1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Driver for FPGA Accelerated Function Unit (AFU) DMA Region Management
4  *
5  * Copyright (C) 2017-2018 Intel Corporation, Inc.
6  *
7  * Authors:
8  *   Wu Hao <hao.wu@intel.com>
9  *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
10  */
11 
12 #include <linux/dma-mapping.h>
13 #include <linux/sched/signal.h>
14 #include <linux/uaccess.h>
15 #include <linux/mm.h>
16 
17 #include "dfl-afu.h"
18 
19 static void put_all_pages(struct page **pages, int npages)
20 {
21 	int i;
22 
23 	for (i = 0; i < npages; i++)
24 		if (pages[i])
25 			put_page(pages[i]);
26 }
27 
28 void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
29 {
30 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
31 
32 	afu->dma_regions = RB_ROOT;
33 }
34 
35 /**
36  * afu_dma_pin_pages - pin pages of given dma memory region
37  * @pdata: feature device platform data
38  * @region: dma memory region to be pinned
39  *
40  * Pin all the pages of given dfl_afu_dma_region.
41  * Return 0 for success or negative error code.
42  */
43 static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
44 			     struct dfl_afu_dma_region *region)
45 {
46 	int npages = region->length >> PAGE_SHIFT;
47 	struct device *dev = &pdata->dev->dev;
48 	int ret, pinned;
49 
50 	ret = account_locked_vm(current->mm, npages, true);
51 	if (ret)
52 		return ret;
53 
54 	region->pages = kcalloc(npages, sizeof(struct page *), GFP_KERNEL);
55 	if (!region->pages) {
56 		ret = -ENOMEM;
57 		goto unlock_vm;
58 	}
59 
60 	pinned = get_user_pages_fast(region->user_addr, npages, FOLL_WRITE,
61 				     region->pages);
62 	if (pinned < 0) {
63 		ret = pinned;
64 		goto put_pages;
65 	} else if (pinned != npages) {
66 		ret = -EFAULT;
67 		goto free_pages;
68 	}
69 
70 	dev_dbg(dev, "%d pages pinned\n", pinned);
71 
72 	return 0;
73 
74 put_pages:
75 	put_all_pages(region->pages, pinned);
76 free_pages:
77 	kfree(region->pages);
78 unlock_vm:
79 	account_locked_vm(current->mm, npages, false);
80 	return ret;
81 }
82 
83 /**
84  * afu_dma_unpin_pages - unpin pages of given dma memory region
85  * @pdata: feature device platform data
86  * @region: dma memory region to be unpinned
87  *
88  * Unpin all the pages of given dfl_afu_dma_region.
89  * Return 0 for success or negative error code.
90  */
91 static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
92 				struct dfl_afu_dma_region *region)
93 {
94 	long npages = region->length >> PAGE_SHIFT;
95 	struct device *dev = &pdata->dev->dev;
96 
97 	put_all_pages(region->pages, npages);
98 	kfree(region->pages);
99 	account_locked_vm(current->mm, npages, false);
100 
101 	dev_dbg(dev, "%ld pages unpinned\n", npages);
102 }
103 
104 /**
105  * afu_dma_check_continuous_pages - check if pages are continuous
106  * @region: dma memory region
107  *
108  * Return true if pages of given dma memory region have continuous physical
109  * address, otherwise return false.
110  */
111 static bool afu_dma_check_continuous_pages(struct dfl_afu_dma_region *region)
112 {
113 	int npages = region->length >> PAGE_SHIFT;
114 	int i;
115 
116 	for (i = 0; i < npages - 1; i++)
117 		if (page_to_pfn(region->pages[i]) + 1 !=
118 				page_to_pfn(region->pages[i + 1]))
119 			return false;
120 
121 	return true;
122 }
123 
124 /**
125  * dma_region_check_iova - check if memory area is fully contained in the region
126  * @region: dma memory region
127  * @iova: address of the dma memory area
128  * @size: size of the dma memory area
129  *
130  * Compare the dma memory area defined by @iova and @size with given dma region.
131  * Return true if memory area is fully contained in the region, otherwise false.
132  */
133 static bool dma_region_check_iova(struct dfl_afu_dma_region *region,
134 				  u64 iova, u64 size)
135 {
136 	if (!size && region->iova != iova)
137 		return false;
138 
139 	return (region->iova <= iova) &&
140 		(region->length + region->iova >= iova + size);
141 }
142 
143 /**
144  * afu_dma_region_add - add given dma region to rbtree
145  * @pdata: feature device platform data
146  * @region: dma region to be added
147  *
148  * Return 0 for success, -EEXIST if dma region has already been added.
149  *
150  * Needs to be called with pdata->lock heold.
151  */
152 static int afu_dma_region_add(struct dfl_feature_platform_data *pdata,
153 			      struct dfl_afu_dma_region *region)
154 {
155 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
156 	struct rb_node **new, *parent = NULL;
157 
158 	dev_dbg(&pdata->dev->dev, "add region (iova = %llx)\n",
159 		(unsigned long long)region->iova);
160 
161 	new = &afu->dma_regions.rb_node;
162 
163 	while (*new) {
164 		struct dfl_afu_dma_region *this;
165 
166 		this = container_of(*new, struct dfl_afu_dma_region, node);
167 
168 		parent = *new;
169 
170 		if (dma_region_check_iova(this, region->iova, region->length))
171 			return -EEXIST;
172 
173 		if (region->iova < this->iova)
174 			new = &((*new)->rb_left);
175 		else if (region->iova > this->iova)
176 			new = &((*new)->rb_right);
177 		else
178 			return -EEXIST;
179 	}
180 
181 	rb_link_node(&region->node, parent, new);
182 	rb_insert_color(&region->node, &afu->dma_regions);
183 
184 	return 0;
185 }
186 
187 /**
188  * afu_dma_region_remove - remove given dma region from rbtree
189  * @pdata: feature device platform data
190  * @region: dma region to be removed
191  *
192  * Needs to be called with pdata->lock heold.
193  */
194 static void afu_dma_region_remove(struct dfl_feature_platform_data *pdata,
195 				  struct dfl_afu_dma_region *region)
196 {
197 	struct dfl_afu *afu;
198 
199 	dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
200 		(unsigned long long)region->iova);
201 
202 	afu = dfl_fpga_pdata_get_private(pdata);
203 	rb_erase(&region->node, &afu->dma_regions);
204 }
205 
206 /**
207  * afu_dma_region_destroy - destroy all regions in rbtree
208  * @pdata: feature device platform data
209  *
210  * Needs to be called with pdata->lock heold.
211  */
212 void afu_dma_region_destroy(struct dfl_feature_platform_data *pdata)
213 {
214 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
215 	struct rb_node *node = rb_first(&afu->dma_regions);
216 	struct dfl_afu_dma_region *region;
217 
218 	while (node) {
219 		region = container_of(node, struct dfl_afu_dma_region, node);
220 
221 		dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
222 			(unsigned long long)region->iova);
223 
224 		rb_erase(node, &afu->dma_regions);
225 
226 		if (region->iova)
227 			dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
228 				       region->iova, region->length,
229 				       DMA_BIDIRECTIONAL);
230 
231 		if (region->pages)
232 			afu_dma_unpin_pages(pdata, region);
233 
234 		node = rb_next(node);
235 		kfree(region);
236 	}
237 }
238 
239 /**
240  * afu_dma_region_find - find the dma region from rbtree based on iova and size
241  * @pdata: feature device platform data
242  * @iova: address of the dma memory area
243  * @size: size of the dma memory area
244  *
245  * It finds the dma region from the rbtree based on @iova and @size:
246  * - if @size == 0, it finds the dma region which starts from @iova
247  * - otherwise, it finds the dma region which fully contains
248  *   [@iova, @iova+size)
249  * If nothing is matched returns NULL.
250  *
251  * Needs to be called with pdata->lock held.
252  */
253 struct dfl_afu_dma_region *
254 afu_dma_region_find(struct dfl_feature_platform_data *pdata, u64 iova, u64 size)
255 {
256 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
257 	struct rb_node *node = afu->dma_regions.rb_node;
258 	struct device *dev = &pdata->dev->dev;
259 
260 	while (node) {
261 		struct dfl_afu_dma_region *region;
262 
263 		region = container_of(node, struct dfl_afu_dma_region, node);
264 
265 		if (dma_region_check_iova(region, iova, size)) {
266 			dev_dbg(dev, "find region (iova = %llx)\n",
267 				(unsigned long long)region->iova);
268 			return region;
269 		}
270 
271 		if (iova < region->iova)
272 			node = node->rb_left;
273 		else if (iova > region->iova)
274 			node = node->rb_right;
275 		else
276 			/* the iova region is not fully covered. */
277 			break;
278 	}
279 
280 	dev_dbg(dev, "region with iova %llx and size %llx is not found\n",
281 		(unsigned long long)iova, (unsigned long long)size);
282 
283 	return NULL;
284 }
285 
286 /**
287  * afu_dma_region_find_iova - find the dma region from rbtree by iova
288  * @pdata: feature device platform data
289  * @iova: address of the dma region
290  *
291  * Needs to be called with pdata->lock held.
292  */
293 static struct dfl_afu_dma_region *
294 afu_dma_region_find_iova(struct dfl_feature_platform_data *pdata, u64 iova)
295 {
296 	return afu_dma_region_find(pdata, iova, 0);
297 }
298 
299 /**
300  * afu_dma_map_region - map memory region for dma
301  * @pdata: feature device platform data
302  * @user_addr: address of the memory region
303  * @length: size of the memory region
304  * @iova: pointer of iova address
305  *
306  * Map memory region defined by @user_addr and @length, and return dma address
307  * of the memory region via @iova.
308  * Return 0 for success, otherwise error code.
309  */
310 int afu_dma_map_region(struct dfl_feature_platform_data *pdata,
311 		       u64 user_addr, u64 length, u64 *iova)
312 {
313 	struct dfl_afu_dma_region *region;
314 	int ret;
315 
316 	/*
317 	 * Check Inputs, only accept page-aligned user memory region with
318 	 * valid length.
319 	 */
320 	if (!PAGE_ALIGNED(user_addr) || !PAGE_ALIGNED(length) || !length)
321 		return -EINVAL;
322 
323 	/* Check overflow */
324 	if (user_addr + length < user_addr)
325 		return -EINVAL;
326 
327 	if (!access_ok((void __user *)(unsigned long)user_addr,
328 		       length))
329 		return -EINVAL;
330 
331 	region = kzalloc(sizeof(*region), GFP_KERNEL);
332 	if (!region)
333 		return -ENOMEM;
334 
335 	region->user_addr = user_addr;
336 	region->length = length;
337 
338 	/* Pin the user memory region */
339 	ret = afu_dma_pin_pages(pdata, region);
340 	if (ret) {
341 		dev_err(&pdata->dev->dev, "failed to pin memory region\n");
342 		goto free_region;
343 	}
344 
345 	/* Only accept continuous pages, return error else */
346 	if (!afu_dma_check_continuous_pages(region)) {
347 		dev_err(&pdata->dev->dev, "pages are not continuous\n");
348 		ret = -EINVAL;
349 		goto unpin_pages;
350 	}
351 
352 	/* As pages are continuous then start to do DMA mapping */
353 	region->iova = dma_map_page(dfl_fpga_pdata_to_parent(pdata),
354 				    region->pages[0], 0,
355 				    region->length,
356 				    DMA_BIDIRECTIONAL);
357 	if (dma_mapping_error(dfl_fpga_pdata_to_parent(pdata), region->iova)) {
358 		dev_err(&pdata->dev->dev, "failed to map for dma\n");
359 		ret = -EFAULT;
360 		goto unpin_pages;
361 	}
362 
363 	*iova = region->iova;
364 
365 	mutex_lock(&pdata->lock);
366 	ret = afu_dma_region_add(pdata, region);
367 	mutex_unlock(&pdata->lock);
368 	if (ret) {
369 		dev_err(&pdata->dev->dev, "failed to add dma region\n");
370 		goto unmap_dma;
371 	}
372 
373 	return 0;
374 
375 unmap_dma:
376 	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
377 		       region->iova, region->length, DMA_BIDIRECTIONAL);
378 unpin_pages:
379 	afu_dma_unpin_pages(pdata, region);
380 free_region:
381 	kfree(region);
382 	return ret;
383 }
384 
385 /**
386  * afu_dma_unmap_region - unmap dma memory region
387  * @pdata: feature device platform data
388  * @iova: dma address of the region
389  *
390  * Unmap dma memory region based on @iova.
391  * Return 0 for success, otherwise error code.
392  */
393 int afu_dma_unmap_region(struct dfl_feature_platform_data *pdata, u64 iova)
394 {
395 	struct dfl_afu_dma_region *region;
396 
397 	mutex_lock(&pdata->lock);
398 	region = afu_dma_region_find_iova(pdata, iova);
399 	if (!region) {
400 		mutex_unlock(&pdata->lock);
401 		return -EINVAL;
402 	}
403 
404 	if (region->in_use) {
405 		mutex_unlock(&pdata->lock);
406 		return -EBUSY;
407 	}
408 
409 	afu_dma_region_remove(pdata, region);
410 	mutex_unlock(&pdata->lock);
411 
412 	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
413 		       region->iova, region->length, DMA_BIDIRECTIONAL);
414 	afu_dma_unpin_pages(pdata, region);
415 	kfree(region);
416 
417 	return 0;
418 }
419