blob: a6f42fc01407e435c477862d380e8a1da55d6656 [file] [log] [blame]
Bastian Blanke9f0fec2011-12-10 19:29:48 +01001#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
Konrad Rzeszutek Wilk01464a62011-12-21 14:19:47 -05009#include <xen/xen.h>
Bastian Blanke9f0fec2011-12-10 19:29:48 +010010#include <xen/page.h>
Daniel De Graafd2fb4c52012-05-08 09:46:57 -040011#include <xen/xenbus.h>
Bastian Blanke9f0fec2011-12-10 19:29:48 +010012#include <xen/xenbus_dev.h>
Daniel De Graafd2fb4c52012-05-08 09:46:57 -040013#include <xen/grant_table.h>
14#include <xen/events.h>
15#include <asm/xen/hypervisor.h>
Bastian Blanke9f0fec2011-12-10 19:29:48 +010016
17#include "xenbus_comms.h"
18
19MODULE_LICENSE("GPL");
20
21static 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
Daniel De Graafd2fb4c52012-05-08 09:46:57 -040029static 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
Lisa Nguyen3d645b02013-05-15 23:48:03 -070073static long xenbus_backend_ioctl(struct file *file, unsigned int cmd,
74 unsigned long data)
Bastian Blanke9f0fec2011-12-10 19:29:48 +010075{
76 if (!capable(CAP_SYS_ADMIN))
77 return -EPERM;
78
79 switch (cmd) {
Lisa Nguyend7e50752013-05-15 23:47:11 -070080 case IOCTL_XENBUS_BACKEND_EVTCHN:
81 if (xen_store_evtchn > 0)
82 return xen_store_evtchn;
83 return -ENODEV;
84 case IOCTL_XENBUS_BACKEND_SETUP:
85 return xenbus_alloc(data);
86 default:
87 return -ENOTTY;
Bastian Blanke9f0fec2011-12-10 19:29:48 +010088 }
89}
90
91static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)
92{
93 size_t size = vma->vm_end - vma->vm_start;
94
95 if (!capable(CAP_SYS_ADMIN))
96 return -EPERM;
97
98 if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0))
99 return -EINVAL;
100
101 if (remap_pfn_range(vma, vma->vm_start,
102 virt_to_pfn(xen_store_interface),
103 size, vma->vm_page_prot))
104 return -EAGAIN;
105
106 return 0;
107}
108
Konrad Rzeszutek Wilkb8b0f552012-08-21 14:49:34 -0400109static const struct file_operations xenbus_backend_fops = {
Bastian Blanke9f0fec2011-12-10 19:29:48 +0100110 .open = xenbus_backend_open,
111 .mmap = xenbus_backend_mmap,
112 .unlocked_ioctl = xenbus_backend_ioctl,
113};
114
115static struct miscdevice xenbus_backend_dev = {
116 .minor = MISC_DYNAMIC_MINOR,
117 .name = "xen/xenbus_backend",
118 .fops = &xenbus_backend_fops,
119};
120
121static int __init xenbus_backend_init(void)
122{
123 int err;
124
125 if (!xen_initial_domain())
126 return -ENODEV;
127
128 err = misc_register(&xenbus_backend_dev);
129 if (err)
130 printk(KERN_ERR "Could not register xenbus backend device\n");
131 return err;
132}
133
134static void __exit xenbus_backend_exit(void)
135{
136 misc_deregister(&xenbus_backend_dev);
137}
138
139module_init(xenbus_backend_init);
140module_exit(xenbus_backend_exit);