arch/arm/xen/mm.c

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