xref: /openbmc/linux/drivers/vfio/group.c (revision 5398be25)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * VFIO core
4  *
5  * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
6  *     Author: Alex Williamson <alex.williamson@redhat.com>
7  *
8  * Derived from original vfio:
9  * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
10  * Author: Tom Lyon, pugs@cisco.com
11  */
12 
13 #include <linux/vfio.h>
14 #include <linux/iommufd.h>
15 #include <linux/anon_inodes.h>
16 #include "vfio.h"
17 
18 static struct vfio {
19 	struct class			*class;
20 	struct list_head		group_list;
21 	struct mutex			group_lock; /* locks group_list */
22 	struct ida			group_ida;
23 	dev_t				group_devt;
24 } vfio;
25 
vfio_device_get_from_name(struct vfio_group * group,char * buf)26 static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
27 						     char *buf)
28 {
29 	struct vfio_device *it, *device = ERR_PTR(-ENODEV);
30 
31 	mutex_lock(&group->device_lock);
32 	list_for_each_entry(it, &group->device_list, group_next) {
33 		int ret;
34 
35 		if (it->ops->match) {
36 			ret = it->ops->match(it, buf);
37 			if (ret < 0) {
38 				device = ERR_PTR(ret);
39 				break;
40 			}
41 		} else {
42 			ret = !strcmp(dev_name(it->dev), buf);
43 		}
44 
45 		if (ret && vfio_device_try_get_registration(it)) {
46 			device = it;
47 			break;
48 		}
49 	}
50 	mutex_unlock(&group->device_lock);
51 
52 	return device;
53 }
54 
55 /*
56  * VFIO Group fd, /dev/vfio/$GROUP
57  */
vfio_group_has_iommu(struct vfio_group * group)58 static bool vfio_group_has_iommu(struct vfio_group *group)
59 {
60 	lockdep_assert_held(&group->group_lock);
61 	/*
62 	 * There can only be users if there is a container, and if there is a
63 	 * container there must be users.
64 	 */
65 	WARN_ON(!group->container != !group->container_users);
66 
67 	return group->container || group->iommufd;
68 }
69 
70 /*
71  * VFIO_GROUP_UNSET_CONTAINER should fail if there are other users or
72  * if there was no container to unset.  Since the ioctl is called on
73  * the group, we know that still exists, therefore the only valid
74  * transition here is 1->0.
75  */
vfio_group_ioctl_unset_container(struct vfio_group * group)76 static int vfio_group_ioctl_unset_container(struct vfio_group *group)
77 {
78 	int ret = 0;
79 
80 	mutex_lock(&group->group_lock);
81 	if (!vfio_group_has_iommu(group)) {
82 		ret = -EINVAL;
83 		goto out_unlock;
84 	}
85 	if (group->container) {
86 		if (group->container_users != 1) {
87 			ret = -EBUSY;
88 			goto out_unlock;
89 		}
90 		vfio_group_detach_container(group);
91 	}
92 	if (group->iommufd) {
93 		iommufd_ctx_put(group->iommufd);
94 		group->iommufd = NULL;
95 	}
96 
97 out_unlock:
98 	mutex_unlock(&group->group_lock);
99 	return ret;
100 }
101 
vfio_group_ioctl_set_container(struct vfio_group * group,int __user * arg)102 static int vfio_group_ioctl_set_container(struct vfio_group *group,
103 					  int __user *arg)
104 {
105 	struct vfio_container *container;
106 	struct iommufd_ctx *iommufd;
107 	struct fd f;
108 	int ret;
109 	int fd;
110 
111 	if (get_user(fd, arg))
112 		return -EFAULT;
113 
114 	f = fdget(fd);
115 	if (!f.file)
116 		return -EBADF;
117 
118 	mutex_lock(&group->group_lock);
119 	if (vfio_group_has_iommu(group)) {
120 		ret = -EINVAL;
121 		goto out_unlock;
122 	}
123 	if (!group->iommu_group) {
124 		ret = -ENODEV;
125 		goto out_unlock;
126 	}
127 
128 	container = vfio_container_from_file(f.file);
129 	if (container) {
130 		ret = vfio_container_attach_group(container, group);
131 		goto out_unlock;
132 	}
133 
134 	iommufd = iommufd_ctx_from_file(f.file);
135 	if (!IS_ERR(iommufd)) {
136 		if (IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
137 		    group->type == VFIO_NO_IOMMU)
138 			ret = iommufd_vfio_compat_set_no_iommu(iommufd);
139 		else
140 			ret = iommufd_vfio_compat_ioas_create(iommufd);
141 
142 		if (ret) {
143 			iommufd_ctx_put(iommufd);
144 			goto out_unlock;
145 		}
146 
147 		group->iommufd = iommufd;
148 		goto out_unlock;
149 	}
150 
151 	/* The FD passed is not recognized. */
152 	ret = -EBADFD;
153 
154 out_unlock:
155 	mutex_unlock(&group->group_lock);
156 	fdput(f);
157 	return ret;
158 }
159 
vfio_device_group_get_kvm_safe(struct vfio_device * device)160 static void vfio_device_group_get_kvm_safe(struct vfio_device *device)
161 {
162 	spin_lock(&device->group->kvm_ref_lock);
163 	vfio_device_get_kvm_safe(device, device->group->kvm);
164 	spin_unlock(&device->group->kvm_ref_lock);
165 }
166 
vfio_df_group_open(struct vfio_device_file * df)167 static int vfio_df_group_open(struct vfio_device_file *df)
168 {
169 	struct vfio_device *device = df->device;
170 	int ret;
171 
172 	mutex_lock(&device->group->group_lock);
173 	if (!vfio_group_has_iommu(device->group)) {
174 		ret = -EINVAL;
175 		goto out_unlock;
176 	}
177 
178 	mutex_lock(&device->dev_set->lock);
179 
180 	/*
181 	 * Before the first device open, get the KVM pointer currently
182 	 * associated with the group (if there is one) and obtain a reference
183 	 * now that will be held until the open_count reaches 0 again.  Save
184 	 * the pointer in the device for use by drivers.
185 	 */
186 	if (device->open_count == 0)
187 		vfio_device_group_get_kvm_safe(device);
188 
189 	df->iommufd = device->group->iommufd;
190 	if (df->iommufd && vfio_device_is_noiommu(device) && device->open_count == 0) {
191 		/*
192 		 * Require no compat ioas to be assigned to proceed.  The basic
193 		 * statement is that the user cannot have done something that
194 		 * implies they expected translation to exist
195 		 */
196 		if (!capable(CAP_SYS_RAWIO) ||
197 		    vfio_iommufd_device_has_compat_ioas(device, df->iommufd))
198 			ret = -EPERM;
199 		else
200 			ret = 0;
201 		goto out_put_kvm;
202 	}
203 
204 	ret = vfio_df_open(df);
205 	if (ret)
206 		goto out_put_kvm;
207 
208 	if (df->iommufd && device->open_count == 1) {
209 		ret = vfio_iommufd_compat_attach_ioas(device, df->iommufd);
210 		if (ret)
211 			goto out_close_device;
212 	}
213 
214 	/*
215 	 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
216 	 * read/write/mmap and vfio_file_has_device_access()
217 	 */
218 	smp_store_release(&df->access_granted, true);
219 
220 	mutex_unlock(&device->dev_set->lock);
221 	mutex_unlock(&device->group->group_lock);
222 	return 0;
223 
224 out_close_device:
225 	vfio_df_close(df);
226 out_put_kvm:
227 	df->iommufd = NULL;
228 	if (device->open_count == 0)
229 		vfio_device_put_kvm(device);
230 	mutex_unlock(&device->dev_set->lock);
231 out_unlock:
232 	mutex_unlock(&device->group->group_lock);
233 	return ret;
234 }
235 
vfio_df_group_close(struct vfio_device_file * df)236 void vfio_df_group_close(struct vfio_device_file *df)
237 {
238 	struct vfio_device *device = df->device;
239 
240 	mutex_lock(&device->group->group_lock);
241 	mutex_lock(&device->dev_set->lock);
242 
243 	vfio_df_close(df);
244 	df->iommufd = NULL;
245 
246 	if (device->open_count == 0)
247 		vfio_device_put_kvm(device);
248 
249 	mutex_unlock(&device->dev_set->lock);
250 	mutex_unlock(&device->group->group_lock);
251 }
252 
vfio_device_open_file(struct vfio_device * device)253 static struct file *vfio_device_open_file(struct vfio_device *device)
254 {
255 	struct vfio_device_file *df;
256 	struct file *filep;
257 	int ret;
258 
259 	df = vfio_allocate_device_file(device);
260 	if (IS_ERR(df)) {
261 		ret = PTR_ERR(df);
262 		goto err_out;
263 	}
264 
265 	df->group = device->group;
266 
267 	ret = vfio_df_group_open(df);
268 	if (ret)
269 		goto err_free;
270 
271 	/*
272 	 * We can't use anon_inode_getfd() because we need to modify
273 	 * the f_mode flags directly to allow more than just ioctls
274 	 */
275 	filep = anon_inode_getfile("[vfio-device]", &vfio_device_fops,
276 				   df, O_RDWR);
277 	if (IS_ERR(filep)) {
278 		ret = PTR_ERR(filep);
279 		goto err_close_device;
280 	}
281 
282 	/*
283 	 * TODO: add an anon_inode interface to do this.
284 	 * Appears to be missing by lack of need rather than
285 	 * explicitly prevented.  Now there's need.
286 	 */
287 	filep->f_mode |= (FMODE_PREAD | FMODE_PWRITE);
288 
289 	if (device->group->type == VFIO_NO_IOMMU)
290 		dev_warn(device->dev, "vfio-noiommu device opened by user "
291 			 "(%s:%d)\n", current->comm, task_pid_nr(current));
292 	/*
293 	 * On success the ref of device is moved to the file and
294 	 * put in vfio_device_fops_release()
295 	 */
296 	return filep;
297 
298 err_close_device:
299 	vfio_df_group_close(df);
300 err_free:
301 	kfree(df);
302 err_out:
303 	return ERR_PTR(ret);
304 }
305 
vfio_group_ioctl_get_device_fd(struct vfio_group * group,char __user * arg)306 static int vfio_group_ioctl_get_device_fd(struct vfio_group *group,
307 					  char __user *arg)
308 {
309 	struct vfio_device *device;
310 	struct file *filep;
311 	char *buf;
312 	int fdno;
313 	int ret;
314 
315 	buf = strndup_user(arg, PAGE_SIZE);
316 	if (IS_ERR(buf))
317 		return PTR_ERR(buf);
318 
319 	device = vfio_device_get_from_name(group, buf);
320 	kfree(buf);
321 	if (IS_ERR(device))
322 		return PTR_ERR(device);
323 
324 	fdno = get_unused_fd_flags(O_CLOEXEC);
325 	if (fdno < 0) {
326 		ret = fdno;
327 		goto err_put_device;
328 	}
329 
330 	filep = vfio_device_open_file(device);
331 	if (IS_ERR(filep)) {
332 		ret = PTR_ERR(filep);
333 		goto err_put_fdno;
334 	}
335 
336 	fd_install(fdno, filep);
337 	return fdno;
338 
339 err_put_fdno:
340 	put_unused_fd(fdno);
341 err_put_device:
342 	vfio_device_put_registration(device);
343 	return ret;
344 }
345 
vfio_group_ioctl_get_status(struct vfio_group * group,struct vfio_group_status __user * arg)346 static int vfio_group_ioctl_get_status(struct vfio_group *group,
347 				       struct vfio_group_status __user *arg)
348 {
349 	unsigned long minsz = offsetofend(struct vfio_group_status, flags);
350 	struct vfio_group_status status;
351 
352 	if (copy_from_user(&status, arg, minsz))
353 		return -EFAULT;
354 
355 	if (status.argsz < minsz)
356 		return -EINVAL;
357 
358 	status.flags = 0;
359 
360 	mutex_lock(&group->group_lock);
361 	if (!group->iommu_group) {
362 		mutex_unlock(&group->group_lock);
363 		return -ENODEV;
364 	}
365 
366 	/*
367 	 * With the container FD the iommu_group_claim_dma_owner() is done
368 	 * during SET_CONTAINER but for IOMMFD this is done during
369 	 * VFIO_GROUP_GET_DEVICE_FD. Meaning that with iommufd
370 	 * VFIO_GROUP_FLAGS_VIABLE could be set but GET_DEVICE_FD will fail due
371 	 * to viability.
372 	 */
373 	if (vfio_group_has_iommu(group))
374 		status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET |
375 				VFIO_GROUP_FLAGS_VIABLE;
376 	else if (!iommu_group_dma_owner_claimed(group->iommu_group))
377 		status.flags |= VFIO_GROUP_FLAGS_VIABLE;
378 	mutex_unlock(&group->group_lock);
379 
380 	if (copy_to_user(arg, &status, minsz))
381 		return -EFAULT;
382 	return 0;
383 }
384 
vfio_group_fops_unl_ioctl(struct file * filep,unsigned int cmd,unsigned long arg)385 static long vfio_group_fops_unl_ioctl(struct file *filep,
386 				      unsigned int cmd, unsigned long arg)
387 {
388 	struct vfio_group *group = filep->private_data;
389 	void __user *uarg = (void __user *)arg;
390 
391 	switch (cmd) {
392 	case VFIO_GROUP_GET_DEVICE_FD:
393 		return vfio_group_ioctl_get_device_fd(group, uarg);
394 	case VFIO_GROUP_GET_STATUS:
395 		return vfio_group_ioctl_get_status(group, uarg);
396 	case VFIO_GROUP_SET_CONTAINER:
397 		return vfio_group_ioctl_set_container(group, uarg);
398 	case VFIO_GROUP_UNSET_CONTAINER:
399 		return vfio_group_ioctl_unset_container(group);
400 	default:
401 		return -ENOTTY;
402 	}
403 }
404 
vfio_device_block_group(struct vfio_device * device)405 int vfio_device_block_group(struct vfio_device *device)
406 {
407 	struct vfio_group *group = device->group;
408 	int ret = 0;
409 
410 	mutex_lock(&group->group_lock);
411 	if (group->opened_file) {
412 		ret = -EBUSY;
413 		goto out_unlock;
414 	}
415 
416 	group->cdev_device_open_cnt++;
417 
418 out_unlock:
419 	mutex_unlock(&group->group_lock);
420 	return ret;
421 }
422 
vfio_device_unblock_group(struct vfio_device * device)423 void vfio_device_unblock_group(struct vfio_device *device)
424 {
425 	struct vfio_group *group = device->group;
426 
427 	mutex_lock(&group->group_lock);
428 	group->cdev_device_open_cnt--;
429 	mutex_unlock(&group->group_lock);
430 }
431 
vfio_group_fops_open(struct inode * inode,struct file * filep)432 static int vfio_group_fops_open(struct inode *inode, struct file *filep)
433 {
434 	struct vfio_group *group =
435 		container_of(inode->i_cdev, struct vfio_group, cdev);
436 	int ret;
437 
438 	mutex_lock(&group->group_lock);
439 
440 	/*
441 	 * drivers can be zero if this races with vfio_device_remove_group(), it
442 	 * will be stable at 0 under the group rwsem
443 	 */
444 	if (refcount_read(&group->drivers) == 0) {
445 		ret = -ENODEV;
446 		goto out_unlock;
447 	}
448 
449 	if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO)) {
450 		ret = -EPERM;
451 		goto out_unlock;
452 	}
453 
454 	if (group->cdev_device_open_cnt) {
455 		ret = -EBUSY;
456 		goto out_unlock;
457 	}
458 
459 	/*
460 	 * Do we need multiple instances of the group open?  Seems not.
461 	 */
462 	if (group->opened_file) {
463 		ret = -EBUSY;
464 		goto out_unlock;
465 	}
466 	group->opened_file = filep;
467 	filep->private_data = group;
468 	ret = 0;
469 out_unlock:
470 	mutex_unlock(&group->group_lock);
471 	return ret;
472 }
473 
vfio_group_fops_release(struct inode * inode,struct file * filep)474 static int vfio_group_fops_release(struct inode *inode, struct file *filep)
475 {
476 	struct vfio_group *group = filep->private_data;
477 
478 	filep->private_data = NULL;
479 
480 	mutex_lock(&group->group_lock);
481 	/*
482 	 * Device FDs hold a group file reference, therefore the group release
483 	 * is only called when there are no open devices.
484 	 */
485 	WARN_ON(group->notifier.head);
486 	if (group->container)
487 		vfio_group_detach_container(group);
488 	if (group->iommufd) {
489 		iommufd_ctx_put(group->iommufd);
490 		group->iommufd = NULL;
491 	}
492 	group->opened_file = NULL;
493 	mutex_unlock(&group->group_lock);
494 	return 0;
495 }
496 
497 static const struct file_operations vfio_group_fops = {
498 	.owner		= THIS_MODULE,
499 	.unlocked_ioctl	= vfio_group_fops_unl_ioctl,
500 	.compat_ioctl	= compat_ptr_ioctl,
501 	.open		= vfio_group_fops_open,
502 	.release	= vfio_group_fops_release,
503 };
504 
505 /*
506  * Group objects - create, release, get, put, search
507  */
508 static struct vfio_group *
vfio_group_find_from_iommu(struct iommu_group * iommu_group)509 vfio_group_find_from_iommu(struct iommu_group *iommu_group)
510 {
511 	struct vfio_group *group;
512 
513 	lockdep_assert_held(&vfio.group_lock);
514 
515 	/*
516 	 * group->iommu_group from the vfio.group_list cannot be NULL
517 	 * under the vfio.group_lock.
518 	 */
519 	list_for_each_entry(group, &vfio.group_list, vfio_next) {
520 		if (group->iommu_group == iommu_group)
521 			return group;
522 	}
523 	return NULL;
524 }
525 
vfio_group_release(struct device * dev)526 static void vfio_group_release(struct device *dev)
527 {
528 	struct vfio_group *group = container_of(dev, struct vfio_group, dev);
529 
530 	mutex_destroy(&group->device_lock);
531 	mutex_destroy(&group->group_lock);
532 	WARN_ON(group->iommu_group);
533 	WARN_ON(group->cdev_device_open_cnt);
534 	ida_free(&vfio.group_ida, MINOR(group->dev.devt));
535 	kfree(group);
536 }
537 
vfio_group_alloc(struct iommu_group * iommu_group,enum vfio_group_type type)538 static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group,
539 					   enum vfio_group_type type)
540 {
541 	struct vfio_group *group;
542 	int minor;
543 
544 	group = kzalloc(sizeof(*group), GFP_KERNEL);
545 	if (!group)
546 		return ERR_PTR(-ENOMEM);
547 
548 	minor = ida_alloc_max(&vfio.group_ida, MINORMASK, GFP_KERNEL);
549 	if (minor < 0) {
550 		kfree(group);
551 		return ERR_PTR(minor);
552 	}
553 
554 	device_initialize(&group->dev);
555 	group->dev.devt = MKDEV(MAJOR(vfio.group_devt), minor);
556 	group->dev.class = vfio.class;
557 	group->dev.release = vfio_group_release;
558 	cdev_init(&group->cdev, &vfio_group_fops);
559 	group->cdev.owner = THIS_MODULE;
560 
561 	refcount_set(&group->drivers, 1);
562 	mutex_init(&group->group_lock);
563 	spin_lock_init(&group->kvm_ref_lock);
564 	INIT_LIST_HEAD(&group->device_list);
565 	mutex_init(&group->device_lock);
566 	group->iommu_group = iommu_group;
567 	/* put in vfio_group_release() */
568 	iommu_group_ref_get(iommu_group);
569 	group->type = type;
570 	BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);
571 
572 	return group;
573 }
574 
vfio_create_group(struct iommu_group * iommu_group,enum vfio_group_type type)575 static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
576 		enum vfio_group_type type)
577 {
578 	struct vfio_group *group;
579 	struct vfio_group *ret;
580 	int err;
581 
582 	lockdep_assert_held(&vfio.group_lock);
583 
584 	group = vfio_group_alloc(iommu_group, type);
585 	if (IS_ERR(group))
586 		return group;
587 
588 	err = dev_set_name(&group->dev, "%s%d",
589 			   group->type == VFIO_NO_IOMMU ? "noiommu-" : "",
590 			   iommu_group_id(iommu_group));
591 	if (err) {
592 		ret = ERR_PTR(err);
593 		goto err_put;
594 	}
595 
596 	err = cdev_device_add(&group->cdev, &group->dev);
597 	if (err) {
598 		ret = ERR_PTR(err);
599 		goto err_put;
600 	}
601 
602 	list_add(&group->vfio_next, &vfio.group_list);
603 
604 	return group;
605 
606 err_put:
607 	put_device(&group->dev);
608 	return ret;
609 }
610 
vfio_noiommu_group_alloc(struct device * dev,enum vfio_group_type type)611 static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
612 		enum vfio_group_type type)
613 {
614 	struct iommu_group *iommu_group;
615 	struct vfio_group *group;
616 	int ret;
617 
618 	iommu_group = iommu_group_alloc();
619 	if (IS_ERR(iommu_group))
620 		return ERR_CAST(iommu_group);
621 
622 	ret = iommu_group_set_name(iommu_group, "vfio-noiommu");
623 	if (ret)
624 		goto out_put_group;
625 	ret = iommu_group_add_device(iommu_group, dev);
626 	if (ret)
627 		goto out_put_group;
628 
629 	mutex_lock(&vfio.group_lock);
630 	group = vfio_create_group(iommu_group, type);
631 	mutex_unlock(&vfio.group_lock);
632 	if (IS_ERR(group)) {
633 		ret = PTR_ERR(group);
634 		goto out_remove_device;
635 	}
636 	iommu_group_put(iommu_group);
637 	return group;
638 
639 out_remove_device:
640 	iommu_group_remove_device(dev);
641 out_put_group:
642 	iommu_group_put(iommu_group);
643 	return ERR_PTR(ret);
644 }
645 
vfio_group_has_device(struct vfio_group * group,struct device * dev)646 static bool vfio_group_has_device(struct vfio_group *group, struct device *dev)
647 {
648 	struct vfio_device *device;
649 
650 	mutex_lock(&group->device_lock);
651 	list_for_each_entry(device, &group->device_list, group_next) {
652 		if (device->dev == dev) {
653 			mutex_unlock(&group->device_lock);
654 			return true;
655 		}
656 	}
657 	mutex_unlock(&group->device_lock);
658 	return false;
659 }
660 
vfio_group_find_or_alloc(struct device * dev)661 static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
662 {
663 	struct iommu_group *iommu_group;
664 	struct vfio_group *group;
665 
666 	iommu_group = iommu_group_get(dev);
667 	if (!iommu_group && vfio_noiommu) {
668 		/*
669 		 * With noiommu enabled, create an IOMMU group for devices that
670 		 * don't already have one, implying no IOMMU hardware/driver
671 		 * exists.  Taint the kernel because we're about to give a DMA
672 		 * capable device to a user without IOMMU protection.
673 		 */
674 		group = vfio_noiommu_group_alloc(dev, VFIO_NO_IOMMU);
675 		if (!IS_ERR(group)) {
676 			add_taint(TAINT_USER, LOCKDEP_STILL_OK);
677 			dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
678 		}
679 		return group;
680 	}
681 
682 	if (!iommu_group)
683 		return ERR_PTR(-EINVAL);
684 
685 	mutex_lock(&vfio.group_lock);
686 	group = vfio_group_find_from_iommu(iommu_group);
687 	if (group) {
688 		if (WARN_ON(vfio_group_has_device(group, dev)))
689 			group = ERR_PTR(-EINVAL);
690 		else
691 			refcount_inc(&group->drivers);
692 	} else {
693 		group = vfio_create_group(iommu_group, VFIO_IOMMU);
694 	}
695 	mutex_unlock(&vfio.group_lock);
696 
697 	/* The vfio_group holds a reference to the iommu_group */
698 	iommu_group_put(iommu_group);
699 	return group;
700 }
701 
vfio_device_set_group(struct vfio_device * device,enum vfio_group_type type)702 int vfio_device_set_group(struct vfio_device *device,
703 			  enum vfio_group_type type)
704 {
705 	struct vfio_group *group;
706 
707 	if (type == VFIO_IOMMU)
708 		group = vfio_group_find_or_alloc(device->dev);
709 	else
710 		group = vfio_noiommu_group_alloc(device->dev, type);
711 
712 	if (IS_ERR(group))
713 		return PTR_ERR(group);
714 
715 	/* Our reference on group is moved to the device */
716 	device->group = group;
717 	return 0;
718 }
719 
vfio_device_remove_group(struct vfio_device * device)720 void vfio_device_remove_group(struct vfio_device *device)
721 {
722 	struct vfio_group *group = device->group;
723 	struct iommu_group *iommu_group;
724 
725 	if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
726 		iommu_group_remove_device(device->dev);
727 
728 	/* Pairs with vfio_create_group() / vfio_group_get_from_iommu() */
729 	if (!refcount_dec_and_mutex_lock(&group->drivers, &vfio.group_lock))
730 		return;
731 	list_del(&group->vfio_next);
732 
733 	/*
734 	 * We could concurrently probe another driver in the group that might
735 	 * race vfio_device_remove_group() with vfio_get_group(), so we have to
736 	 * ensure that the sysfs is all cleaned up under lock otherwise the
737 	 * cdev_device_add() will fail due to the name aready existing.
738 	 */
739 	cdev_device_del(&group->cdev, &group->dev);
740 
741 	mutex_lock(&group->group_lock);
742 	/*
743 	 * These data structures all have paired operations that can only be
744 	 * undone when the caller holds a live reference on the device. Since
745 	 * all pairs must be undone these WARN_ON's indicate some caller did not
746 	 * properly hold the group reference.
747 	 */
748 	WARN_ON(!list_empty(&group->device_list));
749 	WARN_ON(group->notifier.head);
750 
751 	/*
752 	 * Revoke all users of group->iommu_group. At this point we know there
753 	 * are no devices active because we are unplugging the last one. Setting
754 	 * iommu_group to NULL blocks all new users.
755 	 */
756 	if (group->container)
757 		vfio_group_detach_container(group);
758 	iommu_group = group->iommu_group;
759 	group->iommu_group = NULL;
760 	mutex_unlock(&group->group_lock);
761 	mutex_unlock(&vfio.group_lock);
762 
763 	iommu_group_put(iommu_group);
764 	put_device(&group->dev);
765 }
766 
vfio_device_group_register(struct vfio_device * device)767 void vfio_device_group_register(struct vfio_device *device)
768 {
769 	mutex_lock(&device->group->device_lock);
770 	list_add(&device->group_next, &device->group->device_list);
771 	mutex_unlock(&device->group->device_lock);
772 }
773 
vfio_device_group_unregister(struct vfio_device * device)774 void vfio_device_group_unregister(struct vfio_device *device)
775 {
776 	mutex_lock(&device->group->device_lock);
777 	list_del(&device->group_next);
778 	mutex_unlock(&device->group->device_lock);
779 }
780 
vfio_device_group_use_iommu(struct vfio_device * device)781 int vfio_device_group_use_iommu(struct vfio_device *device)
782 {
783 	struct vfio_group *group = device->group;
784 	int ret = 0;
785 
786 	lockdep_assert_held(&group->group_lock);
787 
788 	if (WARN_ON(!group->container))
789 		return -EINVAL;
790 
791 	ret = vfio_group_use_container(group);
792 	if (ret)
793 		return ret;
794 	vfio_device_container_register(device);
795 	return 0;
796 }
797 
vfio_device_group_unuse_iommu(struct vfio_device * device)798 void vfio_device_group_unuse_iommu(struct vfio_device *device)
799 {
800 	struct vfio_group *group = device->group;
801 
802 	lockdep_assert_held(&group->group_lock);
803 
804 	if (WARN_ON(!group->container))
805 		return;
806 
807 	vfio_device_container_unregister(device);
808 	vfio_group_unuse_container(group);
809 }
810 
vfio_device_has_container(struct vfio_device * device)811 bool vfio_device_has_container(struct vfio_device *device)
812 {
813 	return device->group->container;
814 }
815 
vfio_group_from_file(struct file * file)816 struct vfio_group *vfio_group_from_file(struct file *file)
817 {
818 	struct vfio_group *group = file->private_data;
819 
820 	if (file->f_op != &vfio_group_fops)
821 		return NULL;
822 	return group;
823 }
824 
825 /**
826  * vfio_file_iommu_group - Return the struct iommu_group for the vfio group file
827  * @file: VFIO group file
828  *
829  * The returned iommu_group is valid as long as a ref is held on the file. This
830  * returns a reference on the group. This function is deprecated, only the SPAPR
831  * path in kvm should call it.
832  */
vfio_file_iommu_group(struct file * file)833 struct iommu_group *vfio_file_iommu_group(struct file *file)
834 {
835 	struct vfio_group *group = vfio_group_from_file(file);
836 	struct iommu_group *iommu_group = NULL;
837 
838 	if (!IS_ENABLED(CONFIG_SPAPR_TCE_IOMMU))
839 		return NULL;
840 
841 	if (!group)
842 		return NULL;
843 
844 	mutex_lock(&group->group_lock);
845 	if (group->iommu_group) {
846 		iommu_group = group->iommu_group;
847 		iommu_group_ref_get(iommu_group);
848 	}
849 	mutex_unlock(&group->group_lock);
850 	return iommu_group;
851 }
852 EXPORT_SYMBOL_GPL(vfio_file_iommu_group);
853 
854 /**
855  * vfio_file_is_group - True if the file is a vfio group file
856  * @file: VFIO group file
857  */
vfio_file_is_group(struct file * file)858 bool vfio_file_is_group(struct file *file)
859 {
860 	return vfio_group_from_file(file);
861 }
862 EXPORT_SYMBOL_GPL(vfio_file_is_group);
863 
vfio_group_enforced_coherent(struct vfio_group * group)864 bool vfio_group_enforced_coherent(struct vfio_group *group)
865 {
866 	struct vfio_device *device;
867 	bool ret = true;
868 
869 	/*
870 	 * If the device does not have IOMMU_CAP_ENFORCE_CACHE_COHERENCY then
871 	 * any domain later attached to it will also not support it. If the cap
872 	 * is set then the iommu_domain eventually attached to the device/group
873 	 * must use a domain with enforce_cache_coherency().
874 	 */
875 	mutex_lock(&group->device_lock);
876 	list_for_each_entry(device, &group->device_list, group_next) {
877 		if (!device_iommu_capable(device->dev,
878 					  IOMMU_CAP_ENFORCE_CACHE_COHERENCY)) {
879 			ret = false;
880 			break;
881 		}
882 	}
883 	mutex_unlock(&group->device_lock);
884 	return ret;
885 }
886 
vfio_group_set_kvm(struct vfio_group * group,struct kvm * kvm)887 void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
888 {
889 	spin_lock(&group->kvm_ref_lock);
890 	group->kvm = kvm;
891 	spin_unlock(&group->kvm_ref_lock);
892 }
893 
894 /**
895  * vfio_file_has_dev - True if the VFIO file is a handle for device
896  * @file: VFIO file to check
897  * @device: Device that must be part of the file
898  *
899  * Returns true if given file has permission to manipulate the given device.
900  */
vfio_file_has_dev(struct file * file,struct vfio_device * device)901 bool vfio_file_has_dev(struct file *file, struct vfio_device *device)
902 {
903 	struct vfio_group *group = vfio_group_from_file(file);
904 
905 	if (!group)
906 		return false;
907 
908 	return group == device->group;
909 }
910 EXPORT_SYMBOL_GPL(vfio_file_has_dev);
911 
vfio_devnode(const struct device * dev,umode_t * mode)912 static char *vfio_devnode(const struct device *dev, umode_t *mode)
913 {
914 	return kasprintf(GFP_KERNEL, "vfio/%s", dev_name(dev));
915 }
916 
vfio_group_init(void)917 int __init vfio_group_init(void)
918 {
919 	int ret;
920 
921 	ida_init(&vfio.group_ida);
922 	mutex_init(&vfio.group_lock);
923 	INIT_LIST_HEAD(&vfio.group_list);
924 
925 	ret = vfio_container_init();
926 	if (ret)
927 		return ret;
928 
929 	/* /dev/vfio/$GROUP */
930 	vfio.class = class_create("vfio");
931 	if (IS_ERR(vfio.class)) {
932 		ret = PTR_ERR(vfio.class);
933 		goto err_group_class;
934 	}
935 
936 	vfio.class->devnode = vfio_devnode;
937 
938 	ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK + 1, "vfio");
939 	if (ret)
940 		goto err_alloc_chrdev;
941 	return 0;
942 
943 err_alloc_chrdev:
944 	class_destroy(vfio.class);
945 	vfio.class = NULL;
946 err_group_class:
947 	vfio_container_cleanup();
948 	return ret;
949 }
950 
vfio_group_cleanup(void)951 void vfio_group_cleanup(void)
952 {
953 	WARN_ON(!list_empty(&vfio.group_list));
954 	ida_destroy(&vfio.group_ida);
955 	unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
956 	class_destroy(vfio.class);
957 	vfio.class = NULL;
958 	vfio_container_cleanup();
959 }
960