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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; | |
30 | }; | |
31 | ||
32 | static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep) | |
33 | { | |
34 | struct vfio_group *vfio_group; | |
35 | struct vfio_group *(*fn)(struct file *); | |
36 | ||
37 | fn = symbol_get(vfio_group_get_external_user); | |
38 | if (!fn) | |
39 | return ERR_PTR(-EINVAL); | |
40 | ||
41 | vfio_group = fn(filep); | |
42 | ||
43 | symbol_put(vfio_group_get_external_user); | |
44 | ||
45 | return vfio_group; | |
46 | } | |
47 | ||
48 | static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) | |
49 | { | |
50 | void (*fn)(struct vfio_group *); | |
51 | ||
52 | fn = symbol_get(vfio_group_put_external_user); | |
53 | if (!fn) | |
54 | return; | |
55 | ||
56 | fn(vfio_group); | |
57 | ||
58 | symbol_put(vfio_group_put_external_user); | |
59 | } | |
60 | ||
61 | static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) | |
62 | { | |
63 | struct kvm_vfio *kv = dev->private; | |
64 | struct vfio_group *vfio_group; | |
65 | struct kvm_vfio_group *kvg; | |
66 | void __user *argp = (void __user *)arg; | |
67 | struct fd f; | |
68 | int32_t fd; | |
69 | int ret; | |
70 | ||
71 | switch (attr) { | |
72 | case KVM_DEV_VFIO_GROUP_ADD: | |
73 | if (get_user(fd, (int32_t __user *)argp)) | |
74 | return -EFAULT; | |
75 | ||
76 | f = fdget(fd); | |
77 | if (!f.file) | |
78 | return -EBADF; | |
79 | ||
80 | vfio_group = kvm_vfio_group_get_external_user(f.file); | |
81 | fdput(f); | |
82 | ||
83 | if (IS_ERR(vfio_group)) | |
84 | return PTR_ERR(vfio_group); | |
85 | ||
86 | mutex_lock(&kv->lock); | |
87 | ||
88 | list_for_each_entry(kvg, &kv->group_list, node) { | |
89 | if (kvg->vfio_group == vfio_group) { | |
90 | mutex_unlock(&kv->lock); | |
91 | kvm_vfio_group_put_external_user(vfio_group); | |
92 | return -EEXIST; | |
93 | } | |
94 | } | |
95 | ||
96 | kvg = kzalloc(sizeof(*kvg), GFP_KERNEL); | |
97 | if (!kvg) { | |
98 | mutex_unlock(&kv->lock); | |
99 | kvm_vfio_group_put_external_user(vfio_group); | |
100 | return -ENOMEM; | |
101 | } | |
102 | ||
103 | list_add_tail(&kvg->node, &kv->group_list); | |
104 | kvg->vfio_group = vfio_group; | |
105 | ||
106 | mutex_unlock(&kv->lock); | |
107 | ||
108 | return 0; | |
109 | ||
110 | case KVM_DEV_VFIO_GROUP_DEL: | |
111 | if (get_user(fd, (int32_t __user *)argp)) | |
112 | return -EFAULT; | |
113 | ||
114 | f = fdget(fd); | |
115 | if (!f.file) | |
116 | return -EBADF; | |
117 | ||
118 | vfio_group = kvm_vfio_group_get_external_user(f.file); | |
119 | fdput(f); | |
120 | ||
121 | if (IS_ERR(vfio_group)) | |
122 | return PTR_ERR(vfio_group); | |
123 | ||
124 | ret = -ENOENT; | |
125 | ||
126 | mutex_lock(&kv->lock); | |
127 | ||
128 | list_for_each_entry(kvg, &kv->group_list, node) { | |
129 | if (kvg->vfio_group != vfio_group) | |
130 | continue; | |
131 | ||
132 | list_del(&kvg->node); | |
133 | kvm_vfio_group_put_external_user(kvg->vfio_group); | |
134 | kfree(kvg); | |
135 | ret = 0; | |
136 | break; | |
137 | } | |
138 | ||
139 | mutex_unlock(&kv->lock); | |
140 | ||
141 | kvm_vfio_group_put_external_user(vfio_group); | |
142 | ||
143 | return ret; | |
144 | } | |
145 | ||
146 | return -ENXIO; | |
147 | } | |
148 | ||
149 | static int kvm_vfio_set_attr(struct kvm_device *dev, | |
150 | struct kvm_device_attr *attr) | |
151 | { | |
152 | switch (attr->group) { | |
153 | case KVM_DEV_VFIO_GROUP: | |
154 | return kvm_vfio_set_group(dev, attr->attr, attr->addr); | |
155 | } | |
156 | ||
157 | return -ENXIO; | |
158 | } | |
159 | ||
160 | static int kvm_vfio_has_attr(struct kvm_device *dev, | |
161 | struct kvm_device_attr *attr) | |
162 | { | |
163 | switch (attr->group) { | |
164 | case KVM_DEV_VFIO_GROUP: | |
165 | switch (attr->attr) { | |
166 | case KVM_DEV_VFIO_GROUP_ADD: | |
167 | case KVM_DEV_VFIO_GROUP_DEL: | |
168 | return 0; | |
169 | } | |
170 | ||
171 | break; | |
172 | } | |
173 | ||
174 | return -ENXIO; | |
175 | } | |
176 | ||
177 | static void kvm_vfio_destroy(struct kvm_device *dev) | |
178 | { | |
179 | struct kvm_vfio *kv = dev->private; | |
180 | struct kvm_vfio_group *kvg, *tmp; | |
181 | ||
182 | list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) { | |
183 | kvm_vfio_group_put_external_user(kvg->vfio_group); | |
184 | list_del(&kvg->node); | |
185 | kfree(kvg); | |
186 | } | |
187 | ||
188 | kfree(kv); | |
189 | kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */ | |
190 | } | |
191 | ||
192 | static int kvm_vfio_create(struct kvm_device *dev, u32 type) | |
193 | { | |
194 | struct kvm_device *tmp; | |
195 | struct kvm_vfio *kv; | |
196 | ||
197 | /* Only one VFIO "device" per VM */ | |
198 | list_for_each_entry(tmp, &dev->kvm->devices, vm_node) | |
199 | if (tmp->ops == &kvm_vfio_ops) | |
200 | return -EBUSY; | |
201 | ||
202 | kv = kzalloc(sizeof(*kv), GFP_KERNEL); | |
203 | if (!kv) | |
204 | return -ENOMEM; | |
205 | ||
206 | INIT_LIST_HEAD(&kv->group_list); | |
207 | mutex_init(&kv->lock); | |
208 | ||
209 | dev->private = kv; | |
210 | ||
211 | return 0; | |
212 | } | |
213 | ||
214 | struct kvm_device_ops kvm_vfio_ops = { | |
215 | .name = "kvm-vfio", | |
216 | .create = kvm_vfio_create, | |
217 | .destroy = kvm_vfio_destroy, | |
218 | .set_attr = kvm_vfio_set_attr, | |
219 | .has_attr = kvm_vfio_has_attr, | |
220 | }; |