Re: [PATCH 13/22] virtio_pci: new, capability-aware driver.

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Mar 21, 2013 at 06:59:34PM +1030, Rusty Russell wrote:
> Differences:
> 1) Uses 4 pci capabilities to demark common, irq, notify and dev-specific areas.
> 2) Guest sets queue size, using host-provided maximum.
> 3) Guest sets queue alignment, rather than ABI-defined 4096.
> 4) More than 32 feature bits (a lot more!).
> 
> Signed-off-by: Rusty Russell <rustcorp.com.au>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> ---
>  drivers/virtio/Makefile     |    1 +
>  drivers/virtio/virtio_pci.c |  979 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 980 insertions(+)
>  create mode 100644 drivers/virtio/virtio_pci.c
> 
> diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
> index 23834f5..eec0a42 100644
> --- a/drivers/virtio/Makefile
> +++ b/drivers/virtio/Makefile
> @@ -1,4 +1,5 @@
>  obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
>  obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
> +obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
>  obj-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
>  obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
> new file mode 100644
> index 0000000..b86b99c
> --- /dev/null
> +++ b/drivers/virtio/virtio_pci.c
> @@ -0,0 +1,979 @@
> +/*
> + * Virtio PCI driver
> + *
> + * This module allows virtio devices to be used over a virtual PCI
> + * device.  Copyright 2011, Rusty Russell IBM Corporation, but based
> + * on the older virtio_pci_legacy.c, which was Copyright IBM
> + * Corp. 2007.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +#define VIRTIO_PCI_NO_LEGACY
> +#include <linux/module.h>
> +#include <linux/list.h>
> +#include <linux/pci.h>
> +#include <linux/slab.h>
> +#include <linux/interrupt.h>
> +#include <linux/virtio.h>
> +#include <linux/virtio_config.h>
> +#include <linux/virtio_ring.h>
> +#include <linux/virtio_pci.h>
> +#include <linux/highmem.h>
> +#include <linux/spinlock.h>
> +
> +MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
> +MODULE_DESCRIPTION("virtio-pci");
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION("2");
> +
> +/* Our device structure */
> +struct virtio_pci_device {
> +	struct virtio_device vdev;
> +	struct pci_dev *pci_dev;
> +
> +	/* The IO mapping for the PCI config space */
> +	struct virtio_pci_common_cfg __iomem *common;
> +	/* Where to read and clear interrupt */
> +	u8 __iomem *isr;
> +	/* Write the virtqueue index here to notify device of activity. */
> +	__le16 __iomem *notify;
> +	/* Device-specific data. */
> +	void __iomem *device;
> +
> +	/* a list of queues so we can dispatch IRQs */
> +	spinlock_t lock;
> +	struct list_head virtqueues;
> +
> +	/* MSI-X support */
> +	int msix_enabled;
> +	int intx_enabled;
> +	struct msix_entry *msix_entries;
> +	cpumask_var_t *msix_affinity_masks;
> +	/* Name strings for interrupts. This size should be enough,
> +	 * and I'm too lazy to allocate each name separately. */
> +	char (*msix_names)[256];
> +	/* Number of available vectors */
> +	unsigned msix_vectors;
> +	/* Vectors allocated, excluding per-vq vectors if any */
> +	unsigned msix_used_vectors;
> +
> +	/* Status saved during hibernate/restore */
> +	u8 saved_status;
> +
> +	/* Whether we have vector per vq */
> +	bool per_vq_vectors;
> +};
> +
> +/* Constants for MSI-X */
> +/* Use first vector for configuration changes, second and the rest for
> + * virtqueues Thus, we need at least 2 vectors for MSI. */
> +enum {
> +	VP_MSIX_CONFIG_VECTOR = 0,
> +	VP_MSIX_VQ_VECTOR = 1,
> +};

In the future, I have a plan to allow one vector only.  To make this
work without exits for data path VQ, we could make hypervisor set a bit
in guest memory whenever it wants to signal a configuration change.
Guest will execute a config write that will make the hypervisor clear
this register.

I guess this can wait, we are putting too stuff much into this
new layout patchset already.

> +
> +struct virtio_pci_vq_info {
> +	/* the actual virtqueue */
> +	struct virtqueue *vq;
> +
> +	/* the pages used for the queue. */
> +	void *queue;
> +
> +	/* the list node for the virtqueues list */
> +	struct list_head node;
> +
> +	/* MSI-X vector (or none) */
> +	unsigned msix_vector;
> +};
> +
> +/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
> +static DEFINE_PCI_DEVICE_TABLE(virtio_pci_id_table) = {
> +	{ PCI_DEVICE(0x1af4, PCI_ANY_ID) },
> +	{ 0 }
> +};
> +
> +MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
> +
> +/* Convert a generic virtio device to our structure */
> +static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
> +{
> +	return container_of(vdev, struct virtio_pci_device, vdev);
> +}
> +
> +/* There is no iowrite64.  We use two 32-bit ops. */
> +static void iowrite64(u64 val, const __le64 *addr)
> +{
> +	iowrite32((u32)val, (__le32 *)addr);
> +	iowrite32(val >> 32, (__le32 *)addr + 1);
> +}
> +
> +/* There is no ioread64.  We use two 32-bit ops. */
> +static u64 ioread64(__le64 *addr)
> +{
> +	return ioread32(addr) | ((u64)ioread32((__le32 *)addr + 1) << 32);
> +}
> +
> +static u64 vp_get_features(struct virtio_device *vdev)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	u64 features;
> +
> +	iowrite32(0, &vp_dev->common->device_feature_select);
> +	features = ioread32(&vp_dev->common->device_feature);
> +	iowrite32(1, &vp_dev->common->device_feature_select);
> +	features |= ((u64)ioread32(&vp_dev->common->device_feature) << 32);
> +	return features;
> +}
> +
> +static void vp_finalize_features(struct virtio_device *vdev)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +
> +	/* Give virtio_ring a chance to accept features. */
> +	vring_transport_features(vdev);
> +
> +	iowrite32(0, &vp_dev->common->guest_feature_select);
> +	iowrite32((u32)vdev->features, &vp_dev->common->guest_feature);
> +	iowrite32(1, &vp_dev->common->guest_feature_select);
> +	iowrite32(vdev->features >> 32, &vp_dev->common->guest_feature);
> +}
> +
> +/* virtio config->get() implementation */
> +static void vp_get(struct virtio_device *vdev, unsigned offset,
> +		   void *buf, unsigned len)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	void __iomem *ioaddr = vp_dev->device + offset;
> +	u8 *ptr = buf;
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		ptr[i] = ioread8(ioaddr + i);
> +}
> +
> +#define VP_GETx(bits)							\
> +static u##bits vp_get##bits(struct virtio_device *vdev, unsigned int offset) \
> +{									\
> +	u##bits v;							\
> +	vp_get(vdev, offset, &v, sizeof(v));				\
> +	return v;							\
> +}
> +
> +VP_GETx(8)
> +VP_GETx(16)
> +VP_GETx(32)
> +VP_GETx(64)
> +
> +/* the config->set() implementation.  it's symmetric to the config->get()
> + * implementation */
> +static void vp_set(struct virtio_device *vdev, unsigned offset,
> +		   const void *buf, unsigned len)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	void __iomem *ioaddr = vp_dev->device + offset;
> +	const u8 *ptr = buf;
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		iowrite8(ptr[i], ioaddr + i);
> +}
> +
> +#define VP_SETx(bits)							\
> +static void vp_set##bits(struct virtio_device *vdev, unsigned int offset, \
> +			 u##bits v)					\
> +{									\
> +	vp_set(vdev, offset, &v, sizeof(v));				\
> +}
> +
> +VP_SETx(8)
> +VP_SETx(16)
> +VP_SETx(32)
> +VP_SETx(64)
> +
> +/* config->{get,set}_status() implementations */
> +static u8 vp_get_status(struct virtio_device *vdev)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	return ioread8(&vp_dev->common->device_status);
> +}
> +
> +static void vp_set_status(struct virtio_device *vdev, u8 status)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	/* We should never be setting status to 0. */
> +	BUG_ON(status == 0);
> +	iowrite8(status, &vp_dev->common->device_status);
> +}
> +
> +/* wait for pending irq handlers */
> +static 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(vp_dev->msix_entries[i].vector);
> +}
> +
> +static void vp_reset(struct virtio_device *vdev)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	/* 0 status means a reset. */
> +	iowrite8(0, &vp_dev->common->device_status);
> +	/* Flush out the status write, and flush in device writes,
> +	 * including MSi-X interrupts, if any. */

MSI-X ?

> +	ioread8(&vp_dev->common->device_status);
> +	/* Flush pending VQ/configuration callbacks. */
> +	vp_synchronize_vectors(vdev);
> +}
> +
> +/* the notify function used when creating a virt queue */
> +static void vp_notify(struct virtqueue *vq)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> +
> +	/* we write the queue's selector into the notification register to
> +	 * signal the other end */
> +	iowrite16(vq->index, vp_dev->notify);
> +}
> +
> +/* 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;
> +	struct virtio_driver *drv;
> +	drv = container_of(vp_dev->vdev.dev.driver,
> +			   struct virtio_driver, driver);
> +
> +	if (drv->config_changed)
> +		drv->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 void vp_free_vectors(struct virtio_device *vdev)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	int i;
> +
> +	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(vp_dev->msix_entries[i].vector, 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 */
> +		iowrite16(VIRTIO_MSI_NO_VECTOR, &vp_dev->common->msix_config);
> +		/* Flush the write out to device */
> +		ioread16(&vp_dev->common->msix_config);
> +
> +		pci_disable_msix(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_entries);
> +	vp_dev->msix_entries = NULL;
> +	kfree(vp_dev->msix_affinity_masks);
> +	vp_dev->msix_affinity_masks = NULL;
> +}
> +
> +static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
> +				   bool per_vq_vectors)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	const char *name = dev_name(&vp_dev->vdev.dev);
> +	unsigned i, v;
> +	int err = -ENOMEM;
> +
> +	vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
> +				       GFP_KERNEL);
> +	if (!vp_dev->msix_entries)
> +		goto error;
> +	vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
> +				     GFP_KERNEL);
> +	if (!vp_dev->msix_names)
> +		goto error;
> +	vp_dev->msix_affinity_masks
> +		= kzalloc(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;
> +
> +	for (i = 0; i < nvectors; ++i)
> +		vp_dev->msix_entries[i].entry = i;
> +
> +	/* pci_enable_msix returns positive if we can't get this many. */
> +	err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors);
> +	if (err > 0)
> +		err = -ENOSPC;
> +	if (err)
> +		goto error;
> +	vp_dev->msix_vectors = nvectors;
> +	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(vp_dev->msix_entries[v].vector,
> +			  vp_config_changed, 0, vp_dev->msix_names[v],
> +			  vp_dev);
> +	if (err)
> +		goto error;
> +	++vp_dev->msix_used_vectors;
> +
> +	iowrite16(v, &vp_dev->common->msix_config);
> +	/* Verify we had enough resources to assign the vector */
> +	v = ioread16(&vp_dev->common->msix_config);
> +	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(vp_dev->msix_entries[v].vector,
> +				  vp_vring_interrupt, 0, vp_dev->msix_names[v],
> +				  vp_dev);
> +		if (err)
> +			goto error;
> +		++vp_dev->msix_used_vectors;
> +	}
> +	return 0;
> +error:
> +	vp_free_vectors(vdev);
> +	return err;
> +}
> +
> +static int vp_request_intx(struct virtio_device *vdev)
> +{
> +	int err;
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +
> +	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
> +			  IRQF_SHARED, dev_name(&vdev->dev), vp_dev);
> +	if (!err)
> +		vp_dev->intx_enabled = 1;
> +	return err;
> +}
> +
> +static size_t vring_pci_size(u16 num)
> +{
> +	/* We only need a cacheline separation. */
> +	return PAGE_ALIGN(vring_size(num, SMP_CACHE_BYTES));
> +}
> +
> +static void *alloc_virtqueue_pages(u16 *num)
> +{
> +	void *pages;
> +
> +	/* 1024 entries uses about 32k */
> +	if (*num > 1024)
> +		*num = 1024;
> +
> +	for (; *num; *num /= 2) {
> +		pages = alloc_pages_exact(vring_pci_size(*num),
> +					  GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
> +		if (pages)
> +			return pages;
> +	}
> +	return NULL;
> +}
> +
> +static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
> +				  void (*callback)(struct virtqueue *vq),
> +				  const char *name,
> +				  u16 msix_vec)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	struct virtio_pci_vq_info *info;
> +	struct virtqueue *vq;
> +	u16 num;
> +	int err;
> +
> +	/* Select the queue we're interested in */
> +	iowrite16(index, &vp_dev->common->queue_select);
> +
> +	switch (ioread64(&vp_dev->common->queue_address)) {
> +	case 0xFFFFFFFFFFFFFFFFULL:
> +		return ERR_PTR(-ENOENT);
> +	case 0:
> +		/* Uninitialized.  Excellent. */
> +		break;
> +	default:
> +		/* We've already set this up? */
> +		return ERR_PTR(-EBUSY);
> +	}
> +
> +	/* Maximum size must be a power of 2. */
> +	num = ioread16(&vp_dev->common->queue_size);
> +	if (num & (num - 1)) {
> +		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	/* allocate and fill out our structure the represents an active
> +	 * queue */
> +	info = kmalloc(sizeof(struct virtio_pci_vq_info), GFP_KERNEL);
> +	if (!info)
> +		return ERR_PTR(-ENOMEM);
> +
> +	info->msix_vector = msix_vec;
> +
> +	info->queue = alloc_virtqueue_pages(&num);
> +	if (info->queue == NULL) {
> +		err = -ENOMEM;
> +		goto out_info;
> +	}
> +
> +	/* create the vring */
> +	vq = vring_new_virtqueue(index, num, SMP_CACHE_BYTES, vdev,
> +				 true, info->queue, vp_notify, callback, name);
> +	if (!vq) {
> +		err = -ENOMEM;
> +		goto out_alloc_pages;
> +	}
> +
> +	vq->priv = info;
> +	info->vq = vq;
> +
> +	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
> +		iowrite16(msix_vec, &vp_dev->common->queue_msix_vector);
> +		msix_vec = ioread16(&vp_dev->common->queue_msix_vector);
> +		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
> +			err = -EBUSY;
> +			goto out_new_virtqueue;
> +		}
> +	}
> +
> +	if (callback) {
> +		unsigned long flags;
> +		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);
> +	}
> +
> +	/* Activate the queue. */
> +	iowrite64(virt_to_phys(info->queue), &vp_dev->common->queue_address);
> +	iowrite16(SMP_CACHE_BYTES, &vp_dev->common->queue_align);
> +	iowrite16(num, &vp_dev->common->queue_size);
> +
> +	return vq;
> +
> +out_new_virtqueue:
> +	vring_del_virtqueue(vq);
> +out_alloc_pages:
> +	free_pages_exact(info->queue, vring_pci_size(num));
> +out_info:
> +	kfree(info);
> +	return ERR_PTR(err);
> +}
> +
> +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 = vq->priv;
> +	unsigned long flags, size = vring_pci_size(vq->vring.num);
> +
> +	spin_lock_irqsave(&vp_dev->lock, flags);
> +	list_del(&info->node);
> +	spin_unlock_irqrestore(&vp_dev->lock, flags);
> +
> +	/* Select and deactivate the queue */
> +	iowrite16(vq->index, &vp_dev->common->queue_select);
> +
> +	if (vp_dev->msix_enabled) {
> +		iowrite16(VIRTIO_MSI_NO_VECTOR,
> +			  &vp_dev->common->queue_msix_vector);
> +		/* Flush the write out to device */
> +		ioread16(&vp_dev->common->queue_msix_vector);
> +	}
> +
> +	vring_del_virtqueue(vq);
> +
> +	/* This is for our own benefit, not the device's! */
> +	iowrite64(0, &vp_dev->common->queue_address);
> +	iowrite16(0, &vp_dev->common->queue_size);
> +	iowrite16(0, &vp_dev->common->queue_align);
> +
> +	free_pages_exact(info->queue, size);
> +	kfree(info);
> +}
> +
> +/* the config->del_vqs() implementation */
> +static void vp_del_vqs(struct virtio_device *vdev)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	struct virtqueue *vq, *n;
> +	struct virtio_pci_vq_info *info;
> +
> +	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
> +		info = vq->priv;
> +		if (vp_dev->per_vq_vectors &&
> +			info->msix_vector != VIRTIO_MSI_NO_VECTOR)
> +			free_irq(vp_dev->msix_entries[info->msix_vector].vector,
> +				 vq);
> +		vp_del_vq(vq);
> +	}
> +	vp_dev->per_vq_vectors = false;
> +
> +	vp_free_vectors(vdev);
> +}
> +
> +static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs,
> +			      struct virtqueue *vqs[],
> +			      vq_callback_t *callbacks[],
> +			      const char *names[],
> +			      bool use_msix,
> +			      bool per_vq_vectors)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	u16 msix_vec;
> +	int i, err, nvectors, allocated_vectors;
> +
> +	if (!use_msix) {
> +		/* Old style: one normal interrupt for change and all vqs. */
> +		err = vp_request_intx(vdev);
> +		if (err)
> +			goto error_request;
> +	} else {
> +		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);
> +		if (err)
> +			goto error_request;
> +	}
> +
> +	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;
> +		} else if (!callbacks[i] || !vp_dev->msix_enabled)
> +			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] = setup_vq(vdev, i, callbacks[i], names[i], 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(vp_dev->msix_entries[msix_vec].vector,
> +				  vring_interrupt, 0,
> +				  vp_dev->msix_names[msix_vec],
> +				  vqs[i]);
> +		if (err) {
> +			vp_del_vq(vqs[i]);
> +			goto error_find;
> +		}
> +	}
> +	return 0;
> +
> +error_find:
> +	vp_del_vqs(vdev);
> +
> +error_request:
> +	return err;
> +}
> +
> +/* the config->find_vqs() implementation */
> +static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
> +		       struct virtqueue *vqs[],
> +		       vq_callback_t *callbacks[],
> +		       const char *names[])
> +{
> +	int err;
> +
> +	/* Try MSI-X with one vector per queue. */
> +	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, true, true);
> +	if (!err)
> +		return 0;
> +	/* Fallback: MSI-X with one vector for config, one shared for queues. */
> +	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
> +				 true, false);
> +	if (!err)
> +		return 0;
> +	/* Finally fall back to regular interrupts. */
> +	return vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
> +				  false, false);
> +}
> +
> +static 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
> + */
> +static int vp_set_vq_affinity(struct virtqueue *vq, int cpu)
> +{
> +	struct virtio_device *vdev = vq->vdev;
> +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> +	struct virtio_pci_vq_info *info = vq->priv;
> +	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 = vp_dev->msix_entries[info->msix_vector].vector;
> +		if (cpu == -1)
> +			irq_set_affinity_hint(irq, NULL);
> +		else {
> +			cpumask_set_cpu(cpu, mask);
> +			irq_set_affinity_hint(irq, mask);
> +		}
> +	}
> +	return 0;
> +}
> +
> +static const struct virtio_config_ops virtio_pci_config_ops = {
> +	.get8		= vp_get8,
> +	.set8		= vp_set8,
> +	.get16		= vp_get16,
> +	.set16		= vp_set16,
> +	.get32		= vp_get32,
> +	.set32		= vp_set32,
> +	.get64		= vp_get64,
> +	.set64		= vp_set64,
> +	.get_status	= vp_get_status,
> +	.set_status	= vp_set_status,
> +	.reset		= vp_reset,
> +	.find_vqs	= vp_find_vqs,
> +	.del_vqs	= vp_del_vqs,
> +	.get_features	= vp_get_features,
> +	.finalize_features = vp_finalize_features,
> +	.bus_name	= vp_bus_name,
> +	.set_vq_affinity = vp_set_vq_affinity,
> +};
> +
> +static void virtio_pci_release_dev(struct device *_d)
> +{
> +	/*
> +	 * No need for a release method as we allocate/free
> +	 * all devices together with the pci devices.
> +	 * Provide an empty one to avoid getting a warning from core.
> +	 */
> +}
> +
> +static void __iomem *map_capability(struct pci_dev *dev, int off, size_t expect)
> +{
> +	u8 bar;
> +	u32 offset, length;
> +	void __iomem *p;
> +
> +	pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap, bar),
> +			     &bar);
> +	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
> +			     &offset);
> +	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> +			     &length);
> +
> +	if (length < expect) {
> +		dev_err(&dev->dev,
> +			"virtio_pci: small capability len %u (%u expected)\n",
> +			length, expect);
> +		return NULL;
> +	}
> +
> +	/* We want uncachable mapping, even if bar is cachable. */
> +	p = pci_iomap_range(dev, bar, offset, length, PAGE_SIZE, true);
> +	if (!p)
> +		dev_err(&dev->dev,
> +			"virtio_pci: unable to map virtio %u@%u on bar %i\n",
> +			length, offset, bar);
> +	return p;
> +}
> +
> +
> +/* the PCI probing function */
> +static int virtio_pci_probe(struct pci_dev *pci_dev,
> +			    const struct pci_device_id *id)
> +{
> +	struct virtio_pci_device *vp_dev;
> +	int err, common, isr, notify, device;
> +
> +	/* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
> +	if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
> +		return -ENODEV;
> +
> +	if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION) {
> +		printk(KERN_ERR "virtio_pci: expected ABI version %d, got %d\n",
> +		       VIRTIO_PCI_ABI_VERSION, pci_dev->revision);
> +		return -ENODEV;
> +	}
> +
> +	/* check for a common config: if not, use legacy mode (bar 0). */
> +	common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
> +					    IORESOURCE_IO|IORESOURCE_MEM);
> +	if (!common) {
> +		dev_info(&pci_dev->dev,
> +			 "virtio_pci: leaving for legacy driver\n");
> +		return -ENODEV;
> +	}
> +
> +	/* If common is there, these should be too... */
> +	isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
> +					 IORESOURCE_IO|IORESOURCE_MEM);
> +	notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
> +					    IORESOURCE_IO|IORESOURCE_MEM);
> +	device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
> +					    IORESOURCE_IO|IORESOURCE_MEM);
> +	if (!isr || !notify || !device) {
> +		dev_err(&pci_dev->dev,
> +			"virtio_pci: missing capabilities %i/%i/%i/%i\n",
> +			common, isr, notify, device);
> +		return -EINVAL;
> +	}
> +
> +	/* allocate our structure and fill it out */
> +	vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
> +	if (vp_dev == NULL)
> +		return -ENOMEM;
> +
> +	vp_dev->vdev.dev.parent = &pci_dev->dev;
> +	vp_dev->vdev.dev.release = virtio_pci_release_dev;
> +	vp_dev->vdev.config = &virtio_pci_config_ops;
> +	vp_dev->pci_dev = pci_dev;
> +	INIT_LIST_HEAD(&vp_dev->virtqueues);
> +	spin_lock_init(&vp_dev->lock);
> +
> +	/* Disable MSI/MSIX to bring device to a known good state. */
> +	pci_msi_off(pci_dev);
> +
> +	/* enable the device */
> +	err = pci_enable_device(pci_dev);
> +	if (err)
> +		goto out;
> +
> +	err = pci_request_regions(pci_dev, "virtio-pci");
> +	if (err)
> +		goto out_enable_device;
> +
> +	err = -EINVAL;
> +	vp_dev->common = map_capability(pci_dev, common,
> +					sizeof(struct virtio_pci_common_cfg));
> +	if (!vp_dev->common)
> +		goto out_req_regions;
> +	vp_dev->isr = map_capability(pci_dev, isr, sizeof(u8));
> +	if (!vp_dev->isr)
> +		goto out_map_common;
> +	vp_dev->notify = map_capability(pci_dev, notify, sizeof(u16));
> +	if (!vp_dev->notify)
> +		goto out_map_isr;
> +	vp_dev->device = map_capability(pci_dev, device, 0);
> +	if (!vp_dev->device)
> +		goto out_map_notify;
> +
> +	pci_set_drvdata(pci_dev, vp_dev);
> +	pci_set_master(pci_dev);
> +
> +	/* we use the subsystem vendor/device id as the virtio vendor/device
> +	 * id.  this allows us to use the same PCI vendor/device id for all
> +	 * virtio devices and to identify the particular virtio driver by
> +	 * the subsystem ids */
> +	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
> +	vp_dev->vdev.id.device = pci_dev->subsystem_device;
> +
> +	/* finally register the virtio device */
> +	err = register_virtio_device(&vp_dev->vdev);
> +	if (err)
> +		goto out_set_drvdata;
> +
> +	return 0;
> +
> +out_set_drvdata:
> +	pci_set_drvdata(pci_dev, NULL);
> +	pci_iounmap(pci_dev, vp_dev->device);
> +out_map_notify:
> +	pci_iounmap(pci_dev, vp_dev->notify);
> +out_map_isr:
> +	pci_iounmap(pci_dev, vp_dev->isr);
> +out_map_common:
> +	pci_iounmap(pci_dev, vp_dev->common);
> +out_req_regions:
> +	pci_release_regions(pci_dev);
> +out_enable_device:
> +	pci_disable_device(pci_dev);
> +out:
> +	kfree(vp_dev);
> +	return err;
> +}
> +
> +static void virtio_pci_remove(struct pci_dev *pci_dev)
> +{
> +	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> +
> +	unregister_virtio_device(&vp_dev->vdev);
> +
> +	vp_del_vqs(&vp_dev->vdev);
> +	pci_set_drvdata(pci_dev, NULL);
> +	pci_iounmap(pci_dev, vp_dev->device);
> +	pci_iounmap(pci_dev, vp_dev->notify);
> +	pci_iounmap(pci_dev, vp_dev->isr);
> +	pci_iounmap(pci_dev, vp_dev->common);
> +	pci_release_regions(pci_dev);
> +	pci_disable_device(pci_dev);
> +	kfree(vp_dev);
> +}
> +
> +#ifdef CONFIG_PM
> +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);
> +	struct virtio_driver *drv;
> +	int ret;
> +
> +	drv = container_of(vp_dev->vdev.dev.driver,
> +			   struct virtio_driver, driver);
> +
> +	ret = 0;
> +	vp_dev->saved_status = vp_get_status(&vp_dev->vdev);
> +	if (drv && drv->freeze)
> +		ret = drv->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);
> +	struct virtio_driver *drv;
> +	int ret;
> +
> +	drv = container_of(vp_dev->vdev.dev.driver,
> +			   struct virtio_driver, driver);
> +
> +	ret = pci_enable_device(pci_dev);
> +	if (ret)
> +		return ret;
> +
> +	pci_set_master(pci_dev);
> +	vp_finalize_features(&vp_dev->vdev);
> +
> +	if (drv && drv->restore)
> +		ret = drv->restore(&vp_dev->vdev);
> +
> +	/* Finally, tell the device we're all set */
> +	if (!ret)
> +		vp_set_status(&vp_dev->vdev, vp_dev->saved_status);
> +
> +	return ret;
> +}
> +
> +static const struct dev_pm_ops virtio_pci_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)
> +};
> +#endif
> +
> +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
> + 	.driver.pm	= &virtio_pci_pm_ops,
> +#endif
> +};
> +
> +module_pci_driver(virtio_pci_driver);
> -- 
> 1.7.10.4
> 
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