linux/drivers/xen/swiotlb-xen.c
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   1/*
   2 *  Copyright 2010
   3 *  by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
   4 *
   5 * This code provides a IOMMU for Xen PV guests with PCI passthrough.
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License v2.0 as published by
   9 * the Free Software Foundation
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * PV guests under Xen are running in an non-contiguous memory architecture.
  17 *
  18 * When PCI pass-through is utilized, this necessitates an IOMMU for
  19 * translating bus (DMA) to virtual and vice-versa and also providing a
  20 * mechanism to have contiguous pages for device drivers operations (say DMA
  21 * operations).
  22 *
  23 * Specifically, under Xen the Linux idea of pages is an illusion. It
  24 * assumes that pages start at zero and go up to the available memory. To
  25 * help with that, the Linux Xen MMU provides a lookup mechanism to
  26 * translate the page frame numbers (PFN) to machine frame numbers (MFN)
  27 * and vice-versa. The MFN are the "real" frame numbers. Furthermore
  28 * memory is not contiguous. Xen hypervisor stitches memory for guests
  29 * from different pools, which means there is no guarantee that PFN==MFN
  30 * and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are
  31 * allocated in descending order (high to low), meaning the guest might
  32 * never get any MFN's under the 4GB mark.
  33 *
  34 */
  35
  36#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  37
  38#include <linux/bootmem.h>
  39#include <linux/dma-mapping.h>
  40#include <linux/export.h>
  41#include <xen/swiotlb-xen.h>
  42#include <xen/page.h>
  43#include <xen/xen-ops.h>
  44#include <xen/hvc-console.h>
  45
  46#include <asm/dma-mapping.h>
  47#include <asm/xen/page-coherent.h>
  48
  49#include <trace/events/swiotlb.h>
  50/*
  51 * Used to do a quick range check in swiotlb_tbl_unmap_single and
  52 * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
  53 * API.
  54 */
  55
  56#ifndef CONFIG_X86
  57static unsigned long dma_alloc_coherent_mask(struct device *dev,
  58                                            gfp_t gfp)
  59{
  60        unsigned long dma_mask = 0;
  61
  62        dma_mask = dev->coherent_dma_mask;
  63        if (!dma_mask)
  64                dma_mask = (gfp & GFP_DMA) ? DMA_BIT_MASK(24) : DMA_BIT_MASK(32);
  65
  66        return dma_mask;
  67}
  68#endif
  69
  70static char *xen_io_tlb_start, *xen_io_tlb_end;
  71static unsigned long xen_io_tlb_nslabs;
  72/*
  73 * Quick lookup value of the bus address of the IOTLB.
  74 */
  75
  76static u64 start_dma_addr;
  77
  78/*
  79 * Both of these functions should avoid XEN_PFN_PHYS because phys_addr_t
  80 * can be 32bit when dma_addr_t is 64bit leading to a loss in
  81 * information if the shift is done before casting to 64bit.
  82 */
  83static inline dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
  84{
  85        unsigned long bfn = pfn_to_bfn(XEN_PFN_DOWN(paddr));
  86        dma_addr_t dma = (dma_addr_t)bfn << XEN_PAGE_SHIFT;
  87
  88        dma |= paddr & ~XEN_PAGE_MASK;
  89
  90        return dma;
  91}
  92
  93static inline phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
  94{
  95        unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr));
  96        dma_addr_t dma = (dma_addr_t)xen_pfn << XEN_PAGE_SHIFT;
  97        phys_addr_t paddr = dma;
  98
  99        paddr |= baddr & ~XEN_PAGE_MASK;
 100
 101        return paddr;
 102}
 103
 104static inline dma_addr_t xen_virt_to_bus(void *address)
 105{
 106        return xen_phys_to_bus(virt_to_phys(address));
 107}
 108
 109static int check_pages_physically_contiguous(unsigned long xen_pfn,
 110                                             unsigned int offset,
 111                                             size_t length)
 112{
 113        unsigned long next_bfn;
 114        int i;
 115        int nr_pages;
 116
 117        next_bfn = pfn_to_bfn(xen_pfn);
 118        nr_pages = (offset + length + XEN_PAGE_SIZE-1) >> XEN_PAGE_SHIFT;
 119
 120        for (i = 1; i < nr_pages; i++) {
 121                if (pfn_to_bfn(++xen_pfn) != ++next_bfn)
 122                        return 0;
 123        }
 124        return 1;
 125}
 126
 127static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
 128{
 129        unsigned long xen_pfn = XEN_PFN_DOWN(p);
 130        unsigned int offset = p & ~XEN_PAGE_MASK;
 131
 132        if (offset + size <= XEN_PAGE_SIZE)
 133                return 0;
 134        if (check_pages_physically_contiguous(xen_pfn, offset, size))
 135                return 0;
 136        return 1;
 137}
 138
 139static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
 140{
 141        unsigned long bfn = XEN_PFN_DOWN(dma_addr);
 142        unsigned long xen_pfn = bfn_to_local_pfn(bfn);
 143        phys_addr_t paddr = XEN_PFN_PHYS(xen_pfn);
 144
 145        /* If the address is outside our domain, it CAN
 146         * have the same virtual address as another address
 147         * in our domain. Therefore _only_ check address within our domain.
 148         */
 149        if (pfn_valid(PFN_DOWN(paddr))) {
 150                return paddr >= virt_to_phys(xen_io_tlb_start) &&
 151                       paddr < virt_to_phys(xen_io_tlb_end);
 152        }
 153        return 0;
 154}
 155
 156static int max_dma_bits = 32;
 157
 158static int
 159xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
 160{
 161        int i, rc;
 162        int dma_bits;
 163        dma_addr_t dma_handle;
 164        phys_addr_t p = virt_to_phys(buf);
 165
 166        dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
 167
 168        i = 0;
 169        do {
 170                int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
 171
 172                do {
 173                        rc = xen_create_contiguous_region(
 174                                p + (i << IO_TLB_SHIFT),
 175                                get_order(slabs << IO_TLB_SHIFT),
 176                                dma_bits, &dma_handle);
 177                } while (rc && dma_bits++ < max_dma_bits);
 178                if (rc)
 179                        return rc;
 180
 181                i += slabs;
 182        } while (i < nslabs);
 183        return 0;
 184}
 185static unsigned long xen_set_nslabs(unsigned long nr_tbl)
 186{
 187        if (!nr_tbl) {
 188                xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
 189                xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
 190        } else
 191                xen_io_tlb_nslabs = nr_tbl;
 192
 193        return xen_io_tlb_nslabs << IO_TLB_SHIFT;
 194}
 195
 196enum xen_swiotlb_err {
 197        XEN_SWIOTLB_UNKNOWN = 0,
 198        XEN_SWIOTLB_ENOMEM,
 199        XEN_SWIOTLB_EFIXUP
 200};
 201
 202static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
 203{
 204        switch (err) {
 205        case XEN_SWIOTLB_ENOMEM:
 206                return "Cannot allocate Xen-SWIOTLB buffer\n";
 207        case XEN_SWIOTLB_EFIXUP:
 208                return "Failed to get contiguous memory for DMA from Xen!\n"\
 209                    "You either: don't have the permissions, do not have"\
 210                    " enough free memory under 4GB, or the hypervisor memory"\
 211                    " is too fragmented!";
 212        default:
 213                break;
 214        }
 215        return "";
 216}
 217int __ref xen_swiotlb_init(int verbose, bool early)
 218{
 219        unsigned long bytes, order;
 220        int rc = -ENOMEM;
 221        enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
 222        unsigned int repeat = 3;
 223
 224        xen_io_tlb_nslabs = swiotlb_nr_tbl();
 225retry:
 226        bytes = xen_set_nslabs(xen_io_tlb_nslabs);
 227        order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
 228        /*
 229         * Get IO TLB memory from any location.
 230         */
 231        if (early)
 232                xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
 233        else {
 234#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
 235#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
 236                while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
 237                        xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order);
 238                        if (xen_io_tlb_start)
 239                                break;
 240                        order--;
 241                }
 242                if (order != get_order(bytes)) {
 243                        pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
 244                                (PAGE_SIZE << order) >> 20);
 245                        xen_io_tlb_nslabs = SLABS_PER_PAGE << order;
 246                        bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
 247                }
 248        }
 249        if (!xen_io_tlb_start) {
 250                m_ret = XEN_SWIOTLB_ENOMEM;
 251                goto error;
 252        }
 253        xen_io_tlb_end = xen_io_tlb_start + bytes;
 254        /*
 255         * And replace that memory with pages under 4GB.
 256         */
 257        rc = xen_swiotlb_fixup(xen_io_tlb_start,
 258                               bytes,
 259                               xen_io_tlb_nslabs);
 260        if (rc) {
 261                if (early)
 262                        free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
 263                else {
 264                        free_pages((unsigned long)xen_io_tlb_start, order);
 265                        xen_io_tlb_start = NULL;
 266                }
 267                m_ret = XEN_SWIOTLB_EFIXUP;
 268                goto error;
 269        }
 270        start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
 271        if (early) {
 272                if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
 273                         verbose))
 274                        panic("Cannot allocate SWIOTLB buffer");
 275                rc = 0;
 276        } else
 277                rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
 278
 279        if (!rc)
 280                swiotlb_set_max_segment(PAGE_SIZE);
 281
 282        return rc;
 283error:
 284        if (repeat--) {
 285                xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
 286                                        (xen_io_tlb_nslabs >> 1));
 287                pr_info("Lowering to %luMB\n",
 288                        (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
 289                goto retry;
 290        }
 291        pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc);
 292        if (early)
 293                panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
 294        else
 295                free_pages((unsigned long)xen_io_tlb_start, order);
 296        return rc;
 297}
 298void *
 299xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 300                           dma_addr_t *dma_handle, gfp_t flags,
 301                           unsigned long attrs)
 302{
 303        void *ret;
 304        int order = get_order(size);
 305        u64 dma_mask = DMA_BIT_MASK(32);
 306        phys_addr_t phys;
 307        dma_addr_t dev_addr;
 308
 309        /*
 310        * Ignore region specifiers - the kernel's ideas of
 311        * pseudo-phys memory layout has nothing to do with the
 312        * machine physical layout.  We can't allocate highmem
 313        * because we can't return a pointer to it.
 314        */
 315        flags &= ~(__GFP_DMA | __GFP_HIGHMEM);
 316
 317        /* On ARM this function returns an ioremap'ped virtual address for
 318         * which virt_to_phys doesn't return the corresponding physical
 319         * address. In fact on ARM virt_to_phys only works for kernel direct
 320         * mapped RAM memory. Also see comment below.
 321         */
 322        ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs);
 323
 324        if (!ret)
 325                return ret;
 326
 327        if (hwdev && hwdev->coherent_dma_mask)
 328                dma_mask = dma_alloc_coherent_mask(hwdev, flags);
 329
 330        /* At this point dma_handle is the physical address, next we are
 331         * going to set it to the machine address.
 332         * Do not use virt_to_phys(ret) because on ARM it doesn't correspond
 333         * to *dma_handle. */
 334        phys = *dma_handle;
 335        dev_addr = xen_phys_to_bus(phys);
 336        if (((dev_addr + size - 1 <= dma_mask)) &&
 337            !range_straddles_page_boundary(phys, size))
 338                *dma_handle = dev_addr;
 339        else {
 340                if (xen_create_contiguous_region(phys, order,
 341                                                 fls64(dma_mask), dma_handle) != 0) {
 342                        xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
 343                        return NULL;
 344                }
 345        }
 346        memset(ret, 0, size);
 347        return ret;
 348}
 349EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent);
 350
 351void
 352xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
 353                          dma_addr_t dev_addr, unsigned long attrs)
 354{
 355        int order = get_order(size);
 356        phys_addr_t phys;
 357        u64 dma_mask = DMA_BIT_MASK(32);
 358
 359        if (hwdev && hwdev->coherent_dma_mask)
 360                dma_mask = hwdev->coherent_dma_mask;
 361
 362        /* do not use virt_to_phys because on ARM it doesn't return you the
 363         * physical address */
 364        phys = xen_bus_to_phys(dev_addr);
 365
 366        if (((dev_addr + size - 1 > dma_mask)) ||
 367            range_straddles_page_boundary(phys, size))
 368                xen_destroy_contiguous_region(phys, order);
 369
 370        xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
 371}
 372EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);
 373
 374
 375/*
 376 * Map a single buffer of the indicated size for DMA in streaming mode.  The
 377 * physical address to use is returned.
 378 *
 379 * Once the device is given the dma address, the device owns this memory until
 380 * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
 381 */
 382dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 383                                unsigned long offset, size_t size,
 384                                enum dma_data_direction dir,
 385                                unsigned long attrs)
 386{
 387        phys_addr_t map, phys = page_to_phys(page) + offset;
 388        dma_addr_t dev_addr = xen_phys_to_bus(phys);
 389
 390        BUG_ON(dir == DMA_NONE);
 391        /*
 392         * If the address happens to be in the device's DMA window,
 393         * we can safely return the device addr and not worry about bounce
 394         * buffering it.
 395         */
 396        if (dma_capable(dev, dev_addr, size) &&
 397            !range_straddles_page_boundary(phys, size) &&
 398                !xen_arch_need_swiotlb(dev, phys, dev_addr) &&
 399                (swiotlb_force != SWIOTLB_FORCE)) {
 400                /* we are not interested in the dma_addr returned by
 401                 * xen_dma_map_page, only in the potential cache flushes executed
 402                 * by the function. */
 403                xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs);
 404                return dev_addr;
 405        }
 406
 407        /*
 408         * Oh well, have to allocate and map a bounce buffer.
 409         */
 410        trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
 411
 412        map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,
 413                                     attrs);
 414        if (map == SWIOTLB_MAP_ERROR)
 415                return DMA_ERROR_CODE;
 416
 417        dev_addr = xen_phys_to_bus(map);
 418        xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT),
 419                                        dev_addr, map & ~PAGE_MASK, size, dir, attrs);
 420
 421        /*
 422         * Ensure that the address returned is DMA'ble
 423         */
 424        if (dma_capable(dev, dev_addr, size))
 425                return dev_addr;
 426
 427        attrs |= DMA_ATTR_SKIP_CPU_SYNC;
 428        swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
 429
 430        return DMA_ERROR_CODE;
 431}
 432EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
 433
 434/*
 435 * Unmap a single streaming mode DMA translation.  The dma_addr and size must
 436 * match what was provided for in a previous xen_swiotlb_map_page call.  All
 437 * other usages are undefined.
 438 *
 439 * After this call, reads by the cpu to the buffer are guaranteed to see
 440 * whatever the device wrote there.
 441 */
 442static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,
 443                             size_t size, enum dma_data_direction dir,
 444                             unsigned long attrs)
 445{
 446        phys_addr_t paddr = xen_bus_to_phys(dev_addr);
 447
 448        BUG_ON(dir == DMA_NONE);
 449
 450        xen_dma_unmap_page(hwdev, dev_addr, size, dir, attrs);
 451
 452        /* NOTE: We use dev_addr here, not paddr! */
 453        if (is_xen_swiotlb_buffer(dev_addr)) {
 454                swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);
 455                return;
 456        }
 457
 458        if (dir != DMA_FROM_DEVICE)
 459                return;
 460
 461        /*
 462         * phys_to_virt doesn't work with hihgmem page but we could
 463         * call dma_mark_clean() with hihgmem page here. However, we
 464         * are fine since dma_mark_clean() is null on POWERPC. We can
 465         * make dma_mark_clean() take a physical address if necessary.
 466         */
 467        dma_mark_clean(phys_to_virt(paddr), size);
 468}
 469
 470void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
 471                            size_t size, enum dma_data_direction dir,
 472                            unsigned long attrs)
 473{
 474        xen_unmap_single(hwdev, dev_addr, size, dir, attrs);
 475}
 476EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_page);
 477
 478/*
 479 * Make physical memory consistent for a single streaming mode DMA translation
 480 * after a transfer.
 481 *
 482 * If you perform a xen_swiotlb_map_page() but wish to interrogate the buffer
 483 * using the cpu, yet do not wish to teardown the dma mapping, you must
 484 * call this function before doing so.  At the next point you give the dma
 485 * address back to the card, you must first perform a
 486 * xen_swiotlb_dma_sync_for_device, and then the device again owns the buffer
 487 */
 488static void
 489xen_swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
 490                        size_t size, enum dma_data_direction dir,
 491                        enum dma_sync_target target)
 492{
 493        phys_addr_t paddr = xen_bus_to_phys(dev_addr);
 494
 495        BUG_ON(dir == DMA_NONE);
 496
 497        if (target == SYNC_FOR_CPU)
 498                xen_dma_sync_single_for_cpu(hwdev, dev_addr, size, dir);
 499
 500        /* NOTE: We use dev_addr here, not paddr! */
 501        if (is_xen_swiotlb_buffer(dev_addr))
 502                swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target);
 503
 504        if (target == SYNC_FOR_DEVICE)
 505                xen_dma_sync_single_for_device(hwdev, dev_addr, size, dir);
 506
 507        if (dir != DMA_FROM_DEVICE)
 508                return;
 509
 510        dma_mark_clean(phys_to_virt(paddr), size);
 511}
 512
 513void
 514xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
 515                                size_t size, enum dma_data_direction dir)
 516{
 517        xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
 518}
 519EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_cpu);
 520
 521void
 522xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
 523                                   size_t size, enum dma_data_direction dir)
 524{
 525        xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
 526}
 527EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_device);
 528
 529/*
 530 * Map a set of buffers described by scatterlist in streaming mode for DMA.
 531 * This is the scatter-gather version of the above xen_swiotlb_map_page
 532 * interface.  Here the scatter gather list elements are each tagged with the
 533 * appropriate dma address and length.  They are obtained via
 534 * sg_dma_{address,length}(SG).
 535 *
 536 * NOTE: An implementation may be able to use a smaller number of
 537 *       DMA address/length pairs than there are SG table elements.
 538 *       (for example via virtual mapping capabilities)
 539 *       The routine returns the number of addr/length pairs actually
 540 *       used, at most nents.
 541 *
 542 * Device ownership issues as mentioned above for xen_swiotlb_map_page are the
 543 * same here.
 544 */
 545int
 546xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 547                         int nelems, enum dma_data_direction dir,
 548                         unsigned long attrs)
 549{
 550        struct scatterlist *sg;
 551        int i;
 552
 553        BUG_ON(dir == DMA_NONE);
 554
 555        for_each_sg(sgl, sg, nelems, i) {
 556                phys_addr_t paddr = sg_phys(sg);
 557                dma_addr_t dev_addr = xen_phys_to_bus(paddr);
 558
 559                if (swiotlb_force == SWIOTLB_FORCE ||
 560                    xen_arch_need_swiotlb(hwdev, paddr, dev_addr) ||
 561                    !dma_capable(hwdev, dev_addr, sg->length) ||
 562                    range_straddles_page_boundary(paddr, sg->length)) {
 563                        phys_addr_t map = swiotlb_tbl_map_single(hwdev,
 564                                                                 start_dma_addr,
 565                                                                 sg_phys(sg),
 566                                                                 sg->length,
 567                                                                 dir, attrs);
 568                        if (map == SWIOTLB_MAP_ERROR) {
 569                                dev_warn(hwdev, "swiotlb buffer is full\n");
 570                                /* Don't panic here, we expect map_sg users
 571                                   to do proper error handling. */
 572                                attrs |= DMA_ATTR_SKIP_CPU_SYNC;
 573                                xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
 574                                                           attrs);
 575                                sg_dma_len(sgl) = 0;
 576                                return 0;
 577                        }
 578                        dev_addr = xen_phys_to_bus(map);
 579                        xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT),
 580                                                dev_addr,
 581                                                map & ~PAGE_MASK,
 582                                                sg->length,
 583                                                dir,
 584                                                attrs);
 585                        sg->dma_address = dev_addr;
 586                } else {
 587                        /* we are not interested in the dma_addr returned by
 588                         * xen_dma_map_page, only in the potential cache flushes executed
 589                         * by the function. */
 590                        xen_dma_map_page(hwdev, pfn_to_page(paddr >> PAGE_SHIFT),
 591                                                dev_addr,
 592                                                paddr & ~PAGE_MASK,
 593                                                sg->length,
 594                                                dir,
 595                                                attrs);
 596                        sg->dma_address = dev_addr;
 597                }
 598                sg_dma_len(sg) = sg->length;
 599        }
 600        return nelems;
 601}
 602EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs);
 603
 604/*
 605 * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
 606 * concerning calls here are the same as for swiotlb_unmap_page() above.
 607 */
 608void
 609xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 610                           int nelems, enum dma_data_direction dir,
 611                           unsigned long attrs)
 612{
 613        struct scatterlist *sg;
 614        int i;
 615
 616        BUG_ON(dir == DMA_NONE);
 617
 618        for_each_sg(sgl, sg, nelems, i)
 619                xen_unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir, attrs);
 620
 621}
 622EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs);
 623
 624/*
 625 * Make physical memory consistent for a set of streaming mode DMA translations
 626 * after a transfer.
 627 *
 628 * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
 629 * and usage.
 630 */
 631static void
 632xen_swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
 633                    int nelems, enum dma_data_direction dir,
 634                    enum dma_sync_target target)
 635{
 636        struct scatterlist *sg;
 637        int i;
 638
 639        for_each_sg(sgl, sg, nelems, i)
 640                xen_swiotlb_sync_single(hwdev, sg->dma_address,
 641                                        sg_dma_len(sg), dir, target);
 642}
 643
 644void
 645xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
 646                            int nelems, enum dma_data_direction dir)
 647{
 648        xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
 649}
 650EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_cpu);
 651
 652void
 653xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
 654                               int nelems, enum dma_data_direction dir)
 655{
 656        xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
 657}
 658EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device);
 659
 660/*
 661 * Return whether the given device DMA address mask can be supported
 662 * properly.  For example, if your device can only drive the low 24-bits
 663 * during bus mastering, then you would pass 0x00ffffff as the mask to
 664 * this function.
 665 */
 666int
 667xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 668{
 669        return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
 670}
 671EXPORT_SYMBOL_GPL(xen_swiotlb_dma_supported);
 672
 673int
 674xen_swiotlb_set_dma_mask(struct device *dev, u64 dma_mask)
 675{
 676        if (!dev->dma_mask || !xen_swiotlb_dma_supported(dev, dma_mask))
 677                return -EIO;
 678
 679        *dev->dma_mask = dma_mask;
 680
 681        return 0;
 682}
 683EXPORT_SYMBOL_GPL(xen_swiotlb_set_dma_mask);
 684
 685/*
 686 * Create userspace mapping for the DMA-coherent memory.
 687 * This function should be called with the pages from the current domain only,
 688 * passing pages mapped from other domains would lead to memory corruption.
 689 */
 690int
 691xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 692                     void *cpu_addr, dma_addr_t dma_addr, size_t size,
 693                     unsigned long attrs)
 694{
 695#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
 696        if (__generic_dma_ops(dev)->mmap)
 697                return __generic_dma_ops(dev)->mmap(dev, vma, cpu_addr,
 698                                                    dma_addr, size, attrs);
 699#endif
 700        return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size);
 701}
 702EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mmap);
 703
 704/*
 705 * This function should be called with the pages from the current domain only,
 706 * passing pages mapped from other domains would lead to memory corruption.
 707 */
 708int
 709xen_swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
 710                        void *cpu_addr, dma_addr_t handle, size_t size,
 711                        unsigned long attrs)
 712{
 713#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
 714        if (__generic_dma_ops(dev)->get_sgtable) {
 715#if 0
 716        /*
 717         * This check verifies that the page belongs to the current domain and
 718         * is not one mapped from another domain.
 719         * This check is for debug only, and should not go to production build
 720         */
 721                unsigned long bfn = PHYS_PFN(dma_to_phys(dev, handle));
 722                BUG_ON (!page_is_ram(bfn));
 723#endif
 724                return __generic_dma_ops(dev)->get_sgtable(dev, sgt, cpu_addr,
 725                                                           handle, size, attrs);
 726        }
 727#endif
 728        return dma_common_get_sgtable(dev, sgt, cpu_addr, handle, size);
 729}
 730EXPORT_SYMBOL_GPL(xen_swiotlb_get_sgtable);
 731