134 lines
3.0 KiB
C
134 lines
3.0 KiB
C
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
|
|
#include <linux/slab.h>
|
|
#include <linux/types.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/miscdevice.h>
|
|
#include <linux/init.h>
|
|
#include <linux/capability.h>
|
|
|
|
#include <xen/xen.h>
|
|
#include <xen/page.h>
|
|
#include <xen/xenbus.h>
|
|
#include <xen/xenbus_dev.h>
|
|
#include <xen/grant_table.h>
|
|
#include <xen/events.h>
|
|
#include <asm/xen/hypervisor.h>
|
|
|
|
#include "xenbus.h"
|
|
|
|
static int xenbus_backend_open(struct inode *inode, struct file *filp)
|
|
{
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
return nonseekable_open(inode, filp);
|
|
}
|
|
|
|
static long xenbus_alloc(domid_t domid)
|
|
{
|
|
struct evtchn_alloc_unbound arg;
|
|
int err = -EEXIST;
|
|
|
|
xs_suspend();
|
|
|
|
/* If xenstored_ready is nonzero, that means we have already talked to
|
|
* xenstore and set up watches. These watches will be restored by
|
|
* xs_resume, but that requires communication over the port established
|
|
* below that is not visible to anyone until the ioctl returns.
|
|
*
|
|
* This can be resolved by splitting the ioctl into two parts
|
|
* (postponing the resume until xenstored is active) but this is
|
|
* unnecessarily complex for the intended use where xenstored is only
|
|
* started once - so return -EEXIST if it's already running.
|
|
*/
|
|
if (xenstored_ready)
|
|
goto out_err;
|
|
|
|
gnttab_grant_foreign_access_ref(GNTTAB_RESERVED_XENSTORE, domid,
|
|
virt_to_gfn(xen_store_interface), 0 /* writable */);
|
|
|
|
arg.dom = DOMID_SELF;
|
|
arg.remote_dom = domid;
|
|
|
|
err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &arg);
|
|
if (err)
|
|
goto out_err;
|
|
|
|
if (xen_store_evtchn > 0)
|
|
xb_deinit_comms();
|
|
|
|
xen_store_evtchn = arg.port;
|
|
|
|
xs_resume();
|
|
|
|
return arg.port;
|
|
|
|
out_err:
|
|
xs_suspend_cancel();
|
|
return err;
|
|
}
|
|
|
|
static long xenbus_backend_ioctl(struct file *file, unsigned int cmd,
|
|
unsigned long data)
|
|
{
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
switch (cmd) {
|
|
case IOCTL_XENBUS_BACKEND_EVTCHN:
|
|
if (xen_store_evtchn > 0)
|
|
return xen_store_evtchn;
|
|
return -ENODEV;
|
|
case IOCTL_XENBUS_BACKEND_SETUP:
|
|
return xenbus_alloc(data);
|
|
default:
|
|
return -ENOTTY;
|
|
}
|
|
}
|
|
|
|
static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
|
size_t size = vma->vm_end - vma->vm_start;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0))
|
|
return -EINVAL;
|
|
|
|
if (remap_pfn_range(vma, vma->vm_start,
|
|
virt_to_pfn(xen_store_interface),
|
|
size, vma->vm_page_prot))
|
|
return -EAGAIN;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct file_operations xenbus_backend_fops = {
|
|
.open = xenbus_backend_open,
|
|
.mmap = xenbus_backend_mmap,
|
|
.unlocked_ioctl = xenbus_backend_ioctl,
|
|
};
|
|
|
|
static struct miscdevice xenbus_backend_dev = {
|
|
.minor = MISC_DYNAMIC_MINOR,
|
|
.name = "xen/xenbus_backend",
|
|
.fops = &xenbus_backend_fops,
|
|
};
|
|
|
|
static int __init xenbus_backend_init(void)
|
|
{
|
|
int err;
|
|
|
|
if (!xen_initial_domain())
|
|
return -ENODEV;
|
|
|
|
err = misc_register(&xenbus_backend_dev);
|
|
if (err)
|
|
pr_err("Could not register xenbus backend device\n");
|
|
return err;
|
|
}
|
|
device_initcall(xenbus_backend_init);
|