1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright 2010 4 * by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> 5 * 6 * This code provides a IOMMU for Xen PV guests with PCI passthrough. 7 * 8 * PV guests under Xen are running in an non-contiguous memory architecture. 9 * 10 * When PCI pass-through is utilized, this necessitates an IOMMU for 11 * translating bus (DMA) to virtual and vice-versa and also providing a 12 * mechanism to have contiguous pages for device drivers operations (say DMA 13 * operations). 14 * 15 * Specifically, under Xen the Linux idea of pages is an illusion. It 16 * assumes that pages start at zero and go up to the available memory. To 17 * help with that, the Linux Xen MMU provides a lookup mechanism to 18 * translate the page frame numbers (PFN) to machine frame numbers (MFN) 19 * and vice-versa. The MFN are the "real" frame numbers. Furthermore 20 * memory is not contiguous. Xen hypervisor stitches memory for guests 21 * from different pools, which means there is no guarantee that PFN==MFN 22 * and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are 23 * allocated in descending order (high to low), meaning the guest might 24 * never get any MFN's under the 4GB mark. 25 */ 26 27 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt 28 29 #include <linux/memblock.h> 30 #include <linux/dma-direct.h> 31 #include <linux/dma-map-ops.h> 32 #include <linux/export.h> 33 #include <xen/swiotlb-xen.h> 34 #include <xen/page.h> 35 #include <xen/xen-ops.h> 36 #include <xen/hvc-console.h> 37 38 #include <asm/dma-mapping.h> 39 40 #include <trace/events/swiotlb.h> 41 #define MAX_DMA_BITS 32 42 43 /* 44 * Quick lookup value of the bus address of the IOTLB. 45 */ 46 47 static inline phys_addr_t xen_phys_to_bus(struct device *dev, phys_addr_t paddr) 48 { 49 unsigned long bfn = pfn_to_bfn(XEN_PFN_DOWN(paddr)); 50 phys_addr_t baddr = (phys_addr_t)bfn << XEN_PAGE_SHIFT; 51 52 baddr |= paddr & ~XEN_PAGE_MASK; 53 return baddr; 54 } 55 56 static inline dma_addr_t xen_phys_to_dma(struct device *dev, phys_addr_t paddr) 57 { 58 return phys_to_dma(dev, xen_phys_to_bus(dev, paddr)); 59 } 60 61 static inline phys_addr_t xen_bus_to_phys(struct device *dev, 62 phys_addr_t baddr) 63 { 64 unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr)); 65 phys_addr_t paddr = (xen_pfn << XEN_PAGE_SHIFT) | 66 (baddr & ~XEN_PAGE_MASK); 67 68 return paddr; 69 } 70 71 static inline phys_addr_t xen_dma_to_phys(struct device *dev, 72 dma_addr_t dma_addr) 73 { 74 return xen_bus_to_phys(dev, dma_to_phys(dev, dma_addr)); 75 } 76 77 static inline int range_straddles_page_boundary(phys_addr_t p, size_t size) 78 { 79 unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p); 80 unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size); 81 82 next_bfn = pfn_to_bfn(xen_pfn); 83 84 for (i = 1; i < nr_pages; i++) 85 if (pfn_to_bfn(++xen_pfn) != ++next_bfn) 86 return 1; 87 88 return 0; 89 } 90 91 static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr) 92 { 93 unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr)); 94 unsigned long xen_pfn = bfn_to_local_pfn(bfn); 95 phys_addr_t paddr = (phys_addr_t)xen_pfn << XEN_PAGE_SHIFT; 96 97 /* If the address is outside our domain, it CAN 98 * have the same virtual address as another address 99 * in our domain. Therefore _only_ check address within our domain. 100 */ 101 if (pfn_valid(PFN_DOWN(paddr))) 102 return is_swiotlb_buffer(dev, paddr); 103 return 0; 104 } 105 106 #ifdef CONFIG_X86 107 int xen_swiotlb_fixup(void *buf, unsigned long nslabs) 108 { 109 int rc; 110 unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT); 111 unsigned int i, dma_bits = order + PAGE_SHIFT; 112 dma_addr_t dma_handle; 113 phys_addr_t p = virt_to_phys(buf); 114 115 BUILD_BUG_ON(IO_TLB_SEGSIZE & (IO_TLB_SEGSIZE - 1)); 116 BUG_ON(nslabs % IO_TLB_SEGSIZE); 117 118 i = 0; 119 do { 120 do { 121 rc = xen_create_contiguous_region( 122 p + (i << IO_TLB_SHIFT), order, 123 dma_bits, &dma_handle); 124 } while (rc && dma_bits++ < MAX_DMA_BITS); 125 if (rc) 126 return rc; 127 128 i += IO_TLB_SEGSIZE; 129 } while (i < nslabs); 130 return 0; 131 } 132 133 static void * 134 xen_swiotlb_alloc_coherent(struct device *dev, size_t size, 135 dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs) 136 { 137 u64 dma_mask = dev->coherent_dma_mask; 138 int order = get_order(size); 139 phys_addr_t phys; 140 void *ret; 141 142 /* Align the allocation to the Xen page size */ 143 size = 1UL << (order + XEN_PAGE_SHIFT); 144 145 ret = (void *)__get_free_pages(flags, get_order(size)); 146 if (!ret) 147 return ret; 148 phys = virt_to_phys(ret); 149 150 *dma_handle = xen_phys_to_dma(dev, phys); 151 if (*dma_handle + size - 1 > dma_mask || 152 range_straddles_page_boundary(phys, size)) { 153 if (xen_create_contiguous_region(phys, order, fls64(dma_mask), 154 dma_handle) != 0) 155 goto out_free_pages; 156 SetPageXenRemapped(virt_to_page(ret)); 157 } 158 159 memset(ret, 0, size); 160 return ret; 161 162 out_free_pages: 163 free_pages((unsigned long)ret, get_order(size)); 164 return NULL; 165 } 166 167 static void 168 xen_swiotlb_free_coherent(struct device *dev, size_t size, void *vaddr, 169 dma_addr_t dma_handle, unsigned long attrs) 170 { 171 phys_addr_t phys = virt_to_phys(vaddr); 172 int order = get_order(size); 173 174 /* Convert the size to actually allocated. */ 175 size = 1UL << (order + XEN_PAGE_SHIFT); 176 177 if (WARN_ON_ONCE(dma_handle + size - 1 > dev->coherent_dma_mask) || 178 WARN_ON_ONCE(range_straddles_page_boundary(phys, size))) 179 return; 180 181 if (TestClearPageXenRemapped(virt_to_page(vaddr))) 182 xen_destroy_contiguous_region(phys, order); 183 free_pages((unsigned long)vaddr, get_order(size)); 184 } 185 #endif /* CONFIG_X86 */ 186 187 /* 188 * Map a single buffer of the indicated size for DMA in streaming mode. The 189 * physical address to use is returned. 190 * 191 * Once the device is given the dma address, the device owns this memory until 192 * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed. 193 */ 194 static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, 195 unsigned long offset, size_t size, 196 enum dma_data_direction dir, 197 unsigned long attrs) 198 { 199 phys_addr_t map, phys = page_to_phys(page) + offset; 200 dma_addr_t dev_addr = xen_phys_to_dma(dev, phys); 201 202 BUG_ON(dir == DMA_NONE); 203 /* 204 * If the address happens to be in the device's DMA window, 205 * we can safely return the device addr and not worry about bounce 206 * buffering it. 207 */ 208 if (dma_capable(dev, dev_addr, size, true) && 209 !range_straddles_page_boundary(phys, size) && 210 !xen_arch_need_swiotlb(dev, phys, dev_addr) && 211 !is_swiotlb_force_bounce(dev)) 212 goto done; 213 214 /* 215 * Oh well, have to allocate and map a bounce buffer. 216 */ 217 trace_swiotlb_bounced(dev, dev_addr, size); 218 219 map = swiotlb_tbl_map_single(dev, phys, size, size, 0, dir, attrs); 220 if (map == (phys_addr_t)DMA_MAPPING_ERROR) 221 return DMA_MAPPING_ERROR; 222 223 phys = map; 224 dev_addr = xen_phys_to_dma(dev, map); 225 226 /* 227 * Ensure that the address returned is DMA'ble 228 */ 229 if (unlikely(!dma_capable(dev, dev_addr, size, true))) { 230 swiotlb_tbl_unmap_single(dev, map, size, dir, 231 attrs | DMA_ATTR_SKIP_CPU_SYNC); 232 return DMA_MAPPING_ERROR; 233 } 234 235 done: 236 if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { 237 if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dev_addr)))) 238 arch_sync_dma_for_device(phys, size, dir); 239 else 240 xen_dma_sync_for_device(dev, dev_addr, size, dir); 241 } 242 return dev_addr; 243 } 244 245 /* 246 * Unmap a single streaming mode DMA translation. The dma_addr and size must 247 * match what was provided for in a previous xen_swiotlb_map_page call. All 248 * other usages are undefined. 249 * 250 * After this call, reads by the cpu to the buffer are guaranteed to see 251 * whatever the device wrote there. 252 */ 253 static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, 254 size_t size, enum dma_data_direction dir, unsigned long attrs) 255 { 256 phys_addr_t paddr = xen_dma_to_phys(hwdev, dev_addr); 257 258 BUG_ON(dir == DMA_NONE); 259 260 if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { 261 if (pfn_valid(PFN_DOWN(dma_to_phys(hwdev, dev_addr)))) 262 arch_sync_dma_for_cpu(paddr, size, dir); 263 else 264 xen_dma_sync_for_cpu(hwdev, dev_addr, size, dir); 265 } 266 267 /* NOTE: We use dev_addr here, not paddr! */ 268 if (is_xen_swiotlb_buffer(hwdev, dev_addr)) 269 swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs); 270 } 271 272 static void 273 xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, 274 size_t size, enum dma_data_direction dir) 275 { 276 phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr); 277 278 if (!dev_is_dma_coherent(dev)) { 279 if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr)))) 280 arch_sync_dma_for_cpu(paddr, size, dir); 281 else 282 xen_dma_sync_for_cpu(dev, dma_addr, size, dir); 283 } 284 285 if (is_xen_swiotlb_buffer(dev, dma_addr)) 286 swiotlb_sync_single_for_cpu(dev, paddr, size, dir); 287 } 288 289 static void 290 xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, 291 size_t size, enum dma_data_direction dir) 292 { 293 phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr); 294 295 if (is_xen_swiotlb_buffer(dev, dma_addr)) 296 swiotlb_sync_single_for_device(dev, paddr, size, dir); 297 298 if (!dev_is_dma_coherent(dev)) { 299 if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr)))) 300 arch_sync_dma_for_device(paddr, size, dir); 301 else 302 xen_dma_sync_for_device(dev, dma_addr, size, dir); 303 } 304 } 305 306 /* 307 * Unmap a set of streaming mode DMA translations. Again, cpu read rules 308 * concerning calls here are the same as for swiotlb_unmap_page() above. 309 */ 310 static void 311 xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, 312 enum dma_data_direction dir, unsigned long attrs) 313 { 314 struct scatterlist *sg; 315 int i; 316 317 BUG_ON(dir == DMA_NONE); 318 319 for_each_sg(sgl, sg, nelems, i) 320 xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg), 321 dir, attrs); 322 323 } 324 325 static int 326 xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems, 327 enum dma_data_direction dir, unsigned long attrs) 328 { 329 struct scatterlist *sg; 330 int i; 331 332 BUG_ON(dir == DMA_NONE); 333 334 for_each_sg(sgl, sg, nelems, i) { 335 sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg), 336 sg->offset, sg->length, dir, attrs); 337 if (sg->dma_address == DMA_MAPPING_ERROR) 338 goto out_unmap; 339 sg_dma_len(sg) = sg->length; 340 } 341 342 return nelems; 343 out_unmap: 344 xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); 345 sg_dma_len(sgl) = 0; 346 return -EIO; 347 } 348 349 static void 350 xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl, 351 int nelems, enum dma_data_direction dir) 352 { 353 struct scatterlist *sg; 354 int i; 355 356 for_each_sg(sgl, sg, nelems, i) { 357 xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address, 358 sg->length, dir); 359 } 360 } 361 362 static void 363 xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl, 364 int nelems, enum dma_data_direction dir) 365 { 366 struct scatterlist *sg; 367 int i; 368 369 for_each_sg(sgl, sg, nelems, i) { 370 xen_swiotlb_sync_single_for_device(dev, sg->dma_address, 371 sg->length, dir); 372 } 373 } 374 375 /* 376 * Return whether the given device DMA address mask can be supported 377 * properly. For example, if your device can only drive the low 24-bits 378 * during bus mastering, then you would pass 0x00ffffff as the mask to 379 * this function. 380 */ 381 static int 382 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask) 383 { 384 return xen_phys_to_dma(hwdev, default_swiotlb_limit()) <= mask; 385 } 386 387 const struct dma_map_ops xen_swiotlb_dma_ops = { 388 #ifdef CONFIG_X86 389 .alloc = xen_swiotlb_alloc_coherent, 390 .free = xen_swiotlb_free_coherent, 391 #else 392 .alloc = dma_direct_alloc, 393 .free = dma_direct_free, 394 #endif 395 .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu, 396 .sync_single_for_device = xen_swiotlb_sync_single_for_device, 397 .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu, 398 .sync_sg_for_device = xen_swiotlb_sync_sg_for_device, 399 .map_sg = xen_swiotlb_map_sg, 400 .unmap_sg = xen_swiotlb_unmap_sg, 401 .map_page = xen_swiotlb_map_page, 402 .unmap_page = xen_swiotlb_unmap_page, 403 .dma_supported = xen_swiotlb_dma_supported, 404 .mmap = dma_common_mmap, 405 .get_sgtable = dma_common_get_sgtable, 406 .alloc_pages = dma_common_alloc_pages, 407 .free_pages = dma_common_free_pages, 408 }; 409