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41 results

timex.h

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    xen-pcifront.c 26.81 KiB
    /*
     * Xen PCI Frontend.
     *
     *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
     */
    #include <linux/module.h>
    #include <linux/init.h>
    #include <linux/mm.h>
    #include <xen/xenbus.h>
    #include <xen/events.h>
    #include <xen/grant_table.h>
    #include <xen/page.h>
    #include <linux/spinlock.h>
    #include <linux/pci.h>
    #include <linux/msi.h>
    #include <xen/interface/io/pciif.h>
    #include <asm/xen/pci.h>
    #include <linux/interrupt.h>
    #include <linux/atomic.h>
    #include <linux/workqueue.h>
    #include <linux/bitops.h>
    #include <linux/time.h>
    
    #include <asm/xen/swiotlb-xen.h>
    #define INVALID_GRANT_REF (0)
    #define INVALID_EVTCHN    (-1)
    
    struct pci_bus_entry {
    	struct list_head list;
    	struct pci_bus *bus;
    };
    
    #define _PDEVB_op_active		(0)
    #define PDEVB_op_active			(1 << (_PDEVB_op_active))
    
    struct pcifront_device {
    	struct xenbus_device *xdev;
    	struct list_head root_buses;
    
    	int evtchn;
    	int gnt_ref;
    
    	int irq;
    
    	/* Lock this when doing any operations in sh_info */
    	spinlock_t sh_info_lock;
    	struct xen_pci_sharedinfo *sh_info;
    	struct work_struct op_work;
    	unsigned long flags;
    
    };
    
    struct pcifront_sd {
    	int domain;
    	struct pcifront_device *pdev;
    };
    
    static inline struct pcifront_device *
    pcifront_get_pdev(struct pcifront_sd *sd)
    {
    	return sd->pdev;
    }
    
    static inline void pcifront_init_sd(struct pcifront_sd *sd,
    				    unsigned int domain, unsigned int bus,
    				    struct pcifront_device *pdev)
    {
    	sd->domain = domain;
    	sd->pdev = pdev;
    }
    
    static DEFINE_SPINLOCK(pcifront_dev_lock);
    static struct pcifront_device *pcifront_dev;
    
    static int verbose_request;
    module_param(verbose_request, int, 0644);
    
    static int errno_to_pcibios_err(int errno)
    {
    	switch (errno) {
    	case XEN_PCI_ERR_success:
    		return PCIBIOS_SUCCESSFUL;
    
    	case XEN_PCI_ERR_dev_not_found:
    		return PCIBIOS_DEVICE_NOT_FOUND;
    
    	case XEN_PCI_ERR_invalid_offset:
    	case XEN_PCI_ERR_op_failed:
    		return PCIBIOS_BAD_REGISTER_NUMBER;
    
    	case XEN_PCI_ERR_not_implemented:
    		return PCIBIOS_FUNC_NOT_SUPPORTED;
    
    	case XEN_PCI_ERR_access_denied:
    		return PCIBIOS_SET_FAILED;
    	}
    	return errno;
    }
    
    static inline void schedule_pcifront_aer_op(struct pcifront_device *pdev)
    {
    	if (test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
    		&& !test_and_set_bit(_PDEVB_op_active, &pdev->flags)) {
    		dev_dbg(&pdev->xdev->dev, "schedule aer frontend job\n");
    		schedule_work(&pdev->op_work);
    	}
    }
    
    static int do_pci_op(struct pcifront_device *pdev, struct xen_pci_op *op)
    {
    	int err = 0;
    	struct xen_pci_op *active_op = &pdev->sh_info->op;
    	unsigned long irq_flags;
    	evtchn_port_t port = pdev->evtchn;
    	unsigned irq = pdev->irq;
    	s64 ns, ns_timeout;
    	struct timeval tv;
    
    	spin_lock_irqsave(&pdev->sh_info_lock, irq_flags);
    
    	memcpy(active_op, op, sizeof(struct xen_pci_op));
    
    	/* Go */
    	wmb();
    	set_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
    	notify_remote_via_evtchn(port);
    
    	/*
    	 * We set a poll timeout of 3 seconds but give up on return after
    	 * 2 seconds. It is better to time out too late rather than too early
    	 * (in the latter case we end up continually re-executing poll() with a
    	 * timeout in the past). 1s difference gives plenty of slack for error.
    	 */
    	do_gettimeofday(&tv);
    	ns_timeout = timeval_to_ns(&tv) + 2 * (s64)NSEC_PER_SEC;
    
    	xen_clear_irq_pending(irq);
    
    	while (test_bit(_XEN_PCIF_active,
    			(unsigned long *)&pdev->sh_info->flags)) {
    		xen_poll_irq_timeout(irq, jiffies + 3*HZ);
    		xen_clear_irq_pending(irq);
    		do_gettimeofday(&tv);
    		ns = timeval_to_ns(&tv);
    		if (ns > ns_timeout) {
    			dev_err(&pdev->xdev->dev,
    				"pciback not responding!!!\n");
    			clear_bit(_XEN_PCIF_active,
    				  (unsigned long *)&pdev->sh_info->flags);
    			err = XEN_PCI_ERR_dev_not_found;
    			goto out;
    		}
    	}
    
    	/*
    	* We might lose backend service request since we
    	* reuse same evtchn with pci_conf backend response. So re-schedule
    	* aer pcifront service.
    	*/
    	if (test_bit(_XEN_PCIB_active,
    			(unsigned long *)&pdev->sh_info->flags)) {
    		dev_err(&pdev->xdev->dev,
    			"schedule aer pcifront service\n");
    		schedule_pcifront_aer_op(pdev);
    	}
    
    	memcpy(op, active_op, sizeof(struct xen_pci_op));
    
    	err = op->err;
    out:
    	spin_unlock_irqrestore(&pdev->sh_info_lock, irq_flags);
    	return err;
    }
    
    /* Access to this function is spinlocked in drivers/pci/access.c */
    static int pcifront_bus_read(struct pci_bus *bus, unsigned int devfn,
    			     int where, int size, u32 *val)
    {
    	int err = 0;
    	struct xen_pci_op op = {
    		.cmd    = XEN_PCI_OP_conf_read,
    		.domain = pci_domain_nr(bus),
    		.bus    = bus->number,
    		.devfn  = devfn,
    		.offset = where,
    		.size   = size,
    	};
    	struct pcifront_sd *sd = bus->sysdata;
    	struct pcifront_device *pdev = pcifront_get_pdev(sd);
    
    	if (verbose_request)
    		dev_info(&pdev->xdev->dev,
    			 "read dev=%04x:%02x:%02x.%d - offset %x size %d\n",
    			 pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
    			 PCI_FUNC(devfn), where, size);
    
    	err = do_pci_op(pdev, &op);
    
    	if (likely(!err)) {
    		if (verbose_request)
    			dev_info(&pdev->xdev->dev, "read got back value %x\n",
    				 op.value);
    
    		*val = op.value;
    	} else if (err == -ENODEV) {
    		/* No device here, pretend that it just returned 0 */
    		err = 0;
    		*val = 0;
    	}
    
    	return errno_to_pcibios_err(err);
    }
    
    /* Access to this function is spinlocked in drivers/pci/access.c */
    static int pcifront_bus_write(struct pci_bus *bus, unsigned int devfn,
    			      int where, int size, u32 val)
    {
    	struct xen_pci_op op = {
    		.cmd    = XEN_PCI_OP_conf_write,
    		.domain = pci_domain_nr(bus),
    		.bus    = bus->number,
    		.devfn  = devfn,
    		.offset = where,
    		.size   = size,
    		.value  = val,
    	};
    	struct pcifront_sd *sd = bus->sysdata;
    	struct pcifront_device *pdev = pcifront_get_pdev(sd);
    
    	if (verbose_request)
    		dev_info(&pdev->xdev->dev,
    			 "write dev=%04x:%02x:%02x.%d - "
    			 "offset %x size %d val %x\n",
    			 pci_domain_nr(bus), bus->number,
    			 PCI_SLOT(devfn), PCI_FUNC(devfn), where, size, val);
    
    	return errno_to_pcibios_err(do_pci_op(pdev, &op));
    }
    
    static struct pci_ops pcifront_bus_ops = {
    	.read = pcifront_bus_read,
    	.write = pcifront_bus_write,
    };
    
    #ifdef CONFIG_PCI_MSI
    static int pci_frontend_enable_msix(struct pci_dev *dev,
    				    int vector[], int nvec)
    {
    	int err;
    	int i;
    	struct xen_pci_op op = {
    		.cmd    = XEN_PCI_OP_enable_msix,
    		.domain = pci_domain_nr(dev->bus),
    		.bus = dev->bus->number,
    		.devfn = dev->devfn,
    		.value = nvec,
    	};
    	struct pcifront_sd *sd = dev->bus->sysdata;
    	struct pcifront_device *pdev = pcifront_get_pdev(sd);
    	struct msi_desc *entry;
    
    	if (nvec > SH_INFO_MAX_VEC) {
    		dev_err(&dev->dev, "too much vector for pci frontend: %x."
    				   " Increase SH_INFO_MAX_VEC.\n", nvec);
    		return -EINVAL;
    	}
    
    	i = 0;
    	list_for_each_entry(entry, &dev->msi_list, list) {
    		op.msix_entries[i].entry = entry->msi_attrib.entry_nr;
    		/* Vector is useless at this point. */
    		op.msix_entries[i].vector = -1;
    		i++;
    	}
    
    	err = do_pci_op(pdev, &op);
    
    	if (likely(!err)) {
    		if (likely(!op.value)) {
    			/* we get the result */
    			for (i = 0; i < nvec; i++) {
    				if (op.msix_entries[i].vector <= 0) {
    					dev_warn(&dev->dev, "MSI-X entry %d is invalid: %d!\n",
    						i, op.msix_entries[i].vector);
    					err = -EINVAL;
    					vector[i] = -1;
    					continue;
    				}
    				vector[i] = op.msix_entries[i].vector;
    			}
    		} else {
    			printk(KERN_DEBUG "enable msix get value %x\n",
    				op.value);
    			err = op.value;
    		}
    	} else {
    		dev_err(&dev->dev, "enable msix get err %x\n", err);
    	}
    	return err;
    }
    
    static void pci_frontend_disable_msix(struct pci_dev *dev)
    {
    	int err;
    	struct xen_pci_op op = {
    		.cmd    = XEN_PCI_OP_disable_msix,
    		.domain = pci_domain_nr(dev->bus),
    		.bus = dev->bus->number,
    		.devfn = dev->devfn,
    	};
    	struct pcifront_sd *sd = dev->bus->sysdata;
    	struct pcifront_device *pdev = pcifront_get_pdev(sd);
    
    	err = do_pci_op(pdev, &op);
    
    	/* What should do for error ? */
    	if (err)
    		dev_err(&dev->dev, "pci_disable_msix get err %x\n", err);
    }
    
    static int pci_frontend_enable_msi(struct pci_dev *dev, int vector[])
    {
    	int err;
    	struct xen_pci_op op = {
    		.cmd    = XEN_PCI_OP_enable_msi,
    		.domain = pci_domain_nr(dev->bus),
    		.bus = dev->bus->number,
    		.devfn = dev->devfn,
    	};
    	struct pcifront_sd *sd = dev->bus->sysdata;
    	struct pcifront_device *pdev = pcifront_get_pdev(sd);
    
    	err = do_pci_op(pdev, &op);
    	if (likely(!err)) {
    		vector[0] = op.value;
    		if (op.value <= 0) {
    			dev_warn(&dev->dev, "MSI entry is invalid: %d!\n",
    				op.value);
    			err = -EINVAL;
    			vector[0] = -1;
    		}
    	} else {
    		dev_err(&dev->dev, "pci frontend enable msi failed for dev "
    				    "%x:%x\n", op.bus, op.devfn);
    		err = -EINVAL;
    	}
    	return err;
    }
    
    static void pci_frontend_disable_msi(struct pci_dev *dev)
    {
    	int err;
    	struct xen_pci_op op = {
    		.cmd    = XEN_PCI_OP_disable_msi,
    		.domain = pci_domain_nr(dev->bus),
    		.bus = dev->bus->number,
    		.devfn = dev->devfn,
    	};
    	struct pcifront_sd *sd = dev->bus->sysdata;
    	struct pcifront_device *pdev = pcifront_get_pdev(sd);
    
    	err = do_pci_op(pdev, &op);
    	if (err == XEN_PCI_ERR_dev_not_found) {
    		/* XXX No response from backend, what shall we do? */
    		printk(KERN_DEBUG "get no response from backend for disable MSI\n");
    		return;
    	}
    	if (err)
    		/* how can pciback notify us fail? */
    		printk(KERN_DEBUG "get fake response frombackend\n");
    }
    
    static struct xen_pci_frontend_ops pci_frontend_ops = {
    	.enable_msi = pci_frontend_enable_msi,
    	.disable_msi = pci_frontend_disable_msi,
    	.enable_msix = pci_frontend_enable_msix,
    	.disable_msix = pci_frontend_disable_msix,
    };
    
    static void pci_frontend_registrar(int enable)
    {
    	if (enable)
    		xen_pci_frontend = &pci_frontend_ops;
    	else
    		xen_pci_frontend = NULL;
    };
    #else
    static inline void pci_frontend_registrar(int enable) { };
    #endif /* CONFIG_PCI_MSI */
    
    /* Claim resources for the PCI frontend as-is, backend won't allow changes */
    static int pcifront_claim_resource(struct pci_dev *dev, void *data)
    {
    	struct pcifront_device *pdev = data;
    	int i;
    	struct resource *r;
    
    	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
    		r = &dev->resource[i];
    
    		if (!r->parent && r->start && r->flags) {
    			dev_info(&pdev->xdev->dev, "claiming resource %s/%d\n",
    				pci_name(dev), i);
    			if (pci_claim_resource(dev, i)) {
    				dev_err(&pdev->xdev->dev, "Could not claim resource %s/%d! "
    					"Device offline. Try using e820_host=1 in the guest config.\n",
    					pci_name(dev), i);
    			}
    		}
    	}
    
    	return 0;
    }
    
    static int pcifront_scan_bus(struct pcifront_device *pdev,
    				unsigned int domain, unsigned int bus,
    				struct pci_bus *b)
    {
    	struct pci_dev *d;
    	unsigned int devfn;
    
    	/* Scan the bus for functions and add.
    	 * We omit handling of PCI bridge attachment because pciback prevents
    	 * bridges from being exported.
    	 */
    	for (devfn = 0; devfn < 0x100; devfn++) {
    		d = pci_get_slot(b, devfn);
    		if (d) {
    			/* Device is already known. */
    			pci_dev_put(d);
    			continue;
    		}
    
    		d = pci_scan_single_device(b, devfn);
    		if (d)
    			dev_info(&pdev->xdev->dev, "New device on "
    				 "%04x:%02x:%02x.%d found.\n", domain, bus,
    				 PCI_SLOT(devfn), PCI_FUNC(devfn));
    	}
    
    	return 0;
    }
    
    static int pcifront_scan_root(struct pcifront_device *pdev,
    				 unsigned int domain, unsigned int bus)
    {
    	struct pci_bus *b;
    	struct pcifront_sd *sd = NULL;
    	struct pci_bus_entry *bus_entry = NULL;
    	int err = 0;
    
    #ifndef CONFIG_PCI_DOMAINS
    	if (domain != 0) {
    		dev_err(&pdev->xdev->dev,
    			"PCI Root in non-zero PCI Domain! domain=%d\n", domain);
    		dev_err(&pdev->xdev->dev,
    			"Please compile with CONFIG_PCI_DOMAINS\n");
    		err = -EINVAL;
    		goto err_out;
    	}
    #endif
    
    	dev_info(&pdev->xdev->dev, "Creating PCI Frontend Bus %04x:%02x\n",
    		 domain, bus);
    
    	bus_entry = kmalloc(sizeof(*bus_entry), GFP_KERNEL);
    	sd = kmalloc(sizeof(*sd), GFP_KERNEL);
    	if (!bus_entry || !sd) {
    		err = -ENOMEM;
    		goto err_out;
    	}
    	pcifront_init_sd(sd, domain, bus, pdev);
    
    	pci_lock_rescan_remove();
    
    	b = pci_scan_bus_parented(&pdev->xdev->dev, bus,
    				  &pcifront_bus_ops, sd);
    	if (!b) {
    		dev_err(&pdev->xdev->dev,
    			"Error creating PCI Frontend Bus!\n");
    		err = -ENOMEM;
    		pci_unlock_rescan_remove();
    		goto err_out;
    	}
    
    	bus_entry->bus = b;
    
    	list_add(&bus_entry->list, &pdev->root_buses);
    
    	/* pci_scan_bus_parented skips devices which do not have a have
    	* devfn==0. The pcifront_scan_bus enumerates all devfn. */
    	err = pcifront_scan_bus(pdev, domain, bus, b);
    
    	/* Claim resources before going "live" with our devices */
    	pci_walk_bus(b, pcifront_claim_resource, pdev);
    
    	/* Create SysFS and notify udev of the devices. Aka: "going live" */
    	pci_bus_add_devices(b);
    
    	pci_unlock_rescan_remove();
    	return err;
    
    err_out:
    	kfree(bus_entry);
    	kfree(sd);
    
    	return err;
    }
    
    static int pcifront_rescan_root(struct pcifront_device *pdev,
    				   unsigned int domain, unsigned int bus)
    {
    	int err;
    	struct pci_bus *b;
    
    #ifndef CONFIG_PCI_DOMAINS
    	if (domain != 0) {
    		dev_err(&pdev->xdev->dev,
    			"PCI Root in non-zero PCI Domain! domain=%d\n", domain);
    		dev_err(&pdev->xdev->dev,
    			"Please compile with CONFIG_PCI_DOMAINS\n");
    		return -EINVAL;
    	}
    #endif
    
    	dev_info(&pdev->xdev->dev, "Rescanning PCI Frontend Bus %04x:%02x\n",
    		 domain, bus);
    
    	b = pci_find_bus(domain, bus);
    	if (!b)
    		/* If the bus is unknown, create it. */
    		return pcifront_scan_root(pdev, domain, bus);
    
    	err = pcifront_scan_bus(pdev, domain, bus, b);
    
    	/* Claim resources before going "live" with our devices */
    	pci_walk_bus(b, pcifront_claim_resource, pdev);
    
    	/* Create SysFS and notify udev of the devices. Aka: "going live" */
    	pci_bus_add_devices(b);
    
    	return err;
    }
    
    static void free_root_bus_devs(struct pci_bus *bus)
    {
    	struct pci_dev *dev;
    
    	while (!list_empty(&bus->devices)) {
    		dev = container_of(bus->devices.next, struct pci_dev,
    				   bus_list);
    		dev_dbg(&dev->dev, "removing device\n");
    		pci_stop_and_remove_bus_device(dev);
    	}
    }
    
    static void pcifront_free_roots(struct pcifront_device *pdev)
    {
    	struct pci_bus_entry *bus_entry, *t;
    
    	dev_dbg(&pdev->xdev->dev, "cleaning up root buses\n");
    
    	pci_lock_rescan_remove();
    	list_for_each_entry_safe(bus_entry, t, &pdev->root_buses, list) {
    		list_del(&bus_entry->list);
    
    		free_root_bus_devs(bus_entry->bus);
    
    		kfree(bus_entry->bus->sysdata);
    
    		device_unregister(bus_entry->bus->bridge);
    		pci_remove_bus(bus_entry->bus);
    
    		kfree(bus_entry);
    	}
    	pci_unlock_rescan_remove();
    }
    
    static pci_ers_result_t pcifront_common_process(int cmd,
    						struct pcifront_device *pdev,
    						pci_channel_state_t state)
    {
    	pci_ers_result_t result;
    	struct pci_driver *pdrv;
    	int bus = pdev->sh_info->aer_op.bus;
    	int devfn = pdev->sh_info->aer_op.devfn;
    	struct pci_dev *pcidev;
    	int flag = 0;
    
    	dev_dbg(&pdev->xdev->dev,
    		"pcifront AER process: cmd %x (bus:%x, devfn%x)",
    		cmd, bus, devfn);
    	result = PCI_ERS_RESULT_NONE;
    
    	pcidev = pci_get_bus_and_slot(bus, devfn);
    	if (!pcidev || !pcidev->driver) {
    		dev_err(&pdev->xdev->dev, "device or AER driver is NULL\n");
    		if (pcidev)
    			pci_dev_put(pcidev);
    		return result;
    	}
    	pdrv = pcidev->driver;
    
    	if (pdrv) {
    		if (pdrv->err_handler && pdrv->err_handler->error_detected) {
    			dev_dbg(&pcidev->dev,
    				"trying to call AER service\n");
    			if (pcidev) {
    				flag = 1;
    				switch (cmd) {
    				case XEN_PCI_OP_aer_detected:
    					result = pdrv->err_handler->
    						 error_detected(pcidev, state);
    					break;
    				case XEN_PCI_OP_aer_mmio:
    					result = pdrv->err_handler->
    						 mmio_enabled(pcidev);
    					break;
    				case XEN_PCI_OP_aer_slotreset:
    					result = pdrv->err_handler->
    						 slot_reset(pcidev);
    					break;
    				case XEN_PCI_OP_aer_resume:
    					pdrv->err_handler->resume(pcidev);
    					break;
    				default:
    					dev_err(&pdev->xdev->dev,
    						"bad request in aer recovery "
    						"operation!\n");
    
    				}
    			}
    		}
    	}
    	if (!flag)
    		result = PCI_ERS_RESULT_NONE;
    
    	return result;
    }
    
    
    static void pcifront_do_aer(struct work_struct *data)
    {
    	struct pcifront_device *pdev =
    		container_of(data, struct pcifront_device, op_work);
    	int cmd = pdev->sh_info->aer_op.cmd;
    	pci_channel_state_t state =
    		(pci_channel_state_t)pdev->sh_info->aer_op.err;
    
    	/*If a pci_conf op is in progress,
    		we have to wait until it is done before service aer op*/
    	dev_dbg(&pdev->xdev->dev,
    		"pcifront service aer bus %x devfn %x\n",
    		pdev->sh_info->aer_op.bus, pdev->sh_info->aer_op.devfn);
    
    	pdev->sh_info->aer_op.err = pcifront_common_process(cmd, pdev, state);
    
    	/* Post the operation to the guest. */
    	wmb();
    	clear_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags);
    	notify_remote_via_evtchn(pdev->evtchn);
    
    	/*in case of we lost an aer request in four lines time_window*/
    	smp_mb__before_clear_bit();
    	clear_bit(_PDEVB_op_active, &pdev->flags);
    	smp_mb__after_clear_bit();
    
    	schedule_pcifront_aer_op(pdev);
    
    }
    
    static irqreturn_t pcifront_handler_aer(int irq, void *dev)
    {
    	struct pcifront_device *pdev = dev;
    	schedule_pcifront_aer_op(pdev);
    	return IRQ_HANDLED;
    }
    static int pcifront_connect_and_init_dma(struct pcifront_device *pdev)
    {
    	int err = 0;
    
    	spin_lock(&pcifront_dev_lock);
    
    	if (!pcifront_dev) {
    		dev_info(&pdev->xdev->dev, "Installing PCI frontend\n");
    		pcifront_dev = pdev;
    	} else
    		err = -EEXIST;
    
    	spin_unlock(&pcifront_dev_lock);
    
    	if (!err && !swiotlb_nr_tbl()) {
    		err = pci_xen_swiotlb_init_late();
    		if (err)
    			dev_err(&pdev->xdev->dev, "Could not setup SWIOTLB!\n");
    	}
    	return err;
    }
    
    static void pcifront_disconnect(struct pcifront_device *pdev)
    {
    	spin_lock(&pcifront_dev_lock);
    
    	if (pdev == pcifront_dev) {
    		dev_info(&pdev->xdev->dev,
    			 "Disconnecting PCI Frontend Buses\n");
    		pcifront_dev = NULL;
    	}
    
    	spin_unlock(&pcifront_dev_lock);
    }
    static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
    {
    	struct pcifront_device *pdev;
    
    	pdev = kzalloc(sizeof(struct pcifront_device), GFP_KERNEL);
    	if (pdev == NULL)
    		goto out;
    
    	pdev->sh_info =
    	    (struct xen_pci_sharedinfo *)__get_free_page(GFP_KERNEL);
    	if (pdev->sh_info == NULL) {
    		kfree(pdev);
    		pdev = NULL;
    		goto out;
    	}
    	pdev->sh_info->flags = 0;
    
    	/*Flag for registering PV AER handler*/
    	set_bit(_XEN_PCIB_AERHANDLER, (void *)&pdev->sh_info->flags);
    
    	dev_set_drvdata(&xdev->dev, pdev);
    	pdev->xdev = xdev;
    
    	INIT_LIST_HEAD(&pdev->root_buses);
    
    	spin_lock_init(&pdev->sh_info_lock);
    
    	pdev->evtchn = INVALID_EVTCHN;
    	pdev->gnt_ref = INVALID_GRANT_REF;
    	pdev->irq = -1;
    
    	INIT_WORK(&pdev->op_work, pcifront_do_aer);
    
    	dev_dbg(&xdev->dev, "Allocated pdev @ 0x%p pdev->sh_info @ 0x%p\n",
    		pdev, pdev->sh_info);
    out:
    	return pdev;
    }
    
    static void free_pdev(struct pcifront_device *pdev)
    {
    	dev_dbg(&pdev->xdev->dev, "freeing pdev @ 0x%p\n", pdev);
    
    	pcifront_free_roots(pdev);
    
    	cancel_work_sync(&pdev->op_work);
    
    	if (pdev->irq >= 0)
    		unbind_from_irqhandler(pdev->irq, pdev);
    
    	if (pdev->evtchn != INVALID_EVTCHN)
    		xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
    
    	if (pdev->gnt_ref != INVALID_GRANT_REF)
    		gnttab_end_foreign_access(pdev->gnt_ref, 0 /* r/w page */,
    					  (unsigned long)pdev->sh_info);
    	else
    		free_page((unsigned long)pdev->sh_info);
    
    	dev_set_drvdata(&pdev->xdev->dev, NULL);
    
    	kfree(pdev);
    }
    
    static int pcifront_publish_info(struct pcifront_device *pdev)
    {
    	int err = 0;
    	struct xenbus_transaction trans;
    
    	err = xenbus_grant_ring(pdev->xdev, virt_to_mfn(pdev->sh_info));
    	if (err < 0)
    		goto out;
    
    	pdev->gnt_ref = err;
    
    	err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
    	if (err)
    		goto out;
    
    	err = bind_evtchn_to_irqhandler(pdev->evtchn, pcifront_handler_aer,
    		0, "pcifront", pdev);
    
    	if (err < 0)
    		return err;
    
    	pdev->irq = err;
    
    do_publish:
    	err = xenbus_transaction_start(&trans);
    	if (err) {
    		xenbus_dev_fatal(pdev->xdev, err,
    				 "Error writing configuration for backend "
    				 "(start transaction)");
    		goto out;
    	}
    
    	err = xenbus_printf(trans, pdev->xdev->nodename,
    			    "pci-op-ref", "%u", pdev->gnt_ref);
    	if (!err)
    		err = xenbus_printf(trans, pdev->xdev->nodename,
    				    "event-channel", "%u", pdev->evtchn);
    	if (!err)
    		err = xenbus_printf(trans, pdev->xdev->nodename,
    				    "magic", XEN_PCI_MAGIC);
    
    	if (err) {
    		xenbus_transaction_end(trans, 1);
    		xenbus_dev_fatal(pdev->xdev, err,
    				 "Error writing configuration for backend");
    		goto out;
    	} else {
    		err = xenbus_transaction_end(trans, 0);
    		if (err == -EAGAIN)
    			goto do_publish;
    		else if (err) {
    			xenbus_dev_fatal(pdev->xdev, err,
    					 "Error completing transaction "
    					 "for backend");
    			goto out;
    		}
    	}
    
    	xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
    
    	dev_dbg(&pdev->xdev->dev, "publishing successful!\n");
    
    out:
    	return err;
    }
    
    static int pcifront_try_connect(struct pcifront_device *pdev)
    {
    	int err = -EFAULT;
    	int i, num_roots, len;
    	char str[64];
    	unsigned int domain, bus;
    
    
    	/* Only connect once */
    	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
    	    XenbusStateInitialised)
    		goto out;
    
    	err = pcifront_connect_and_init_dma(pdev);
    	if (err && err != -EEXIST) {
    		xenbus_dev_fatal(pdev->xdev, err,
    				 "Error setting up PCI Frontend");
    		goto out;
    	}
    
    	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
    			   "root_num", "%d", &num_roots);
    	if (err == -ENOENT) {
    		xenbus_dev_error(pdev->xdev, err,
    				 "No PCI Roots found, trying 0000:00");
    		err = pcifront_scan_root(pdev, 0, 0);
    		num_roots = 0;
    	} else if (err != 1) {
    		if (err == 0)
    			err = -EINVAL;
    		xenbus_dev_fatal(pdev->xdev, err,
    				 "Error reading number of PCI roots");
    		goto out;
    	}
    
    	for (i = 0; i < num_roots; 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->otherend, str,
    				   "%x:%x", &domain, &bus);
    		if (err != 2) {
    			if (err >= 0)
    				err = -EINVAL;
    			xenbus_dev_fatal(pdev->xdev, err,
    					 "Error reading PCI root %d", i);
    			goto out;
    		}
    
    		err = pcifront_scan_root(pdev, domain, bus);
    		if (err) {
    			xenbus_dev_fatal(pdev->xdev, err,
    					 "Error scanning PCI root %04x:%02x",
    					 domain, bus);
    			goto out;
    		}
    	}
    
    	err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
    
    out:
    	return err;
    }
    
    static int pcifront_try_disconnect(struct pcifront_device *pdev)
    {
    	int err = 0;
    	enum xenbus_state prev_state;
    
    
    	prev_state = xenbus_read_driver_state(pdev->xdev->nodename);
    
    	if (prev_state >= XenbusStateClosing)
    		goto out;
    
    	if (prev_state == XenbusStateConnected) {
    		pcifront_free_roots(pdev);
    		pcifront_disconnect(pdev);
    	}
    
    	err = xenbus_switch_state(pdev->xdev, XenbusStateClosed);
    
    out:
    
    	return err;
    }
    
    static int pcifront_attach_devices(struct pcifront_device *pdev)
    {
    	int err = -EFAULT;
    	int i, num_roots, len;
    	unsigned int domain, bus;
    	char str[64];
    
    	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
    	    XenbusStateReconfiguring)
    		goto out;
    
    	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
    			   "root_num", "%d", &num_roots);
    	if (err == -ENOENT) {
    		xenbus_dev_error(pdev->xdev, err,
    				 "No PCI Roots found, trying 0000:00");
    		err = pcifront_rescan_root(pdev, 0, 0);
    		num_roots = 0;
    	} else if (err != 1) {
    		if (err == 0)
    			err = -EINVAL;
    		xenbus_dev_fatal(pdev->xdev, err,
    				 "Error reading number of PCI roots");
    		goto out;
    	}
    
    	for (i = 0; i < num_roots; 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->otherend, str,
    				   "%x:%x", &domain, &bus);
    		if (err != 2) {
    			if (err >= 0)
    				err = -EINVAL;
    			xenbus_dev_fatal(pdev->xdev, err,
    					 "Error reading PCI root %d", i);
    			goto out;
    		}
    
    		err = pcifront_rescan_root(pdev, domain, bus);
    		if (err) {
    			xenbus_dev_fatal(pdev->xdev, err,
    					 "Error scanning PCI root %04x:%02x",
    					 domain, bus);
    			goto out;
    		}
    	}
    
    	xenbus_switch_state(pdev->xdev, XenbusStateConnected);
    
    out:
    	return err;
    }
    
    static int pcifront_detach_devices(struct pcifront_device *pdev)
    {
    	int err = 0;
    	int i, num_devs;
    	unsigned int domain, bus, slot, func;
    	struct pci_dev *pci_dev;
    	char str[64];
    
    	if (xenbus_read_driver_state(pdev->xdev->nodename) !=
    	    XenbusStateConnected)
    		goto out;
    
    	err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, "num_devs", "%d",
    			   &num_devs);
    	if (err != 1) {
    		if (err >= 0)
    			err = -EINVAL;
    		xenbus_dev_fatal(pdev->xdev, err,
    				 "Error reading number of PCI devices");
    		goto out;
    	}
    
    	/* Find devices being detached and remove them. */
    	for (i = 0; i < num_devs; i++) {
    		int l, state;
    		l = snprintf(str, sizeof(str), "state-%d", i);
    		if (unlikely(l >= (sizeof(str) - 1))) {
    			err = -ENOMEM;
    			goto out;
    		}
    		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str, "%d",
    				   &state);
    		if (err != 1)
    			state = XenbusStateUnknown;
    
    		if (state != XenbusStateClosing)
    			continue;
    
    		/* Remove device. */
    		l = snprintf(str, sizeof(str), "vdev-%d", i);
    		if (unlikely(l >= (sizeof(str) - 1))) {
    			err = -ENOMEM;
    			goto out;
    		}
    		err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
    				   "%x:%x:%x.%x", &domain, &bus, &slot, &func);
    		if (err != 4) {
    			if (err >= 0)
    				err = -EINVAL;
    			xenbus_dev_fatal(pdev->xdev, err,
    					 "Error reading PCI device %d", i);
    			goto out;
    		}
    
    		pci_dev = pci_get_domain_bus_and_slot(domain, bus,
    				PCI_DEVFN(slot, func));
    		if (!pci_dev) {
    			dev_dbg(&pdev->xdev->dev,
    				"Cannot get PCI device %04x:%02x:%02x.%d\n",
    				domain, bus, slot, func);
    			continue;
    		}
    		pci_lock_rescan_remove();
    		pci_stop_and_remove_bus_device(pci_dev);
    		pci_dev_put(pci_dev);
    		pci_unlock_rescan_remove();
    
    		dev_dbg(&pdev->xdev->dev,
    			"PCI device %04x:%02x:%02x.%d removed.\n",
    			domain, bus, slot, func);
    	}
    
    	err = xenbus_switch_state(pdev->xdev, XenbusStateReconfiguring);
    
    out:
    	return err;
    }
    
    static void __init_refok pcifront_backend_changed(struct xenbus_device *xdev,
    						  enum xenbus_state be_state)
    {
    	struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
    
    	switch (be_state) {
    	case XenbusStateUnknown:
    	case XenbusStateInitialising:
    	case XenbusStateInitWait:
    	case XenbusStateInitialised:
    		break;
    
    	case XenbusStateConnected:
    		pcifront_try_connect(pdev);
    		break;
    
    	case XenbusStateClosed:
    		if (xdev->state == XenbusStateClosed)
    			break;
    		/* Missed the backend's CLOSING state -- fallthrough */
    	case XenbusStateClosing:
    		dev_warn(&xdev->dev, "backend going away!\n");
    		pcifront_try_disconnect(pdev);
    		break;
    
    	case XenbusStateReconfiguring:
    		pcifront_detach_devices(pdev);
    		break;
    
    	case XenbusStateReconfigured:
    		pcifront_attach_devices(pdev);
    		break;
    	}
    }
    
    static int pcifront_xenbus_probe(struct xenbus_device *xdev,
    				 const struct xenbus_device_id *id)
    {
    	int err = 0;
    	struct pcifront_device *pdev = alloc_pdev(xdev);
    
    	if (pdev == NULL) {
    		err = -ENOMEM;
    		xenbus_dev_fatal(xdev, err,
    				 "Error allocating pcifront_device struct");
    		goto out;
    	}
    
    	err = pcifront_publish_info(pdev);
    	if (err)
    		free_pdev(pdev);
    
    out:
    	return err;
    }
    
    static int pcifront_xenbus_remove(struct xenbus_device *xdev)
    {
    	struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
    	if (pdev)
    		free_pdev(pdev);
    
    	return 0;
    }
    
    static const struct xenbus_device_id xenpci_ids[] = {
    	{"pci"},
    	{""},
    };
    
    static DEFINE_XENBUS_DRIVER(xenpci, "pcifront",
    	.probe			= pcifront_xenbus_probe,
    	.remove			= pcifront_xenbus_remove,
    	.otherend_changed	= pcifront_backend_changed,
    );
    
    static int __init pcifront_init(void)
    {
    	if (!xen_pv_domain() || xen_initial_domain())
    		return -ENODEV;
    
    	pci_frontend_registrar(1 /* enable */);
    
    	return xenbus_register_frontend(&xenpci_driver);
    }
    
    static void __exit pcifront_cleanup(void)
    {
    	xenbus_unregister_driver(&xenpci_driver);
    	pci_frontend_registrar(0 /* disable */);
    }
    module_init(pcifront_init);
    module_exit(pcifront_cleanup);
    
    MODULE_DESCRIPTION("Xen PCI passthrough frontend.");
    MODULE_LICENSE("GPL");
    MODULE_ALIAS("xen:pci");