3 * by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
5 * This code provides a IOMMU for Xen PV guests with PCI passthrough.
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
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.
16 * PV guests under Xen are running in an non-contiguous memory architecture.
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
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.
36 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
38 #include <linux/bootmem.h>
39 #include <linux/dma-mapping.h>
40 #include <linux/export.h>
41 #include <xen/swiotlb-xen.h>
43 #include <xen/xen-ops.h>
44 #include <xen/hvc-console.h>
46 #include <asm/dma-mapping.h>
47 #include <asm/xen/page-coherent.h>
49 #include <trace/events/swiotlb.h>
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
57 static unsigned long dma_alloc_coherent_mask(struct device *dev,
60 unsigned long dma_mask = 0;
62 dma_mask = dev->coherent_dma_mask;
64 dma_mask = (gfp & GFP_DMA) ? DMA_BIT_MASK(24) : DMA_BIT_MASK(32);
70 static char *xen_io_tlb_start, *xen_io_tlb_end;
71 static unsigned long xen_io_tlb_nslabs;
73 * Quick lookup value of the bus address of the IOTLB.
76 static u64 start_dma_addr;
79 * Both of these functions should avoid 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.
83 static inline dma_addr_t xen_phys_to_bus(phys_addr_t paddr)
85 unsigned long mfn = pfn_to_mfn(PFN_DOWN(paddr));
86 dma_addr_t dma = (dma_addr_t)mfn << PAGE_SHIFT;
88 dma |= paddr & ~PAGE_MASK;
93 static inline phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
95 unsigned long pfn = mfn_to_pfn(PFN_DOWN(baddr));
96 dma_addr_t dma = (dma_addr_t)pfn << PAGE_SHIFT;
97 phys_addr_t paddr = dma;
99 paddr |= baddr & ~PAGE_MASK;
104 static inline dma_addr_t xen_virt_to_bus(void *address)
106 return xen_phys_to_bus(virt_to_phys(address));
109 static int check_pages_physically_contiguous(unsigned long pfn,
113 unsigned long next_mfn;
117 next_mfn = pfn_to_mfn(pfn);
118 nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT;
120 for (i = 1; i < nr_pages; i++) {
121 if (pfn_to_mfn(++pfn) != ++next_mfn)
127 static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
129 unsigned long pfn = PFN_DOWN(p);
130 unsigned int offset = p & ~PAGE_MASK;
132 if (offset + size <= PAGE_SIZE)
134 if (check_pages_physically_contiguous(pfn, offset, size))
139 static int is_xen_swiotlb_buffer(dma_addr_t dma_addr)
141 unsigned long mfn = PFN_DOWN(dma_addr);
142 unsigned long pfn = mfn_to_local_pfn(mfn);
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.
149 if (pfn_valid(pfn)) {
150 paddr = PFN_PHYS(pfn);
151 return paddr >= virt_to_phys(xen_io_tlb_start) &&
152 paddr < virt_to_phys(xen_io_tlb_end);
157 static int max_dma_bits = 32;
160 xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs)
164 dma_addr_t dma_handle;
165 phys_addr_t p = virt_to_phys(buf);
167 dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT;
171 int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE);
174 rc = xen_create_contiguous_region(
175 p + (i << IO_TLB_SHIFT),
176 get_order(slabs << IO_TLB_SHIFT),
177 dma_bits, &dma_handle);
178 } while (rc && dma_bits++ < max_dma_bits);
183 } while (i < nslabs);
186 static unsigned long xen_set_nslabs(unsigned long nr_tbl)
189 xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
190 xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
192 xen_io_tlb_nslabs = nr_tbl;
194 return xen_io_tlb_nslabs << IO_TLB_SHIFT;
197 enum xen_swiotlb_err {
198 XEN_SWIOTLB_UNKNOWN = 0,
203 static const char *xen_swiotlb_error(enum xen_swiotlb_err err)
206 case XEN_SWIOTLB_ENOMEM:
207 return "Cannot allocate Xen-SWIOTLB buffer\n";
208 case XEN_SWIOTLB_EFIXUP:
209 return "Failed to get contiguous memory for DMA from Xen!\n"\
210 "You either: don't have the permissions, do not have"\
211 " enough free memory under 4GB, or the hypervisor memory"\
212 " is too fragmented!";
218 int __ref xen_swiotlb_init(int verbose, bool early)
220 unsigned long bytes, order;
222 enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
223 unsigned int repeat = 3;
225 xen_io_tlb_nslabs = swiotlb_nr_tbl();
227 bytes = xen_set_nslabs(xen_io_tlb_nslabs);
228 order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
230 * Get IO TLB memory from any location.
233 xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
235 #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
236 #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
237 while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
238 xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order);
239 if (xen_io_tlb_start)
243 if (order != get_order(bytes)) {
244 pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
245 (PAGE_SIZE << order) >> 20);
246 xen_io_tlb_nslabs = SLABS_PER_PAGE << order;
247 bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
250 if (!xen_io_tlb_start) {
251 m_ret = XEN_SWIOTLB_ENOMEM;
254 xen_io_tlb_end = xen_io_tlb_start + bytes;
256 * And replace that memory with pages under 4GB.
258 rc = xen_swiotlb_fixup(xen_io_tlb_start,
263 free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
265 free_pages((unsigned long)xen_io_tlb_start, order);
266 xen_io_tlb_start = NULL;
268 m_ret = XEN_SWIOTLB_EFIXUP;
271 start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
273 if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
275 panic("Cannot allocate SWIOTLB buffer");
278 rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
282 xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */
283 (xen_io_tlb_nslabs >> 1));
284 pr_info("Lowering to %luMB\n",
285 (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20);
288 pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc);
290 panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
292 free_pages((unsigned long)xen_io_tlb_start, order);
296 xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
297 dma_addr_t *dma_handle, gfp_t flags,
298 struct dma_attrs *attrs)
301 int order = get_order(size);
302 u64 dma_mask = DMA_BIT_MASK(32);
307 * Ignore region specifiers - the kernel's ideas of
308 * pseudo-phys memory layout has nothing to do with the
309 * machine physical layout. We can't allocate highmem
310 * because we can't return a pointer to it.
312 flags &= ~(__GFP_DMA | __GFP_HIGHMEM);
314 if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret))
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.
322 ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs);
327 if (hwdev && hwdev->coherent_dma_mask)
328 dma_mask = dma_alloc_coherent_mask(hwdev, flags);
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
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;
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);
346 memset(ret, 0, size);
349 EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent);
352 xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
353 dma_addr_t dev_addr, struct dma_attrs *attrs)
355 int order = get_order(size);
357 u64 dma_mask = DMA_BIT_MASK(32);
359 if (dma_release_from_coherent(hwdev, order, vaddr))
362 if (hwdev && hwdev->coherent_dma_mask)
363 dma_mask = hwdev->coherent_dma_mask;
365 /* do not use virt_to_phys because on ARM it doesn't return you the
366 * physical address */
367 phys = xen_bus_to_phys(dev_addr);
369 if (((dev_addr + size - 1 > dma_mask)) ||
370 range_straddles_page_boundary(phys, size))
371 xen_destroy_contiguous_region(phys, order);
373 xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);
375 EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent);
379 * Map a single buffer of the indicated size for DMA in streaming mode. The
380 * physical address to use is returned.
382 * Once the device is given the dma address, the device owns this memory until
383 * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
385 dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
386 unsigned long offset, size_t size,
387 enum dma_data_direction dir,
388 struct dma_attrs *attrs)
390 phys_addr_t map, phys = page_to_phys(page) + offset;
391 dma_addr_t dev_addr = xen_phys_to_bus(phys);
393 BUG_ON(dir == DMA_NONE);
395 * If the address happens to be in the device's DMA window,
396 * we can safely return the device addr and not worry about bounce
399 if (dma_capable(dev, dev_addr, size) &&
400 !range_straddles_page_boundary(phys, size) &&
401 !xen_arch_need_swiotlb(dev, PFN_DOWN(phys), PFN_DOWN(dev_addr)) &&
403 /* we are not interested in the dma_addr returned by
404 * xen_dma_map_page, only in the potential cache flushes executed
405 * by the function. */
406 xen_dma_map_page(dev, page, dev_addr, offset, size, dir, attrs);
411 * Oh well, have to allocate and map a bounce buffer.
413 trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
415 map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir);
416 if (map == SWIOTLB_MAP_ERROR)
417 return DMA_ERROR_CODE;
419 xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT),
420 dev_addr, map & ~PAGE_MASK, size, dir, attrs);
421 dev_addr = xen_phys_to_bus(map);
424 * Ensure that the address returned is DMA'ble
426 if (!dma_capable(dev, dev_addr, size)) {
427 swiotlb_tbl_unmap_single(dev, map, size, dir);
432 EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
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.
439 * After this call, reads by the cpu to the buffer are guaranteed to see
440 * whatever the device wrote there.
442 static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr,
443 size_t size, enum dma_data_direction dir,
444 struct dma_attrs *attrs)
446 phys_addr_t paddr = xen_bus_to_phys(dev_addr);
448 BUG_ON(dir == DMA_NONE);
450 xen_dma_unmap_page(hwdev, dev_addr, size, dir, attrs);
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);
458 if (dir != DMA_FROM_DEVICE)
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.
467 dma_mark_clean(phys_to_virt(paddr), size);
470 void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
471 size_t size, enum dma_data_direction dir,
472 struct dma_attrs *attrs)
474 xen_unmap_single(hwdev, dev_addr, size, dir, attrs);
476 EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_page);
479 * Make physical memory consistent for a single streaming mode DMA translation
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
489 xen_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)
493 phys_addr_t paddr = xen_bus_to_phys(dev_addr);
495 BUG_ON(dir == DMA_NONE);
497 if (target == SYNC_FOR_CPU)
498 xen_dma_sync_single_for_cpu(hwdev, dev_addr, size, dir);
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);
504 if (target == SYNC_FOR_DEVICE)
505 xen_dma_sync_single_for_device(hwdev, dev_addr, size, dir);
507 if (dir != DMA_FROM_DEVICE)
510 dma_mark_clean(phys_to_virt(paddr), size);
514 xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
515 size_t size, enum dma_data_direction dir)
517 xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
519 EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_cpu);
522 xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
523 size_t size, enum dma_data_direction dir)
525 xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
527 EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_device);
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).
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.
542 * Device ownership issues as mentioned above for xen_swiotlb_map_page are the
546 xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
547 int nelems, enum dma_data_direction dir,
548 struct dma_attrs *attrs)
550 struct scatterlist *sg;
553 BUG_ON(dir == DMA_NONE);
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);
560 xen_arch_need_swiotlb(hwdev, PFN_DOWN(paddr), PFN_DOWN(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,
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 xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
577 xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT),
583 sg->dma_address = xen_phys_to_bus(map);
585 /* we are not interested in the dma_addr returned by
586 * xen_dma_map_page, only in the potential cache flushes executed
587 * by the function. */
588 xen_dma_map_page(hwdev, pfn_to_page(paddr >> PAGE_SHIFT),
594 sg->dma_address = dev_addr;
596 sg_dma_len(sg) = sg->length;
600 EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs);
603 * Unmap a set of streaming mode DMA translations. Again, cpu read rules
604 * concerning calls here are the same as for swiotlb_unmap_page() above.
607 xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
608 int nelems, enum dma_data_direction dir,
609 struct dma_attrs *attrs)
611 struct scatterlist *sg;
614 BUG_ON(dir == DMA_NONE);
616 for_each_sg(sgl, sg, nelems, i)
617 xen_unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir, attrs);
620 EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs);
623 * Make physical memory consistent for a set of streaming mode DMA translations
626 * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
630 xen_swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
631 int nelems, enum dma_data_direction dir,
632 enum dma_sync_target target)
634 struct scatterlist *sg;
637 for_each_sg(sgl, sg, nelems, i)
638 xen_swiotlb_sync_single(hwdev, sg->dma_address,
639 sg_dma_len(sg), dir, target);
643 xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
644 int nelems, enum dma_data_direction dir)
646 xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
648 EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_cpu);
651 xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
652 int nelems, enum dma_data_direction dir)
654 xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
656 EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device);
659 xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
663 EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error);
666 * Return whether the given device DMA address mask can be supported
667 * properly. For example, if your device can only drive the low 24-bits
668 * during bus mastering, then you would pass 0x00ffffff as the mask to
672 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
674 return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask;
676 EXPORT_SYMBOL_GPL(xen_swiotlb_dma_supported);
679 xen_swiotlb_set_dma_mask(struct device *dev, u64 dma_mask)
681 if (!dev->dma_mask || !xen_swiotlb_dma_supported(dev, dma_mask))
684 *dev->dma_mask = dma_mask;
688 EXPORT_SYMBOL_GPL(xen_swiotlb_set_dma_mask);