1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2023 Intel Corporation.
4 */
5#include <linux/vfio.h>
6#include <linux/iommufd.h>
7
8#include "vfio.h"
9
10static dev_t device_devt;
11
12void vfio_init_device_cdev(struct vfio_device *device)
13{
14 device->device.devt = MKDEV(MAJOR(device_devt), device->index);
15 cdev_init(&device->cdev, &vfio_device_fops);
16 device->cdev.owner = THIS_MODULE;
17}
18
19/*
20 * device access via the fd opened by this function is blocked until
21 * .open_device() is called successfully during BIND_IOMMUFD.
22 */
23int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep)
24{
25 struct vfio_device *device = container_of(inode->i_cdev,
26 struct vfio_device, cdev);
27 struct vfio_device_file *df;
28 int ret;
29
30 /* Paired with the put in vfio_device_fops_release() */
31 if (!vfio_device_try_get_registration(device))
32 return -ENODEV;
33
34 df = vfio_allocate_device_file(device);
35 if (IS_ERR(ptr: df)) {
36 ret = PTR_ERR(ptr: df);
37 goto err_put_registration;
38 }
39
40 filep->private_data = df;
41
42 return 0;
43
44err_put_registration:
45 vfio_device_put_registration(device);
46 return ret;
47}
48
49static void vfio_df_get_kvm_safe(struct vfio_device_file *df)
50{
51 spin_lock(lock: &df->kvm_ref_lock);
52 vfio_device_get_kvm_safe(device: df->device, kvm: df->kvm);
53 spin_unlock(lock: &df->kvm_ref_lock);
54}
55
56long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
57 struct vfio_device_bind_iommufd __user *arg)
58{
59 struct vfio_device *device = df->device;
60 struct vfio_device_bind_iommufd bind;
61 unsigned long minsz;
62 int ret;
63
64 static_assert(__same_type(arg->out_devid, df->devid));
65
66 minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid);
67
68 if (copy_from_user(to: &bind, from: arg, n: minsz))
69 return -EFAULT;
70
71 if (bind.argsz < minsz || bind.flags || bind.iommufd < 0)
72 return -EINVAL;
73
74 /* BIND_IOMMUFD only allowed for cdev fds */
75 if (df->group)
76 return -EINVAL;
77
78 ret = vfio_device_block_group(device);
79 if (ret)
80 return ret;
81
82 mutex_lock(&device->dev_set->lock);
83 /* one device cannot be bound twice */
84 if (df->access_granted) {
85 ret = -EINVAL;
86 goto out_unlock;
87 }
88
89 df->iommufd = iommufd_ctx_from_fd(fd: bind.iommufd);
90 if (IS_ERR(ptr: df->iommufd)) {
91 ret = PTR_ERR(ptr: df->iommufd);
92 df->iommufd = NULL;
93 goto out_unlock;
94 }
95
96 /*
97 * Before the device open, get the KVM pointer currently
98 * associated with the device file (if there is) and obtain
99 * a reference. This reference is held until device closed.
100 * Save the pointer in the device for use by drivers.
101 */
102 vfio_df_get_kvm_safe(df);
103
104 ret = vfio_df_open(df);
105 if (ret)
106 goto out_put_kvm;
107
108 ret = copy_to_user(to: &arg->out_devid, from: &df->devid,
109 n: sizeof(df->devid)) ? -EFAULT : 0;
110 if (ret)
111 goto out_close_device;
112
113 device->cdev_opened = true;
114 /*
115 * Paired with smp_load_acquire() in vfio_device_fops::ioctl/
116 * read/write/mmap
117 */
118 smp_store_release(&df->access_granted, true);
119 mutex_unlock(lock: &device->dev_set->lock);
120 return 0;
121
122out_close_device:
123 vfio_df_close(df);
124out_put_kvm:
125 vfio_device_put_kvm(device);
126 iommufd_ctx_put(ictx: df->iommufd);
127 df->iommufd = NULL;
128out_unlock:
129 mutex_unlock(lock: &device->dev_set->lock);
130 vfio_device_unblock_group(device);
131 return ret;
132}
133
134void vfio_df_unbind_iommufd(struct vfio_device_file *df)
135{
136 struct vfio_device *device = df->device;
137
138 /*
139 * In the time of close, there is no contention with another one
140 * changing this flag. So read df->access_granted without lock
141 * and no smp_load_acquire() is ok.
142 */
143 if (!df->access_granted)
144 return;
145
146 mutex_lock(&device->dev_set->lock);
147 vfio_df_close(df);
148 vfio_device_put_kvm(device);
149 iommufd_ctx_put(ictx: df->iommufd);
150 device->cdev_opened = false;
151 mutex_unlock(lock: &device->dev_set->lock);
152 vfio_device_unblock_group(device);
153}
154
155int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
156 struct vfio_device_attach_iommufd_pt __user *arg)
157{
158 struct vfio_device *device = df->device;
159 struct vfio_device_attach_iommufd_pt attach;
160 unsigned long minsz;
161 int ret;
162
163 minsz = offsetofend(struct vfio_device_attach_iommufd_pt, pt_id);
164
165 if (copy_from_user(to: &attach, from: arg, n: minsz))
166 return -EFAULT;
167
168 if (attach.argsz < minsz || attach.flags)
169 return -EINVAL;
170
171 mutex_lock(&device->dev_set->lock);
172 ret = device->ops->attach_ioas(device, &attach.pt_id);
173 if (ret)
174 goto out_unlock;
175
176 if (copy_to_user(to: &arg->pt_id, from: &attach.pt_id, n: sizeof(attach.pt_id))) {
177 ret = -EFAULT;
178 goto out_detach;
179 }
180 mutex_unlock(lock: &device->dev_set->lock);
181
182 return 0;
183
184out_detach:
185 device->ops->detach_ioas(device);
186out_unlock:
187 mutex_unlock(lock: &device->dev_set->lock);
188 return ret;
189}
190
191int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
192 struct vfio_device_detach_iommufd_pt __user *arg)
193{
194 struct vfio_device *device = df->device;
195 struct vfio_device_detach_iommufd_pt detach;
196 unsigned long minsz;
197
198 minsz = offsetofend(struct vfio_device_detach_iommufd_pt, flags);
199
200 if (copy_from_user(to: &detach, from: arg, n: minsz))
201 return -EFAULT;
202
203 if (detach.argsz < minsz || detach.flags)
204 return -EINVAL;
205
206 mutex_lock(&device->dev_set->lock);
207 device->ops->detach_ioas(device);
208 mutex_unlock(lock: &device->dev_set->lock);
209
210 return 0;
211}
212
213static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
214{
215 return kasprintf(GFP_KERNEL, fmt: "vfio/devices/%s", dev_name(dev));
216}
217
218int vfio_cdev_init(struct class *device_class)
219{
220 device_class->devnode = vfio_device_devnode;
221 return alloc_chrdev_region(&device_devt, 0,
222 MINORMASK + 1, "vfio-dev");
223}
224
225void vfio_cdev_cleanup(void)
226{
227 unregister_chrdev_region(device_devt, MINORMASK + 1);
228}
229

source code of linux/drivers/vfio/device_cdev.c