On Mon, Nov 17, 2014 at 05:17:17PM +0800, Jason Wang wrote:
> Buggy host may advertised buggy host features (a usual case is that host
> advertise a feature whose dependencies were missed). In this case, driver
> should detect and disable the buggy features by itself.
>
> This patch introduces driver specific sanitize_features() method which is
> called just before features finalizing to detect and disable buggy features
> advertised by host.
>
> Virtio-net will be the first user.
>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
> Cc: Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Hmm this conflicts with virtio 1.0 work: we drop
features as bitmap there.
> ---
> Changes from V2:
> - fix typo
> - rename fix_features to sanitize_features
> ---
> drivers/virtio/virtio.c | 4 ++++
> include/linux/virtio.h | 1 +
> include/linux/virtio_config.h | 12 ++++++++++++
> 3 files changed, 17 insertions(+)
>
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index df598dd..6a86b4f 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -181,6 +181,10 @@ static int virtio_dev_probe(struct device *_d)
> if (device_features & (1 << i))
> set_bit(i, dev->features);
>
> + /* Sanitize buggy features advertised by host */
> + if (drv->sanitize_features)
> + drv->sanitize_features(dev);
> +
> dev->config->finalize_features(dev);
>
> err = drv->probe(dev);
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 65261a7..5aed283 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -142,6 +142,7 @@ struct virtio_driver {
> void (*scan)(struct virtio_device *dev);
> void (*remove)(struct virtio_device *dev);
> void (*config_changed)(struct virtio_device *dev);
> + void (*sanitize_features)(struct virtio_device *dev);
> #ifdef CONFIG_PM
> int (*freeze)(struct virtio_device *dev);
> int (*restore)(struct virtio_device *dev);
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 7f4ef66..7bd89ea 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -96,6 +96,18 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev,
> return test_bit(fbit, vdev->features);
> }
>
> +static inline void virtio_disable_feature(struct virtio_device *vdev,
> + unsigned int fbit)
> +{
> + BUG_ON(fbit >= VIRTIO_TRANSPORT_F_START);
> + BUG_ON(vdev->config->get_status(vdev) &
> + ~(VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER));
> +
> + virtio_check_driver_offered_feature(vdev, fbit);
> +
> + clear_bit(fbit, vdev->features);
> +}
> +
> static inline
> struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
> vq_callback_t *c, const char *n)
> --
> 1.9.1
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