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); 203