drivers/virtio/virtio_pci_common.c - kernel/msm-5.4 - Gitiles

 /*
  * Virtio PCI driver - common functionality for all device versions
  *
  * This module allows virtio devices to be used over a virtual PCI device.
  * This can be used with QEMU based VMMs like KVM or Xen.
  *
  * Copyright IBM Corp. 2007
  * Copyright Red Hat, Inc. 2014
  *
  * Authors:
  *  Anthony Liguori  <aliguori@us.ibm.com>
  *  Rusty Russell <rusty@rustcorp.com.au>
  *  Michael S. Tsirkin <mst@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  *
  */

 #include "virtio_pci_common.h"

 static bool force_legacy = false;

 #if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)
 module_param(force_legacy, bool, 0444);
 MODULE_PARM_DESC(force_legacy,
 		 "Force legacy mode for transitional virtio 1 devices");
 #endif

 /* wait for pending irq handlers */
 void vp_synchronize_vectors(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	int i;

 	if (vp_dev->intx_enabled)
 		synchronize_irq(vp_dev->pci_dev->irq);

 	for (i = 0; i < vp_dev->msix_vectors; ++i)
 		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));
 }

 /* the notify function used when creating a virt queue */
 bool vp_notify(struct virtqueue *vq)
 {
 	/* we write the queue's selector into the notification register to
 	 * signal the other end */
 	iowrite16(vq->index, (void __iomem *)vq->priv);
 	return true;
 }

 /* Handle a configuration change: Tell driver if it wants to know. */
 static irqreturn_t vp_config_changed(int irq, void *opaque)
 {
 	struct virtio_pci_device *vp_dev = opaque;

 	virtio_config_changed(&vp_dev->vdev);
 	return IRQ_HANDLED;
 }

 /* Notify all virtqueues on an interrupt. */
 static irqreturn_t vp_vring_interrupt(int irq, void *opaque)
 {
 	struct virtio_pci_device *vp_dev = opaque;
 	struct virtio_pci_vq_info *info;
 	irqreturn_t ret = IRQ_NONE;
 	unsigned long flags;

 	spin_lock_irqsave(&vp_dev->lock, flags);
 	list_for_each_entry(info, &vp_dev->virtqueues, node) {
 		if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
 			ret = IRQ_HANDLED;
 	}
 	spin_unlock_irqrestore(&vp_dev->lock, flags);

 	return ret;
 }

 /* A small wrapper to also acknowledge the interrupt when it's handled.
  * I really need an EIO hook for the vring so I can ack the interrupt once we
  * know that we'll be handling the IRQ but before we invoke the callback since
  * the callback may notify the host which results in the host attempting to
  * raise an interrupt that we would then mask once we acknowledged the
  * interrupt. */
 static irqreturn_t vp_interrupt(int irq, void *opaque)
 {
 	struct virtio_pci_device *vp_dev = opaque;
 	u8 isr;

 	/* reading the ISR has the effect of also clearing it so it's very
 	 * important to save off the value. */
 	isr = ioread8(vp_dev->isr);

 	/* It's definitely not us if the ISR was not high */
 	if (!isr)
 		return IRQ_NONE;

 	/* Configuration change?  Tell driver if it wants to know. */
 	if (isr & VIRTIO_PCI_ISR_CONFIG)
 		vp_config_changed(irq, opaque);

 	return vp_vring_interrupt(irq, opaque);
 }

 static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
 				   bool per_vq_vectors, struct irq_affinity *desc)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	const char *name = dev_name(&vp_dev->vdev.dev);
 	unsigned flags = PCI_IRQ_MSIX;
 	unsigned i, v;
 	int err = -ENOMEM;

 	vp_dev->msix_vectors = nvectors;

 	vp_dev->msix_names = kmalloc_array(nvectors,
 					   sizeof(*vp_dev->msix_names),
 					   GFP_KERNEL);
 	if (!vp_dev->msix_names)
 		goto error;
 	vp_dev->msix_affinity_masks
 		= kcalloc(nvectors, sizeof(*vp_dev->msix_affinity_masks),
 			  GFP_KERNEL);
 	if (!vp_dev->msix_affinity_masks)
 		goto error;
 	for (i = 0; i < nvectors; ++i)
 		if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],
 					GFP_KERNEL))
 			goto error;

 	if (desc) {
 		flags |= PCI_IRQ_AFFINITY;
 		desc->pre_vectors++; /* virtio config vector */
 	}

 	err = pci_alloc_irq_vectors_affinity(vp_dev->pci_dev, nvectors,
 					     nvectors, flags, desc);
 	if (err < 0)
 		goto error;
 	vp_dev->msix_enabled = 1;

 	/* Set the vector used for configuration */
 	v = vp_dev->msix_used_vectors;
 	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
 		 "%s-config", name);
 	err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
 			  vp_config_changed, 0, vp_dev->msix_names[v],
 			  vp_dev);
 	if (err)
 		goto error;
 	++vp_dev->msix_used_vectors;

 	v = vp_dev->config_vector(vp_dev, v);
 	/* Verify we had enough resources to assign the vector */
 	if (v == VIRTIO_MSI_NO_VECTOR) {
 		err = -EBUSY;
 		goto error;
 	}

 	if (!per_vq_vectors) {
 		/* Shared vector for all VQs */
 		v = vp_dev->msix_used_vectors;
 		snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
 			 "%s-virtqueues", name);
 		err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
 				  vp_vring_interrupt, 0, vp_dev->msix_names[v],
 				  vp_dev);
 		if (err)
 			goto error;
 		++vp_dev->msix_used_vectors;
 	}
 	return 0;
 error:
 	return err;
 }

 static struct virtqueue *vp_setup_vq(struct virtio_device *vdev, unsigned index,
 				     void (*callback)(struct virtqueue *vq),
 				     const char *name,
 				     bool ctx,
 				     u16 msix_vec)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtio_pci_vq_info *info = kmalloc(sizeof *info, GFP_KERNEL);
 	struct virtqueue *vq;
 	unsigned long flags;

 	/* fill out our structure that represents an active queue */
 	if (!info)
 		return ERR_PTR(-ENOMEM);

 	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, ctx,
 			      msix_vec);
 	if (IS_ERR(vq))
 		goto out_info;

 	info->vq = vq;
 	if (callback) {
 		spin_lock_irqsave(&vp_dev->lock, flags);
 		list_add(&info->node, &vp_dev->virtqueues);
 		spin_unlock_irqrestore(&vp_dev->lock, flags);
 	} else {
 		INIT_LIST_HEAD(&info->node);
 	}

 	vp_dev->vqs[index] = info;
 	return vq;

 out_info:
 	kfree(info);
 	return vq;
 }

 static void vp_del_vq(struct virtqueue *vq)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
 	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
 	unsigned long flags;

 	spin_lock_irqsave(&vp_dev->lock, flags);
 	list_del(&info->node);
 	spin_unlock_irqrestore(&vp_dev->lock, flags);

 	vp_dev->del_vq(info);
 	kfree(info);
 }

 /* the config->del_vqs() implementation */
 void vp_del_vqs(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtqueue *vq, *n;
 	int i;

 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
 		if (vp_dev->per_vq_vectors) {
 			int v = vp_dev->vqs[vq->index]->msix_vector;

 			if (v != VIRTIO_MSI_NO_VECTOR) {
 				int irq = pci_irq_vector(vp_dev->pci_dev, v);

 				irq_set_affinity_hint(irq, NULL);
 				free_irq(irq, vq);
 			}
 		}
 		vp_del_vq(vq);
 	}
 	vp_dev->per_vq_vectors = false;

 	if (vp_dev->intx_enabled) {
 		free_irq(vp_dev->pci_dev->irq, vp_dev);
 		vp_dev->intx_enabled = 0;
 	}

 	for (i = 0; i < vp_dev->msix_used_vectors; ++i)
 		free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);

 	for (i = 0; i < vp_dev->msix_vectors; i++)
 		if (vp_dev->msix_affinity_masks[i])
 			free_cpumask_var(vp_dev->msix_affinity_masks[i]);

 	if (vp_dev->msix_enabled) {
 		/* Disable the vector used for configuration */
 		vp_dev->config_vector(vp_dev, VIRTIO_MSI_NO_VECTOR);

 		pci_free_irq_vectors(vp_dev->pci_dev);
 		vp_dev->msix_enabled = 0;
 	}

 	vp_dev->msix_vectors = 0;
 	vp_dev->msix_used_vectors = 0;
 	kfree(vp_dev->msix_names);
 	vp_dev->msix_names = NULL;
 	kfree(vp_dev->msix_affinity_masks);
 	vp_dev->msix_affinity_masks = NULL;
 	kfree(vp_dev->vqs);
 	vp_dev->vqs = NULL;
 }

 static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
 		const char * const names[], bool per_vq_vectors,
 		const bool *ctx,
 		struct irq_affinity *desc)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	u16 msix_vec;
 	int i, err, nvectors, allocated_vectors, queue_idx = 0;

 	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
 	if (!vp_dev->vqs)
 		return -ENOMEM;

 	if (per_vq_vectors) {
 		/* Best option: one for change interrupt, one per vq. */
 		nvectors = 1;
 		for (i = 0; i < nvqs; ++i)
 			if (callbacks[i])
 				++nvectors;
 	} else {
 		/* Second best: one for change, shared for all vqs. */
 		nvectors = 2;
 	}

 	err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors,
 				      per_vq_vectors ? desc : NULL);
 	if (err)
 		goto error_find;

 	vp_dev->per_vq_vectors = per_vq_vectors;
 	allocated_vectors = vp_dev->msix_used_vectors;
 	for (i = 0; i < nvqs; ++i) {
 		if (!names[i]) {
 			vqs[i] = NULL;
 			continue;
 		}

 		if (!callbacks[i])
 			msix_vec = VIRTIO_MSI_NO_VECTOR;
 		else if (vp_dev->per_vq_vectors)
 			msix_vec = allocated_vectors++;
 		else
 			msix_vec = VP_MSIX_VQ_VECTOR;
 		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
 				     ctx ? ctx[i] : false,
 				     msix_vec);
 		if (IS_ERR(vqs[i])) {
 			err = PTR_ERR(vqs[i]);
 			goto error_find;
 		}

 		if (!vp_dev->per_vq_vectors || msix_vec == VIRTIO_MSI_NO_VECTOR)
 			continue;

 		/* allocate per-vq irq if available and necessary */
 		snprintf(vp_dev->msix_names[msix_vec],
 			 sizeof *vp_dev->msix_names,
 			 "%s-%s",
 			 dev_name(&vp_dev->vdev.dev), names[i]);
 		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
 				  vring_interrupt, 0,
 				  vp_dev->msix_names[msix_vec],
 				  vqs[i]);
 		if (err)
 			goto error_find;
 	}
 	return 0;

 error_find:
 	vp_del_vqs(vdev);
 	return err;
 }

 static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
 		const char * const names[], const bool *ctx)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	int i, err, queue_idx = 0;

 	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
 	if (!vp_dev->vqs)
 		return -ENOMEM;

 	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
 			dev_name(&vdev->dev), vp_dev);
 	if (err)
 		goto out_del_vqs;

 	vp_dev->intx_enabled = 1;
 	vp_dev->per_vq_vectors = false;
 	for (i = 0; i < nvqs; ++i) {
 		if (!names[i]) {
 			vqs[i] = NULL;
 			continue;
 		}
 		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
 				     ctx ? ctx[i] : false,
 				     VIRTIO_MSI_NO_VECTOR);
 		if (IS_ERR(vqs[i])) {
 			err = PTR_ERR(vqs[i]);
 			goto out_del_vqs;
 		}
 	}

 	return 0;
 out_del_vqs:
 	vp_del_vqs(vdev);
 	return err;
 }

 /* the config->find_vqs() implementation */
 int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
 		const char * const names[], const bool *ctx,
 		struct irq_affinity *desc)
 {
 	int err;

 	/* Try MSI-X with one vector per queue. */
 	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true, ctx, desc);
 	if (!err)
 		return 0;
 	/* Fallback: MSI-X with one vector for config, one shared for queues. */
 	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false, ctx, desc);
 	if (!err)
 		return 0;
 	/* Finally fall back to regular interrupts. */
 	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);
 }

 const char *vp_bus_name(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	return pci_name(vp_dev->pci_dev);
 }

 /* Setup the affinity for a virtqueue:
  * - force the affinity for per vq vector
  * - OR over all affinities for shared MSI
  * - ignore the affinity request if we're using INTX
  */
 int vp_set_vq_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask)
 {
 	struct virtio_device *vdev = vq->vdev;
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
 	struct cpumask *mask;
 	unsigned int irq;

 	if (!vq->callback)
 		return -EINVAL;

 	if (vp_dev->msix_enabled) {
 		mask = vp_dev->msix_affinity_masks[info->msix_vector];
 		irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
 		if (!cpu_mask)
 			irq_set_affinity_hint(irq, NULL);
 		else {
 			cpumask_copy(mask, cpu_mask);
 			irq_set_affinity_hint(irq, mask);
 		}
 	}
 	return 0;
 }

 const struct cpumask *vp_get_vq_affinity(struct virtio_device *vdev, int index)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	if (!vp_dev->per_vq_vectors ||
 	    vp_dev->vqs[index]->msix_vector == VIRTIO_MSI_NO_VECTOR)
 		return NULL;

 	return pci_irq_get_affinity(vp_dev->pci_dev,
 				    vp_dev->vqs[index]->msix_vector);
 }

 #ifdef CONFIG_PM_SLEEP
 static int virtio_pci_freeze(struct device *dev)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
 	int ret;

 	ret = virtio_device_freeze(&vp_dev->vdev);

 	if (!ret)
 		pci_disable_device(pci_dev);
 	return ret;
 }

 static int virtio_pci_restore(struct device *dev)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
 	int ret;

 	ret = pci_enable_device(pci_dev);
 	if (ret)
 		return ret;

 	pci_set_master(pci_dev);
 	return virtio_device_restore(&vp_dev->vdev);
 }

 static const struct dev_pm_ops virtio_pci_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)
 };
 #endif


 /* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
 static const struct pci_device_id virtio_pci_id_table[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },
 	{ 0 }
 };

 MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);

 static void virtio_pci_release_dev(struct device *_d)
 {
 	struct virtio_device *vdev = dev_to_virtio(_d);
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	/* As struct device is a kobject, it's not safe to
 	 * free the memory (including the reference counter itself)
 	 * until it's release callback. */
 	kfree(vp_dev);
 }

 static int virtio_pci_probe(struct pci_dev *pci_dev,
 			    const struct pci_device_id *id)
 {
 	struct virtio_pci_device *vp_dev, *reg_dev = NULL;
 	int rc;

 	/* allocate our structure and fill it out */
 	vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
 	if (!vp_dev)
 		return -ENOMEM;

 	pci_set_drvdata(pci_dev, vp_dev);
 	vp_dev->vdev.dev.parent = &pci_dev->dev;
 	vp_dev->vdev.dev.release = virtio_pci_release_dev;
 	vp_dev->pci_dev = pci_dev;
 	INIT_LIST_HEAD(&vp_dev->virtqueues);
 	spin_lock_init(&vp_dev->lock);

 	/* enable the device */
 	rc = pci_enable_device(pci_dev);
 	if (rc)
 		goto err_enable_device;

 	if (force_legacy) {
 		rc = virtio_pci_legacy_probe(vp_dev);
 		/* Also try modern mode if we can't map BAR0 (no IO space). */
 		if (rc == -ENODEV || rc == -ENOMEM)
 			rc = virtio_pci_modern_probe(vp_dev);
 		if (rc)
 			goto err_probe;
 	} else {
 		rc = virtio_pci_modern_probe(vp_dev);
 		if (rc == -ENODEV)
 			rc = virtio_pci_legacy_probe(vp_dev);
 		if (rc)
 			goto err_probe;
 	}

 	pci_set_master(pci_dev);

 	rc = register_virtio_device(&vp_dev->vdev);
 	reg_dev = vp_dev;
 	if (rc)
 		goto err_register;

 	return 0;

 err_register:
 	if (vp_dev->ioaddr)
 	     virtio_pci_legacy_remove(vp_dev);
 	else
 	     virtio_pci_modern_remove(vp_dev);
 err_probe:
 	pci_disable_device(pci_dev);
 err_enable_device:
 	if (reg_dev)
 		put_device(&vp_dev->vdev.dev);
 	else
 		kfree(vp_dev);
 	return rc;
 }

 static void virtio_pci_remove(struct pci_dev *pci_dev)
 {
 	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
 	struct device *dev = get_device(&vp_dev->vdev.dev);

 	pci_disable_sriov(pci_dev);

 	unregister_virtio_device(&vp_dev->vdev);

 	if (vp_dev->ioaddr)
 		virtio_pci_legacy_remove(vp_dev);
 	else
 		virtio_pci_modern_remove(vp_dev);

 	pci_disable_device(pci_dev);
 	put_device(dev);
 }

 static int virtio_pci_sriov_configure(struct pci_dev *pci_dev, int num_vfs)
 {
 	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
 	struct virtio_device *vdev = &vp_dev->vdev;
 	int ret;

 	if (!(vdev->config->get_status(vdev) & VIRTIO_CONFIG_S_DRIVER_OK))
 		return -EBUSY;

 	if (!__virtio_test_bit(vdev, VIRTIO_F_SR_IOV))
 		return -EINVAL;

 	if (pci_vfs_assigned(pci_dev))
 		return -EPERM;

 	if (num_vfs == 0) {
 		pci_disable_sriov(pci_dev);
 		return 0;
 	}

 	ret = pci_enable_sriov(pci_dev, num_vfs);
 	if (ret < 0)
 		return ret;

 	return num_vfs;
 }

 static struct pci_driver virtio_pci_driver = {
 	.name		= "virtio-pci",
 	.id_table	= virtio_pci_id_table,
 	.probe		= virtio_pci_probe,
 	.remove		= virtio_pci_remove,
 #ifdef CONFIG_PM_SLEEP
 	.driver.pm	= &virtio_pci_pm_ops,
 #endif
 	.sriov_configure = virtio_pci_sriov_configure,
 };

 module_pci_driver(virtio_pci_driver);

 MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
 MODULE_DESCRIPTION("virtio-pci");
 MODULE_LICENSE("GPL");
 MODULE_VERSION("1");
	/*
	* Virtio PCI driver - common functionality for all device versions
	*
	* This module allows virtio devices to be used over a virtual PCI device.
	* This can be used with QEMU based VMMs like KVM or Xen.
	*
	* Copyright IBM Corp. 2007
	* Copyright Red Hat, Inc. 2014
	*
	* Authors:
	* Anthony Liguori <aliguori@us.ibm.com>
	* Rusty Russell <rusty@rustcorp.com.au>
	* Michael S. Tsirkin <mst@redhat.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	* See the COPYING file in the top-level directory.
	*
	*/

	#include "virtio_pci_common.h"

	static bool force_legacy = false;

	#if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)
	module_param(force_legacy, bool, 0444);
	MODULE_PARM_DESC(force_legacy,
	"Force legacy mode for transitional virtio 1 devices");
	#endif

	/* wait for pending irq handlers */
	void vp_synchronize_vectors(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	int i;

	if (vp_dev->intx_enabled)
	synchronize_irq(vp_dev->pci_dev->irq);

	for (i = 0; i < vp_dev->msix_vectors; ++i)
	synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));
	}

	/* the notify function used when creating a virt queue */
	bool vp_notify(struct virtqueue *vq)
	{
	/* we write the queue's selector into the notification register to
	* signal the other end */
	iowrite16(vq->index, (void __iomem *)vq->priv);
	return true;
	}

	/* Handle a configuration change: Tell driver if it wants to know. */
	static irqreturn_t vp_config_changed(int irq, void *opaque)
	{
	struct virtio_pci_device *vp_dev = opaque;

	virtio_config_changed(&vp_dev->vdev);
	return IRQ_HANDLED;
	}

	/* Notify all virtqueues on an interrupt. */
	static irqreturn_t vp_vring_interrupt(int irq, void *opaque)
	{
	struct virtio_pci_device *vp_dev = opaque;
	struct virtio_pci_vq_info *info;
	irqreturn_t ret = IRQ_NONE;
	unsigned long flags;

	spin_lock_irqsave(&vp_dev->lock, flags);
	list_for_each_entry(info, &vp_dev->virtqueues, node) {
	if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
	ret = IRQ_HANDLED;
	}
	spin_unlock_irqrestore(&vp_dev->lock, flags);

	return ret;
	}

	/* A small wrapper to also acknowledge the interrupt when it's handled.
	* I really need an EIO hook for the vring so I can ack the interrupt once we
	* know that we'll be handling the IRQ but before we invoke the callback since
	* the callback may notify the host which results in the host attempting to
	* raise an interrupt that we would then mask once we acknowledged the
	* interrupt. */
	static irqreturn_t vp_interrupt(int irq, void *opaque)
	{
	struct virtio_pci_device *vp_dev = opaque;
	u8 isr;

	/* reading the ISR has the effect of also clearing it so it's very
	* important to save off the value. */
	isr = ioread8(vp_dev->isr);

	/* It's definitely not us if the ISR was not high */
	if (!isr)
	return IRQ_NONE;

	/* Configuration change? Tell driver if it wants to know. */
	if (isr & VIRTIO_PCI_ISR_CONFIG)
	vp_config_changed(irq, opaque);

	return vp_vring_interrupt(irq, opaque);
	}

	static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
	bool per_vq_vectors, struct irq_affinity *desc)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	const char *name = dev_name(&vp_dev->vdev.dev);
	unsigned flags = PCI_IRQ_MSIX;
	unsigned i, v;
	int err = -ENOMEM;

	vp_dev->msix_vectors = nvectors;

	vp_dev->msix_names = kmalloc_array(nvectors,
	sizeof(*vp_dev->msix_names),
	GFP_KERNEL);
	if (!vp_dev->msix_names)
	goto error;
	vp_dev->msix_affinity_masks
	= kcalloc(nvectors, sizeof(*vp_dev->msix_affinity_masks),
	GFP_KERNEL);
	if (!vp_dev->msix_affinity_masks)
	goto error;
	for (i = 0; i < nvectors; ++i)
	if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],
	GFP_KERNEL))
	goto error;

	if (desc) {
	flags \|= PCI_IRQ_AFFINITY;
	desc->pre_vectors++; /* virtio config vector */
	}

	err = pci_alloc_irq_vectors_affinity(vp_dev->pci_dev, nvectors,
	nvectors, flags, desc);
	if (err < 0)
	goto error;
	vp_dev->msix_enabled = 1;

	/* Set the vector used for configuration */
	v = vp_dev->msix_used_vectors;
	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
	"%s-config", name);
	err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
	vp_config_changed, 0, vp_dev->msix_names[v],
	vp_dev);
	if (err)
	goto error;
	++vp_dev->msix_used_vectors;

	v = vp_dev->config_vector(vp_dev, v);
	/* Verify we had enough resources to assign the vector */
	if (v == VIRTIO_MSI_NO_VECTOR) {
	err = -EBUSY;
	goto error;
	}

	if (!per_vq_vectors) {
	/* Shared vector for all VQs */
	v = vp_dev->msix_used_vectors;
	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
	"%s-virtqueues", name);
	err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
	vp_vring_interrupt, 0, vp_dev->msix_names[v],
	vp_dev);
	if (err)
	goto error;
	++vp_dev->msix_used_vectors;
	}
	return 0;
	error:
	return err;
	}

	static struct virtqueue vp_setup_vq(struct virtio_device vdev, unsigned index,
	void (callback)(struct virtqueue vq),
	const char *name,
	bool ctx,
	u16 msix_vec)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtio_pci_vq_info info = kmalloc(sizeof info, GFP_KERNEL);
	struct virtqueue *vq;
	unsigned long flags;

	/* fill out our structure that represents an active queue */
	if (!info)
	return ERR_PTR(-ENOMEM);

	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, ctx,
	msix_vec);
	if (IS_ERR(vq))
	goto out_info;

	info->vq = vq;
	if (callback) {
	spin_lock_irqsave(&vp_dev->lock, flags);
	list_add(&info->node, &vp_dev->virtqueues);
	spin_unlock_irqrestore(&vp_dev->lock, flags);
	} else {
	INIT_LIST_HEAD(&info->node);
	}

	vp_dev->vqs[index] = info;
	return vq;

	out_info:
	kfree(info);
	return vq;
	}

	static void vp_del_vq(struct virtqueue *vq)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
	unsigned long flags;

	spin_lock_irqsave(&vp_dev->lock, flags);
	list_del(&info->node);
	spin_unlock_irqrestore(&vp_dev->lock, flags);

	vp_dev->del_vq(info);
	kfree(info);
	}

	/* the config->del_vqs() implementation */
	void vp_del_vqs(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtqueue vq, n;
	int i;

	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
	if (vp_dev->per_vq_vectors) {
	int v = vp_dev->vqs[vq->index]->msix_vector;

	if (v != VIRTIO_MSI_NO_VECTOR) {
	int irq = pci_irq_vector(vp_dev->pci_dev, v);

	irq_set_affinity_hint(irq, NULL);
	free_irq(irq, vq);
	}
	}
	vp_del_vq(vq);
	}
	vp_dev->per_vq_vectors = false;

	if (vp_dev->intx_enabled) {
	free_irq(vp_dev->pci_dev->irq, vp_dev);
	vp_dev->intx_enabled = 0;
	}

	for (i = 0; i < vp_dev->msix_used_vectors; ++i)
	free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);

	for (i = 0; i < vp_dev->msix_vectors; i++)
	if (vp_dev->msix_affinity_masks[i])
	free_cpumask_var(vp_dev->msix_affinity_masks[i]);

	if (vp_dev->msix_enabled) {
	/* Disable the vector used for configuration */
	vp_dev->config_vector(vp_dev, VIRTIO_MSI_NO_VECTOR);

	pci_free_irq_vectors(vp_dev->pci_dev);
	vp_dev->msix_enabled = 0;
	}

	vp_dev->msix_vectors = 0;
	vp_dev->msix_used_vectors = 0;
	kfree(vp_dev->msix_names);
	vp_dev->msix_names = NULL;
	kfree(vp_dev->msix_affinity_masks);
	vp_dev->msix_affinity_masks = NULL;
	kfree(vp_dev->vqs);
	vp_dev->vqs = NULL;
	}

	static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
	struct virtqueue vqs[], vq_callback_t callbacks[],
	const char * const names[], bool per_vq_vectors,
	const bool *ctx,
	struct irq_affinity *desc)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	u16 msix_vec;
	int i, err, nvectors, allocated_vectors, queue_idx = 0;

	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
	if (!vp_dev->vqs)
	return -ENOMEM;

	if (per_vq_vectors) {
	/* Best option: one for change interrupt, one per vq. */
	nvectors = 1;
	for (i = 0; i < nvqs; ++i)
	if (callbacks[i])
	++nvectors;
	} else {
	/* Second best: one for change, shared for all vqs. */
	nvectors = 2;
	}

	err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors,
	per_vq_vectors ? desc : NULL);
	if (err)
	goto error_find;

	vp_dev->per_vq_vectors = per_vq_vectors;
	allocated_vectors = vp_dev->msix_used_vectors;
	for (i = 0; i < nvqs; ++i) {
	if (!names[i]) {
	vqs[i] = NULL;
	continue;
	}

	if (!callbacks[i])
	msix_vec = VIRTIO_MSI_NO_VECTOR;
	else if (vp_dev->per_vq_vectors)
	msix_vec = allocated_vectors++;
	else
	msix_vec = VP_MSIX_VQ_VECTOR;
	vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
	ctx ? ctx[i] : false,
	msix_vec);
	if (IS_ERR(vqs[i])) {
	err = PTR_ERR(vqs[i]);
	goto error_find;
	}

	if (!vp_dev->per_vq_vectors \|\| msix_vec == VIRTIO_MSI_NO_VECTOR)
	continue;

	/* allocate per-vq irq if available and necessary */
	snprintf(vp_dev->msix_names[msix_vec],
	sizeof *vp_dev->msix_names,
	"%s-%s",
	dev_name(&vp_dev->vdev.dev), names[i]);
	err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
	vring_interrupt, 0,
	vp_dev->msix_names[msix_vec],
	vqs[i]);
	if (err)
	goto error_find;
	}
	return 0;

	error_find:
	vp_del_vqs(vdev);
	return err;
	}

	static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs,
	struct virtqueue vqs[], vq_callback_t callbacks[],
	const char * const names[], const bool *ctx)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	int i, err, queue_idx = 0;

	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
	if (!vp_dev->vqs)
	return -ENOMEM;

	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
	dev_name(&vdev->dev), vp_dev);
	if (err)
	goto out_del_vqs;

	vp_dev->intx_enabled = 1;
	vp_dev->per_vq_vectors = false;
	for (i = 0; i < nvqs; ++i) {
	if (!names[i]) {
	vqs[i] = NULL;
	continue;
	}
	vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
	ctx ? ctx[i] : false,
	VIRTIO_MSI_NO_VECTOR);
	if (IS_ERR(vqs[i])) {
	err = PTR_ERR(vqs[i]);
	goto out_del_vqs;
	}
	}

	return 0;
	out_del_vqs:
	vp_del_vqs(vdev);
	return err;
	}

	/* the config->find_vqs() implementation */
	int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
	struct virtqueue vqs[], vq_callback_t callbacks[],
	const char * const names[], const bool *ctx,
	struct irq_affinity *desc)
	{
	int err;

	/* Try MSI-X with one vector per queue. */
	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true, ctx, desc);
	if (!err)
	return 0;
	/* Fallback: MSI-X with one vector for config, one shared for queues. */
	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false, ctx, desc);
	if (!err)
	return 0;
	/* Finally fall back to regular interrupts. */
	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);
	}

	const char vp_bus_name(struct virtio_device vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	return pci_name(vp_dev->pci_dev);
	}

	/* Setup the affinity for a virtqueue:
	* - force the affinity for per vq vector
	* - OR over all affinities for shared MSI
	* - ignore the affinity request if we're using INTX
	*/
	int vp_set_vq_affinity(struct virtqueue vq, const struct cpumask cpu_mask)
	{
	struct virtio_device *vdev = vq->vdev;
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
	struct cpumask *mask;
	unsigned int irq;

	if (!vq->callback)
	return -EINVAL;

	if (vp_dev->msix_enabled) {
	mask = vp_dev->msix_affinity_masks[info->msix_vector];
	irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
	if (!cpu_mask)
	irq_set_affinity_hint(irq, NULL);
	else {
	cpumask_copy(mask, cpu_mask);
	irq_set_affinity_hint(irq, mask);
	}
	}
	return 0;
	}

	const struct cpumask vp_get_vq_affinity(struct virtio_device vdev, int index)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	if (!vp_dev->per_vq_vectors \|\|
	vp_dev->vqs[index]->msix_vector == VIRTIO_MSI_NO_VECTOR)
	return NULL;

	return pci_irq_get_affinity(vp_dev->pci_dev,
	vp_dev->vqs[index]->msix_vector);
	}

	#ifdef CONFIG_PM_SLEEP
	static int virtio_pci_freeze(struct device *dev)
	{
	struct pci_dev *pci_dev = to_pci_dev(dev);
	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
	int ret;

	ret = virtio_device_freeze(&vp_dev->vdev);

	if (!ret)
	pci_disable_device(pci_dev);
	return ret;
	}

	static int virtio_pci_restore(struct device *dev)
	{
	struct pci_dev *pci_dev = to_pci_dev(dev);
	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
	int ret;

	ret = pci_enable_device(pci_dev);
	if (ret)
	return ret;

	pci_set_master(pci_dev);
	return virtio_device_restore(&vp_dev->vdev);
	}

	static const struct dev_pm_ops virtio_pci_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)
	};
	#endif


	/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
	static const struct pci_device_id virtio_pci_id_table[] = {
	{ PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },
	{ 0 }
	};

	MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);

	static void virtio_pci_release_dev(struct device *_d)
	{
	struct virtio_device *vdev = dev_to_virtio(_d);
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	/* As struct device is a kobject, it's not safe to
	* free the memory (including the reference counter itself)
	* until it's release callback. */
	kfree(vp_dev);
	}

	static int virtio_pci_probe(struct pci_dev *pci_dev,
	const struct pci_device_id *id)
	{
	struct virtio_pci_device vp_dev, reg_dev = NULL;
	int rc;

	/* allocate our structure and fill it out */
	vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
	if (!vp_dev)
	return -ENOMEM;

	pci_set_drvdata(pci_dev, vp_dev);
	vp_dev->vdev.dev.parent = &pci_dev->dev;
	vp_dev->vdev.dev.release = virtio_pci_release_dev;
	vp_dev->pci_dev = pci_dev;
	INIT_LIST_HEAD(&vp_dev->virtqueues);
	spin_lock_init(&vp_dev->lock);

	/* enable the device */
	rc = pci_enable_device(pci_dev);
	if (rc)
	goto err_enable_device;

	if (force_legacy) {
	rc = virtio_pci_legacy_probe(vp_dev);
	/* Also try modern mode if we can't map BAR0 (no IO space). */
	if (rc == -ENODEV \|\| rc == -ENOMEM)
	rc = virtio_pci_modern_probe(vp_dev);
	if (rc)
	goto err_probe;
	} else {
	rc = virtio_pci_modern_probe(vp_dev);
	if (rc == -ENODEV)
	rc = virtio_pci_legacy_probe(vp_dev);
	if (rc)
	goto err_probe;
	}

	pci_set_master(pci_dev);

	rc = register_virtio_device(&vp_dev->vdev);
	reg_dev = vp_dev;
	if (rc)
	goto err_register;

	return 0;

	err_register:
	if (vp_dev->ioaddr)
	virtio_pci_legacy_remove(vp_dev);
	else
	virtio_pci_modern_remove(vp_dev);
	err_probe:
	pci_disable_device(pci_dev);
	err_enable_device:
	if (reg_dev)
	put_device(&vp_dev->vdev.dev);
	else
	kfree(vp_dev);
	return rc;
	}

	static void virtio_pci_remove(struct pci_dev *pci_dev)
	{
	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
	struct device *dev = get_device(&vp_dev->vdev.dev);

	pci_disable_sriov(pci_dev);

	unregister_virtio_device(&vp_dev->vdev);

	if (vp_dev->ioaddr)
	virtio_pci_legacy_remove(vp_dev);
	else
	virtio_pci_modern_remove(vp_dev);

	pci_disable_device(pci_dev);
	put_device(dev);
	}

	static int virtio_pci_sriov_configure(struct pci_dev *pci_dev, int num_vfs)
	{
	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
	struct virtio_device *vdev = &vp_dev->vdev;
	int ret;

	if (!(vdev->config->get_status(vdev) & VIRTIO_CONFIG_S_DRIVER_OK))
	return -EBUSY;

	if (!__virtio_test_bit(vdev, VIRTIO_F_SR_IOV))
	return -EINVAL;

	if (pci_vfs_assigned(pci_dev))
	return -EPERM;

	if (num_vfs == 0) {
	pci_disable_sriov(pci_dev);
	return 0;
	}

	ret = pci_enable_sriov(pci_dev, num_vfs);
	if (ret < 0)
	return ret;

	return num_vfs;
	}

	static struct pci_driver virtio_pci_driver = {
	.name = "virtio-pci",
	.id_table = virtio_pci_id_table,
	.probe = virtio_pci_probe,
	.remove = virtio_pci_remove,
	#ifdef CONFIG_PM_SLEEP
	.driver.pm = &virtio_pci_pm_ops,
	#endif
	.sriov_configure = virtio_pci_sriov_configure,
	};

	module_pci_driver(virtio_pci_driver);

	MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
	MODULE_DESCRIPTION("virtio-pci");
	MODULE_LICENSE("GPL");
	MODULE_VERSION("1");