1 /*
2 * VFIO-KVM bridge pseudo device
3 *
4 * Copyright (C) 2013 Red Hat, Inc. All rights reserved.
5 * Author: Alex Williamson <alex.williamson@redhat.com>
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
12 #include <linux/errno.h>
13 #include <linux/file.h>
14 #include <linux/kvm_host.h>
15 #include <linux/list.h>
16 #include <linux/module.h>
17 #include <linux/mutex.h>
18 #include <linux/slab.h>
19 #include <linux/uaccess.h>
20 #include <linux/vfio.h>
21 #include "vfio.h"
22
23 struct kvm_vfio_group {
24 struct list_head node;
25 struct vfio_group *vfio_group;
26 };
27
28 struct kvm_vfio {
29 struct list_head group_list;
30 struct mutex lock;
31 bool noncoherent;
32 };
33
kvm_vfio_group_get_external_user(struct file * filep)34 static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
35 {
36 struct vfio_group *vfio_group;
37 struct vfio_group *(*fn)(struct file *);
38
39 fn = symbol_get(vfio_group_get_external_user);
40 if (!fn)
41 return ERR_PTR(-EINVAL);
42
43 vfio_group = fn(filep);
44
45 symbol_put(vfio_group_get_external_user);
46
47 return vfio_group;
48 }
49
kvm_vfio_external_group_match_file(struct vfio_group * group,struct file * filep)50 static bool kvm_vfio_external_group_match_file(struct vfio_group *group,
51 struct file *filep)
52 {
53 bool ret, (*fn)(struct vfio_group *, struct file *);
54
55 fn = symbol_get(vfio_external_group_match_file);
56 if (!fn)
57 return false;
58
59 ret = fn(group, filep);
60
61 symbol_put(vfio_external_group_match_file);
62
63 return ret;
64 }
65
kvm_vfio_group_put_external_user(struct vfio_group * vfio_group)66 static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
67 {
68 void (*fn)(struct vfio_group *);
69
70 fn = symbol_get(vfio_group_put_external_user);
71 if (!fn)
72 return;
73
74 fn(vfio_group);
75
76 symbol_put(vfio_group_put_external_user);
77 }
78
kvm_vfio_group_is_coherent(struct vfio_group * vfio_group)79 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
80 {
81 long (*fn)(struct vfio_group *, unsigned long);
82 long ret;
83
84 fn = symbol_get(vfio_external_check_extension);
85 if (!fn)
86 return false;
87
88 ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
89
90 symbol_put(vfio_external_check_extension);
91
92 return ret > 0;
93 }
94
95 /*
96 * Groups can use the same or different IOMMU domains. If the same then
97 * adding a new group may change the coherency of groups we've previously
98 * been told about. We don't want to care about any of that so we retest
99 * each group and bail as soon as we find one that's noncoherent. This
100 * means we only ever [un]register_noncoherent_dma once for the whole device.
101 */
kvm_vfio_update_coherency(struct kvm_device * dev)102 static void kvm_vfio_update_coherency(struct kvm_device *dev)
103 {
104 struct kvm_vfio *kv = dev->private;
105 bool noncoherent = false;
106 struct kvm_vfio_group *kvg;
107
108 mutex_lock(&kv->lock);
109
110 list_for_each_entry(kvg, &kv->group_list, node) {
111 if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
112 noncoherent = true;
113 break;
114 }
115 }
116
117 if (noncoherent != kv->noncoherent) {
118 kv->noncoherent = noncoherent;
119
120 if (kv->noncoherent)
121 kvm_arch_register_noncoherent_dma(dev->kvm);
122 else
123 kvm_arch_unregister_noncoherent_dma(dev->kvm);
124 }
125
126 mutex_unlock(&kv->lock);
127 }
128
kvm_vfio_set_group(struct kvm_device * dev,long attr,u64 arg)129 static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
130 {
131 struct kvm_vfio *kv = dev->private;
132 struct vfio_group *vfio_group;
133 struct kvm_vfio_group *kvg;
134 int32_t __user *argp = (int32_t __user *)(unsigned long)arg;
135 struct fd f;
136 int32_t fd;
137 int ret;
138
139 switch (attr) {
140 case KVM_DEV_VFIO_GROUP_ADD:
141 if (get_user(fd, argp))
142 return -EFAULT;
143
144 f = fdget(fd);
145 if (!f.file)
146 return -EBADF;
147
148 vfio_group = kvm_vfio_group_get_external_user(f.file);
149 fdput(f);
150
151 if (IS_ERR(vfio_group))
152 return PTR_ERR(vfio_group);
153
154 mutex_lock(&kv->lock);
155
156 list_for_each_entry(kvg, &kv->group_list, node) {
157 if (kvg->vfio_group == vfio_group) {
158 mutex_unlock(&kv->lock);
159 kvm_vfio_group_put_external_user(vfio_group);
160 return -EEXIST;
161 }
162 }
163
164 kvg = kzalloc(sizeof(*kvg), GFP_KERNEL);
165 if (!kvg) {
166 mutex_unlock(&kv->lock);
167 kvm_vfio_group_put_external_user(vfio_group);
168 return -ENOMEM;
169 }
170
171 list_add_tail(&kvg->node, &kv->group_list);
172 kvg->vfio_group = vfio_group;
173
174 kvm_arch_start_assignment(dev->kvm);
175
176 mutex_unlock(&kv->lock);
177
178 kvm_vfio_update_coherency(dev);
179
180 return 0;
181
182 case KVM_DEV_VFIO_GROUP_DEL:
183 if (get_user(fd, argp))
184 return -EFAULT;
185
186 f = fdget(fd);
187 if (!f.file)
188 return -EBADF;
189
190 ret = -ENOENT;
191
192 mutex_lock(&kv->lock);
193
194 list_for_each_entry(kvg, &kv->group_list, node) {
195 if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
196 f.file))
197 continue;
198
199 list_del(&kvg->node);
200 kvm_vfio_group_put_external_user(kvg->vfio_group);
201 kfree(kvg);
202 ret = 0;
203 break;
204 }
205
206 kvm_arch_end_assignment(dev->kvm);
207
208 mutex_unlock(&kv->lock);
209
210 fdput(f);
211
212 kvm_vfio_update_coherency(dev);
213
214 return ret;
215 }
216
217 return -ENXIO;
218 }
219
kvm_vfio_set_attr(struct kvm_device * dev,struct kvm_device_attr * attr)220 static int kvm_vfio_set_attr(struct kvm_device *dev,
221 struct kvm_device_attr *attr)
222 {
223 switch (attr->group) {
224 case KVM_DEV_VFIO_GROUP:
225 return kvm_vfio_set_group(dev, attr->attr, attr->addr);
226 }
227
228 return -ENXIO;
229 }
230
kvm_vfio_has_attr(struct kvm_device * dev,struct kvm_device_attr * attr)231 static int kvm_vfio_has_attr(struct kvm_device *dev,
232 struct kvm_device_attr *attr)
233 {
234 switch (attr->group) {
235 case KVM_DEV_VFIO_GROUP:
236 switch (attr->attr) {
237 case KVM_DEV_VFIO_GROUP_ADD:
238 case KVM_DEV_VFIO_GROUP_DEL:
239 return 0;
240 }
241
242 break;
243 }
244
245 return -ENXIO;
246 }
247
kvm_vfio_destroy(struct kvm_device * dev)248 static void kvm_vfio_destroy(struct kvm_device *dev)
249 {
250 struct kvm_vfio *kv = dev->private;
251 struct kvm_vfio_group *kvg, *tmp;
252
253 list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {
254 kvm_vfio_group_put_external_user(kvg->vfio_group);
255 list_del(&kvg->node);
256 kfree(kvg);
257 kvm_arch_end_assignment(dev->kvm);
258 }
259
260 kvm_vfio_update_coherency(dev);
261
262 kfree(kv);
263 kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */
264 }
265
266 static int kvm_vfio_create(struct kvm_device *dev, u32 type);
267
268 static struct kvm_device_ops kvm_vfio_ops = {
269 .name = "kvm-vfio",
270 .create = kvm_vfio_create,
271 .destroy = kvm_vfio_destroy,
272 .set_attr = kvm_vfio_set_attr,
273 .has_attr = kvm_vfio_has_attr,
274 };
275
kvm_vfio_create(struct kvm_device * dev,u32 type)276 static int kvm_vfio_create(struct kvm_device *dev, u32 type)
277 {
278 struct kvm_device *tmp;
279 struct kvm_vfio *kv;
280
281 /* Only one VFIO "device" per VM */
282 list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
283 if (tmp->ops == &kvm_vfio_ops)
284 return -EBUSY;
285
286 kv = kzalloc(sizeof(*kv), GFP_KERNEL);
287 if (!kv)
288 return -ENOMEM;
289
290 INIT_LIST_HEAD(&kv->group_list);
291 mutex_init(&kv->lock);
292
293 dev->private = kv;
294
295 return 0;
296 }
297
kvm_vfio_ops_init(void)298 int kvm_vfio_ops_init(void)
299 {
300 return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
301 }
302
kvm_vfio_ops_exit(void)303 void kvm_vfio_ops_exit(void)
304 {
305 kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
306 }
307