drivers/xen/swiotlb-xen.c

   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         phys_addr_t algn = 1ULL << (get_order(size) + PAGE_SHIFT);
  82
  83         next_bfn = pfn_to_bfn(xen_pfn);
  84
  85         /* If buffer is physically aligned, ensure DMA alignment. */
  86         if (IS_ALIGNED(p, algn) &&
  87             !IS_ALIGNED((phys_addr_t)next_bfn << XEN_PAGE_SHIFT, algn))
  88                 return 1;
  89
  90         for (i = 1; i < nr_pages; i++)
  91                 if (pfn_to_bfn(++xen_pfn) != ++next_bfn)
  92                         return 1;
  93
  94         return 0;
  95 }
  96
  97 static struct io_tlb_pool *xen_swiotlb_find_pool(struct device *dev,
  98                                                  dma_addr_t dma_addr)
  99 {
 100         unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr));
 101         unsigned long xen_pfn = bfn_to_local_pfn(bfn);
 102         phys_addr_t paddr = (phys_addr_t)xen_pfn << XEN_PAGE_SHIFT;
 103
 104         /* If the address is outside our domain, it CAN
 105          * have the same virtual address as another address
 106          * in our domain. Therefore _only_ check address within our domain.
 107          */
 108         if (pfn_valid(PFN_DOWN(paddr)))
 109                 return swiotlb_find_pool(dev, paddr);
 110         return NULL;
 111 }
 112
 113 #ifdef CONFIG_X86
 114 int xen_swiotlb_fixup(void *buf, unsigned long nslabs)
 115 {
 116         int rc;
 117         unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT);
 118         unsigned int i, dma_bits = order + PAGE_SHIFT;
 119         dma_addr_t dma_handle;
 120         phys_addr_t p = virt_to_phys(buf);
 121
 122         BUILD_BUG_ON(IO_TLB_SEGSIZE & (IO_TLB_SEGSIZE - 1));
 123         BUG_ON(nslabs % IO_TLB_SEGSIZE);
 124
 125         i = 0;
 126         do {
 127                 do {
 128                         rc = xen_create_contiguous_region(
 129                                 p + (i << IO_TLB_SHIFT), order,
 130                                 dma_bits, &dma_handle);
 131                 } while (rc && dma_bits++ < MAX_DMA_BITS);
 132                 if (rc)
 133                         return rc;
 134
 135                 i += IO_TLB_SEGSIZE;
 136         } while (i < nslabs);
 137         return 0;
 138 }
 139
 140 static void *
 141 xen_swiotlb_alloc_coherent(struct device *dev, size_t size,
 142                 dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
 143 {
 144         u64 dma_mask = dev->coherent_dma_mask;
 145         int order = get_order(size);
 146         phys_addr_t phys;
 147         void *ret;
 148
 149         /* Align the allocation to the Xen page size */
 150         size = ALIGN(size, XEN_PAGE_SIZE);
 151
 152         ret = (void *)__get_free_pages(flags, get_order(size));
 153         if (!ret)
 154                 return ret;
 155         phys = virt_to_phys(ret);
 156
 157         *dma_handle = xen_phys_to_dma(dev, phys);
 158         if (*dma_handle + size - 1 > dma_mask ||
 159             range_straddles_page_boundary(phys, size)) {
 160                 if (xen_create_contiguous_region(phys, order, fls64(dma_mask),
 161                                 dma_handle) != 0)
 162                         goto out_free_pages;
 163                 SetPageXenRemapped(virt_to_page(ret));
 164         }
 165
 166         memset(ret, 0, size);
 167         return ret;
 168
 169 out_free_pages:
 170         free_pages((unsigned long)ret, get_order(size));
 171         return NULL;
 172 }
 173
 174 static void
 175 xen_swiotlb_free_coherent(struct device *dev, size_t size, void *vaddr,
 176                 dma_addr_t dma_handle, unsigned long attrs)
 177 {
 178         phys_addr_t phys = virt_to_phys(vaddr);
 179         int order = get_order(size);
 180
 181         /* Convert the size to actually allocated. */
 182         size = ALIGN(size, XEN_PAGE_SIZE);
 183
 184         if (WARN_ON_ONCE(dma_handle + size - 1 > dev->coherent_dma_mask) ||
 185             WARN_ON_ONCE(range_straddles_page_boundary(phys, size)))
 186                 return;
 187
 188         if (TestClearPageXenRemapped(virt_to_page(vaddr)))
 189                 xen_destroy_contiguous_region(phys, order);
 190         free_pages((unsigned long)vaddr, get_order(size));
 191 }
 192 #endif /* CONFIG_X86 */
 193
 194 /*
 195  * Map a single buffer of the indicated size for DMA in streaming mode.  The
 196  * physical address to use is returned.
 197  *
 198  * Once the device is given the dma address, the device owns this memory until
 199  * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
 200  */
 201 static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 202                                 unsigned long offset, size_t size,
 203                                 enum dma_data_direction dir,
 204                                 unsigned long attrs)
 205 {
 206         phys_addr_t map, phys = page_to_phys(page) + offset;
 207         dma_addr_t dev_addr = xen_phys_to_dma(dev, phys);
 208
 209         BUG_ON(dir == DMA_NONE);
 210         /*
 211          * If the address happens to be in the device's DMA window,
 212          * we can safely return the device addr and not worry about bounce
 213          * buffering it.
 214          */
 215         if (dma_capable(dev, dev_addr, size, true) &&
 216             !range_straddles_page_boundary(phys, size) &&
 217                 !xen_arch_need_swiotlb(dev, phys, dev_addr) &&
 218                 !is_swiotlb_force_bounce(dev))
 219                 goto done;
 220
 221         /*
 222          * Oh well, have to allocate and map a bounce buffer.
 223          */
 224         trace_swiotlb_bounced(dev, dev_addr, size);
 225
 226         map = swiotlb_tbl_map_single(dev, phys, size, 0, dir, attrs);
 227         if (map == (phys_addr_t)DMA_MAPPING_ERROR)
 228                 return DMA_MAPPING_ERROR;
 229
 230         phys = map;
 231         dev_addr = xen_phys_to_dma(dev, map);
 232
 233         /*
 234          * Ensure that the address returned is DMA'ble
 235          */
 236         if (unlikely(!dma_capable(dev, dev_addr, size, true))) {
 237                 __swiotlb_tbl_unmap_single(dev, map, size, dir,
 238                                 attrs | DMA_ATTR_SKIP_CPU_SYNC,
 239                                 swiotlb_find_pool(dev, map));
 240                 return DMA_MAPPING_ERROR;
 241         }
 242
 243 done:
 244         if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 245                 if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dev_addr))))
 246                         arch_sync_dma_for_device(phys, size, dir);
 247                 else
 248                         xen_dma_sync_for_device(dev, dev_addr, size, dir);
 249         }
 250         return dev_addr;
 251 }
 252
 253 /*
 254  * Unmap a single streaming mode DMA translation.  The dma_addr and size must
 255  * match what was provided for in a previous xen_swiotlb_map_page call.  All
 256  * other usages are undefined.
 257  *
 258  * After this call, reads by the cpu to the buffer are guaranteed to see
 259  * whatever the device wrote there.
 260  */
 261 static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
 262                 size_t size, enum dma_data_direction dir, unsigned long attrs)
 263 {
 264         phys_addr_t paddr = xen_dma_to_phys(hwdev, dev_addr);
 265         struct io_tlb_pool *pool;
 266
 267         BUG_ON(dir == DMA_NONE);
 268
 269         if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 270                 if (pfn_valid(PFN_DOWN(dma_to_phys(hwdev, dev_addr))))
 271                         arch_sync_dma_for_cpu(paddr, size, dir);
 272                 else
 273                         xen_dma_sync_for_cpu(hwdev, dev_addr, size, dir);
 274         }
 275
 276         /* NOTE: We use dev_addr here, not paddr! */
 277         pool = xen_swiotlb_find_pool(hwdev, dev_addr);
 278         if (pool)
 279                 __swiotlb_tbl_unmap_single(hwdev, paddr, size, dir,
 280                                            attrs, pool);
 281 }
 282
 283 static void
 284 xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
 285                 size_t size, enum dma_data_direction dir)
 286 {
 287         phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr);
 288         struct io_tlb_pool *pool;
 289
 290         if (!dev_is_dma_coherent(dev)) {
 291                 if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr))))
 292                         arch_sync_dma_for_cpu(paddr, size, dir);
 293                 else
 294                         xen_dma_sync_for_cpu(dev, dma_addr, size, dir);
 295         }
 296
 297         pool = xen_swiotlb_find_pool(dev, dma_addr);
 298         if (pool)
 299                 __swiotlb_sync_single_for_cpu(dev, paddr, size, dir, pool);
 300 }
 301
 302 static void
 303 xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
 304                 size_t size, enum dma_data_direction dir)
 305 {
 306         phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr);
 307         struct io_tlb_pool *pool;
 308
 309         pool = xen_swiotlb_find_pool(dev, dma_addr);
 310         if (pool)
 311                 __swiotlb_sync_single_for_device(dev, paddr, size, dir, pool);
 312
 313         if (!dev_is_dma_coherent(dev)) {
 314                 if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr))))
 315                         arch_sync_dma_for_device(paddr, size, dir);
 316                 else
 317                         xen_dma_sync_for_device(dev, dma_addr, size, dir);
 318         }
 319 }
 320
 321 /*
 322  * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
 323  * concerning calls here are the same as for swiotlb_unmap_page() above.
 324  */
 325 static void
 326 xen_swiotlb_unmap_sg(struct device *hwdev, 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                 xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg),
 336                                 dir, attrs);
 337
 338 }
 339
 340 static int
 341 xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems,
 342                 enum dma_data_direction dir, unsigned long attrs)
 343 {
 344         struct scatterlist *sg;
 345         int i;
 346
 347         BUG_ON(dir == DMA_NONE);
 348
 349         for_each_sg(sgl, sg, nelems, i) {
 350                 sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg),
 351                                 sg->offset, sg->length, dir, attrs);
 352                 if (sg->dma_address == DMA_MAPPING_ERROR)
 353                         goto out_unmap;
 354                 sg_dma_len(sg) = sg->length;
 355         }
 356
 357         return nelems;
 358 out_unmap:
 359         xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
 360         sg_dma_len(sgl) = 0;
 361         return -EIO;
 362 }
 363
 364 static void
 365 xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
 366                             int nelems, enum dma_data_direction dir)
 367 {
 368         struct scatterlist *sg;
 369         int i;
 370
 371         for_each_sg(sgl, sg, nelems, i) {
 372                 xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address,
 373                                 sg->length, dir);
 374         }
 375 }
 376
 377 static void
 378 xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
 379                                int nelems, enum dma_data_direction dir)
 380 {
 381         struct scatterlist *sg;
 382         int i;
 383
 384         for_each_sg(sgl, sg, nelems, i) {
 385                 xen_swiotlb_sync_single_for_device(dev, sg->dma_address,
 386                                 sg->length, dir);
 387         }
 388 }
 389
 390 /*
 391  * Return whether the given device DMA address mask can be supported
 392  * properly.  For example, if your device can only drive the low 24-bits
 393  * during bus mastering, then you would pass 0x00ffffff as the mask to
 394  * this function.
 395  */
 396 static int
 397 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 398 {
 399         return xen_phys_to_dma(hwdev, default_swiotlb_limit()) <= mask;
 400 }
 401
 402 const struct dma_map_ops xen_swiotlb_dma_ops = {
 403 #ifdef CONFIG_X86
 404         .alloc = xen_swiotlb_alloc_coherent,
 405         .free = xen_swiotlb_free_coherent,
 406 #else
 407         .alloc = dma_direct_alloc,
 408         .free = dma_direct_free,
 409 #endif
 410         .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
 411         .sync_single_for_device = xen_swiotlb_sync_single_for_device,
 412         .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
 413         .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
 414         .map_sg = xen_swiotlb_map_sg,
 415         .unmap_sg = xen_swiotlb_unmap_sg,
 416         .map_page = xen_swiotlb_map_page,
 417         .unmap_page = xen_swiotlb_unmap_page,
 418         .dma_supported = xen_swiotlb_dma_supported,
 419         .mmap = dma_common_mmap,
 420         .get_sgtable = dma_common_get_sgtable,
 421         .alloc_pages_op = dma_common_alloc_pages,
 422         .free_pages = dma_common_free_pages,
 423         .max_mapping_size = swiotlb_max_mapping_size,
 424 };