1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/cpu.h> 3 #include <linux/dma-mapping.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/vmalloc.h> 12 #include <linux/swiotlb.h> 13 14 #include <xen/xen.h> 15 #include <xen/interface/grant_table.h> 16 #include <xen/interface/memory.h> 17 #include <xen/page.h> 18 #include <xen/swiotlb-xen.h> 19 20 #include <asm/cacheflush.h> 21 #include <asm/xen/hypercall.h> 22 #include <asm/xen/interface.h> 23 24 unsigned long xen_get_swiotlb_free_pages(unsigned int order) 25 { 26 struct memblock_region *reg; 27 gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM; 28 29 for_each_memblock(memory, reg) { 30 if (reg->base < (phys_addr_t)0xffffffff) { 31 flags |= __GFP_DMA; 32 break; 33 } 34 } 35 return __get_free_pages(flags, order); 36 } 37 38 enum dma_cache_op { 39 DMA_UNMAP, 40 DMA_MAP, 41 }; 42 static bool hypercall_cflush = false; 43 44 /* functions called by SWIOTLB */ 45 46 static void dma_cache_maint(dma_addr_t handle, unsigned long offset, 47 size_t size, enum dma_data_direction dir, enum dma_cache_op op) 48 { 49 struct gnttab_cache_flush cflush; 50 unsigned long xen_pfn; 51 size_t left = size; 52 53 xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE; 54 offset %= XEN_PAGE_SIZE; 55 56 do { 57 size_t len = left; 58 59 /* buffers in highmem or foreign pages cannot cross page 60 * boundaries */ 61 if (len + offset > XEN_PAGE_SIZE) 62 len = XEN_PAGE_SIZE - offset; 63 64 cflush.op = 0; 65 cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT; 66 cflush.offset = offset; 67 cflush.length = len; 68 69 if (op == DMA_UNMAP && dir != DMA_TO_DEVICE) 70 cflush.op = GNTTAB_CACHE_INVAL; 71 if (op == DMA_MAP) { 72 if (dir == DMA_FROM_DEVICE) 73 cflush.op = GNTTAB_CACHE_INVAL; 74 else 75 cflush.op = GNTTAB_CACHE_CLEAN; 76 } 77 if (cflush.op) 78 HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1); 79 80 offset = 0; 81 xen_pfn++; 82 left -= len; 83 } while (left); 84 } 85 86 static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle, 87 size_t size, enum dma_data_direction dir) 88 { 89 dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP); 90 } 91 92 static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle, 93 size_t size, enum dma_data_direction dir) 94 { 95 dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP); 96 } 97 98 void __xen_dma_map_page(struct device *hwdev, struct page *page, 99 dma_addr_t dev_addr, unsigned long offset, size_t size, 100 enum dma_data_direction dir, unsigned long attrs) 101 { 102 if (is_device_dma_coherent(hwdev)) 103 return; 104 if (attrs & DMA_ATTR_SKIP_CPU_SYNC) 105 return; 106 107 __xen_dma_page_cpu_to_dev(hwdev, dev_addr, size, dir); 108 } 109 110 void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle, 111 size_t size, enum dma_data_direction dir, 112 unsigned long attrs) 113 114 { 115 if (is_device_dma_coherent(hwdev)) 116 return; 117 if (attrs & DMA_ATTR_SKIP_CPU_SYNC) 118 return; 119 120 __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir); 121 } 122 123 void __xen_dma_sync_single_for_cpu(struct device *hwdev, 124 dma_addr_t handle, size_t size, enum dma_data_direction dir) 125 { 126 if (is_device_dma_coherent(hwdev)) 127 return; 128 __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir); 129 } 130 131 void __xen_dma_sync_single_for_device(struct device *hwdev, 132 dma_addr_t handle, size_t size, enum dma_data_direction dir) 133 { 134 if (is_device_dma_coherent(hwdev)) 135 return; 136 __xen_dma_page_cpu_to_dev(hwdev, handle, size, dir); 137 } 138 139 bool xen_arch_need_swiotlb(struct device *dev, 140 phys_addr_t phys, 141 dma_addr_t dev_addr) 142 { 143 unsigned int xen_pfn = XEN_PFN_DOWN(phys); 144 unsigned int bfn = XEN_PFN_DOWN(dev_addr); 145 146 /* 147 * The swiotlb buffer should be used if 148 * - Xen doesn't have the cache flush hypercall 149 * - The Linux page refers to foreign memory 150 * - The device doesn't support coherent DMA request 151 * 152 * The Linux page may be spanned acrros multiple Xen page, although 153 * it's not possible to have a mix of local and foreign Xen page. 154 * Furthermore, range_straddles_page_boundary is already checking 155 * if buffer is physically contiguous in the host RAM. 156 * 157 * Therefore we only need to check the first Xen page to know if we 158 * require a bounce buffer because the device doesn't support coherent 159 * memory and we are not able to flush the cache. 160 */ 161 return (!hypercall_cflush && (xen_pfn != bfn) && 162 !is_device_dma_coherent(dev)); 163 } 164 165 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order, 166 unsigned int address_bits, 167 dma_addr_t *dma_handle) 168 { 169 if (!xen_initial_domain()) 170 return -EINVAL; 171 172 /* we assume that dom0 is mapped 1:1 for now */ 173 *dma_handle = pstart; 174 return 0; 175 } 176 EXPORT_SYMBOL_GPL(xen_create_contiguous_region); 177 178 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order) 179 { 180 return; 181 } 182 EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region); 183 184 const struct dma_map_ops *xen_dma_ops; 185 EXPORT_SYMBOL(xen_dma_ops); 186 187 int __init xen_mm_init(void) 188 { 189 struct gnttab_cache_flush cflush; 190 if (!xen_initial_domain()) 191 return 0; 192 xen_swiotlb_init(1, false); 193 xen_dma_ops = &xen_swiotlb_dma_ops; 194 195 cflush.op = 0; 196 cflush.a.dev_bus_addr = 0; 197 cflush.offset = 0; 198 cflush.length = 0; 199 if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS) 200 hypercall_cflush = true; 201 return 0; 202 } 203 arch_initcall(xen_mm_init); 204