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Subject[PATCH V7 5/8] virtio: introduce a vDPA based transport
Date
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: Jason Wang <jasowang@redhat.com>
---
drivers/virtio/Kconfig | 13 ++
drivers/virtio/Makefile | 1 +
drivers/virtio/virtio_vdpa.c | 396 +++++++++++++++++++++++++++++++++++
3 files changed, 410 insertions(+)
create mode 100644 drivers/virtio/virtio_vdpa.c

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 9c4fdb64d9ac..99e424570644 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -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
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index fdf5eacd0d0a..3407ac03fe60 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -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/
diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
new file mode 100644
index 000000000000..c30eb55030be
--- /dev/null
+++ b/drivers/virtio/virtio_vdpa.c
@@ -0,0 +1,396 @@
+// 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);
--
2.20.1
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