * Therefore we only need to check the first Xen page to know if we
 159          * require a bounce buffer because the device doesn't support coherent
 160          * memory and we are not able to flush the cache.
 161          */
 162         return (!hypercall_cflush && (xen_pfn != bfn) &&
 163                 !is_device_dma_coherent(dev));
 164 }
 165
 166 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
 167                                  unsigned int address_bits,
 168                                  dma_addr_t *dma_handle)
 169 {
 170         if (!xen_initial_domain())
 171                 return -EINVAL;
 172
 173         /* we assume that dom0 is mapped 1:1 for now */
 174         *dma_handle = pstart;
 175         return 0;
 176 }
 177 EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
 178
 179 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
 180 {
 181         return;
 182 }
 183 EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 184
 185 const struct dma_map_ops *xen_dma_ops;
 186 EXPORT_SYMBOL(xen_dma_ops);
 187
 188 int __init xen_mm_init(void)
 189 {
 190         struct gnttab_cache_flush cflush;
 191         if (!xen_initial_domain())
 192                 return 0;
 193         xen_swiotlb_init(1, false);
 194         xen_dma_ops = &xen_swiotlb_dma_ops;
 195
 196         cflush.op = 0;
 197         cflush.a.dev_bus_addr = 0;
 198         cflush.offset = 0;
 199         cflush.length = 0;
 200         if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
 201                 hypercall_cflush = true;
 202         return 0;
 203 }
 204 arch_initcall(xen_mm_init);