Commit | Line | Data |
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e9f0fec3 BB |
1 | #include <linux/slab.h> |
2 | #include <linux/types.h> | |
3 | #include <linux/mm.h> | |
4 | #include <linux/fs.h> | |
5 | #include <linux/miscdevice.h> | |
6 | #include <linux/module.h> | |
7 | #include <linux/capability.h> | |
8 | ||
01464a60 | 9 | #include <xen/xen.h> |
e9f0fec3 | 10 | #include <xen/page.h> |
d2fb4c51 | 11 | #include <xen/xenbus.h> |
e9f0fec3 | 12 | #include <xen/xenbus_dev.h> |
d2fb4c51 DDG |
13 | #include <xen/grant_table.h> |
14 | #include <xen/events.h> | |
15 | #include <asm/xen/hypervisor.h> | |
e9f0fec3 BB |
16 | |
17 | #include "xenbus_comms.h" | |
18 | ||
19 | MODULE_LICENSE("GPL"); | |
20 | ||
21 | static int xenbus_backend_open(struct inode *inode, struct file *filp) | |
22 | { | |
23 | if (!capable(CAP_SYS_ADMIN)) | |
24 | return -EPERM; | |
25 | ||
26 | return nonseekable_open(inode, filp); | |
27 | } | |
28 | ||
d2fb4c51 DDG |
29 | static long xenbus_alloc(domid_t domid) |
30 | { | |
31 | struct evtchn_alloc_unbound arg; | |
32 | int err = -EEXIST; | |
33 | ||
34 | xs_suspend(); | |
35 | ||
36 | /* If xenstored_ready is nonzero, that means we have already talked to | |
37 | * xenstore and set up watches. These watches will be restored by | |
38 | * xs_resume, but that requires communication over the port established | |
39 | * below that is not visible to anyone until the ioctl returns. | |
40 | * | |
41 | * This can be resolved by splitting the ioctl into two parts | |
42 | * (postponing the resume until xenstored is active) but this is | |
43 | * unnecessarily complex for the intended use where xenstored is only | |
44 | * started once - so return -EEXIST if it's already running. | |
45 | */ | |
46 | if (xenstored_ready) | |
47 | goto out_err; | |
48 | ||
49 | gnttab_grant_foreign_access_ref(GNTTAB_RESERVED_XENSTORE, domid, | |
50 | virt_to_mfn(xen_store_interface), 0 /* writable */); | |
51 | ||
52 | arg.dom = DOMID_SELF; | |
53 | arg.remote_dom = domid; | |
54 | ||
55 | err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &arg); | |
56 | if (err) | |
57 | goto out_err; | |
58 | ||
59 | if (xen_store_evtchn > 0) | |
60 | xb_deinit_comms(); | |
61 | ||
62 | xen_store_evtchn = arg.port; | |
63 | ||
64 | xs_resume(); | |
65 | ||
66 | return arg.port; | |
67 | ||
68 | out_err: | |
69 | xs_suspend_cancel(); | |
70 | return err; | |
71 | } | |
72 | ||
e9f0fec3 BB |
73 | static long xenbus_backend_ioctl(struct file *file, unsigned int cmd, unsigned long data) |
74 | { | |
75 | if (!capable(CAP_SYS_ADMIN)) | |
76 | return -EPERM; | |
77 | ||
78 | switch (cmd) { | |
79 | case IOCTL_XENBUS_BACKEND_EVTCHN: | |
80 | if (xen_store_evtchn > 0) | |
81 | return xen_store_evtchn; | |
82 | return -ENODEV; | |
83 | ||
d2fb4c51 DDG |
84 | case IOCTL_XENBUS_BACKEND_SETUP: |
85 | return xenbus_alloc(data); | |
86 | ||
e9f0fec3 BB |
87 | default: |
88 | return -ENOTTY; | |
89 | } | |
90 | } | |
91 | ||
92 | static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma) | |
93 | { | |
94 | size_t size = vma->vm_end - vma->vm_start; | |
95 | ||
96 | if (!capable(CAP_SYS_ADMIN)) | |
97 | return -EPERM; | |
98 | ||
99 | if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0)) | |
100 | return -EINVAL; | |
101 | ||
102 | if (remap_pfn_range(vma, vma->vm_start, | |
103 | virt_to_pfn(xen_store_interface), | |
104 | size, vma->vm_page_prot)) | |
105 | return -EAGAIN; | |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
110 | const struct file_operations xenbus_backend_fops = { | |
111 | .open = xenbus_backend_open, | |
112 | .mmap = xenbus_backend_mmap, | |
113 | .unlocked_ioctl = xenbus_backend_ioctl, | |
114 | }; | |
115 | ||
116 | static struct miscdevice xenbus_backend_dev = { | |
117 | .minor = MISC_DYNAMIC_MINOR, | |
118 | .name = "xen/xenbus_backend", | |
119 | .fops = &xenbus_backend_fops, | |
120 | }; | |
121 | ||
122 | static int __init xenbus_backend_init(void) | |
123 | { | |
124 | int err; | |
125 | ||
126 | if (!xen_initial_domain()) | |
127 | return -ENODEV; | |
128 | ||
129 | err = misc_register(&xenbus_backend_dev); | |
130 | if (err) | |
131 | printk(KERN_ERR "Could not register xenbus backend device\n"); | |
132 | return err; | |
133 | } | |
134 | ||
135 | static void __exit xenbus_backend_exit(void) | |
136 | { | |
137 | misc_deregister(&xenbus_backend_dev); | |
138 | } | |
139 | ||
140 | module_init(xenbus_backend_init); | |
141 | module_exit(xenbus_backend_exit); |