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, struct dma_attrs *attrs) 102 { 103 if (is_device_dma_coherent(hwdev)) 104 return; 105 if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs)) 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 struct dma_attrs *attrs) 114 115 { 116 if (is_device_dma_coherent(hwdev)) 117 return; 118 if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs)) 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 struct dma_map_ops *xen_dma_ops; 186 EXPORT_SYMBOL(xen_dma_ops); 187 188 static struct dma_map_ops xen_swiotlb_dma_ops = { 189 .mapping_error = xen_swiotlb_dma_mapping_error, 190 .alloc = xen_swiotlb_alloc_coherent, 191 .free = xen_swiotlb_free_coherent, 192 .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu, 193 .sync_single_for_device = xen_swiotlb_sync_single_for_device, 194 .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu, 195 .sync_sg_for_device = xen_swiotlb_sync_sg_for_device, 196 .map_sg = xen_swiotlb_map_sg_attrs, 197 .unmap_sg = xen_swiotlb_unmap_sg_attrs, 198 .map_page = xen_swiotlb_map_page, 199 .unmap_page = xen_swiotlb_unmap_page, 200 .dma_supported = xen_swiotlb_dma_supported, 201 .set_dma_mask = xen_swiotlb_set_dma_mask, 202 }; 203 204 int __init xen_mm_init(void) 205 { 206 struct gnttab_cache_flush cflush; 207 if (!xen_initial_domain()) 208 return 0; 209 xen_swiotlb_init(1, false); 210 xen_dma_ops = &xen_swiotlb_dma_ops; 211 212 cflush.op = 0; 213 cflush.a.dev_bus_addr = 0; 214 cflush.offset = 0; 215 cflush.length = 0; 216 if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS) 217 hypercall_cflush = true; 218 return 0; 219 } 220 arch_initcall(xen_mm_init); 221