v4.19.13 snapshot.
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
new file mode 100644
index 0000000..581c4e1
--- /dev/null
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -0,0 +1,743 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCI Backend Xenbus Setup - handles setup with frontend and xend
+ *
+ * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+#include <xen/xenbus.h>
+#include <xen/events.h>
+#include <asm/xen/pci.h>
+#include "pciback.h"
+
+#define INVALID_EVTCHN_IRQ (-1)
+
+static bool __read_mostly passthrough;
+module_param(passthrough, bool, S_IRUGO);
+MODULE_PARM_DESC(passthrough,
+ "Option to specify how to export PCI topology to guest:\n"\
+ " 0 - (default) Hide the true PCI topology and makes the frontend\n"\
+ " there is a single PCI bus with only the exported devices on it.\n"\
+ " For example, a device at 03:05.0 will be re-assigned to 00:00.0\n"\
+ " while second device at 02:1a.1 will be re-assigned to 00:01.1.\n"\
+ " 1 - Passthrough provides a real view of the PCI topology to the\n"\
+ " frontend (for example, a device at 06:01.b will still appear at\n"\
+ " 06:01.b to the frontend). This is similar to how Xen 2.0.x\n"\
+ " exposed PCI devices to its driver domains. This may be required\n"\
+ " for drivers which depend on finding their hardward in certain\n"\
+ " bus/slot locations.");
+
+static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
+{
+ struct xen_pcibk_device *pdev;
+
+ pdev = kzalloc(sizeof(struct xen_pcibk_device), GFP_KERNEL);
+ if (pdev == NULL)
+ goto out;
+ dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
+
+ pdev->xdev = xdev;
+
+ mutex_init(&pdev->dev_lock);
+
+ pdev->sh_info = NULL;
+ pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
+ pdev->be_watching = 0;
+
+ INIT_WORK(&pdev->op_work, xen_pcibk_do_op);
+
+ if (xen_pcibk_init_devices(pdev)) {
+ kfree(pdev);
+ pdev = NULL;
+ }
+
+ dev_set_drvdata(&xdev->dev, pdev);
+
+out:
+ return pdev;
+}
+
+static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
+{
+ mutex_lock(&pdev->dev_lock);
+ /* Ensure the guest can't trigger our handler before removing devices */
+ if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ) {
+ unbind_from_irqhandler(pdev->evtchn_irq, pdev);
+ pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
+ }
+
+ /* If the driver domain started an op, make sure we complete it
+ * before releasing the shared memory */
+
+ flush_work(&pdev->op_work);
+
+ if (pdev->sh_info != NULL) {
+ xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
+ pdev->sh_info = NULL;
+ }
+ mutex_unlock(&pdev->dev_lock);
+}
+
+static void free_pdev(struct xen_pcibk_device *pdev)
+{
+ if (pdev->be_watching) {
+ unregister_xenbus_watch(&pdev->be_watch);
+ pdev->be_watching = 0;
+ }
+
+ xen_pcibk_disconnect(pdev);
+
+ /* N.B. This calls pcistub_put_pci_dev which does the FLR on all
+ * of the PCIe devices. */
+ xen_pcibk_release_devices(pdev);
+
+ dev_set_drvdata(&pdev->xdev->dev, NULL);
+ pdev->xdev = NULL;
+
+ kfree(pdev);
+}
+
+static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
+ int remote_evtchn)
+{
+ int err = 0;
+ void *vaddr;
+
+ dev_dbg(&pdev->xdev->dev,
+ "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
+ gnt_ref, remote_evtchn);
+
+ err = xenbus_map_ring_valloc(pdev->xdev, &gnt_ref, 1, &vaddr);
+ if (err < 0) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error mapping other domain page in ours.");
+ goto out;
+ }
+
+ pdev->sh_info = vaddr;
+
+ err = bind_interdomain_evtchn_to_irqhandler(
+ pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
+ 0, DRV_NAME, pdev);
+ if (err < 0) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error binding event channel to IRQ");
+ goto out;
+ }
+ pdev->evtchn_irq = err;
+ err = 0;
+
+ dev_dbg(&pdev->xdev->dev, "Attached!\n");
+out:
+ return err;
+}
+
+static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
+{
+ int err = 0;
+ int gnt_ref, remote_evtchn;
+ char *magic = NULL;
+
+
+ mutex_lock(&pdev->dev_lock);
+ /* Make sure we only do this setup once */
+ if (xenbus_read_driver_state(pdev->xdev->nodename) !=
+ XenbusStateInitialised)
+ goto out;
+
+ /* Wait for frontend to state that it has published the configuration */
+ if (xenbus_read_driver_state(pdev->xdev->otherend) !=
+ XenbusStateInitialised)
+ goto out;
+
+ dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
+
+ err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
+ "pci-op-ref", "%u", &gnt_ref,
+ "event-channel", "%u", &remote_evtchn,
+ "magic", NULL, &magic, NULL);
+ if (err) {
+ /* If configuration didn't get read correctly, wait longer */
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error reading configuration from frontend");
+ goto out;
+ }
+
+ if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
+ xenbus_dev_fatal(pdev->xdev, -EFAULT,
+ "version mismatch (%s/%s) with pcifront - "
+ "halting " DRV_NAME,
+ magic, XEN_PCI_MAGIC);
+ err = -EFAULT;
+ goto out;
+ }
+
+ err = xen_pcibk_do_attach(pdev, gnt_ref, remote_evtchn);
+ if (err)
+ goto out;
+
+ dev_dbg(&pdev->xdev->dev, "Connecting...\n");
+
+ err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
+ if (err)
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error switching to connected state!");
+
+ dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
+out:
+ mutex_unlock(&pdev->dev_lock);
+
+ kfree(magic);
+
+ return err;
+}
+
+static int xen_pcibk_publish_pci_dev(struct xen_pcibk_device *pdev,
+ unsigned int domain, unsigned int bus,
+ unsigned int devfn, unsigned int devid)
+{
+ int err;
+ int len;
+ char str[64];
+
+ len = snprintf(str, sizeof(str), "vdev-%d", devid);
+ if (unlikely(len >= (sizeof(str) - 1))) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ /* Note: The PV protocol uses %02x, don't change it */
+ err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
+ "%04x:%02x:%02x.%02x", domain, bus,
+ PCI_SLOT(devfn), PCI_FUNC(devfn));
+
+out:
+ return err;
+}
+
+static int xen_pcibk_export_device(struct xen_pcibk_device *pdev,
+ int domain, int bus, int slot, int func,
+ int devid)
+{
+ struct pci_dev *dev;
+ int err = 0;
+
+ dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
+ domain, bus, slot, func);
+
+ dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
+ if (!dev) {
+ err = -EINVAL;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Couldn't locate PCI device "
+ "(%04x:%02x:%02x.%d)! "
+ "perhaps already in-use?",
+ domain, bus, slot, func);
+ goto out;
+ }
+
+ err = xen_pcibk_add_pci_dev(pdev, dev, devid,
+ xen_pcibk_publish_pci_dev);
+ if (err)
+ goto out;
+
+ dev_info(&dev->dev, "registering for %d\n", pdev->xdev->otherend_id);
+ if (xen_register_device_domain_owner(dev,
+ pdev->xdev->otherend_id) != 0) {
+ dev_err(&dev->dev, "Stealing ownership from dom%d.\n",
+ xen_find_device_domain_owner(dev));
+ xen_unregister_device_domain_owner(dev);
+ xen_register_device_domain_owner(dev, pdev->xdev->otherend_id);
+ }
+
+ /* TODO: It'd be nice to export a bridge and have all of its children
+ * get exported with it. This may be best done in xend (which will
+ * have to calculate resource usage anyway) but we probably want to
+ * put something in here to ensure that if a bridge gets given to a
+ * driver domain, that all devices under that bridge are not given
+ * to other driver domains (as he who controls the bridge can disable
+ * it and stop the other devices from working).
+ */
+out:
+ return err;
+}
+
+static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev,
+ int domain, int bus, int slot, int func)
+{
+ int err = 0;
+ struct pci_dev *dev;
+
+ dev_dbg(&pdev->xdev->dev, "removing dom %x bus %x slot %x func %x\n",
+ domain, bus, slot, func);
+
+ dev = xen_pcibk_get_pci_dev(pdev, domain, bus, PCI_DEVFN(slot, func));
+ if (!dev) {
+ err = -EINVAL;
+ dev_dbg(&pdev->xdev->dev, "Couldn't locate PCI device "
+ "(%04x:%02x:%02x.%d)! not owned by this domain\n",
+ domain, bus, slot, func);
+ goto out;
+ }
+
+ dev_dbg(&dev->dev, "unregistering for %d\n", pdev->xdev->otherend_id);
+ xen_unregister_device_domain_owner(dev);
+
+ /* N.B. This ends up calling pcistub_put_pci_dev which ends up
+ * doing the FLR. */
+ xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */);
+
+out:
+ return err;
+}
+
+static int xen_pcibk_publish_pci_root(struct xen_pcibk_device *pdev,
+ unsigned int domain, unsigned int bus)
+{
+ unsigned int d, b;
+ int i, root_num, len, err;
+ char str[64];
+
+ dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
+
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
+ "root_num", "%d", &root_num);
+ if (err == 0 || err == -ENOENT)
+ root_num = 0;
+ else if (err < 0)
+ goto out;
+
+ /* Verify that we haven't already published this pci root */
+ for (i = 0; i < root_num; i++) {
+ len = snprintf(str, sizeof(str), "root-%d", i);
+ if (unlikely(len >= (sizeof(str) - 1))) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
+ str, "%x:%x", &d, &b);
+ if (err < 0)
+ goto out;
+ if (err != 2) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ if (d == domain && b == bus) {
+ err = 0;
+ goto out;
+ }
+ }
+
+ len = snprintf(str, sizeof(str), "root-%d", root_num);
+ if (unlikely(len >= (sizeof(str) - 1))) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
+ root_num, domain, bus);
+
+ err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
+ "%04x:%02x", domain, bus);
+ if (err)
+ goto out;
+
+ err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
+ "root_num", "%d", (root_num + 1));
+
+out:
+ return err;
+}
+
+static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
+{
+ int err = 0;
+ int num_devs;
+ int domain, bus, slot, func;
+ unsigned int substate;
+ int i, len;
+ char state_str[64];
+ char dev_str[64];
+
+
+ dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
+
+ mutex_lock(&pdev->dev_lock);
+ /* Make sure we only reconfigure once */
+ if (xenbus_read_driver_state(pdev->xdev->nodename) !=
+ XenbusStateReconfiguring)
+ goto out;
+
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
+ &num_devs);
+ if (err != 1) {
+ if (err >= 0)
+ err = -EINVAL;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error reading number of devices");
+ goto out;
+ }
+
+ for (i = 0; i < num_devs; i++) {
+ len = snprintf(state_str, sizeof(state_str), "state-%d", i);
+ if (unlikely(len >= (sizeof(state_str) - 1))) {
+ err = -ENOMEM;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "String overflow while reading "
+ "configuration");
+ goto out;
+ }
+ substate = xenbus_read_unsigned(pdev->xdev->nodename, state_str,
+ XenbusStateUnknown);
+
+ switch (substate) {
+ case XenbusStateInitialising:
+ dev_dbg(&pdev->xdev->dev, "Attaching dev-%d ...\n", i);
+
+ len = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
+ if (unlikely(len >= (sizeof(dev_str) - 1))) {
+ err = -ENOMEM;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "String overflow while "
+ "reading configuration");
+ goto out;
+ }
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
+ dev_str, "%x:%x:%x.%x",
+ &domain, &bus, &slot, &func);
+ if (err < 0) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error reading device "
+ "configuration");
+ goto out;
+ }
+ if (err != 4) {
+ err = -EINVAL;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error parsing pci device "
+ "configuration");
+ goto out;
+ }
+
+ err = xen_pcibk_export_device(pdev, domain, bus, slot,
+ func, i);
+ if (err)
+ goto out;
+
+ /* Publish pci roots. */
+ err = xen_pcibk_publish_pci_roots(pdev,
+ xen_pcibk_publish_pci_root);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error while publish PCI root"
+ "buses for frontend");
+ goto out;
+ }
+
+ err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
+ state_str, "%d",
+ XenbusStateInitialised);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error switching substate of "
+ "dev-%d\n", i);
+ goto out;
+ }
+ break;
+
+ case XenbusStateClosing:
+ dev_dbg(&pdev->xdev->dev, "Detaching dev-%d ...\n", i);
+
+ len = snprintf(dev_str, sizeof(dev_str), "vdev-%d", i);
+ if (unlikely(len >= (sizeof(dev_str) - 1))) {
+ err = -ENOMEM;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "String overflow while "
+ "reading configuration");
+ goto out;
+ }
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
+ dev_str, "%x:%x:%x.%x",
+ &domain, &bus, &slot, &func);
+ if (err < 0) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error reading device "
+ "configuration");
+ goto out;
+ }
+ if (err != 4) {
+ err = -EINVAL;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error parsing pci device "
+ "configuration");
+ goto out;
+ }
+
+ err = xen_pcibk_remove_device(pdev, domain, bus, slot,
+ func);
+ if (err)
+ goto out;
+
+ /* TODO: If at some point we implement support for pci
+ * root hot-remove on pcifront side, we'll need to
+ * remove unnecessary xenstore nodes of pci roots here.
+ */
+
+ break;
+
+ default:
+ break;
+ }
+ }
+
+ err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error switching to reconfigured state!");
+ goto out;
+ }
+
+out:
+ mutex_unlock(&pdev->dev_lock);
+ return 0;
+}
+
+static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
+ enum xenbus_state fe_state)
+{
+ struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
+
+ dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
+
+ switch (fe_state) {
+ case XenbusStateInitialised:
+ xen_pcibk_attach(pdev);
+ break;
+
+ case XenbusStateReconfiguring:
+ xen_pcibk_reconfigure(pdev);
+ break;
+
+ case XenbusStateConnected:
+ /* pcifront switched its state from reconfiguring to connected.
+ * Then switch to connected state.
+ */
+ xenbus_switch_state(xdev, XenbusStateConnected);
+ break;
+
+ case XenbusStateClosing:
+ xen_pcibk_disconnect(pdev);
+ xenbus_switch_state(xdev, XenbusStateClosing);
+ break;
+
+ case XenbusStateClosed:
+ xen_pcibk_disconnect(pdev);
+ xenbus_switch_state(xdev, XenbusStateClosed);
+ if (xenbus_dev_is_online(xdev))
+ break;
+ /* fall through if not online */
+ case XenbusStateUnknown:
+ dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
+ device_unregister(&xdev->dev);
+ break;
+
+ default:
+ break;
+ }
+}
+
+static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
+{
+ /* Get configuration from xend (if available now) */
+ int domain, bus, slot, func;
+ int err = 0;
+ int i, num_devs;
+ char dev_str[64];
+ char state_str[64];
+
+ mutex_lock(&pdev->dev_lock);
+ /* It's possible we could get the call to setup twice, so make sure
+ * we're not already connected.
+ */
+ if (xenbus_read_driver_state(pdev->xdev->nodename) !=
+ XenbusStateInitWait)
+ goto out;
+
+ dev_dbg(&pdev->xdev->dev, "getting be setup\n");
+
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
+ &num_devs);
+ if (err != 1) {
+ if (err >= 0)
+ err = -EINVAL;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error reading number of devices");
+ goto out;
+ }
+
+ for (i = 0; i < num_devs; i++) {
+ int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
+ if (unlikely(l >= (sizeof(dev_str) - 1))) {
+ err = -ENOMEM;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "String overflow while reading "
+ "configuration");
+ goto out;
+ }
+
+ err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
+ "%x:%x:%x.%x", &domain, &bus, &slot, &func);
+ if (err < 0) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error reading device configuration");
+ goto out;
+ }
+ if (err != 4) {
+ err = -EINVAL;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error parsing pci device "
+ "configuration");
+ goto out;
+ }
+
+ err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
+ if (err)
+ goto out;
+
+ /* Switch substate of this device. */
+ l = snprintf(state_str, sizeof(state_str), "state-%d", i);
+ if (unlikely(l >= (sizeof(state_str) - 1))) {
+ err = -ENOMEM;
+ xenbus_dev_fatal(pdev->xdev, err,
+ "String overflow while reading "
+ "configuration");
+ goto out;
+ }
+ err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
+ "%d", XenbusStateInitialised);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err, "Error switching "
+ "substate of dev-%d\n", i);
+ goto out;
+ }
+ }
+
+ err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
+ if (err) {
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error while publish PCI root buses "
+ "for frontend");
+ goto out;
+ }
+
+ err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
+ if (err)
+ xenbus_dev_fatal(pdev->xdev, err,
+ "Error switching to initialised state!");
+
+out:
+ mutex_unlock(&pdev->dev_lock);
+ if (!err)
+ /* see if pcifront is already configured (if not, we'll wait) */
+ xen_pcibk_attach(pdev);
+ return err;
+}
+
+static void xen_pcibk_be_watch(struct xenbus_watch *watch,
+ const char *path, const char *token)
+{
+ struct xen_pcibk_device *pdev =
+ container_of(watch, struct xen_pcibk_device, be_watch);
+
+ switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
+ case XenbusStateInitWait:
+ xen_pcibk_setup_backend(pdev);
+ break;
+
+ default:
+ break;
+ }
+}
+
+static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
+ const struct xenbus_device_id *id)
+{
+ int err = 0;
+ struct xen_pcibk_device *pdev = alloc_pdev(dev);
+
+ if (pdev == NULL) {
+ err = -ENOMEM;
+ xenbus_dev_fatal(dev, err,
+ "Error allocating xen_pcibk_device struct");
+ goto out;
+ }
+
+ /* wait for xend to configure us */
+ err = xenbus_switch_state(dev, XenbusStateInitWait);
+ if (err)
+ goto out;
+
+ /* watch the backend node for backend configuration information */
+ err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
+ xen_pcibk_be_watch);
+ if (err)
+ goto out;
+
+ pdev->be_watching = 1;
+
+ /* We need to force a call to our callback here in case
+ * xend already configured us!
+ */
+ xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
+
+out:
+ return err;
+}
+
+static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
+{
+ struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
+
+ if (pdev != NULL)
+ free_pdev(pdev);
+
+ return 0;
+}
+
+static const struct xenbus_device_id xen_pcibk_ids[] = {
+ {"pci"},
+ {""},
+};
+
+static struct xenbus_driver xen_pcibk_driver = {
+ .name = DRV_NAME,
+ .ids = xen_pcibk_ids,
+ .probe = xen_pcibk_xenbus_probe,
+ .remove = xen_pcibk_xenbus_remove,
+ .otherend_changed = xen_pcibk_frontend_changed,
+};
+
+const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
+
+int __init xen_pcibk_xenbus_register(void)
+{
+ xen_pcibk_backend = &xen_pcibk_vpci_backend;
+ if (passthrough)
+ xen_pcibk_backend = &xen_pcibk_passthrough_backend;
+ pr_info("backend is %s\n", xen_pcibk_backend->name);
+ return xenbus_register_backend(&xen_pcibk_driver);
+}
+
+void __exit xen_pcibk_xenbus_unregister(void)
+{
+ xenbus_unregister_driver(&xen_pcibk_driver);
+}