1 /*
2  * VFIO: IOMMU DMA mapping support for TCE on POWER
3  *
4  * Copyright (C) 2013 IBM Corp.  All rights reserved.
5  *     Author: Alexey Kardashevskiy <aik@ozlabs.ru>
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 version 2 as
9  * published by the Free Software Foundation.
10  *
11  * Derived from original vfio_iommu_type1.c:
12  * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
13  *     Author: Alex Williamson <alex.williamson@redhat.com>
14  */
15 
16 #include <linux/module.h>
17 #include <linux/pci.h>
18 #include <linux/slab.h>
19 #include <linux/uaccess.h>
20 #include <linux/err.h>
21 #include <linux/vfio.h>
22 #include <asm/iommu.h>
23 #include <asm/tce.h>
24 
25 #define DRIVER_VERSION  "0.1"
26 #define DRIVER_AUTHOR   "aik@ozlabs.ru"
27 #define DRIVER_DESC     "VFIO IOMMU SPAPR TCE"
28 
29 static void tce_iommu_detach_group(void *iommu_data,
30 		struct iommu_group *iommu_group);
31 
32 /*
33  * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
34  *
35  * This code handles mapping and unmapping of user data buffers
36  * into DMA'ble space using the IOMMU
37  */
38 
39 /*
40  * The container descriptor supports only a single group per container.
41  * Required by the API as the container is not supplied with the IOMMU group
42  * at the moment of initialization.
43  */
44 struct tce_container {
45 	struct mutex lock;
46 	struct iommu_table *tbl;
47 	bool enabled;
48 };
49 
50 static int tce_iommu_enable(struct tce_container *container)
51 {
52 	int ret = 0;
53 	unsigned long locked, lock_limit, npages;
54 	struct iommu_table *tbl = container->tbl;
55 
56 	if (!container->tbl)
57 		return -ENXIO;
58 
59 	if (!current->mm)
60 		return -ESRCH; /* process exited */
61 
62 	if (container->enabled)
63 		return -EBUSY;
64 
65 	/*
66 	 * When userspace pages are mapped into the IOMMU, they are effectively
67 	 * locked memory, so, theoretically, we need to update the accounting
68 	 * of locked pages on each map and unmap.  For powerpc, the map unmap
69 	 * paths can be very hot, though, and the accounting would kill
70 	 * performance, especially since it would be difficult to impossible
71 	 * to handle the accounting in real mode only.
72 	 *
73 	 * To address that, rather than precisely accounting every page, we
74 	 * instead account for a worst case on locked memory when the iommu is
75 	 * enabled and disabled.  The worst case upper bound on locked memory
76 	 * is the size of the whole iommu window, which is usually relatively
77 	 * small (compared to total memory sizes) on POWER hardware.
78 	 *
79 	 * Also we don't have a nice way to fail on H_PUT_TCE due to ulimits,
80 	 * that would effectively kill the guest at random points, much better
81 	 * enforcing the limit based on the max that the guest can map.
82 	 */
83 	down_write(&current->mm->mmap_sem);
84 	npages = (tbl->it_size << IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
85 	locked = current->mm->locked_vm + npages;
86 	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
87 	if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
88 		pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n",
89 				rlimit(RLIMIT_MEMLOCK));
90 		ret = -ENOMEM;
91 	} else {
92 
93 		current->mm->locked_vm += npages;
94 		container->enabled = true;
95 	}
96 	up_write(&current->mm->mmap_sem);
97 
98 	return ret;
99 }
100 
101 static void tce_iommu_disable(struct tce_container *container)
102 {
103 	if (!container->enabled)
104 		return;
105 
106 	container->enabled = false;
107 
108 	if (!container->tbl || !current->mm)
109 		return;
110 
111 	down_write(&current->mm->mmap_sem);
112 	current->mm->locked_vm -= (container->tbl->it_size <<
113 			IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
114 	up_write(&current->mm->mmap_sem);
115 }
116 
117 static void *tce_iommu_open(unsigned long arg)
118 {
119 	struct tce_container *container;
120 
121 	if (arg != VFIO_SPAPR_TCE_IOMMU) {
122 		pr_err("tce_vfio: Wrong IOMMU type\n");
123 		return ERR_PTR(-EINVAL);
124 	}
125 
126 	container = kzalloc(sizeof(*container), GFP_KERNEL);
127 	if (!container)
128 		return ERR_PTR(-ENOMEM);
129 
130 	mutex_init(&container->lock);
131 
132 	return container;
133 }
134 
135 static void tce_iommu_release(void *iommu_data)
136 {
137 	struct tce_container *container = iommu_data;
138 
139 	WARN_ON(container->tbl && !container->tbl->it_group);
140 	tce_iommu_disable(container);
141 
142 	if (container->tbl && container->tbl->it_group)
143 		tce_iommu_detach_group(iommu_data, container->tbl->it_group);
144 
145 	mutex_destroy(&container->lock);
146 
147 	kfree(container);
148 }
149 
150 static long tce_iommu_ioctl(void *iommu_data,
151 				 unsigned int cmd, unsigned long arg)
152 {
153 	struct tce_container *container = iommu_data;
154 	unsigned long minsz;
155 	long ret;
156 
157 	switch (cmd) {
158 	case VFIO_CHECK_EXTENSION:
159 		return (arg == VFIO_SPAPR_TCE_IOMMU) ? 1 : 0;
160 
161 	case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
162 		struct vfio_iommu_spapr_tce_info info;
163 		struct iommu_table *tbl = container->tbl;
164 
165 		if (WARN_ON(!tbl))
166 			return -ENXIO;
167 
168 		minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
169 				dma32_window_size);
170 
171 		if (copy_from_user(&info, (void __user *)arg, minsz))
172 			return -EFAULT;
173 
174 		if (info.argsz < minsz)
175 			return -EINVAL;
176 
177 		info.dma32_window_start = tbl->it_offset << IOMMU_PAGE_SHIFT_4K;
178 		info.dma32_window_size = tbl->it_size << IOMMU_PAGE_SHIFT_4K;
179 		info.flags = 0;
180 
181 		if (copy_to_user((void __user *)arg, &info, minsz))
182 			return -EFAULT;
183 
184 		return 0;
185 	}
186 	case VFIO_IOMMU_MAP_DMA: {
187 		struct vfio_iommu_type1_dma_map param;
188 		struct iommu_table *tbl = container->tbl;
189 		unsigned long tce, i;
190 
191 		if (!tbl)
192 			return -ENXIO;
193 
194 		BUG_ON(!tbl->it_group);
195 
196 		minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);
197 
198 		if (copy_from_user(&param, (void __user *)arg, minsz))
199 			return -EFAULT;
200 
201 		if (param.argsz < minsz)
202 			return -EINVAL;
203 
204 		if (param.flags & ~(VFIO_DMA_MAP_FLAG_READ |
205 				VFIO_DMA_MAP_FLAG_WRITE))
206 			return -EINVAL;
207 
208 		if ((param.size & ~IOMMU_PAGE_MASK_4K) ||
209 				(param.vaddr & ~IOMMU_PAGE_MASK_4K))
210 			return -EINVAL;
211 
212 		/* iova is checked by the IOMMU API */
213 		tce = param.vaddr;
214 		if (param.flags & VFIO_DMA_MAP_FLAG_READ)
215 			tce |= TCE_PCI_READ;
216 		if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
217 			tce |= TCE_PCI_WRITE;
218 
219 		ret = iommu_tce_put_param_check(tbl, param.iova, tce);
220 		if (ret)
221 			return ret;
222 
223 		for (i = 0; i < (param.size >> IOMMU_PAGE_SHIFT_4K); ++i) {
224 			ret = iommu_put_tce_user_mode(tbl,
225 					(param.iova >> IOMMU_PAGE_SHIFT_4K) + i,
226 					tce);
227 			if (ret)
228 				break;
229 			tce += IOMMU_PAGE_SIZE_4K;
230 		}
231 		if (ret)
232 			iommu_clear_tces_and_put_pages(tbl,
233 					param.iova >> IOMMU_PAGE_SHIFT_4K, i);
234 
235 		iommu_flush_tce(tbl);
236 
237 		return ret;
238 	}
239 	case VFIO_IOMMU_UNMAP_DMA: {
240 		struct vfio_iommu_type1_dma_unmap param;
241 		struct iommu_table *tbl = container->tbl;
242 
243 		if (WARN_ON(!tbl))
244 			return -ENXIO;
245 
246 		minsz = offsetofend(struct vfio_iommu_type1_dma_unmap,
247 				size);
248 
249 		if (copy_from_user(&param, (void __user *)arg, minsz))
250 			return -EFAULT;
251 
252 		if (param.argsz < minsz)
253 			return -EINVAL;
254 
255 		/* No flag is supported now */
256 		if (param.flags)
257 			return -EINVAL;
258 
259 		if (param.size & ~IOMMU_PAGE_MASK_4K)
260 			return -EINVAL;
261 
262 		ret = iommu_tce_clear_param_check(tbl, param.iova, 0,
263 				param.size >> IOMMU_PAGE_SHIFT_4K);
264 		if (ret)
265 			return ret;
266 
267 		ret = iommu_clear_tces_and_put_pages(tbl,
268 				param.iova >> IOMMU_PAGE_SHIFT_4K,
269 				param.size >> IOMMU_PAGE_SHIFT_4K);
270 		iommu_flush_tce(tbl);
271 
272 		return ret;
273 	}
274 	case VFIO_IOMMU_ENABLE:
275 		mutex_lock(&container->lock);
276 		ret = tce_iommu_enable(container);
277 		mutex_unlock(&container->lock);
278 		return ret;
279 
280 
281 	case VFIO_IOMMU_DISABLE:
282 		mutex_lock(&container->lock);
283 		tce_iommu_disable(container);
284 		mutex_unlock(&container->lock);
285 		return 0;
286 	}
287 
288 	return -ENOTTY;
289 }
290 
291 static int tce_iommu_attach_group(void *iommu_data,
292 		struct iommu_group *iommu_group)
293 {
294 	int ret;
295 	struct tce_container *container = iommu_data;
296 	struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
297 
298 	BUG_ON(!tbl);
299 	mutex_lock(&container->lock);
300 
301 	/* pr_debug("tce_vfio: Attaching group #%u to iommu %p\n",
302 			iommu_group_id(iommu_group), iommu_group); */
303 	if (container->tbl) {
304 		pr_warn("tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n",
305 				iommu_group_id(container->tbl->it_group),
306 				iommu_group_id(iommu_group));
307 		ret = -EBUSY;
308 	} else if (container->enabled) {
309 		pr_err("tce_vfio: attaching group #%u to enabled container\n",
310 				iommu_group_id(iommu_group));
311 		ret = -EBUSY;
312 	} else {
313 		ret = iommu_take_ownership(tbl);
314 		if (!ret)
315 			container->tbl = tbl;
316 	}
317 
318 	mutex_unlock(&container->lock);
319 
320 	return ret;
321 }
322 
323 static void tce_iommu_detach_group(void *iommu_data,
324 		struct iommu_group *iommu_group)
325 {
326 	struct tce_container *container = iommu_data;
327 	struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
328 
329 	BUG_ON(!tbl);
330 	mutex_lock(&container->lock);
331 	if (tbl != container->tbl) {
332 		pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
333 				iommu_group_id(iommu_group),
334 				iommu_group_id(tbl->it_group));
335 	} else {
336 		if (container->enabled) {
337 			pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
338 					iommu_group_id(tbl->it_group));
339 			tce_iommu_disable(container);
340 		}
341 
342 		/* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
343 				iommu_group_id(iommu_group), iommu_group); */
344 		container->tbl = NULL;
345 		iommu_release_ownership(tbl);
346 	}
347 	mutex_unlock(&container->lock);
348 }
349 
350 const struct vfio_iommu_driver_ops tce_iommu_driver_ops = {
351 	.name		= "iommu-vfio-powerpc",
352 	.owner		= THIS_MODULE,
353 	.open		= tce_iommu_open,
354 	.release	= tce_iommu_release,
355 	.ioctl		= tce_iommu_ioctl,
356 	.attach_group	= tce_iommu_attach_group,
357 	.detach_group	= tce_iommu_detach_group,
358 };
359 
360 static int __init tce_iommu_init(void)
361 {
362 	return vfio_register_iommu_driver(&tce_iommu_driver_ops);
363 }
364 
365 static void __exit tce_iommu_cleanup(void)
366 {
367 	vfio_unregister_iommu_driver(&tce_iommu_driver_ops);
368 }
369 
370 module_init(tce_iommu_init);
371 module_exit(tce_iommu_cleanup);
372 
373 MODULE_VERSION(DRIVER_VERSION);
374 MODULE_LICENSE("GPL v2");
375 MODULE_AUTHOR(DRIVER_AUTHOR);
376 MODULE_DESCRIPTION(DRIVER_DESC);
377 
378