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ec53500f AW |
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 | ||
22 | struct kvm_vfio_group { | |
23 | struct list_head node; | |
24 | struct vfio_group *vfio_group; | |
25 | }; | |
26 | ||
27 | struct kvm_vfio { | |
28 | struct list_head group_list; | |
29 | struct mutex lock; | |
e0f0bbc5 | 30 | bool noncoherent; |
ec53500f AW |
31 | }; |
32 | ||
33 | static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep) | |
34 | { | |
35 | struct vfio_group *vfio_group; | |
36 | struct vfio_group *(*fn)(struct file *); | |
37 | ||
38 | fn = symbol_get(vfio_group_get_external_user); | |
39 | if (!fn) | |
40 | return ERR_PTR(-EINVAL); | |
41 | ||
42 | vfio_group = fn(filep); | |
43 | ||
44 | symbol_put(vfio_group_get_external_user); | |
45 | ||
46 | return vfio_group; | |
47 | } | |
48 | ||
49 | static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) | |
50 | { | |
51 | void (*fn)(struct vfio_group *); | |
52 | ||
53 | fn = symbol_get(vfio_group_put_external_user); | |
54 | if (!fn) | |
55 | return; | |
56 | ||
57 | fn(vfio_group); | |
58 | ||
59 | symbol_put(vfio_group_put_external_user); | |
60 | } | |
61 | ||
9d830d47 AW |
62 | static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group) |
63 | { | |
64 | long (*fn)(struct vfio_group *, unsigned long); | |
65 | long ret; | |
66 | ||
67 | fn = symbol_get(vfio_external_check_extension); | |
68 | if (!fn) | |
69 | return false; | |
70 | ||
71 | ret = fn(vfio_group, VFIO_DMA_CC_IOMMU); | |
72 | ||
73 | symbol_put(vfio_external_check_extension); | |
74 | ||
75 | return ret > 0; | |
76 | } | |
77 | ||
e0f0bbc5 AW |
78 | /* |
79 | * Groups can use the same or different IOMMU domains. If the same then | |
80 | * adding a new group may change the coherency of groups we've previously | |
81 | * been told about. We don't want to care about any of that so we retest | |
82 | * each group and bail as soon as we find one that's noncoherent. This | |
83 | * means we only ever [un]register_noncoherent_dma once for the whole device. | |
84 | */ | |
85 | static void kvm_vfio_update_coherency(struct kvm_device *dev) | |
86 | { | |
87 | struct kvm_vfio *kv = dev->private; | |
88 | bool noncoherent = false; | |
89 | struct kvm_vfio_group *kvg; | |
90 | ||
91 | mutex_lock(&kv->lock); | |
92 | ||
93 | list_for_each_entry(kvg, &kv->group_list, node) { | |
9d830d47 AW |
94 | if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) { |
95 | noncoherent = true; | |
96 | break; | |
97 | } | |
e0f0bbc5 AW |
98 | } |
99 | ||
100 | if (noncoherent != kv->noncoherent) { | |
101 | kv->noncoherent = noncoherent; | |
102 | ||
103 | if (kv->noncoherent) | |
104 | kvm_arch_register_noncoherent_dma(dev->kvm); | |
105 | else | |
106 | kvm_arch_unregister_noncoherent_dma(dev->kvm); | |
107 | } | |
108 | ||
109 | mutex_unlock(&kv->lock); | |
110 | } | |
111 | ||
ec53500f AW |
112 | static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) |
113 | { | |
114 | struct kvm_vfio *kv = dev->private; | |
115 | struct vfio_group *vfio_group; | |
116 | struct kvm_vfio_group *kvg; | |
e81d1ad3 | 117 | int32_t __user *argp = (int32_t __user *)(unsigned long)arg; |
ec53500f AW |
118 | struct fd f; |
119 | int32_t fd; | |
120 | int ret; | |
121 | ||
122 | switch (attr) { | |
123 | case KVM_DEV_VFIO_GROUP_ADD: | |
e81d1ad3 | 124 | if (get_user(fd, argp)) |
ec53500f AW |
125 | return -EFAULT; |
126 | ||
127 | f = fdget(fd); | |
128 | if (!f.file) | |
129 | return -EBADF; | |
130 | ||
131 | vfio_group = kvm_vfio_group_get_external_user(f.file); | |
132 | fdput(f); | |
133 | ||
134 | if (IS_ERR(vfio_group)) | |
135 | return PTR_ERR(vfio_group); | |
136 | ||
137 | mutex_lock(&kv->lock); | |
138 | ||
139 | list_for_each_entry(kvg, &kv->group_list, node) { | |
140 | if (kvg->vfio_group == vfio_group) { | |
141 | mutex_unlock(&kv->lock); | |
142 | kvm_vfio_group_put_external_user(vfio_group); | |
143 | return -EEXIST; | |
144 | } | |
145 | } | |
146 | ||
147 | kvg = kzalloc(sizeof(*kvg), GFP_KERNEL); | |
148 | if (!kvg) { | |
149 | mutex_unlock(&kv->lock); | |
150 | kvm_vfio_group_put_external_user(vfio_group); | |
151 | return -ENOMEM; | |
152 | } | |
153 | ||
154 | list_add_tail(&kvg->node, &kv->group_list); | |
155 | kvg->vfio_group = vfio_group; | |
156 | ||
157 | mutex_unlock(&kv->lock); | |
158 | ||
e0f0bbc5 AW |
159 | kvm_vfio_update_coherency(dev); |
160 | ||
ec53500f AW |
161 | return 0; |
162 | ||
163 | case KVM_DEV_VFIO_GROUP_DEL: | |
e81d1ad3 | 164 | if (get_user(fd, argp)) |
ec53500f AW |
165 | return -EFAULT; |
166 | ||
167 | f = fdget(fd); | |
168 | if (!f.file) | |
169 | return -EBADF; | |
170 | ||
171 | vfio_group = kvm_vfio_group_get_external_user(f.file); | |
172 | fdput(f); | |
173 | ||
174 | if (IS_ERR(vfio_group)) | |
175 | return PTR_ERR(vfio_group); | |
176 | ||
177 | ret = -ENOENT; | |
178 | ||
179 | mutex_lock(&kv->lock); | |
180 | ||
181 | list_for_each_entry(kvg, &kv->group_list, node) { | |
182 | if (kvg->vfio_group != vfio_group) | |
183 | continue; | |
184 | ||
185 | list_del(&kvg->node); | |
186 | kvm_vfio_group_put_external_user(kvg->vfio_group); | |
187 | kfree(kvg); | |
188 | ret = 0; | |
189 | break; | |
190 | } | |
191 | ||
192 | mutex_unlock(&kv->lock); | |
193 | ||
194 | kvm_vfio_group_put_external_user(vfio_group); | |
195 | ||
e0f0bbc5 AW |
196 | kvm_vfio_update_coherency(dev); |
197 | ||
ec53500f AW |
198 | return ret; |
199 | } | |
200 | ||
201 | return -ENXIO; | |
202 | } | |
203 | ||
204 | static int kvm_vfio_set_attr(struct kvm_device *dev, | |
205 | struct kvm_device_attr *attr) | |
206 | { | |
207 | switch (attr->group) { | |
208 | case KVM_DEV_VFIO_GROUP: | |
209 | return kvm_vfio_set_group(dev, attr->attr, attr->addr); | |
210 | } | |
211 | ||
212 | return -ENXIO; | |
213 | } | |
214 | ||
215 | static int kvm_vfio_has_attr(struct kvm_device *dev, | |
216 | struct kvm_device_attr *attr) | |
217 | { | |
218 | switch (attr->group) { | |
219 | case KVM_DEV_VFIO_GROUP: | |
220 | switch (attr->attr) { | |
221 | case KVM_DEV_VFIO_GROUP_ADD: | |
222 | case KVM_DEV_VFIO_GROUP_DEL: | |
223 | return 0; | |
224 | } | |
225 | ||
226 | break; | |
227 | } | |
228 | ||
229 | return -ENXIO; | |
230 | } | |
231 | ||
232 | static void kvm_vfio_destroy(struct kvm_device *dev) | |
233 | { | |
234 | struct kvm_vfio *kv = dev->private; | |
235 | struct kvm_vfio_group *kvg, *tmp; | |
236 | ||
237 | list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) { | |
238 | kvm_vfio_group_put_external_user(kvg->vfio_group); | |
239 | list_del(&kvg->node); | |
240 | kfree(kvg); | |
241 | } | |
242 | ||
e0f0bbc5 AW |
243 | kvm_vfio_update_coherency(dev); |
244 | ||
ec53500f AW |
245 | kfree(kv); |
246 | kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */ | |
247 | } | |
248 | ||
249 | static int kvm_vfio_create(struct kvm_device *dev, u32 type) | |
250 | { | |
251 | struct kvm_device *tmp; | |
252 | struct kvm_vfio *kv; | |
253 | ||
254 | /* Only one VFIO "device" per VM */ | |
255 | list_for_each_entry(tmp, &dev->kvm->devices, vm_node) | |
256 | if (tmp->ops == &kvm_vfio_ops) | |
257 | return -EBUSY; | |
258 | ||
259 | kv = kzalloc(sizeof(*kv), GFP_KERNEL); | |
260 | if (!kv) | |
261 | return -ENOMEM; | |
262 | ||
263 | INIT_LIST_HEAD(&kv->group_list); | |
264 | mutex_init(&kv->lock); | |
265 | ||
266 | dev->private = kv; | |
267 | ||
268 | return 0; | |
269 | } | |
270 | ||
271 | struct kvm_device_ops kvm_vfio_ops = { | |
272 | .name = "kvm-vfio", | |
273 | .create = kvm_vfio_create, | |
274 | .destroy = kvm_vfio_destroy, | |
275 | .set_attr = kvm_vfio_set_attr, | |
276 | .has_attr = kvm_vfio_has_attr, | |
277 | }; |