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/memblock.h>
39 #include <linux/dma-direct.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
56 static char *xen_io_tlb_start
, *xen_io_tlb_end
;
57 static unsigned long xen_io_tlb_nslabs
;
59 * Quick lookup value of the bus address of the IOTLB.
62 static u64 start_dma_addr
;
65 * Both of these functions should avoid XEN_PFN_PHYS because phys_addr_t
66 * can be 32bit when dma_addr_t is 64bit leading to a loss in
67 * information if the shift is done before casting to 64bit.
69 static inline dma_addr_t
xen_phys_to_bus(phys_addr_t paddr
)
71 unsigned long bfn
= pfn_to_bfn(XEN_PFN_DOWN(paddr
));
72 dma_addr_t dma
= (dma_addr_t
)bfn
<< XEN_PAGE_SHIFT
;
74 dma
|= paddr
& ~XEN_PAGE_MASK
;
79 static inline phys_addr_t
xen_bus_to_phys(dma_addr_t baddr
)
81 unsigned long xen_pfn
= bfn_to_pfn(XEN_PFN_DOWN(baddr
));
82 dma_addr_t dma
= (dma_addr_t
)xen_pfn
<< XEN_PAGE_SHIFT
;
83 phys_addr_t paddr
= dma
;
85 paddr
|= baddr
& ~XEN_PAGE_MASK
;
90 static inline dma_addr_t
xen_virt_to_bus(void *address
)
92 return xen_phys_to_bus(virt_to_phys(address
));
95 static int check_pages_physically_contiguous(unsigned long xen_pfn
,
99 unsigned long next_bfn
;
103 next_bfn
= pfn_to_bfn(xen_pfn
);
104 nr_pages
= (offset
+ length
+ XEN_PAGE_SIZE
-1) >> XEN_PAGE_SHIFT
;
106 for (i
= 1; i
< nr_pages
; i
++) {
107 if (pfn_to_bfn(++xen_pfn
) != ++next_bfn
)
113 static inline int range_straddles_page_boundary(phys_addr_t p
, size_t size
)
115 unsigned long xen_pfn
= XEN_PFN_DOWN(p
);
116 unsigned int offset
= p
& ~XEN_PAGE_MASK
;
118 if (offset
+ size
<= XEN_PAGE_SIZE
)
120 if (check_pages_physically_contiguous(xen_pfn
, offset
, size
))
125 static int is_xen_swiotlb_buffer(dma_addr_t dma_addr
)
127 unsigned long bfn
= XEN_PFN_DOWN(dma_addr
);
128 unsigned long xen_pfn
= bfn_to_local_pfn(bfn
);
129 phys_addr_t paddr
= XEN_PFN_PHYS(xen_pfn
);
131 /* If the address is outside our domain, it CAN
132 * have the same virtual address as another address
133 * in our domain. Therefore _only_ check address within our domain.
135 if (pfn_valid(PFN_DOWN(paddr
))) {
136 return paddr
>= virt_to_phys(xen_io_tlb_start
) &&
137 paddr
< virt_to_phys(xen_io_tlb_end
);
142 static int max_dma_bits
= 32;
145 xen_swiotlb_fixup(void *buf
, size_t size
, unsigned long nslabs
)
149 dma_addr_t dma_handle
;
150 phys_addr_t p
= virt_to_phys(buf
);
152 dma_bits
= get_order(IO_TLB_SEGSIZE
<< IO_TLB_SHIFT
) + PAGE_SHIFT
;
156 int slabs
= min(nslabs
- i
, (unsigned long)IO_TLB_SEGSIZE
);
159 rc
= xen_create_contiguous_region(
160 p
+ (i
<< IO_TLB_SHIFT
),
161 get_order(slabs
<< IO_TLB_SHIFT
),
162 dma_bits
, &dma_handle
);
163 } while (rc
&& dma_bits
++ < max_dma_bits
);
168 } while (i
< nslabs
);
171 static unsigned long xen_set_nslabs(unsigned long nr_tbl
)
174 xen_io_tlb_nslabs
= (64 * 1024 * 1024 >> IO_TLB_SHIFT
);
175 xen_io_tlb_nslabs
= ALIGN(xen_io_tlb_nslabs
, IO_TLB_SEGSIZE
);
177 xen_io_tlb_nslabs
= nr_tbl
;
179 return xen_io_tlb_nslabs
<< IO_TLB_SHIFT
;
182 enum xen_swiotlb_err
{
183 XEN_SWIOTLB_UNKNOWN
= 0,
188 static const char *xen_swiotlb_error(enum xen_swiotlb_err err
)
191 case XEN_SWIOTLB_ENOMEM
:
192 return "Cannot allocate Xen-SWIOTLB buffer\n";
193 case XEN_SWIOTLB_EFIXUP
:
194 return "Failed to get contiguous memory for DMA from Xen!\n"\
195 "You either: don't have the permissions, do not have"\
196 " enough free memory under 4GB, or the hypervisor memory"\
197 " is too fragmented!";
203 int __ref
xen_swiotlb_init(int verbose
, bool early
)
205 unsigned long bytes
, order
;
207 enum xen_swiotlb_err m_ret
= XEN_SWIOTLB_UNKNOWN
;
208 unsigned int repeat
= 3;
210 xen_io_tlb_nslabs
= swiotlb_nr_tbl();
212 bytes
= xen_set_nslabs(xen_io_tlb_nslabs
);
213 order
= get_order(xen_io_tlb_nslabs
<< IO_TLB_SHIFT
);
215 * Get IO TLB memory from any location.
218 xen_io_tlb_start
= memblock_alloc(PAGE_ALIGN(bytes
),
220 if (!xen_io_tlb_start
)
221 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
222 __func__
, PAGE_ALIGN(bytes
), PAGE_SIZE
);
224 #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
225 #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
226 while ((SLABS_PER_PAGE
<< order
) > IO_TLB_MIN_SLABS
) {
227 xen_io_tlb_start
= (void *)xen_get_swiotlb_free_pages(order
);
228 if (xen_io_tlb_start
)
232 if (order
!= get_order(bytes
)) {
233 pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n",
234 (PAGE_SIZE
<< order
) >> 20);
235 xen_io_tlb_nslabs
= SLABS_PER_PAGE
<< order
;
236 bytes
= xen_io_tlb_nslabs
<< IO_TLB_SHIFT
;
239 if (!xen_io_tlb_start
) {
240 m_ret
= XEN_SWIOTLB_ENOMEM
;
243 xen_io_tlb_end
= xen_io_tlb_start
+ bytes
;
245 * And replace that memory with pages under 4GB.
247 rc
= xen_swiotlb_fixup(xen_io_tlb_start
,
252 memblock_free(__pa(xen_io_tlb_start
),
255 free_pages((unsigned long)xen_io_tlb_start
, order
);
256 xen_io_tlb_start
= NULL
;
258 m_ret
= XEN_SWIOTLB_EFIXUP
;
261 start_dma_addr
= xen_virt_to_bus(xen_io_tlb_start
);
263 if (swiotlb_init_with_tbl(xen_io_tlb_start
, xen_io_tlb_nslabs
,
265 panic("Cannot allocate SWIOTLB buffer");
268 rc
= swiotlb_late_init_with_tbl(xen_io_tlb_start
, xen_io_tlb_nslabs
);
271 swiotlb_set_max_segment(PAGE_SIZE
);
276 xen_io_tlb_nslabs
= max(1024UL, /* Min is 2MB */
277 (xen_io_tlb_nslabs
>> 1));
278 pr_info("Lowering to %luMB\n",
279 (xen_io_tlb_nslabs
<< IO_TLB_SHIFT
) >> 20);
282 pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret
), rc
);
284 panic("%s (rc:%d)", xen_swiotlb_error(m_ret
), rc
);
286 free_pages((unsigned long)xen_io_tlb_start
, order
);
291 xen_swiotlb_alloc_coherent(struct device
*hwdev
, size_t size
,
292 dma_addr_t
*dma_handle
, gfp_t flags
,
296 int order
= get_order(size
);
297 u64 dma_mask
= DMA_BIT_MASK(32);
302 * Ignore region specifiers - the kernel's ideas of
303 * pseudo-phys memory layout has nothing to do with the
304 * machine physical layout. We can't allocate highmem
305 * because we can't return a pointer to it.
307 flags
&= ~(__GFP_DMA
| __GFP_HIGHMEM
);
309 /* Convert the size to actually allocated. */
310 size
= 1UL << (order
+ XEN_PAGE_SHIFT
);
312 /* On ARM this function returns an ioremap'ped virtual address for
313 * which virt_to_phys doesn't return the corresponding physical
314 * address. In fact on ARM virt_to_phys only works for kernel direct
315 * mapped RAM memory. Also see comment below.
317 ret
= xen_alloc_coherent_pages(hwdev
, size
, dma_handle
, flags
, attrs
);
322 if (hwdev
&& hwdev
->coherent_dma_mask
)
323 dma_mask
= hwdev
->coherent_dma_mask
;
325 /* At this point dma_handle is the physical address, next we are
326 * going to set it to the machine address.
327 * Do not use virt_to_phys(ret) because on ARM it doesn't correspond
330 dev_addr
= xen_phys_to_bus(phys
);
331 if (((dev_addr
+ size
- 1 <= dma_mask
)) &&
332 !range_straddles_page_boundary(phys
, size
))
333 *dma_handle
= dev_addr
;
335 if (xen_create_contiguous_region(phys
, order
,
336 fls64(dma_mask
), dma_handle
) != 0) {
337 xen_free_coherent_pages(hwdev
, size
, ret
, (dma_addr_t
)phys
, attrs
);
341 memset(ret
, 0, size
);
346 xen_swiotlb_free_coherent(struct device
*hwdev
, size_t size
, void *vaddr
,
347 dma_addr_t dev_addr
, unsigned long attrs
)
349 int order
= get_order(size
);
351 u64 dma_mask
= DMA_BIT_MASK(32);
353 if (hwdev
&& hwdev
->coherent_dma_mask
)
354 dma_mask
= hwdev
->coherent_dma_mask
;
356 /* do not use virt_to_phys because on ARM it doesn't return you the
357 * physical address */
358 phys
= xen_bus_to_phys(dev_addr
);
360 /* Convert the size to actually allocated. */
361 size
= 1UL << (order
+ XEN_PAGE_SHIFT
);
363 if (((dev_addr
+ size
- 1 <= dma_mask
)) ||
364 range_straddles_page_boundary(phys
, size
))
365 xen_destroy_contiguous_region(phys
, order
);
367 xen_free_coherent_pages(hwdev
, size
, vaddr
, (dma_addr_t
)phys
, attrs
);
371 * Map a single buffer of the indicated size for DMA in streaming mode. The
372 * physical address to use is returned.
374 * Once the device is given the dma address, the device owns this memory until
375 * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
377 static dma_addr_t
xen_swiotlb_map_page(struct device
*dev
, struct page
*page
,
378 unsigned long offset
, size_t size
,
379 enum dma_data_direction dir
,
382 phys_addr_t map
, phys
= page_to_phys(page
) + offset
;
383 dma_addr_t dev_addr
= xen_phys_to_bus(phys
);
385 BUG_ON(dir
== DMA_NONE
);
387 * If the address happens to be in the device's DMA window,
388 * we can safely return the device addr and not worry about bounce
391 if (dma_capable(dev
, dev_addr
, size
) &&
392 !range_straddles_page_boundary(phys
, size
) &&
393 !xen_arch_need_swiotlb(dev
, phys
, dev_addr
) &&
394 swiotlb_force
!= SWIOTLB_FORCE
)
398 * Oh well, have to allocate and map a bounce buffer.
400 trace_swiotlb_bounced(dev
, dev_addr
, size
, swiotlb_force
);
402 map
= swiotlb_tbl_map_single(dev
, start_dma_addr
, phys
, size
, dir
,
404 if (map
== DMA_MAPPING_ERROR
)
405 return DMA_MAPPING_ERROR
;
407 dev_addr
= xen_phys_to_bus(map
);
410 * Ensure that the address returned is DMA'ble
412 if (unlikely(!dma_capable(dev
, dev_addr
, size
))) {
413 swiotlb_tbl_unmap_single(dev
, map
, size
, dir
,
414 attrs
| DMA_ATTR_SKIP_CPU_SYNC
);
415 return DMA_MAPPING_ERROR
;
418 page
= pfn_to_page(map
>> PAGE_SHIFT
);
419 offset
= map
& ~PAGE_MASK
;
422 * we are not interested in the dma_addr returned by xen_dma_map_page,
423 * only in the potential cache flushes executed by the function.
425 xen_dma_map_page(dev
, page
, dev_addr
, offset
, size
, dir
, attrs
);
430 * Unmap a single streaming mode DMA translation. The dma_addr and size must
431 * match what was provided for in a previous xen_swiotlb_map_page call. All
432 * other usages are undefined.
434 * After this call, reads by the cpu to the buffer are guaranteed to see
435 * whatever the device wrote there.
437 static void xen_unmap_single(struct device
*hwdev
, dma_addr_t dev_addr
,
438 size_t size
, enum dma_data_direction dir
,
441 phys_addr_t paddr
= xen_bus_to_phys(dev_addr
);
443 BUG_ON(dir
== DMA_NONE
);
445 xen_dma_unmap_page(hwdev
, dev_addr
, size
, dir
, attrs
);
447 /* NOTE: We use dev_addr here, not paddr! */
448 if (is_xen_swiotlb_buffer(dev_addr
))
449 swiotlb_tbl_unmap_single(hwdev
, paddr
, size
, dir
, attrs
);
452 static void xen_swiotlb_unmap_page(struct device
*hwdev
, dma_addr_t dev_addr
,
453 size_t size
, enum dma_data_direction dir
,
456 xen_unmap_single(hwdev
, dev_addr
, size
, dir
, attrs
);
460 xen_swiotlb_sync_single_for_cpu(struct device
*dev
, dma_addr_t dma_addr
,
461 size_t size
, enum dma_data_direction dir
)
463 phys_addr_t paddr
= xen_bus_to_phys(dma_addr
);
465 xen_dma_sync_single_for_cpu(dev
, dma_addr
, size
, dir
);
467 if (is_xen_swiotlb_buffer(dma_addr
))
468 swiotlb_tbl_sync_single(dev
, paddr
, size
, dir
, SYNC_FOR_CPU
);
472 xen_swiotlb_sync_single_for_device(struct device
*dev
, dma_addr_t dma_addr
,
473 size_t size
, enum dma_data_direction dir
)
475 phys_addr_t paddr
= xen_bus_to_phys(dma_addr
);
477 if (is_xen_swiotlb_buffer(dma_addr
))
478 swiotlb_tbl_sync_single(dev
, paddr
, size
, dir
, SYNC_FOR_DEVICE
);
480 xen_dma_sync_single_for_device(dev
, dma_addr
, size
, dir
);
484 * Unmap a set of streaming mode DMA translations. Again, cpu read rules
485 * concerning calls here are the same as for swiotlb_unmap_page() above.
488 xen_swiotlb_unmap_sg(struct device
*hwdev
, struct scatterlist
*sgl
, int nelems
,
489 enum dma_data_direction dir
, unsigned long attrs
)
491 struct scatterlist
*sg
;
494 BUG_ON(dir
== DMA_NONE
);
496 for_each_sg(sgl
, sg
, nelems
, i
)
497 xen_unmap_single(hwdev
, sg
->dma_address
, sg_dma_len(sg
), dir
, attrs
);
502 xen_swiotlb_map_sg(struct device
*dev
, struct scatterlist
*sgl
, int nelems
,
503 enum dma_data_direction dir
, unsigned long attrs
)
505 struct scatterlist
*sg
;
508 BUG_ON(dir
== DMA_NONE
);
510 for_each_sg(sgl
, sg
, nelems
, i
) {
511 sg
->dma_address
= xen_swiotlb_map_page(dev
, sg_page(sg
),
512 sg
->offset
, sg
->length
, dir
, attrs
);
513 if (sg
->dma_address
== DMA_MAPPING_ERROR
)
515 sg_dma_len(sg
) = sg
->length
;
520 xen_swiotlb_unmap_sg(dev
, sgl
, i
, dir
, attrs
| DMA_ATTR_SKIP_CPU_SYNC
);
526 xen_swiotlb_sync_sg_for_cpu(struct device
*dev
, struct scatterlist
*sgl
,
527 int nelems
, enum dma_data_direction dir
)
529 struct scatterlist
*sg
;
532 for_each_sg(sgl
, sg
, nelems
, i
) {
533 xen_swiotlb_sync_single_for_cpu(dev
, sg
->dma_address
,
539 xen_swiotlb_sync_sg_for_device(struct device
*dev
, struct scatterlist
*sgl
,
540 int nelems
, enum dma_data_direction dir
)
542 struct scatterlist
*sg
;
545 for_each_sg(sgl
, sg
, nelems
, i
) {
546 xen_swiotlb_sync_single_for_device(dev
, sg
->dma_address
,
552 * Return whether the given device DMA address mask can be supported
553 * properly. For example, if your device can only drive the low 24-bits
554 * during bus mastering, then you would pass 0x00ffffff as the mask to
558 xen_swiotlb_dma_supported(struct device
*hwdev
, u64 mask
)
560 return xen_virt_to_bus(xen_io_tlb_end
- 1) <= mask
;
564 * Create userspace mapping for the DMA-coherent memory.
565 * This function should be called with the pages from the current domain only,
566 * passing pages mapped from other domains would lead to memory corruption.
569 xen_swiotlb_dma_mmap(struct device
*dev
, struct vm_area_struct
*vma
,
570 void *cpu_addr
, dma_addr_t dma_addr
, size_t size
,
574 if (xen_get_dma_ops(dev
)->mmap
)
575 return xen_get_dma_ops(dev
)->mmap(dev
, vma
, cpu_addr
,
576 dma_addr
, size
, attrs
);
578 return dma_common_mmap(dev
, vma
, cpu_addr
, dma_addr
, size
, attrs
);
582 * This function should be called with the pages from the current domain only,
583 * passing pages mapped from other domains would lead to memory corruption.
586 xen_swiotlb_get_sgtable(struct device
*dev
, struct sg_table
*sgt
,
587 void *cpu_addr
, dma_addr_t handle
, size_t size
,
591 if (xen_get_dma_ops(dev
)->get_sgtable
) {
594 * This check verifies that the page belongs to the current domain and
595 * is not one mapped from another domain.
596 * This check is for debug only, and should not go to production build
598 unsigned long bfn
= PHYS_PFN(dma_to_phys(dev
, handle
));
599 BUG_ON (!page_is_ram(bfn
));
601 return xen_get_dma_ops(dev
)->get_sgtable(dev
, sgt
, cpu_addr
,
602 handle
, size
, attrs
);
605 return dma_common_get_sgtable(dev
, sgt
, cpu_addr
, handle
, size
, attrs
);
608 const struct dma_map_ops xen_swiotlb_dma_ops
= {
609 .alloc
= xen_swiotlb_alloc_coherent
,
610 .free
= xen_swiotlb_free_coherent
,
611 .sync_single_for_cpu
= xen_swiotlb_sync_single_for_cpu
,
612 .sync_single_for_device
= xen_swiotlb_sync_single_for_device
,
613 .sync_sg_for_cpu
= xen_swiotlb_sync_sg_for_cpu
,
614 .sync_sg_for_device
= xen_swiotlb_sync_sg_for_device
,
615 .map_sg
= xen_swiotlb_map_sg
,
616 .unmap_sg
= xen_swiotlb_unmap_sg
,
617 .map_page
= xen_swiotlb_map_page
,
618 .unmap_page
= xen_swiotlb_unmap_page
,
619 .dma_supported
= xen_swiotlb_dma_supported
,
620 .mmap
= xen_swiotlb_dma_mmap
,
621 .get_sgtable
= xen_swiotlb_get_sgtable
,