Commit c043b4a8 authored by Jason Wang's avatar Jason Wang Committed by Michael S. Tsirkin
Browse files

virtio: introduce a vDPA based transport 



This patch introduces a vDPA transport for virtio. This is used to
use kernel virtio driver to drive the vDPA device that is capable
of populating virtqueue directly.

A new virtio-vdpa driver will be registered to the vDPA bus, when a
new virtio-vdpa device is probed, it will register the device with
vdpa based config ops. This means it is a software transport between
vDPA driver and vDPA device. The transport was implemented through
bus_ops of vDPA parent.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200326140125.19794-7-jasowang@redhat.com


Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 961e9c84

drivers/virtio/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -43,6 +43,19 @@ config VIRTIO_PCI_LEGACY 


	  If unsure, say Y.



config VIRTIO_VDPA

	tristate "vDPA driver for virtio devices"

	select VDPA

	select VIRTIO

	help

	  This driver provides support for virtio based paravirtual

	  device driver over vDPA bus. For this to be useful, you need

	  an appropriate vDPA device implementation that operates on a

	  physical device to allow the datapath of virtio to be

	  offloaded to hardware.



	  If unsure, say M.



config VIRTIO_PMEM

	tristate "Support for virtio pmem driver"

	depends on VIRTIO

drivers/virtio/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -6,4 +6,5 @@ virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o 
virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o

obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o

obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o

obj-$(CONFIG_VIRTIO_VDPA) += virtio_vdpa.o

obj-$(CONFIG_VDPA) += vdpa/

drivers/virtio/virtio_vdpa.c

0 → 100644
+396 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * VIRTIO based driver for vDPA device

 *

 * Copyright (c) 2020, Red Hat. All rights reserved.

 *     Author: Jason Wang <jasowang@redhat.com>

 *

 */



#include <linux/init.h>

#include <linux/module.h>

#include <linux/device.h>

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/uuid.h>

#include <linux/virtio.h>

#include <linux/vdpa.h>

#include <linux/virtio_config.h>

#include <linux/virtio_ring.h>



#define MOD_VERSION  "0.1"

#define MOD_AUTHOR   "Jason Wang <jasowang@redhat.com>"

#define MOD_DESC     "vDPA bus driver for virtio devices"

#define MOD_LICENSE  "GPL v2"



struct virtio_vdpa_device {

	struct virtio_device vdev;

	struct vdpa_device *vdpa;

	u64 features;



	/* The lock to protect virtqueue list */

	spinlock_t lock;

	/* List of virtio_vdpa_vq_info */

	struct list_head virtqueues;

};



struct virtio_vdpa_vq_info {

	/* the actual virtqueue */

	struct virtqueue *vq;



	/* the list node for the virtqueues list */

	struct list_head node;

};



static inline struct virtio_vdpa_device *

to_virtio_vdpa_device(struct virtio_device *dev)

{

	return container_of(dev, struct virtio_vdpa_device, vdev);

}



static struct vdpa_device *vd_get_vdpa(struct virtio_device *vdev)

{

	return to_virtio_vdpa_device(vdev)->vdpa;

}



static void virtio_vdpa_get(struct virtio_device *vdev, unsigned offset,

			    void *buf, unsigned len)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	ops->get_config(vdpa, offset, buf, len);

}



static void virtio_vdpa_set(struct virtio_device *vdev, unsigned offset,

			    const void *buf, unsigned len)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	ops->set_config(vdpa, offset, buf, len);

}



static u32 virtio_vdpa_generation(struct virtio_device *vdev)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	if (ops->get_generation)

		return ops->get_generation(vdpa);



	return 0;

}



static u8 virtio_vdpa_get_status(struct virtio_device *vdev)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	return ops->get_status(vdpa);

}



static void virtio_vdpa_set_status(struct virtio_device *vdev, u8 status)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	return ops->set_status(vdpa, status);

}



static void virtio_vdpa_reset(struct virtio_device *vdev)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	return ops->set_status(vdpa, 0);

}



static bool virtio_vdpa_notify(struct virtqueue *vq)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	ops->kick_vq(vdpa, vq->index);



	return true;

}



static irqreturn_t virtio_vdpa_config_cb(void *private)

{

	struct virtio_vdpa_device *vd_dev = private;



	virtio_config_changed(&vd_dev->vdev);



	return IRQ_HANDLED;

}



static irqreturn_t virtio_vdpa_virtqueue_cb(void *private)

{

	struct virtio_vdpa_vq_info *info = private;



	return vring_interrupt(0, info->vq);

}



static struct virtqueue *

virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,

		     void (*callback)(struct virtqueue *vq),

		     const char *name, bool ctx)

{

	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;

	struct virtio_vdpa_vq_info *info;

	struct vdpa_callback cb;

	struct virtqueue *vq;

	u64 desc_addr, driver_addr, device_addr;

	unsigned long flags;

	u32 align, num;

	int err;



	if (!name)

		return NULL;



	/* Queue shouldn't already be set up. */

	if (ops->get_vq_ready(vdpa, index))

		return ERR_PTR(-ENOENT);



	/* Allocate and fill out our active queue description */

	info = kmalloc(sizeof(*info), GFP_KERNEL);

	if (!info)

		return ERR_PTR(-ENOMEM);



	num = ops->get_vq_num_max(vdpa);

	if (num == 0) {

		err = -ENOENT;

		goto error_new_virtqueue;

	}



	/* Create the vring */

	align = ops->get_vq_align(vdpa);

	vq = vring_create_virtqueue(index, num, align, vdev,

				    true, true, ctx,

				    virtio_vdpa_notify, callback, name);

	if (!vq) {

		err = -ENOMEM;

		goto error_new_virtqueue;

	}



	/* Setup virtqueue callback */

	cb.callback = virtio_vdpa_virtqueue_cb;

	cb.private = info;

	ops->set_vq_cb(vdpa, index, &cb);

	ops->set_vq_num(vdpa, index, virtqueue_get_vring_size(vq));



	desc_addr = virtqueue_get_desc_addr(vq);

	driver_addr = virtqueue_get_avail_addr(vq);

	device_addr = virtqueue_get_used_addr(vq);



	if (ops->set_vq_address(vdpa, index,

				desc_addr, driver_addr,

				device_addr)) {

		err = -EINVAL;

		goto err_vq;

	}



	ops->set_vq_ready(vdpa, index, 1);



	vq->priv = info;

	info->vq = vq;



	spin_lock_irqsave(&vd_dev->lock, flags);

	list_add(&info->node, &vd_dev->virtqueues);

	spin_unlock_irqrestore(&vd_dev->lock, flags);



	return vq;



err_vq:

	vring_del_virtqueue(vq);

error_new_virtqueue:

	ops->set_vq_ready(vdpa, index, 0);

	/* VDPA driver should make sure vq is stopeed here */

	WARN_ON(ops->get_vq_ready(vdpa, index));

	kfree(info);

	return ERR_PTR(err);

}



static void virtio_vdpa_del_vq(struct virtqueue *vq)

{

	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vq->vdev);

	struct vdpa_device *vdpa = vd_dev->vdpa;

	const struct vdpa_config_ops *ops = vdpa->config;

	struct virtio_vdpa_vq_info *info = vq->priv;

	unsigned int index = vq->index;

	unsigned long flags;



	spin_lock_irqsave(&vd_dev->lock, flags);

	list_del(&info->node);

	spin_unlock_irqrestore(&vd_dev->lock, flags);



	/* Select and deactivate the queue */

	ops->set_vq_ready(vdpa, index, 0);

	WARN_ON(ops->get_vq_ready(vdpa, index));



	vring_del_virtqueue(vq);



	kfree(info);

}



static void virtio_vdpa_del_vqs(struct virtio_device *vdev)

{

	struct virtqueue *vq, *n;



	list_for_each_entry_safe(vq, n, &vdev->vqs, list)

		virtio_vdpa_del_vq(vq);

}



static int virtio_vdpa_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)

{

	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;

	struct vdpa_callback cb;

	int i, err, queue_idx = 0;



	for (i = 0; i < nvqs; ++i) {

		if (!names[i]) {

			vqs[i] = NULL;

			continue;

		}



		vqs[i] = virtio_vdpa_setup_vq(vdev, queue_idx++,

					      callbacks[i], names[i], ctx ?

					      ctx[i] : false);

		if (IS_ERR(vqs[i])) {

			err = PTR_ERR(vqs[i]);

			goto err_setup_vq;

		}

	}



	cb.callback = virtio_vdpa_config_cb;

	cb.private = vd_dev;

	ops->set_config_cb(vdpa, &cb);



	return 0;



err_setup_vq:

	virtio_vdpa_del_vqs(vdev);

	return err;

}



static u64 virtio_vdpa_get_features(struct virtio_device *vdev)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	return ops->get_features(vdpa);

}



static int virtio_vdpa_finalize_features(struct virtio_device *vdev)

{

	struct vdpa_device *vdpa = vd_get_vdpa(vdev);

	const struct vdpa_config_ops *ops = vdpa->config;



	/* Give virtio_ring a chance to accept features. */

	vring_transport_features(vdev);



	return ops->set_features(vdpa, vdev->features);

}



static const char *virtio_vdpa_bus_name(struct virtio_device *vdev)

{

	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);

	struct vdpa_device *vdpa = vd_dev->vdpa;



	return dev_name(&vdpa->dev);

}



static const struct virtio_config_ops virtio_vdpa_config_ops = {

	.get		= virtio_vdpa_get,

	.set		= virtio_vdpa_set,

	.generation	= virtio_vdpa_generation,

	.get_status	= virtio_vdpa_get_status,

	.set_status	= virtio_vdpa_set_status,

	.reset		= virtio_vdpa_reset,

	.find_vqs	= virtio_vdpa_find_vqs,

	.del_vqs	= virtio_vdpa_del_vqs,

	.get_features	= virtio_vdpa_get_features,

	.finalize_features = virtio_vdpa_finalize_features,

	.bus_name	= virtio_vdpa_bus_name,

};



static void virtio_vdpa_release_dev(struct device *_d)

{

	struct virtio_device *vdev =

	       container_of(_d, struct virtio_device, dev);

	struct virtio_vdpa_device *vd_dev =

	       container_of(vdev, struct virtio_vdpa_device, vdev);



	kfree(vd_dev);

}



static int virtio_vdpa_probe(struct vdpa_device *vdpa)

{

	const struct vdpa_config_ops *ops = vdpa->config;

	struct virtio_vdpa_device *vd_dev, *reg_dev = NULL;

	int ret = -EINVAL;



	vd_dev = kzalloc(sizeof(*vd_dev), GFP_KERNEL);

	if (!vd_dev)

		return -ENOMEM;



	vd_dev->vdev.dev.parent = vdpa_get_dma_dev(vdpa);

	vd_dev->vdev.dev.release = virtio_vdpa_release_dev;

	vd_dev->vdev.config = &virtio_vdpa_config_ops;

	vd_dev->vdpa = vdpa;

	INIT_LIST_HEAD(&vd_dev->virtqueues);

	spin_lock_init(&vd_dev->lock);



	vd_dev->vdev.id.device = ops->get_device_id(vdpa);

	if (vd_dev->vdev.id.device == 0)

		goto err;



	vd_dev->vdev.id.vendor = ops->get_vendor_id(vdpa);

	ret = register_virtio_device(&vd_dev->vdev);

	reg_dev = vd_dev;

	if (ret)

		goto err;



	vdpa_set_drvdata(vdpa, vd_dev);



	return 0;



err:

	if (reg_dev)

		put_device(&vd_dev->vdev.dev);

	else

		kfree(vd_dev);

	return ret;

}



static void virtio_vdpa_remove(struct vdpa_device *vdpa)

{

	struct virtio_vdpa_device *vd_dev = vdpa_get_drvdata(vdpa);



	unregister_virtio_device(&vd_dev->vdev);

}



static struct vdpa_driver virtio_vdpa_driver = {

	.driver = {

		.name	= "virtio_vdpa",

	},

	.probe	= virtio_vdpa_probe,

	.remove = virtio_vdpa_remove,

};



module_vdpa_driver(virtio_vdpa_driver);



MODULE_VERSION(MOD_VERSION);

MODULE_LICENSE(MOD_LICENSE);

MODULE_AUTHOR(MOD_AUTHOR);

MODULE_DESCRIPTION(MOD_DESC);

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