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hw/virtio: add config support to vhost-user-device

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To use the generic device the user will need to provide the config
region size via the command line. We also add a notifier so the guest
can be pinged if the remote daemon updates the config.

With these changes:

  -device vhost-user-device-pci,virtio-id=41,num_vqs=2,config_size=8

is equivalent to:

  -device vhost-user-gpio-pci

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230710153522.3469097-11-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Bennée 2023-07-10 16:35:12 +01:00 committed by Michael S. Tsirkin
parent eee7780973
commit f92a2d61cd
2 changed files with 58 additions and 1 deletions
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58
hw/virtio/vhost-user-device.c
View File

@ -117,6 +117,42 @@ static uint64_t vub_get_features(VirtIODevice *vdev,
return vub->vhost_dev.features & ~(1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
}
/*
* To handle VirtIO config we need to know the size of the config
* space. We don't cache the config but re-fetch it from the guest
* every time in case something has changed.
*/
static void vub_get_config(VirtIODevice *vdev, uint8_t *config)
{
VHostUserBase *vub = VHOST_USER_BASE(vdev);
Error *local_err = NULL;
/*
* There will have been a warning during vhost_dev_init, but lets
* assert here as nothing will go right now.
*/
g_assert(vub->config_size && vub->vhost_user.supports_config == true);
if (vhost_dev_get_config(&vub->vhost_dev, config,
vub->config_size, &local_err)) {
error_report_err(local_err);
}
}
/*
* When the daemon signals an update to the config we just need to
* signal the guest as we re-read the config on demand above.
*/
static int vub_config_notifier(struct vhost_dev *dev)
{
virtio_notify_config(dev->vdev);
return 0;
}
const VhostDevConfigOps vub_config_ops = {
.vhost_dev_config_notifier = vub_config_notifier,
};
static void vub_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
/*
@ -141,12 +177,21 @@ static int vub_connect(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserBase *vub = VHOST_USER_BASE(vdev);
struct vhost_dev *vhost_dev = &vub->vhost_dev;
if (vub->connected) {
return 0;
}
vub->connected = true;
/*
* If we support VHOST_USER_GET_CONFIG we must enable the notifier
* so we can ping the guest when it updates.
*/
if (vub->vhost_user.supports_config) {
vhost_dev_set_config_notifier(vhost_dev, &vub_config_ops);
}
/* restore vhost state */
if (virtio_device_started(vdev, vdev->status)) {
vub_start(vdev);
@ -214,11 +259,20 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
vub->num_vqs = 1; /* reasonable default? */
}
/*
* We can't handle config requests unless we know the size of the
* config region, specialisations of the vhost-user-device will be
* able to set this.
*/
if (vub->config_size) {
vub->vhost_user.supports_config = true;
}
if (!vhost_user_init(&vub->vhost_user, &vub->chardev, errp)) {
return;
}
virtio_init(vdev, vub->virtio_id, 0);
virtio_init(vdev, vub->virtio_id, vub->config_size);
/*
* Disable guest notifiers, by default all notifications will be via the
@ -268,6 +322,7 @@ static void vub_class_init(ObjectClass *klass, void *data)
vdc->realize = vub_device_realize;
vdc->unrealize = vub_device_unrealize;
vdc->get_features = vub_get_features;
vdc->get_config = vub_get_config;
vdc->set_status = vub_set_status;
}
@ -295,6 +350,7 @@ static Property vud_properties[] = {
DEFINE_PROP_CHR("chardev", VHostUserBase, chardev),
DEFINE_PROP_UINT16("virtio-id", VHostUserBase, virtio_id, 0),
DEFINE_PROP_UINT32("num_vqs", VHostUserBase, num_vqs, 1),
DEFINE_PROP_UINT32("config_size", VHostUserBase, config_size, 0),
DEFINE_PROP_END_OF_LIST(),
};

1
include/hw/virtio/vhost-user-device.h
View File

@ -22,6 +22,7 @@ struct VHostUserBase {
CharBackend chardev;
uint16_t virtio_id;
uint32_t num_vqs;
uint32_t config_size;
/* State tracking */
VhostUserState vhost_user;
struct vhost_virtqueue *vhost_vq;