diff options
Diffstat (limited to 'drivers/xen/xenbus/xenbus_dev_backend.c')
| -rw-r--r-- | drivers/xen/xenbus/xenbus_dev_backend.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_dev_backend.c b/drivers/xen/xenbus/xenbus_dev_backend.c index 3d3be78c1093..be738c43104b 100644 --- a/drivers/xen/xenbus/xenbus_dev_backend.c +++ b/drivers/xen/xenbus/xenbus_dev_backend.c @@ -8,7 +8,11 @@ #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_comms.h" @@ -22,6 +26,50 @@ static int xenbus_backend_open(struct inode *inode, struct file *filp) 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_mfn(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)) @@ -33,6 +81,9 @@ static long xenbus_backend_ioctl(struct file *file, unsigned int cmd, unsigned l return xen_store_evtchn; return -ENODEV; + case IOCTL_XENBUS_BACKEND_SETUP: + return xenbus_alloc(data); + default: return -ENOTTY; } |