On Tue, 9 Jul 2024 16:02:13 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> Sometime, it would be useful to disable the configure change
> notification from the driver. So this patch allows this by introducing
> a variable config_change_driver_disabled and only allow the configure
> change notification callback to be triggered when it is allowed by
> both the virtio core and the driver. It is set to false by default to
> hold the current semantic so we don't need to change any drivers.
>
> The first user for this would be virtio-net.
>
> Cc: Venkat Venkatsubra <venkat.x.venkatsubra@xxxxxxxxxx>
> Cc: Gia-Khanh Nguyen <gia-khanh.nguyen@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/virtio/virtio.c | 39 ++++++++++++++++++++++++++++++++++++---
> include/linux/virtio.h | 7 +++++++
> 2 files changed, 43 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 73bab89b5326..23a96fbc2810 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -127,10 +127,12 @@ static void __virtio_config_changed(struct virtio_device *dev)
> {
> struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
>
> - if (!dev->config_core_enabled)
> + if (!dev->config_core_enabled || dev->config_driver_disabled)
> dev->config_change_pending = true;
> - else if (drv && drv->config_changed)
> + else if (drv && drv->config_changed) {
> drv->config_changed(dev);
> + dev->config_change_pending = false;
> + }
> }
>
> void virtio_config_changed(struct virtio_device *dev)
> @@ -143,6 +145,38 @@ void virtio_config_changed(struct virtio_device *dev)
> }
> EXPORT_SYMBOL_GPL(virtio_config_changed);
>
> +/**
> + * virtio_config_driver_disable - disable config change reporting by drivers
> + * @dev: the device to reset
> + *
> + * This is only allowed to be called by a driver and disalbing can't
> + * be nested.
> + */
> +void virtio_config_driver_disable(struct virtio_device *dev)
> +{
> + spin_lock_irq(&dev->config_lock);
> + dev->config_driver_disabled = true;
> + spin_unlock_irq(&dev->config_lock);
> +}
> +EXPORT_SYMBOL_GPL(virtio_config_driver_disable);
> +
> +/**
> + * virtio_config_driver_enable - enable config change reporting by drivers
> + * @dev: the device to reset
> + *
> + * This is only allowed to be called by a driver and enabling can't
> + * be nested.
> + */
> +void virtio_config_driver_enable(struct virtio_device *dev)
> +{
> + spin_lock_irq(&dev->config_lock);
> + dev->config_driver_disabled = false;
> + if (dev->config_change_pending)
> + __virtio_config_changed(dev);
> + spin_unlock_irq(&dev->config_lock);
> +}
> +EXPORT_SYMBOL_GPL(virtio_config_driver_enable);
> +
> static void virtio_config_core_disable(struct virtio_device *dev)
> {
> spin_lock_irq(&dev->config_lock);
> @@ -156,7 +190,6 @@ static void virtio_config_core_enable(struct virtio_device *dev)
> dev->config_core_enabled = true;
> if (dev->config_change_pending)
> __virtio_config_changed(dev);
> - dev->config_change_pending = false;
> spin_unlock_irq(&dev->config_lock);
> }
>
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index a6f6df72f01a..2be73de6f1f3 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -116,6 +116,8 @@ struct virtio_admin_cmd {
> * @index: unique position on the virtio bus
> * @failed: saved value for VIRTIO_CONFIG_S_FAILED bit (for restore)
> * @config_core_enabled: configuration change reporting enabled by core
> + * @config_driver_disabled: configuration change reporting disabled by
> + * a driver
> * @config_change_pending: configuration change reported while disabled
> * @config_lock: protects configuration change reporting
> * @vqs_list_lock: protects @vqs.
> @@ -133,6 +135,7 @@ struct virtio_device {
> int index;
> bool failed;
> bool config_core_enabled;
> + bool config_driver_disabled;
> bool config_change_pending;
> spinlock_t config_lock;
> spinlock_t vqs_list_lock;
> @@ -163,6 +166,10 @@ void __virtqueue_break(struct virtqueue *_vq);
> void __virtqueue_unbreak(struct virtqueue *_vq);
>
> void virtio_config_changed(struct virtio_device *dev);
> +
> +void virtio_config_driver_disable(struct virtio_device *dev);
> +void virtio_config_driver_enable(struct virtio_device *dev);
> +
> #ifdef CONFIG_PM_SLEEP
> int virtio_device_freeze(struct virtio_device *dev);
> int virtio_device_restore(struct virtio_device *dev);
> --
> 2.31.1
>
