1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * VFIO-KVM bridge pseudo device
4 *
5 * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
6 *     Author: Alex Williamson <alex.williamson@redhat.com>
7 */
8
9#include <linux/errno.h>
10#include <linux/file.h>
11#include <linux/kvm_host.h>
12#include <linux/list.h>
13#include <linux/module.h>
14#include <linux/mutex.h>
15#include <linux/slab.h>
16#include <linux/uaccess.h>
17#include <linux/vfio.h>
18#include "vfio.h"
19
20#ifdef CONFIG_SPAPR_TCE_IOMMU
21#include <asm/kvm_ppc.h>
22#endif
23
24struct kvm_vfio_file {
25	struct list_head node;
26	struct file *file;
27#ifdef CONFIG_SPAPR_TCE_IOMMU
28	struct iommu_group *iommu_group;
29#endif
30};
31
32struct kvm_vfio {
33	struct list_head file_list;
34	struct mutex lock;
35	bool noncoherent;
36};
37
38static void kvm_vfio_file_set_kvm(struct file *file, struct kvm *kvm)
39{
40	void (*fn)(struct file *file, struct kvm *kvm);
41
42	fn = symbol_get(vfio_file_set_kvm);
43	if (!fn)
44		return;
45
46	fn(file, kvm);
47
48	symbol_put(vfio_file_set_kvm);
49}
50
51static bool kvm_vfio_file_enforced_coherent(struct file *file)
52{
53	bool (*fn)(struct file *file);
54	bool ret;
55
56	fn = symbol_get(vfio_file_enforced_coherent);
57	if (!fn)
58		return false;
59
60	ret = fn(file);
61
62	symbol_put(vfio_file_enforced_coherent);
63
64	return ret;
65}
66
67static bool kvm_vfio_file_is_valid(struct file *file)
68{
69	bool (*fn)(struct file *file);
70	bool ret;
71
72	fn = symbol_get(vfio_file_is_valid);
73	if (!fn)
74		return false;
75
76	ret = fn(file);
77
78	symbol_put(vfio_file_is_valid);
79
80	return ret;
81}
82
83#ifdef CONFIG_SPAPR_TCE_IOMMU
84static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)
85{
86	struct iommu_group *(*fn)(struct file *file);
87	struct iommu_group *ret;
88
89	fn = symbol_get(vfio_file_iommu_group);
90	if (!fn)
91		return NULL;
92
93	ret = fn(file);
94
95	symbol_put(vfio_file_iommu_group);
96
97	return ret;
98}
99
100static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
101					     struct kvm_vfio_file *kvf)
102{
103	if (WARN_ON_ONCE(!kvf->iommu_group))
104		return;
105
106	kvm_spapr_tce_release_iommu_group(kvm, kvf->iommu_group);
107	iommu_group_put(kvf->iommu_group);
108	kvf->iommu_group = NULL;
109}
110#endif
111
112/*
113 * Groups/devices can use the same or different IOMMU domains. If the same
114 * then adding a new group/device may change the coherency of groups/devices
115 * we've previously been told about. We don't want to care about any of
116 * that so we retest each group/device and bail as soon as we find one that's
117 * noncoherent.  This means we only ever [un]register_noncoherent_dma once
118 * for the whole device.
119 */
120static void kvm_vfio_update_coherency(struct kvm_device *dev)
121{
122	struct kvm_vfio *kv = dev->private;
123	bool noncoherent = false;
124	struct kvm_vfio_file *kvf;
125
126	list_for_each_entry(kvf, &kv->file_list, node) {
127		if (!kvm_vfio_file_enforced_coherent(kvf->file)) {
128			noncoherent = true;
129			break;
130		}
131	}
132
133	if (noncoherent != kv->noncoherent) {
134		kv->noncoherent = noncoherent;
135
136		if (kv->noncoherent)
137			kvm_arch_register_noncoherent_dma(dev->kvm);
138		else
139			kvm_arch_unregister_noncoherent_dma(dev->kvm);
140	}
141}
142
143static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
144{
145	struct kvm_vfio *kv = dev->private;
146	struct kvm_vfio_file *kvf;
147	struct file *filp;
148	int ret = 0;
149
150	filp = fget(fd);
151	if (!filp)
152		return -EBADF;
153
154	/* Ensure the FD is a vfio FD. */
155	if (!kvm_vfio_file_is_valid(filp)) {
156		ret = -EINVAL;
157		goto out_fput;
158	}
159
160	mutex_lock(&kv->lock);
161
162	list_for_each_entry(kvf, &kv->file_list, node) {
163		if (kvf->file == filp) {
164			ret = -EEXIST;
165			goto out_unlock;
166		}
167	}
168
169	kvf = kzalloc(sizeof(*kvf), GFP_KERNEL_ACCOUNT);
170	if (!kvf) {
171		ret = -ENOMEM;
172		goto out_unlock;
173	}
174
175	kvf->file = get_file(filp);
176	list_add_tail(&kvf->node, &kv->file_list);
177
178	kvm_arch_start_assignment(dev->kvm);
179	kvm_vfio_file_set_kvm(kvf->file, dev->kvm);
180	kvm_vfio_update_coherency(dev);
181
182out_unlock:
183	mutex_unlock(&kv->lock);
184out_fput:
185	fput(filp);
186	return ret;
187}
188
189static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
190{
191	struct kvm_vfio *kv = dev->private;
192	struct kvm_vfio_file *kvf;
193	struct fd f;
194	int ret;
195
196	f = fdget(fd);
197	if (!f.file)
198		return -EBADF;
199
200	ret = -ENOENT;
201
202	mutex_lock(&kv->lock);
203
204	list_for_each_entry(kvf, &kv->file_list, node) {
205		if (kvf->file != f.file)
206			continue;
207
208		list_del(&kvf->node);
209		kvm_arch_end_assignment(dev->kvm);
210#ifdef CONFIG_SPAPR_TCE_IOMMU
211		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
212#endif
213		kvm_vfio_file_set_kvm(kvf->file, NULL);
214		fput(kvf->file);
215		kfree(kvf);
216		ret = 0;
217		break;
218	}
219
220	kvm_vfio_update_coherency(dev);
221
222	mutex_unlock(&kv->lock);
223
224	fdput(f);
225
226	return ret;
227}
228
229#ifdef CONFIG_SPAPR_TCE_IOMMU
230static int kvm_vfio_file_set_spapr_tce(struct kvm_device *dev,
231				       void __user *arg)
232{
233	struct kvm_vfio_spapr_tce param;
234	struct kvm_vfio *kv = dev->private;
235	struct kvm_vfio_file *kvf;
236	struct fd f;
237	int ret;
238
239	if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
240		return -EFAULT;
241
242	f = fdget(param.groupfd);
243	if (!f.file)
244		return -EBADF;
245
246	ret = -ENOENT;
247
248	mutex_lock(&kv->lock);
249
250	list_for_each_entry(kvf, &kv->file_list, node) {
251		if (kvf->file != f.file)
252			continue;
253
254		if (!kvf->iommu_group) {
255			kvf->iommu_group = kvm_vfio_file_iommu_group(kvf->file);
256			if (WARN_ON_ONCE(!kvf->iommu_group)) {
257				ret = -EIO;
258				goto err_fdput;
259			}
260		}
261
262		ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
263						       kvf->iommu_group);
264		break;
265	}
266
267err_fdput:
268	mutex_unlock(&kv->lock);
269	fdput(f);
270	return ret;
271}
272#endif
273
274static int kvm_vfio_set_file(struct kvm_device *dev, long attr,
275			     void __user *arg)
276{
277	int32_t __user *argp = arg;
278	int32_t fd;
279
280	switch (attr) {
281	case KVM_DEV_VFIO_FILE_ADD:
282		if (get_user(fd, argp))
283			return -EFAULT;
284		return kvm_vfio_file_add(dev, fd);
285
286	case KVM_DEV_VFIO_FILE_DEL:
287		if (get_user(fd, argp))
288			return -EFAULT;
289		return kvm_vfio_file_del(dev, fd);
290
291#ifdef CONFIG_SPAPR_TCE_IOMMU
292	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
293		return kvm_vfio_file_set_spapr_tce(dev, arg);
294#endif
295	}
296
297	return -ENXIO;
298}
299
300static int kvm_vfio_set_attr(struct kvm_device *dev,
301			     struct kvm_device_attr *attr)
302{
303	switch (attr->group) {
304	case KVM_DEV_VFIO_FILE:
305		return kvm_vfio_set_file(dev, attr->attr,
306					 u64_to_user_ptr(attr->addr));
307	}
308
309	return -ENXIO;
310}
311
312static int kvm_vfio_has_attr(struct kvm_device *dev,
313			     struct kvm_device_attr *attr)
314{
315	switch (attr->group) {
316	case KVM_DEV_VFIO_FILE:
317		switch (attr->attr) {
318		case KVM_DEV_VFIO_FILE_ADD:
319		case KVM_DEV_VFIO_FILE_DEL:
320#ifdef CONFIG_SPAPR_TCE_IOMMU
321		case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
322#endif
323			return 0;
324		}
325
326		break;
327	}
328
329	return -ENXIO;
330}
331
332static void kvm_vfio_release(struct kvm_device *dev)
333{
334	struct kvm_vfio *kv = dev->private;
335	struct kvm_vfio_file *kvf, *tmp;
336
337	list_for_each_entry_safe(kvf, tmp, &kv->file_list, node) {
338#ifdef CONFIG_SPAPR_TCE_IOMMU
339		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
340#endif
341		kvm_vfio_file_set_kvm(kvf->file, NULL);
342		fput(kvf->file);
343		list_del(&kvf->node);
344		kfree(kvf);
345		kvm_arch_end_assignment(dev->kvm);
346	}
347
348	kvm_vfio_update_coherency(dev);
349
350	kfree(kv);
351	kfree(dev); /* alloc by kvm_ioctl_create_device, free by .release */
352}
353
354static int kvm_vfio_create(struct kvm_device *dev, u32 type);
355
356static struct kvm_device_ops kvm_vfio_ops = {
357	.name = "kvm-vfio",
358	.create = kvm_vfio_create,
359	.release = kvm_vfio_release,
360	.set_attr = kvm_vfio_set_attr,
361	.has_attr = kvm_vfio_has_attr,
362};
363
364static int kvm_vfio_create(struct kvm_device *dev, u32 type)
365{
366	struct kvm_device *tmp;
367	struct kvm_vfio *kv;
368
369	/* Only one VFIO "device" per VM */
370	list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
371		if (tmp->ops == &kvm_vfio_ops)
372			return -EBUSY;
373
374	kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
375	if (!kv)
376		return -ENOMEM;
377
378	INIT_LIST_HEAD(&kv->file_list);
379	mutex_init(&kv->lock);
380
381	dev->private = kv;
382
383	return 0;
384}
385
386int kvm_vfio_ops_init(void)
387{
388	return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
389}
390
391void kvm_vfio_ops_exit(void)
392{
393	kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
394}
395