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Re: [PATCH v3 10/20] hw/virtio: add config support to vhost-user-device
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH v3 10/20] hw/virtio: add config support to vhost-user-device |
Date: |
Mon, 10 Jul 2023 15:58:07 -0400 |
On Mon, Jul 10, 2023 at 04:35:12PM +0100, Alex Bennée wrote:
> 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>
This one I think it's best to defer until we get a better
handle on how we want the configuration to look.
> ---
> include/hw/virtio/vhost-user-device.h | 1 +
> hw/virtio/vhost-user-device.c | 58 ++++++++++++++++++++++++++-
> 2 files changed, 58 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/virtio/vhost-user-device.h
> b/include/hw/virtio/vhost-user-device.h
> index 9105011e25..3ddf88a146 100644
> --- a/include/hw/virtio/vhost-user-device.h
> +++ b/include/hw/virtio/vhost-user-device.h
> @@ -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;
> diff --git a/hw/virtio/vhost-user-device.c b/hw/virtio/vhost-user-device.c
> index b0239fa033..2b028cae08 100644
> --- a/hw/virtio/vhost-user-device.c
> +++ b/hw/virtio/vhost-user-device.c
> @@ -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(),
> };
>
> --
> 2.39.2
- [PATCH v3 07/20] virtio: add vhost-user-base and a generic vhost-user-device, (continued)
- [PATCH v3 07/20] virtio: add vhost-user-base and a generic vhost-user-device, Alex Bennée, 2023/07/10
- [PATCH v3 11/20] hw/virtio: derive vhost-user-gpio from vhost-user-device, Alex Bennée, 2023/07/10
- [PATCH v3 02/20] include/hw: document the device_class_set_parent_* fns, Alex Bennée, 2023/07/10
- [RFC PATCH v3 15/20] hw/virtio: move vhost_user_init earlier, Alex Bennée, 2023/07/10
- [RFC PATCH v3 19/20] hw/virtio: probe backend for specs if it supports it, Alex Bennée, 2023/07/10
- [PATCH v3 09/20] hw/virtio: derive vhost-user-rng from vhost-user-device, Alex Bennée, 2023/07/10
- [PATCH v3 06/20] include/hw/virtio: document some more usage of notifiers, Alex Bennée, 2023/07/10
- [PATCH v3 08/20] virtio: add PCI stub for vhost-user-device, Alex Bennée, 2023/07/10
- [PATCH v3 10/20] hw/virtio: add config support to vhost-user-device, Alex Bennée, 2023/07/10
- Re: [PATCH v3 10/20] hw/virtio: add config support to vhost-user-device,
Michael S. Tsirkin <=
- [RFC PATCH v3 18/20] hw/virtio: validate F_STANDALONE also supports other protocol features, Alex Bennée, 2023/07/10
- [RFC PATCH v3 17/20] hw/virtio: push down allocation responsibility for vhost_dev->vqs, Alex Bennée, 2023/07/10
- [RFC PATCH v3 14/20] docs/interop: define STANDALONE protocol feature for vhost-user, Alex Bennée, 2023/07/10
- [RFC PATCH v3 13/20] docs/system: add a basic enumeration of vhost-user devices, Alex Bennée, 2023/07/10
- [RFC PATCH v3 16/20] hw/virtio: move virtq initialisation into internal helper, Alex Bennée, 2023/07/10
- [RFC PATCH v3 20/20] hw/virtio: allow vhost-user-device to be driven by backend, Alex Bennée, 2023/07/10
- [PATCH v3 12/20] hw/virtio: derive vhost-user-i2c from vhost-user-base, Alex Bennée, 2023/07/10