This commit was manufactured by cvs2svn to create branch 'vserver'.
[linux-2.6.git] / drivers / xen / pciback / pci_stub.c
diff --git a/drivers/xen/pciback/pci_stub.c b/drivers/xen/pciback/pci_stub.c
new file mode 100644 (file)
index 0000000..b338559
--- /dev/null
@@ -0,0 +1,916 @@
+/*
+ * PCI Stub Driver - Grabs devices in backend to be exported later
+ *
+ * Ryan Wilson <hap9@epoch.ncsc.mil>
+ * Chris Bookholt <hap10@epoch.ncsc.mil>
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/kref.h>
+#include <asm/atomic.h>
+#include "pciback.h"
+#include "conf_space.h"
+#include "conf_space_quirks.h"
+
+static char *pci_devs_to_hide = NULL;
+module_param_named(hide, pci_devs_to_hide, charp, 0444);
+
+struct pcistub_device_id {
+       struct list_head slot_list;
+       int domain;
+       unsigned char bus;
+       unsigned int devfn;
+};
+static LIST_HEAD(pcistub_device_ids);
+static DEFINE_SPINLOCK(device_ids_lock);
+
+struct pcistub_device {
+       struct kref kref;
+       struct list_head dev_list;
+       spinlock_t lock;
+
+       struct pci_dev *dev;
+       struct pciback_device *pdev;    /* non-NULL if struct pci_dev is in use */
+};
+
+/* Access to pcistub_devices & seized_devices lists and the initialize_devices
+ * flag must be locked with pcistub_devices_lock
+ */
+static DEFINE_SPINLOCK(pcistub_devices_lock);
+static LIST_HEAD(pcistub_devices);
+
+/* wait for device_initcall before initializing our devices
+ * (see pcistub_init_devices_late)
+ */
+static int initialize_devices = 0;
+static LIST_HEAD(seized_devices);
+
+static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev)
+{
+       struct pcistub_device *psdev;
+
+       dev_dbg(&dev->dev, "pcistub_device_alloc\n");
+
+       psdev = kzalloc(sizeof(*psdev), GFP_ATOMIC);
+       if (!psdev)
+               return NULL;
+
+       psdev->dev = pci_dev_get(dev);
+       if (!psdev->dev) {
+               kfree(psdev);
+               return NULL;
+       }
+
+       kref_init(&psdev->kref);
+       spin_lock_init(&psdev->lock);
+
+       return psdev;
+}
+
+/* Don't call this directly as it's called by pcistub_device_put */
+static void pcistub_device_release(struct kref *kref)
+{
+       struct pcistub_device *psdev;
+
+       psdev = container_of(kref, struct pcistub_device, kref);
+
+       dev_dbg(&psdev->dev->dev, "pcistub_device_release\n");
+
+       /* Clean-up the device */
+       pciback_reset_device(psdev->dev);
+       pciback_config_free_dyn_fields(psdev->dev);
+       pciback_config_free_dev(psdev->dev);
+       kfree(pci_get_drvdata(psdev->dev));
+       pci_set_drvdata(psdev->dev, NULL);
+
+       pci_dev_put(psdev->dev);
+
+       kfree(psdev);
+}
+
+static inline void pcistub_device_get(struct pcistub_device *psdev)
+{
+       kref_get(&psdev->kref);
+}
+
+static inline void pcistub_device_put(struct pcistub_device *psdev)
+{
+       kref_put(&psdev->kref, pcistub_device_release);
+}
+
+static struct pcistub_device *pcistub_device_find(int domain, int bus,
+                                                 int slot, int func)
+{
+       struct pcistub_device *psdev = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+               if (psdev->dev != NULL
+                   && domain == pci_domain_nr(psdev->dev->bus)
+                   && bus == psdev->dev->bus->number
+                   && PCI_DEVFN(slot, func) == psdev->dev->devfn) {
+                       pcistub_device_get(psdev);
+                       goto out;
+               }
+       }
+
+       /* didn't find it */
+       psdev = NULL;
+
+      out:
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+       return psdev;
+}
+
+static struct pci_dev *pcistub_device_get_pci_dev(struct pciback_device *pdev,
+                                                 struct pcistub_device *psdev)
+{
+       struct pci_dev *pci_dev = NULL;
+       unsigned long flags;
+
+       pcistub_device_get(psdev);
+
+       spin_lock_irqsave(&psdev->lock, flags);
+       if (!psdev->pdev) {
+               psdev->pdev = pdev;
+               pci_dev = psdev->dev;
+       }
+       spin_unlock_irqrestore(&psdev->lock, flags);
+
+       if (!pci_dev)
+               pcistub_device_put(psdev);
+
+       return pci_dev;
+}
+
+struct pci_dev *pcistub_get_pci_dev_by_slot(struct pciback_device *pdev,
+                                           int domain, int bus,
+                                           int slot, int func)
+{
+       struct pcistub_device *psdev;
+       struct pci_dev *found_dev = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+               if (psdev->dev != NULL
+                   && domain == pci_domain_nr(psdev->dev->bus)
+                   && bus == psdev->dev->bus->number
+                   && PCI_DEVFN(slot, func) == psdev->dev->devfn) {
+                       found_dev = pcistub_device_get_pci_dev(pdev, psdev);
+                       break;
+               }
+       }
+
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+       return found_dev;
+}
+
+struct pci_dev *pcistub_get_pci_dev(struct pciback_device *pdev,
+                                   struct pci_dev *dev)
+{
+       struct pcistub_device *psdev;
+       struct pci_dev *found_dev = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+               if (psdev->dev == dev) {
+                       found_dev = pcistub_device_get_pci_dev(pdev, psdev);
+                       break;
+               }
+       }
+
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+       return found_dev;
+}
+
+void pcistub_put_pci_dev(struct pci_dev *dev)
+{
+       struct pcistub_device *psdev, *found_psdev = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+               if (psdev->dev == dev) {
+                       found_psdev = psdev;
+                       break;
+               }
+       }
+
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+       /* Cleanup our device
+        * (so it's ready for the next domain)
+        */
+       pciback_reset_device(found_psdev->dev);
+       pciback_config_free_dyn_fields(found_psdev->dev);
+       pciback_config_reset_dev(found_psdev->dev);
+
+       spin_lock_irqsave(&found_psdev->lock, flags);
+       found_psdev->pdev = NULL;
+       spin_unlock_irqrestore(&found_psdev->lock, flags);
+
+       pcistub_device_put(found_psdev);
+}
+
+static int __devinit pcistub_match_one(struct pci_dev *dev,
+                                      struct pcistub_device_id *pdev_id)
+{
+       /* Match the specified device by domain, bus, slot, func and also if
+        * any of the device's parent bridges match.
+        */
+       for (; dev != NULL; dev = dev->bus->self) {
+               if (pci_domain_nr(dev->bus) == pdev_id->domain
+                   && dev->bus->number == pdev_id->bus
+                   && dev->devfn == pdev_id->devfn)
+                       return 1;
+
+               /* Sometimes topmost bridge links to itself. */
+               if (dev == dev->bus->self)
+                       break;
+       }
+
+       return 0;
+}
+
+static int __devinit pcistub_match(struct pci_dev *dev)
+{
+       struct pcistub_device_id *pdev_id;
+       unsigned long flags;
+       int found = 0;
+
+       spin_lock_irqsave(&device_ids_lock, flags);
+       list_for_each_entry(pdev_id, &pcistub_device_ids, slot_list) {
+               if (pcistub_match_one(dev, pdev_id)) {
+                       found = 1;
+                       break;
+               }
+       }
+       spin_unlock_irqrestore(&device_ids_lock, flags);
+
+       return found;
+}
+
+static int __devinit pcistub_init_device(struct pci_dev *dev)
+{
+       struct pciback_dev_data *dev_data;
+       int err = 0;
+
+       dev_dbg(&dev->dev, "initializing...\n");
+
+       /* The PCI backend is not intended to be a module (or to work with
+        * removable PCI devices (yet). If it were, pciback_config_free()
+        * would need to be called somewhere to free the memory allocated
+        * here and then to call kfree(pci_get_drvdata(psdev->dev)).
+        */
+       dev_data = kzalloc(sizeof(*dev_data), GFP_ATOMIC);
+       if (!dev_data) {
+               err = -ENOMEM;
+               goto out;
+       }
+       pci_set_drvdata(dev, dev_data);
+
+       dev_dbg(&dev->dev, "initializing config\n");
+       err = pciback_config_init_dev(dev);
+       if (err)
+               goto out;
+
+       /* HACK: Force device (& ACPI) to determine what IRQ it's on - we
+        * must do this here because pcibios_enable_device may specify
+        * the pci device's true irq (and possibly its other resources)
+        * if they differ from what's in the configuration space.
+        * This makes the assumption that the device's resources won't
+        * change after this point (otherwise this code may break!)
+        */
+       dev_dbg(&dev->dev, "enabling device\n");
+       err = pci_enable_device(dev);
+       if (err)
+               goto config_release;
+
+       /* Now disable the device (this also ensures some private device
+        * data is setup before we export)
+        */
+       dev_dbg(&dev->dev, "reset device\n");
+       pciback_reset_device(dev);
+
+       return 0;
+
+      config_release:
+       pciback_config_free_dev(dev);
+
+      out:
+       pci_set_drvdata(dev, NULL);
+       kfree(dev_data);
+       return err;
+}
+
+/*
+ * Because some initialization still happens on
+ * devices during fs_initcall, we need to defer
+ * full initialization of our devices until
+ * device_initcall.
+ */
+static int __init pcistub_init_devices_late(void)
+{
+       struct pcistub_device *psdev;
+       unsigned long flags;
+       int err = 0;
+
+       pr_debug("pciback: pcistub_init_devices_late\n");
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       while (!list_empty(&seized_devices)) {
+               psdev = container_of(seized_devices.next,
+                                    struct pcistub_device, dev_list);
+               list_del(&psdev->dev_list);
+
+               spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+               err = pcistub_init_device(psdev->dev);
+               if (err) {
+                       dev_err(&psdev->dev->dev,
+                               "error %d initializing device\n", err);
+                       kfree(psdev);
+                       psdev = NULL;
+               }
+
+               spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+               if (psdev)
+                       list_add_tail(&psdev->dev_list, &pcistub_devices);
+       }
+
+       initialize_devices = 1;
+
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+       return 0;
+}
+
+static int __devinit pcistub_seize(struct pci_dev *dev)
+{
+       struct pcistub_device *psdev;
+       unsigned long flags;
+       int err = 0;
+
+       psdev = pcistub_device_alloc(dev);
+       if (!psdev)
+               return -ENOMEM;
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       if (initialize_devices) {
+               spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+               /* don't want irqs disabled when calling pcistub_init_device */
+               err = pcistub_init_device(psdev->dev);
+
+               spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+               if (!err)
+                       list_add(&psdev->dev_list, &pcistub_devices);
+       } else {
+               dev_dbg(&dev->dev, "deferring initialization\n");
+               list_add(&psdev->dev_list, &seized_devices);
+       }
+
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+       if (err)
+               pcistub_device_put(psdev);
+
+       return err;
+}
+
+static int __devinit pcistub_probe(struct pci_dev *dev,
+                                  const struct pci_device_id *id)
+{
+       int err = 0;
+
+       dev_dbg(&dev->dev, "probing...\n");
+
+       if (pcistub_match(dev)) {
+
+               if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL
+                   && dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
+                       dev_err(&dev->dev, "can't export pci devices that "
+                               "don't have a normal (0) or bridge (1) "
+                               "header type!\n");
+                       err = -ENODEV;
+                       goto out;
+               }
+
+               dev_info(&dev->dev, "seizing device\n");
+               err = pcistub_seize(dev);
+       } else
+               /* Didn't find the device */
+               err = -ENODEV;
+
+      out:
+       return err;
+}
+
+static void pcistub_remove(struct pci_dev *dev)
+{
+       struct pcistub_device *psdev, *found_psdev = NULL;
+       unsigned long flags;
+
+       dev_dbg(&dev->dev, "removing\n");
+
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+
+       pciback_config_quirk_release(dev);
+
+       list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+               if (psdev->dev == dev) {
+                       found_psdev = psdev;
+                       break;
+               }
+       }
+
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+       if (found_psdev) {
+               dev_dbg(&dev->dev, "found device to remove - in use? %p\n",
+                       found_psdev->pdev);
+
+               if (found_psdev->pdev) {
+                       printk(KERN_WARNING "pciback: ****** removing device "
+                              "%s while still in-use! ******\n",
+                              pci_name(found_psdev->dev));
+                       printk(KERN_WARNING "pciback: ****** driver domain may "
+                              "still access this device's i/o resources!\n");
+                       printk(KERN_WARNING "pciback: ****** shutdown driver "
+                              "domain before binding device\n");
+                       printk(KERN_WARNING "pciback: ****** to other drivers "
+                              "or domains\n");
+
+                       pciback_release_pci_dev(found_psdev->pdev,
+                                               found_psdev->dev);
+               }
+
+               spin_lock_irqsave(&pcistub_devices_lock, flags);
+               list_del(&found_psdev->dev_list);
+               spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+
+               /* the final put for releasing from the list */
+               pcistub_device_put(found_psdev);
+       }
+}
+
+static struct pci_device_id pcistub_ids[] = {
+       {
+        .vendor = PCI_ANY_ID,
+        .device = PCI_ANY_ID,
+        .subvendor = PCI_ANY_ID,
+        .subdevice = PCI_ANY_ID,
+        },
+       {0,},
+};
+
+/*
+ * Note: There is no MODULE_DEVICE_TABLE entry here because this isn't
+ * for a normal device. I don't want it to be loaded automatically.
+ */
+
+static struct pci_driver pciback_pci_driver = {
+       .name = "pciback",
+       .id_table = pcistub_ids,
+       .probe = pcistub_probe,
+       .remove = pcistub_remove,
+};
+
+static inline int str_to_slot(const char *buf, int *domain, int *bus,
+                             int *slot, int *func)
+{
+       int err;
+
+       err = sscanf(buf, " %x:%x:%x.%x", domain, bus, slot, func);
+       if (err == 4)
+               return 0;
+       else if (err < 0)
+               return -EINVAL;
+
+       /* try again without domain */
+       *domain = 0;
+       err = sscanf(buf, " %x:%x.%x", bus, slot, func);
+       if (err == 3)
+               return 0;
+
+       return -EINVAL;
+}
+
+static inline int str_to_quirk(const char *buf, int *domain, int *bus, int
+                              *slot, int *func, int *reg, int *size, int *mask)
+{
+       int err;
+
+       err =
+           sscanf(buf, " %04x:%02x:%02x.%1x-%08x:%1x:%08x", domain, bus, slot,
+                  func, reg, size, mask);
+       if (err == 7)
+               return 0;
+       return -EINVAL;
+}
+
+static int pcistub_device_id_add(int domain, int bus, int slot, int func)
+{
+       struct pcistub_device_id *pci_dev_id;
+       unsigned long flags;
+
+       pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_KERNEL);
+       if (!pci_dev_id)
+               return -ENOMEM;
+
+       pci_dev_id->domain = domain;
+       pci_dev_id->bus = bus;
+       pci_dev_id->devfn = PCI_DEVFN(slot, func);
+
+       pr_debug("pciback: wants to seize %04x:%02x:%02x.%01x\n",
+                domain, bus, slot, func);
+
+       spin_lock_irqsave(&device_ids_lock, flags);
+       list_add_tail(&pci_dev_id->slot_list, &pcistub_device_ids);
+       spin_unlock_irqrestore(&device_ids_lock, flags);
+
+       return 0;
+}
+
+static int pcistub_device_id_remove(int domain, int bus, int slot, int func)
+{
+       struct pcistub_device_id *pci_dev_id, *t;
+       int devfn = PCI_DEVFN(slot, func);
+       int err = -ENOENT;
+       unsigned long flags;
+
+       spin_lock_irqsave(&device_ids_lock, flags);
+       list_for_each_entry_safe(pci_dev_id, t, &pcistub_device_ids, slot_list) {
+
+               if (pci_dev_id->domain == domain
+                   && pci_dev_id->bus == bus && pci_dev_id->devfn == devfn) {
+                       /* Don't break; here because it's possible the same
+                        * slot could be in the list more than once
+                        */
+                       list_del(&pci_dev_id->slot_list);
+                       kfree(pci_dev_id);
+
+                       err = 0;
+
+                       pr_debug("pciback: removed %04x:%02x:%02x.%01x from "
+                                "seize list\n", domain, bus, slot, func);
+               }
+       }
+       spin_unlock_irqrestore(&device_ids_lock, flags);
+
+       return err;
+}
+
+static int pcistub_reg_add(int domain, int bus, int slot, int func, int reg,
+                          int size, int mask)
+{
+       int err = 0;
+       struct pcistub_device *psdev;
+       struct pci_dev *dev;
+       struct config_field *field;
+
+       psdev = pcistub_device_find(domain, bus, slot, func);
+       if (!psdev || !psdev->dev) {
+               err = -ENODEV;
+               goto out;
+       }
+       dev = psdev->dev;
+
+       /* check for duplicate field */
+       if (pciback_field_is_dup(dev, reg))
+               goto out;
+
+       field = kzalloc(sizeof(*field), GFP_ATOMIC);
+       if (!field) {
+               err = -ENOMEM;
+               goto out;
+       }
+
+       field->offset = reg;
+       field->size = size;
+       field->mask = mask;
+       field->init = NULL;
+       field->reset = NULL;
+       field->release = NULL;
+       field->clean = pciback_config_field_free;
+
+       err = pciback_config_quirks_add_field(dev, field);
+       if (err)
+               kfree(field);
+      out:
+       return err;
+}
+
+static ssize_t pcistub_slot_add(struct device_driver *drv, const char *buf,
+                               size_t count)
+{
+       int domain, bus, slot, func;
+       int err;
+
+       err = str_to_slot(buf, &domain, &bus, &slot, &func);
+       if (err)
+               goto out;
+
+       err = pcistub_device_id_add(domain, bus, slot, func);
+
+      out:
+       if (!err)
+               err = count;
+       return err;
+}
+
+DRIVER_ATTR(new_slot, S_IWUSR, NULL, pcistub_slot_add);
+
+static ssize_t pcistub_slot_remove(struct device_driver *drv, const char *buf,
+                                  size_t count)
+{
+       int domain, bus, slot, func;
+       int err;
+
+       err = str_to_slot(buf, &domain, &bus, &slot, &func);
+       if (err)
+               goto out;
+
+       err = pcistub_device_id_remove(domain, bus, slot, func);
+
+      out:
+       if (!err)
+               err = count;
+       return err;
+}
+
+DRIVER_ATTR(remove_slot, S_IWUSR, NULL, pcistub_slot_remove);
+
+static ssize_t pcistub_slot_show(struct device_driver *drv, char *buf)
+{
+       struct pcistub_device_id *pci_dev_id;
+       size_t count = 0;
+       unsigned long flags;
+
+       spin_lock_irqsave(&device_ids_lock, flags);
+       list_for_each_entry(pci_dev_id, &pcistub_device_ids, slot_list) {
+               if (count >= PAGE_SIZE)
+                       break;
+
+               count += scnprintf(buf + count, PAGE_SIZE - count,
+                                  "%04x:%02x:%02x.%01x\n",
+                                  pci_dev_id->domain, pci_dev_id->bus,
+                                  PCI_SLOT(pci_dev_id->devfn),
+                                  PCI_FUNC(pci_dev_id->devfn));
+       }
+       spin_unlock_irqrestore(&device_ids_lock, flags);
+
+       return count;
+}
+
+DRIVER_ATTR(slots, S_IRUSR, pcistub_slot_show, NULL);
+
+static ssize_t pcistub_quirk_add(struct device_driver *drv, const char *buf,
+                                size_t count)
+{
+       int domain, bus, slot, func, reg, size, mask;
+       int err;
+
+       err = str_to_quirk(buf, &domain, &bus, &slot, &func, &reg, &size,
+                          &mask);
+       if (err)
+               goto out;
+
+       err = pcistub_reg_add(domain, bus, slot, func, reg, size, mask);
+
+      out:
+       if (!err)
+               err = count;
+       return err;
+}
+
+static ssize_t pcistub_quirk_show(struct device_driver *drv, char *buf)
+{
+       int count = 0;
+       unsigned long flags;
+       extern struct list_head pciback_quirks;
+       struct pciback_config_quirk *quirk;
+       struct pciback_dev_data *dev_data;
+       struct config_field *field;
+       struct config_field_entry *cfg_entry;
+
+       spin_lock_irqsave(&device_ids_lock, flags);
+       list_for_each_entry(quirk, &pciback_quirks, quirks_list) {
+               if (count >= PAGE_SIZE)
+                       goto out;
+
+               count += scnprintf(buf + count, PAGE_SIZE - count,
+                                  "%02x:%02x.%01x\n\t%04x:%04x:%04x:%04x\n",
+                                  quirk->pdev->bus->number,
+                                  PCI_SLOT(quirk->pdev->devfn),
+                                  PCI_FUNC(quirk->pdev->devfn),
+                                  quirk->devid.vendor, quirk->devid.device,
+                                  quirk->devid.subvendor,
+                                  quirk->devid.subdevice);
+
+               dev_data = pci_get_drvdata(quirk->pdev);
+
+               list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
+                       field = cfg_entry->field;
+                       if (count >= PAGE_SIZE)
+                               goto out;
+
+                       count += scnprintf(buf + count, PAGE_SIZE -
+                                          count, "\t\t%08x:%01x:%08x\n",
+                                          field->offset, field->size,
+                                          field->mask);
+               }
+       }
+
+      out:
+       spin_unlock_irqrestore(&device_ids_lock, flags);
+
+       return count;
+}
+
+DRIVER_ATTR(quirks, S_IRUSR | S_IWUSR, pcistub_quirk_show, pcistub_quirk_add);
+
+static ssize_t permissive_add(struct device_driver *drv, const char *buf,
+                             size_t count)
+{
+       int domain, bus, slot, func;
+       int err;
+       struct pcistub_device *psdev;
+       struct pciback_dev_data *dev_data;
+       err = str_to_slot(buf, &domain, &bus, &slot, &func);
+       if (err)
+               goto out;
+       psdev = pcistub_device_find(domain, bus, slot, func);
+       if (!psdev) {
+               err = -ENODEV;
+               goto out;
+       }
+       if (!psdev->dev) {
+               err = -ENODEV;
+               goto release;
+       }
+       dev_data = pci_get_drvdata(psdev->dev);
+       /* the driver data for a device should never be null at this point */
+       if (!dev_data) {
+               err = -ENXIO;
+               goto release;
+       }
+       if (!dev_data->permissive) {
+               dev_data->permissive = 1;
+               /* Let user know that what they're doing could be unsafe */
+               dev_warn(&psdev->dev->dev,
+                        "enabling permissive mode configuration space accesses!\n");
+               dev_warn(&psdev->dev->dev,
+                        "permissive mode is potentially unsafe!\n");
+       }
+      release:
+       pcistub_device_put(psdev);
+      out:
+       if (!err)
+               err = count;
+       return err;
+}
+
+static ssize_t permissive_show(struct device_driver *drv, char *buf)
+{
+       struct pcistub_device *psdev;
+       struct pciback_dev_data *dev_data;
+       size_t count = 0;
+       unsigned long flags;
+       spin_lock_irqsave(&pcistub_devices_lock, flags);
+       list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+               if (count >= PAGE_SIZE)
+                       break;
+               if (!psdev->dev)
+                       continue;
+               dev_data = pci_get_drvdata(psdev->dev);
+               if (!dev_data || !dev_data->permissive)
+                       continue;
+               count +=
+                   scnprintf(buf + count, PAGE_SIZE - count, "%s\n",
+                             pci_name(psdev->dev));
+       }
+       spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+       return count;
+}
+
+DRIVER_ATTR(permissive, S_IRUSR | S_IWUSR, permissive_show, permissive_add);
+
+static int __init pcistub_init(void)
+{
+       int pos = 0;
+       int err = 0;
+       int domain, bus, slot, func;
+       int parsed;
+
+       if (pci_devs_to_hide && *pci_devs_to_hide) {
+               do {
+                       parsed = 0;
+
+                       err = sscanf(pci_devs_to_hide + pos,
+                                    " (%x:%x:%x.%x) %n",
+                                    &domain, &bus, &slot, &func, &parsed);
+                       if (err != 4) {
+                               domain = 0;
+                               err = sscanf(pci_devs_to_hide + pos,
+                                            " (%x:%x.%x) %n",
+                                            &bus, &slot, &func, &parsed);
+                               if (err != 3)
+                                       goto parse_error;
+                       }
+
+                       err = pcistub_device_id_add(domain, bus, slot, func);
+                       if (err)
+                               goto out;
+
+                       /* if parsed<=0, we've reached the end of the string */
+                       pos += parsed;
+               } while (parsed > 0 && pci_devs_to_hide[pos]);
+       }
+
+       /* If we're the first PCI Device Driver to register, we're the
+        * first one to get offered PCI devices as they become
+        * available (and thus we can be the first to grab them)
+        */
+       err = pci_register_driver(&pciback_pci_driver);
+       if (err < 0)
+               goto out;
+
+       driver_create_file(&pciback_pci_driver.driver, &driver_attr_new_slot);
+       driver_create_file(&pciback_pci_driver.driver,
+                          &driver_attr_remove_slot);
+       driver_create_file(&pciback_pci_driver.driver, &driver_attr_slots);
+       driver_create_file(&pciback_pci_driver.driver, &driver_attr_quirks);
+       driver_create_file(&pciback_pci_driver.driver, &driver_attr_permissive);
+
+      out:
+       return err;
+
+      parse_error:
+       printk(KERN_ERR "pciback: Error parsing pci_devs_to_hide at \"%s\"\n",
+              pci_devs_to_hide + pos);
+       return -EINVAL;
+}
+
+#ifndef MODULE
+/*
+ * fs_initcall happens before device_initcall
+ * so pciback *should* get called first (b/c we 
+ * want to suck up any device before other drivers
+ * get a chance by being the first pci device
+ * driver to register)
+ */
+fs_initcall(pcistub_init);
+#endif
+
+static int __init pciback_init(void)
+{
+       int err;
+
+       err = pciback_config_init();
+       if (err)
+               return err;
+
+#ifdef MODULE
+       err = pcistub_init();
+       if (err < 0)
+               return err;
+#endif
+
+       pcistub_init_devices_late();
+       pciback_xenbus_register();
+
+       return 0;
+}
+
+static void __exit pciback_cleanup(void)
+{
+       pciback_xenbus_unregister();
+
+       driver_remove_file(&pciback_pci_driver.driver, &driver_attr_new_slot);
+       driver_remove_file(&pciback_pci_driver.driver,
+                          &driver_attr_remove_slot);
+       driver_remove_file(&pciback_pci_driver.driver, &driver_attr_slots);
+       driver_remove_file(&pciback_pci_driver.driver, &driver_attr_quirks);
+       driver_remove_file(&pciback_pci_driver.driver, &driver_attr_permissive);
+
+       pci_unregister_driver(&pciback_pci_driver);
+}
+
+module_init(pciback_init);
+module_exit(pciback_cleanup);
+
+MODULE_LICENSE("Dual BSD/GPL");