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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 11 12 #include <linux/kernel.h> 13 #include <linux/errno.h> 14 #include <linux/module.h> 15 #include <linux/fs.h> 16 #include <linux/magic.h> 17 18 #include <xen/xen.h> 19 20 #include "xenfs.h" 21 #include "../privcmd.h" 22 #include "../xenbus/xenbus_comms.h" 23 24 #include <asm/xen/hypervisor.h> 25 26 MODULE_DESCRIPTION("Xen filesystem"); 27 MODULE_LICENSE("GPL"); 28 29 static ssize_t capabilities_read(struct file *file, char __user *buf, 30 size_t size, loff_t *off) 31 { 32 char *tmp = ""; 33 34 if (xen_initial_domain()) 35 tmp = "control_d\n"; 36 37 return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp)); 38 } 39 40 static const struct file_operations capabilities_file_ops = { 41 .read = capabilities_read, 42 .llseek = default_llseek, 43 }; 44 45 static int xenfs_fill_super(struct super_block *sb, void *data, int silent) 46 { 47 static struct tree_descr xenfs_files[] = { 48 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, 49 { "capabilities", &capabilities_file_ops, S_IRUGO }, 50 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, 51 {""}, 52 }; 53 54 static struct tree_descr xenfs_init_files[] = { 55 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, 56 { "capabilities", &capabilities_file_ops, S_IRUGO }, 57 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, 58 { "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR}, 59 { "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR}, 60 {""}, 61 }; 62 63 return simple_fill_super(sb, XENFS_SUPER_MAGIC, 64 xen_initial_domain() ? xenfs_init_files : xenfs_files); 65 } 66 67 static struct dentry *xenfs_mount(struct file_system_type *fs_type, 68 int flags, const char *dev_name, 69 void *data) 70 { 71 return mount_single(fs_type, flags, data, xenfs_fill_super); 72 } 73 74 static struct file_system_type xenfs_type = { 75 .owner = THIS_MODULE, 76 .name = "xenfs", 77 .mount = xenfs_mount, 78 .kill_sb = kill_litter_super, 79 }; 80 MODULE_ALIAS_FS("xenfs"); 81 82 static int __init xenfs_init(void) 83 { 84 if (xen_domain()) 85 return register_filesystem(&xenfs_type); 86 87 pr_info("not registering filesystem on non-xen platform\n"); 88 return 0; 89 } 90 91 static void __exit xenfs_exit(void) 92 { 93 if (xen_domain()) 94 unregister_filesystem(&xenfs_type); 95 } 96 97 module_init(xenfs_init); 98 module_exit(xenfs_exit); 99 100