xen: Add privcmd device driver

Access to arbitrary hypercalls is currently provided via xenfs. This
adds a standard character device to handle this. The support in xenfs
remains for backward compatibility and uses the device driver code.

Signed-off-by: Bastian Blank <waldi@debian.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

7 files changed, 53 insertions, 4 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 8795480c2350..a1ced521cf74 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -86,6 +86,7 @@ config XEN_BACKEND
 
 config XENFS
         tristate "Xen filesystem"
+        select XEN_PRIVCMD
         default y
         help
           The xen filesystem provides a way for domains to share
@@ -171,4 +172,10 @@ config XEN_PCIDEV_BACKEND
           xen-pciback.hide=(03:00.0)(04:00.0)
 
           If in doubt, say m.
+
+config XEN_PRIVCMD
+        tristate
+        depends on XEN
+        default m
+
 endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 974fffdf22b2..aa31337192cc 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -19,7 +19,9 @@ obj-$(CONFIG_XEN_TMEM)			+= tmem.o
 obj-$(CONFIG_SWIOTLB_XEN)               += swiotlb-xen.o
 obj-$(CONFIG_XEN_DOM0)                  += pci.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)        += xen-pciback/
+obj-$(CONFIG_XEN_PRIVCMD)               += xen-privcmd.o
 
 xen-evtchn-y                            := evtchn.o
 xen-gntdev-y                            := gntdev.o
 xen-gntalloc-y                          := gntalloc.o
+xen-privcmd-y                           := privcmd.o
diff --git a/drivers/xen/xenfs/privcmd.c b/drivers/xen/privcmd.c
index dbd3b16fd131..4e8d3da89ad5 100644
--- a/drivers/xen/xenfs/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -18,6 +19,7 @@
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
 #include <linux/seq_file.h>
+#include <linux/miscdevice.h>
 
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
@@ -32,6 +34,10 @@
 #include <xen/page.h>
 #include <xen/xen-ops.h>
 
+#include "privcmd.h"
+
+MODULE_LICENSE("GPL");
+
 #ifndef HAVE_ARCH_PRIVCMD_MMAP
 static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma);
 #endif
@@ -394,7 +400,38 @@ static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
 }
 #endif
 
-const struct file_operations privcmd_file_ops = {
+const struct file_operations xen_privcmd_fops = {
+        .owner = THIS_MODULE,
         .unlocked_ioctl = privcmd_ioctl,
         .mmap = privcmd_mmap,
 };
+EXPORT_SYMBOL_GPL(xen_privcmd_fops);
+
+static struct miscdevice privcmd_dev = {
+        .minor = MISC_DYNAMIC_MINOR,
+        .name = "xen/privcmd",
+        .fops = &xen_privcmd_fops,
+};
+
+static int __init privcmd_init(void)
+{
+        int err;
+
+        if (!xen_domain())
+                return -ENODEV;
+
+        err = misc_register(&privcmd_dev);
+        if (err != 0) {
+                printk(KERN_ERR "Could not register Xen privcmd device\n");
+                return err;
+        }
+        return 0;
+}
+
+static void __exit privcmd_exit(void)
+{
+        misc_deregister(&privcmd_dev);
+}
+
+module_init(privcmd_init);
+module_exit(privcmd_exit);
diff --git a/drivers/xen/privcmd.h b/drivers/xen/privcmd.h
new file mode 100644
index 000000000000..14facaeed36f
--- /dev/null
+++ b/drivers/xen/privcmd.h
@@ -0,0 +1,3 @@
+#include <linux/fs.h>
+
+extern const struct file_operations xen_privcmd_fops;
diff --git a/drivers/xen/xenfs/Makefile b/drivers/xen/xenfs/Makefile
index 4fde9440fe1f..5d45ff13cc01 100644
--- a/drivers/xen/xenfs/Makefile
+++ b/drivers/xen/xenfs/Makefile
@@ -1,4 +1,4 @@
 obj-$(CONFIG_XENFS) += xenfs.o
 
-xenfs-y                   = super.o xenbus.o privcmd.o
+xenfs-y                   = super.o xenbus.o
 xenfs-$(CONFIG_XEN_DOM0) += xenstored.o
diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
index 1aa389719846..a55fbf9a1519 100644
--- a/drivers/xen/xenfs/super.c
+++ b/drivers/xen/xenfs/super.c
@@ -16,6 +16,7 @@
 #include <xen/xen.h>
 
 #include "xenfs.h"
+#include "../privcmd.h"
 
 #include <asm/xen/hypervisor.h>
 
@@ -84,7 +85,7 @@ static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
                 [1] = {},
                 { "xenbus", &xenbus_file_ops, S_IRUSR|S_IWUSR },
                 { "capabilities", &capabilities_file_ops, S_IRUGO },
-                { "privcmd", &privcmd_file_ops, S_IRUSR|S_IWUSR },
+                { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
                 {""},
         };
         int rc;
diff --git a/drivers/xen/xenfs/xenfs.h b/drivers/xen/xenfs/xenfs.h
index b68aa6200003..5056306e7aa8 100644
--- a/drivers/xen/xenfs/xenfs.h
+++ b/drivers/xen/xenfs/xenfs.h
@@ -2,7 +2,6 @@
 #define _XENFS_XENBUS_H
 
 extern const struct file_operations xenbus_file_ops;
-extern const struct file_operations privcmd_file_ops;
 extern const struct file_operations xsd_kva_file_ops;
 extern const struct file_operations xsd_port_file_ops;