[PATCH V9 5/6] virtio: introduce a mdev based transport

Jason Wang
2019-11-06T07:14:25Z

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

A new virtio-mdev driver will be registered to the mdev bus, when a
new virtio-mdev device is probed, it will register the device with
mdev based config ops. This means it is a software transport between
mdev driver and mdev device. The transport was implemented through
device specific ops which is a part of mdev_parent_ops now.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/virtio/Kconfig | 13 ++
drivers/virtio/Makefile | 1 +
drivers/virtio/virtio_mdev.c | 406 +++++++++++++++++++++++++++++++++++
3 files changed, 420 insertions(+)
create mode 100644 drivers/virtio/virtio_mdev.c

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 078615cf2afc..558ac607d107 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -43,6 +43,19 @@ config VIRTIO_PCI_LEGACY

If unsure, say Y.

+config VIRTIO_MDEV
+ tristate "MDEV driver for virtio devices"
+ depends on VFIO_MDEV && VIRTIO
+ default n
+ help
+ This driver provides support for virtio based paravirtual
+ device driver over MDEV bus. This requires your environemnt
+ has appropriate virtio mdev device implementation which may
+ operate on the physical device that the datapath of virtio
+ could 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 3a2b5c5dcf46..f2997b6c812f 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -6,3 +6,4 @@ 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_MDEV) += virtio_mdev.o
diff --git a/drivers/virtio/virtio_mdev.c b/drivers/virtio/virtio_mdev.c
new file mode 100644
index 000000000000..9e12ef240493
--- /dev/null
+++ b/drivers/virtio/virtio_mdev.c
@@ -0,0 +1,406 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VIRTIO based driver for Mediated device
+ *
+ * Copyright (c) 2019, 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/mdev.h>
+#include <linux/mdev_virtio_ops.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+
+#define DRIVER_VERSION "0.1"
+#define DRIVER_AUTHOR "Red Hat Corporation"
+#define DRIVER_DESC "VIRTIO based driver for Mediated device"
+
+#define to_virtio_mdev_device(dev) \
+ container_of(dev, struct virtio_mdev_device, vdev)
+
+struct virtio_mdev_device {
+ struct virtio_device vdev;
+ struct mdev_device *mdev;
+ u64 features;
+
+ /* The lock to protect virtqueue list */
+ spinlock_t lock;
+ /* List of virtio_mdev_vq_info */
+ struct list_head virtqueues;
+};
+
+struct virtio_mdev_vq_info {
+ /* the actual virtqueue */
+ struct virtqueue *vq;
+
+ /* the list node for the virtqueues list */
+ struct list_head node;
+};
+
+static struct mdev_device *vm_get_mdev(struct virtio_device *vdev)
+{
+ struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+ struct mdev_device *mdev = vm_dev->mdev;
+
+ return mdev;
+}
+
+static void virtio_mdev_get(struct virtio_device *vdev, unsigned offset,
+ void *buf, unsigned len)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ ops->get_config(mdev, offset, buf, len);
+}
+
+static void virtio_mdev_set(struct virtio_device *vdev, unsigned offset,
+ const void *buf, unsigned len)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ ops->set_config(mdev, offset, buf, len);
+}
+
+static u32 virtio_mdev_generation(struct virtio_device *vdev)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ if (ops->get_generation)
+ return ops->get_generation(mdev);
+
+ return 0;
+}
+
+static u8 virtio_mdev_get_status(struct virtio_device *vdev)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ return ops->get_status(mdev);
+}
+
+static void virtio_mdev_set_status(struct virtio_device *vdev, u8 status)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ return ops->set_status(mdev, status);
+}
+
+static void virtio_mdev_reset(struct virtio_device *vdev)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ return ops->set_status(mdev, 0);
+}
+
+static bool virtio_mdev_notify(struct virtqueue *vq)
+{
+ struct mdev_device *mdev = vm_get_mdev(vq->vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ ops->kick_vq(mdev, vq->index);
+
+ return true;
+}
+
+static irqreturn_t virtio_mdev_config_cb(void *private)
+{
+ struct virtio_mdev_device *vm_dev = private;
+
+ virtio_config_changed(&vm_dev->vdev);
+
+ return IRQ_HANDLED;
+}
+
+static irqreturn_t virtio_mdev_virtqueue_cb(void *private)
+{
+ struct virtio_mdev_vq_info *info = private;
+
+ return vring_interrupt(0, info->vq);
+}
+
+static struct virtqueue *
+virtio_mdev_setup_vq(struct virtio_device *vdev, unsigned int index,
+ void (*callback)(struct virtqueue *vq),
+ const char *name, bool ctx)
+{
+ struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+ struct virtio_mdev_vq_info *info;
+ struct virtio_mdev_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(mdev, 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(mdev);
+ if (num == 0) {
+ err = -ENOENT;
+ goto error_new_virtqueue;
+ }
+
+ /* Create the vring */
+ align = ops->get_vq_align(mdev);
+ vq = vring_create_virtqueue(index, num, align, vdev,
+ true, true, ctx,
+ virtio_mdev_notify, callback, name);
+ if (!vq) {
+ err = -ENOMEM;
+ goto error_new_virtqueue;
+ }
+
+ /* Setup virtqueue callback */
+ cb.callback = virtio_mdev_virtqueue_cb;
+ cb.private = info;
+ ops->set_vq_cb(mdev, index, &cb);
+ ops->set_vq_num(mdev, 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(mdev, index,
+ desc_addr, driver_addr,
+ device_addr)) {
+ err = -EINVAL;
+ goto err_vq;
+ }
+
+ ops->set_vq_ready(mdev, index, 1);
+
+ vq->priv = info;
+ info->vq = vq;
+
+ spin_lock_irqsave(&vm_dev->lock, flags);
+ list_add(&info->node, &vm_dev->virtqueues);
+ spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+ return vq;
+
+err_vq:
+ vring_del_virtqueue(vq);
+error_new_virtqueue:
+ ops->set_vq_ready(mdev, index, 0);
+ WARN_ON(ops->get_vq_ready(mdev, index));
+ kfree(info);
+ return ERR_PTR(err);
+}
+
+static void virtio_mdev_del_vq(struct virtqueue *vq)
+{
+ struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vq->vdev);
+ struct mdev_device *mdev = vm_dev->mdev;
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+ struct virtio_mdev_vq_info *info = vq->priv;
+ unsigned int index = vq->index;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vm_dev->lock, flags);
+ list_del(&info->node);
+ spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+ /* Select and deactivate the queue */
+ ops->set_vq_ready(mdev, index, 0);
+ WARN_ON(ops->get_vq_ready(mdev, index));
+
+ vring_del_virtqueue(vq);
+
+ kfree(info);
+}
+
+static void virtio_mdev_del_vqs(struct virtio_device *vdev)
+{
+ struct virtqueue *vq, *n;
+
+ list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+ virtio_mdev_del_vq(vq);
+}
+
+static int virtio_mdev_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_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+ struct virtio_mdev_callback cb;
+ int i, err, queue_idx = 0;
+
+ for (i = 0; i < nvqs; ++i) {
+ if (!names[i]) {
+ vqs[i] = NULL;
+ continue;
+ }
+
+ vqs[i] = virtio_mdev_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_mdev_config_cb;
+ cb.private = vm_dev;
+ ops->set_config_cb(mdev, &cb);
+
+ return 0;
+
+err_setup_vq:
+ virtio_mdev_del_vqs(vdev);
+ return err;
+}
+
+static u64 virtio_mdev_get_features(struct virtio_device *vdev)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ return ops->get_features(mdev);
+}
+
+static int virtio_mdev_finalize_features(struct virtio_device *vdev)
+{
+ struct mdev_device *mdev = vm_get_mdev(vdev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+ /* Give virtio_ring a chance to accept features. */
+ vring_transport_features(vdev);
+
+ return ops->set_features(mdev, vdev->features);
+}
+
+static const char *virtio_mdev_bus_name(struct virtio_device *vdev)
+{
+ struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+ struct mdev_device *mdev = vm_dev->mdev;
+
+ return dev_name(mdev_dev(mdev));
+}
+
+static const struct virtio_config_ops virtio_mdev_config_ops = {
+ .get = virtio_mdev_get,
+ .set = virtio_mdev_set,
+ .generation = virtio_mdev_generation,
+ .get_status = virtio_mdev_get_status,
+ .set_status = virtio_mdev_set_status,
+ .reset = virtio_mdev_reset,
+ .find_vqs = virtio_mdev_find_vqs,
+ .del_vqs = virtio_mdev_del_vqs,
+ .get_features = virtio_mdev_get_features,
+ .finalize_features = virtio_mdev_finalize_features,
+ .bus_name = virtio_mdev_bus_name,
+};
+
+static void virtio_mdev_release_dev(struct device *_d)
+{
+ struct virtio_device *vdev =
+ container_of(_d, struct virtio_device, dev);
+ struct virtio_mdev_device *vm_dev =
+ container_of(vdev, struct virtio_mdev_device, vdev);
+ struct mdev_device *mdev = vm_dev->mdev;
+
+ devm_kfree(mdev_dev(mdev), vm_dev);
+}
+
+static int virtio_mdev_probe(struct device *dev)
+{
+ struct mdev_device *mdev = mdev_from_dev(dev);
+ const struct mdev_virtio_device_ops *ops = mdev_get_virtio_ops(mdev);
+ struct virtio_mdev_device *vm_dev;
+ int rc;
+
+ vm_dev = devm_kzalloc(dev, sizeof(*vm_dev), GFP_KERNEL);
+ if (!vm_dev)
+ return -ENOMEM;
+
+ vm_dev->vdev.dev.parent = dev;
+ vm_dev->vdev.dev.release = virtio_mdev_release_dev;
+ vm_dev->vdev.config = &virtio_mdev_config_ops;
+ vm_dev->mdev = mdev;
+ INIT_LIST_HEAD(&vm_dev->virtqueues);
+ spin_lock_init(&vm_dev->lock);
+
+ vm_dev->vdev.id.device = ops->get_device_id(mdev);
+ if (vm_dev->vdev.id.device == 0)
+ return -ENODEV;
+
+ vm_dev->vdev.id.vendor = ops->get_vendor_id(mdev);
+ rc = register_virtio_device(&vm_dev->vdev);
+ if (rc)
+ put_device(dev);
+ else
+ dev_set_drvdata(dev, vm_dev);
+
+ return rc;
+}
+
+static void virtio_mdev_remove(struct device *dev)
+{
+ struct virtio_mdev_device *vm_dev = dev_get_drvdata(dev);
+
+ unregister_virtio_device(&vm_dev->vdev);
+}
+
+static const struct mdev_class_id virtio_id_table[] = {
+ { MDEV_CLASS_ID_VIRTIO },
+ { 0 },
+};
+
+MODULE_DEVICE_TABLE(mdev, virtio_id_table);
+
+static struct mdev_driver virtio_mdev_driver = {
+ .name = "virtio_mdev",
+ .probe = virtio_mdev_probe,
+ .remove = virtio_mdev_remove,
+ .id_table = virtio_id_table,
+};
+
+static int __init virtio_mdev_init(void)
+{
+ return mdev_register_driver(&virtio_mdev_driver, THIS_MODULE);
+}
+
+static void __exit virtio_mdev_exit(void)
+{
+ mdev_unregister_driver(&virtio_mdev_driver);
+}
+
+module_init(virtio_mdev_init)
+module_exit(virtio_mdev_exit)
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
--
2.19.1