1 /* 2 * xenfs.c - a filesystem for passing info between the a domain and 3 * the hypervisor. 4 * 5 * 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem 6 * and /proc/xen compatibility mount point. 7 * Turned xenfs into a loadable module. 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/errno.h> 12 #include <linux/module.h> 13 #include <linux/fs.h> 14 #include <linux/magic.h> 15 16 #include <xen/xen.h> 17 18 #include "xenfs.h" 19 #include "../privcmd.h" 20 #include "../xenbus/xenbus_comms.h" 21 22 #include <asm/xen/hypervisor.h> 23 24 MODULE_DESCRIPTION("Xen filesystem"); 25 MODULE_LICENSE("GPL"); 26 27 static ssize_t capabilities_read(struct file *file, char __user *buf, 28 size_t size, loff_t *off) 29 { 30 char *tmp = ""; 31 32 if (xen_initial_domain()) 33 tmp = "control_d\n"; 34 35 return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp)); 36 } 37 38 static const struct file_operations capabilities_file_ops = { 39 .read = capabilities_read, 40 .llseek = default_llseek, 41 }; 42 43 static int xenfs_fill_super(struct super_block *sb, void *data, int silent) 44 { 45 static struct tree_descr xenfs_files[] = { 46 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, 47 { "capabilities", &capabilities_file_ops, S_IRUGO }, 48 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, 49 {""}, 50 }; 51 52 static struct tree_descr xenfs_init_files[] = { 53 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, 54 { "capabilities", &capabilities_file_ops, S_IRUGO }, 55 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, 56 { "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR}, 57 { "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR}, 58 {""}, 59 }; 60 61 return simple_fill_super(sb, XENFS_SUPER_MAGIC, 62 xen_initial_domain() ? xenfs_init_files : xenfs_files); 63 } 64 65 static struct dentry *xenfs_mount(struct file_system_type *fs_type, 66 int flags, const char *dev_name, 67 void *data) 68 { 69 return mount_single(fs_type, flags, data, xenfs_fill_super); 70 } 71 72 static struct file_system_type xenfs_type = { 73 .owner = THIS_MODULE, 74 .name = "xenfs", 75 .mount = xenfs_mount, 76 .kill_sb = kill_litter_super, 77 }; 78 MODULE_ALIAS_FS("xenfs"); 79 80 static int __init xenfs_init(void) 81 { 82 if (xen_domain()) 83 return register_filesystem(&xenfs_type); 84 85 printk(KERN_INFO "XENFS: not registering filesystem on non-xen platform\n"); 86 return 0; 87 } 88 89 static void __exit xenfs_exit(void) 90 { 91 if (xen_domain()) 92 unregister_filesystem(&xenfs_type); 93 } 94 95 module_init(xenfs_init); 96 module_exit(xenfs_exit); 97 98