xref: /linux/drivers/xen/swiotlb-xen.c (revision fd31a1bea3c94e01cb7b998485d2d7b14bdc8101)
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 
xen_phys_to_bus(struct device * dev,phys_addr_t paddr)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 
xen_phys_to_dma(struct device * dev,phys_addr_t paddr)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 
xen_bus_to_phys(struct device * dev,phys_addr_t baddr)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 
xen_dma_to_phys(struct device * dev,dma_addr_t dma_addr)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 
range_requires_alignment(phys_addr_t p,size_t size)77 static inline bool range_requires_alignment(phys_addr_t p, size_t size)
78 {
79 	phys_addr_t algn = 1ULL << (get_order(size) + PAGE_SHIFT);
80 	phys_addr_t bus_addr = pfn_to_bfn(XEN_PFN_DOWN(p)) << XEN_PAGE_SHIFT;
81 
82 	return IS_ALIGNED(p, algn) && !IS_ALIGNED(bus_addr, algn);
83 }
84 
range_straddles_page_boundary(phys_addr_t p,size_t size)85 static inline int range_straddles_page_boundary(phys_addr_t p, size_t size)
86 {
87 	unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p);
88 	unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size);
89 
90 	next_bfn = pfn_to_bfn(xen_pfn);
91 
92 	for (i = 1; i < nr_pages; i++)
93 		if (pfn_to_bfn(++xen_pfn) != ++next_bfn)
94 			return 1;
95 
96 	return 0;
97 }
98 
xen_swiotlb_find_pool(struct device * dev,dma_addr_t dma_addr)99 static struct io_tlb_pool *xen_swiotlb_find_pool(struct device *dev,
100 						 dma_addr_t dma_addr)
101 {
102 	unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr));
103 	unsigned long xen_pfn = bfn_to_local_pfn(bfn);
104 	phys_addr_t paddr = (phys_addr_t)xen_pfn << XEN_PAGE_SHIFT;
105 
106 	/* If the address is outside our domain, it CAN
107 	 * have the same virtual address as another address
108 	 * in our domain. Therefore _only_ check address within our domain.
109 	 */
110 	if (pfn_valid(PFN_DOWN(paddr)))
111 		return swiotlb_find_pool(dev, paddr);
112 	return NULL;
113 }
114 
115 #ifdef CONFIG_X86
xen_swiotlb_fixup(void * buf,unsigned long nslabs)116 int __init xen_swiotlb_fixup(void *buf, unsigned long nslabs)
117 {
118 	int rc;
119 	unsigned int order = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT);
120 	unsigned int i, dma_bits = order + PAGE_SHIFT;
121 	dma_addr_t dma_handle;
122 	phys_addr_t p = virt_to_phys(buf);
123 
124 	BUILD_BUG_ON(IO_TLB_SEGSIZE & (IO_TLB_SEGSIZE - 1));
125 	BUG_ON(nslabs % IO_TLB_SEGSIZE);
126 
127 	i = 0;
128 	do {
129 		do {
130 			rc = xen_create_contiguous_region(
131 				p + (i << IO_TLB_SHIFT), order,
132 				dma_bits, &dma_handle);
133 		} while (rc && dma_bits++ < MAX_DMA_BITS);
134 		if (rc)
135 			return rc;
136 
137 		i += IO_TLB_SEGSIZE;
138 	} while (i < nslabs);
139 	return 0;
140 }
141 
142 static void *
xen_swiotlb_alloc_coherent(struct device * dev,size_t size,dma_addr_t * dma_handle,gfp_t flags,unsigned long attrs)143 xen_swiotlb_alloc_coherent(struct device *dev, size_t size,
144 		dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs)
145 {
146 	u64 dma_mask = dev->coherent_dma_mask;
147 	int order = get_order(size);
148 	phys_addr_t phys;
149 	void *ret;
150 
151 	/* Align the allocation to the Xen page size */
152 	size = ALIGN(size, XEN_PAGE_SIZE);
153 
154 	ret = (void *)__get_free_pages(flags, get_order(size));
155 	if (!ret)
156 		return ret;
157 	phys = virt_to_phys(ret);
158 
159 	*dma_handle = xen_phys_to_dma(dev, phys);
160 	if (*dma_handle + size - 1 > dma_mask ||
161 	    range_straddles_page_boundary(phys, size) ||
162 	    range_requires_alignment(phys, size)) {
163 		if (xen_create_contiguous_region(phys, order, fls64(dma_mask),
164 				dma_handle) != 0)
165 			goto out_free_pages;
166 		SetPageXenRemapped(virt_to_page(ret));
167 	}
168 
169 	memset(ret, 0, size);
170 	return ret;
171 
172 out_free_pages:
173 	free_pages((unsigned long)ret, get_order(size));
174 	return NULL;
175 }
176 
177 static void
xen_swiotlb_free_coherent(struct device * dev,size_t size,void * vaddr,dma_addr_t dma_handle,unsigned long attrs)178 xen_swiotlb_free_coherent(struct device *dev, size_t size, void *vaddr,
179 		dma_addr_t dma_handle, unsigned long attrs)
180 {
181 	phys_addr_t phys = virt_to_phys(vaddr);
182 	int order = get_order(size);
183 
184 	/* Convert the size to actually allocated. */
185 	size = ALIGN(size, XEN_PAGE_SIZE);
186 
187 	if (WARN_ON_ONCE(dma_handle + size - 1 > dev->coherent_dma_mask) ||
188 	    WARN_ON_ONCE(range_straddles_page_boundary(phys, size) ||
189 			 range_requires_alignment(phys, size)))
190 	    	return;
191 
192 	if (TestClearPageXenRemapped(virt_to_page(vaddr)))
193 		xen_destroy_contiguous_region(phys, order);
194 	free_pages((unsigned long)vaddr, get_order(size));
195 }
196 #endif /* CONFIG_X86 */
197 
198 /*
199  * Map a single buffer of the indicated size for DMA in streaming mode.  The
200  * physical address to use is returned.
201  *
202  * Once the device is given the dma address, the device owns this memory until
203  * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed.
204  */
xen_swiotlb_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction dir,unsigned long attrs)205 static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
206 				unsigned long offset, size_t size,
207 				enum dma_data_direction dir,
208 				unsigned long attrs)
209 {
210 	phys_addr_t map, phys = page_to_phys(page) + offset;
211 	dma_addr_t dev_addr = xen_phys_to_dma(dev, phys);
212 
213 	BUG_ON(dir == DMA_NONE);
214 	/*
215 	 * If the address happens to be in the device's DMA window,
216 	 * we can safely return the device addr and not worry about bounce
217 	 * buffering it.
218 	 */
219 	if (dma_capable(dev, dev_addr, size, true) &&
220 	    !range_straddles_page_boundary(phys, size) &&
221 		!xen_arch_need_swiotlb(dev, phys, dev_addr) &&
222 		!is_swiotlb_force_bounce(dev))
223 		goto done;
224 
225 	/*
226 	 * Oh well, have to allocate and map a bounce buffer.
227 	 */
228 	trace_swiotlb_bounced(dev, dev_addr, size);
229 
230 	map = swiotlb_tbl_map_single(dev, phys, size, 0, dir, attrs);
231 	if (map == (phys_addr_t)DMA_MAPPING_ERROR)
232 		return DMA_MAPPING_ERROR;
233 
234 	phys = map;
235 	dev_addr = xen_phys_to_dma(dev, map);
236 
237 	/*
238 	 * Ensure that the address returned is DMA'ble
239 	 */
240 	if (unlikely(!dma_capable(dev, dev_addr, size, true))) {
241 		__swiotlb_tbl_unmap_single(dev, map, size, dir,
242 				attrs | DMA_ATTR_SKIP_CPU_SYNC,
243 				swiotlb_find_pool(dev, map));
244 		return DMA_MAPPING_ERROR;
245 	}
246 
247 done:
248 	if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
249 		if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dev_addr))))
250 			arch_sync_dma_for_device(phys, size, dir);
251 		else
252 			xen_dma_sync_for_device(dev, dev_addr, size, dir);
253 	}
254 	return dev_addr;
255 }
256 
257 /*
258  * Unmap a single streaming mode DMA translation.  The dma_addr and size must
259  * match what was provided for in a previous xen_swiotlb_map_page call.  All
260  * other usages are undefined.
261  *
262  * After this call, reads by the cpu to the buffer are guaranteed to see
263  * whatever the device wrote there.
264  */
xen_swiotlb_unmap_page(struct device * hwdev,dma_addr_t dev_addr,size_t size,enum dma_data_direction dir,unsigned long attrs)265 static void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
266 		size_t size, enum dma_data_direction dir, unsigned long attrs)
267 {
268 	phys_addr_t paddr = xen_dma_to_phys(hwdev, dev_addr);
269 	struct io_tlb_pool *pool;
270 
271 	BUG_ON(dir == DMA_NONE);
272 
273 	if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
274 		if (pfn_valid(PFN_DOWN(dma_to_phys(hwdev, dev_addr))))
275 			arch_sync_dma_for_cpu(paddr, size, dir);
276 		else
277 			xen_dma_sync_for_cpu(hwdev, dev_addr, size, dir);
278 	}
279 
280 	/* NOTE: We use dev_addr here, not paddr! */
281 	pool = xen_swiotlb_find_pool(hwdev, dev_addr);
282 	if (pool)
283 		__swiotlb_tbl_unmap_single(hwdev, paddr, size, dir,
284 					   attrs, pool);
285 }
286 
287 static void
xen_swiotlb_sync_single_for_cpu(struct device * dev,dma_addr_t dma_addr,size_t size,enum dma_data_direction dir)288 xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr,
289 		size_t size, enum dma_data_direction dir)
290 {
291 	phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr);
292 	struct io_tlb_pool *pool;
293 
294 	if (!dev_is_dma_coherent(dev)) {
295 		if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr))))
296 			arch_sync_dma_for_cpu(paddr, size, dir);
297 		else
298 			xen_dma_sync_for_cpu(dev, dma_addr, size, dir);
299 	}
300 
301 	pool = xen_swiotlb_find_pool(dev, dma_addr);
302 	if (pool)
303 		__swiotlb_sync_single_for_cpu(dev, paddr, size, dir, pool);
304 }
305 
306 static void
xen_swiotlb_sync_single_for_device(struct device * dev,dma_addr_t dma_addr,size_t size,enum dma_data_direction dir)307 xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr,
308 		size_t size, enum dma_data_direction dir)
309 {
310 	phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr);
311 	struct io_tlb_pool *pool;
312 
313 	pool = xen_swiotlb_find_pool(dev, dma_addr);
314 	if (pool)
315 		__swiotlb_sync_single_for_device(dev, paddr, size, dir, pool);
316 
317 	if (!dev_is_dma_coherent(dev)) {
318 		if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr))))
319 			arch_sync_dma_for_device(paddr, size, dir);
320 		else
321 			xen_dma_sync_for_device(dev, dma_addr, size, dir);
322 	}
323 }
324 
325 /*
326  * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
327  * concerning calls here are the same as for swiotlb_unmap_page() above.
328  */
329 static void
xen_swiotlb_unmap_sg(struct device * hwdev,struct scatterlist * sgl,int nelems,enum dma_data_direction dir,unsigned long attrs)330 xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
331 		enum dma_data_direction dir, unsigned long attrs)
332 {
333 	struct scatterlist *sg;
334 	int i;
335 
336 	BUG_ON(dir == DMA_NONE);
337 
338 	for_each_sg(sgl, sg, nelems, i)
339 		xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg),
340 				dir, attrs);
341 
342 }
343 
344 static int
xen_swiotlb_map_sg(struct device * dev,struct scatterlist * sgl,int nelems,enum dma_data_direction dir,unsigned long attrs)345 xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems,
346 		enum dma_data_direction dir, unsigned long attrs)
347 {
348 	struct scatterlist *sg;
349 	int i;
350 
351 	BUG_ON(dir == DMA_NONE);
352 
353 	for_each_sg(sgl, sg, nelems, i) {
354 		sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg),
355 				sg->offset, sg->length, dir, attrs);
356 		if (sg->dma_address == DMA_MAPPING_ERROR)
357 			goto out_unmap;
358 		sg_dma_len(sg) = sg->length;
359 	}
360 
361 	return nelems;
362 out_unmap:
363 	xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
364 	sg_dma_len(sgl) = 0;
365 	return -EIO;
366 }
367 
368 static void
xen_swiotlb_sync_sg_for_cpu(struct device * dev,struct scatterlist * sgl,int nelems,enum dma_data_direction dir)369 xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl,
370 			    int nelems, enum dma_data_direction dir)
371 {
372 	struct scatterlist *sg;
373 	int i;
374 
375 	for_each_sg(sgl, sg, nelems, i) {
376 		xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address,
377 				sg->length, dir);
378 	}
379 }
380 
381 static void
xen_swiotlb_sync_sg_for_device(struct device * dev,struct scatterlist * sgl,int nelems,enum dma_data_direction dir)382 xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
383 			       int nelems, enum dma_data_direction dir)
384 {
385 	struct scatterlist *sg;
386 	int i;
387 
388 	for_each_sg(sgl, sg, nelems, i) {
389 		xen_swiotlb_sync_single_for_device(dev, sg->dma_address,
390 				sg->length, dir);
391 	}
392 }
393 
394 /*
395  * Return whether the given device DMA address mask can be supported
396  * properly.  For example, if your device can only drive the low 24-bits
397  * during bus mastering, then you would pass 0x00ffffff as the mask to
398  * this function.
399  */
400 static int
xen_swiotlb_dma_supported(struct device * hwdev,u64 mask)401 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
402 {
403 	return xen_phys_to_dma(hwdev, default_swiotlb_limit()) <= mask;
404 }
405 
406 const struct dma_map_ops xen_swiotlb_dma_ops = {
407 #ifdef CONFIG_X86
408 	.alloc = xen_swiotlb_alloc_coherent,
409 	.free = xen_swiotlb_free_coherent,
410 #else
411 	.alloc = dma_direct_alloc,
412 	.free = dma_direct_free,
413 #endif
414 	.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
415 	.sync_single_for_device = xen_swiotlb_sync_single_for_device,
416 	.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
417 	.sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
418 	.map_sg = xen_swiotlb_map_sg,
419 	.unmap_sg = xen_swiotlb_unmap_sg,
420 	.map_page = xen_swiotlb_map_page,
421 	.unmap_page = xen_swiotlb_unmap_page,
422 	.dma_supported = xen_swiotlb_dma_supported,
423 	.mmap = dma_common_mmap,
424 	.get_sgtable = dma_common_get_sgtable,
425 	.alloc_pages_op = dma_common_alloc_pages,
426 	.free_pages = dma_common_free_pages,
427 	.max_mapping_size = swiotlb_max_mapping_size,
428 };
429