Re: [PATCH 1/2] vhost-user: add VHOST_USER_RESET_DEVICE to reset devices

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 29, 2019 at 05:38:02PM -0400, Raphael Norwitz wrote:
> Add a VHOST_USER_RESET_DEVICE message which will reset the vhost user
> backend. Disabling all rings, and resetting all internal state, ready
> for the backend to be reinitialized.
> 
> A backend has to report it supports this features with the
> VHOST_USER_PROTOCOL_F_RESET_DEVICE protocol feature bit. If it does
> so, the new message is used instead of sending a RESET_OWNER which has
> had inconsistent implementations.
> 
> Signed-off-by: David Vrabel <david.vrabel@nutanix.com>
> Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>

Looks good to me, I'll queue it for merge after the release. If possible
please ping me after the release to help make sure it didn't get
dropped. Same for 2/2.


> ---
>  docs/interop/vhost-user.rst | 15 +++++++++++++++
>  hw/virtio/vhost-user.c      |  8 +++++++-
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> index 7827b71..d213d4a 100644
> --- a/docs/interop/vhost-user.rst
> +++ b/docs/interop/vhost-user.rst
> @@ -785,6 +785,7 @@ Protocol features
>    #define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD  10
>    #define VHOST_USER_PROTOCOL_F_HOST_NOTIFIER  11
>    #define VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD 12
> +  #define VHOST_USER_PROTOCOL_F_RESET_DEVICE   13
>  
>  Master message types
>  --------------------
> @@ -1190,6 +1191,20 @@ Master message types
>    ancillary data. The GPU protocol is used to inform the master of
>    rendering state and updates. See vhost-user-gpu.rst for details.
>  
> +``VHOST_USER_RESET_DEVICE``
> +  :id: 34
> +  :equivalent ioctl: N/A
> +  :master payload: N/A
> +  :slave payload: N/A
> +
> +  Ask the vhost user backend to disable all rings and reset all
> +  internal device state to the initial state, ready to be
> +  reinitialized. The backend retains ownership of the device
> +  throughout the reset operation.
> +
> +  Only valid if the ``VHOST_USER_PROTOCOL_F_RESET_DEVICE`` protocol
> +  feature is set by the backend.
> +
>  Slave message types
>  -------------------
>  
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 02a9b25..d27a10f 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -58,6 +58,7 @@ enum VhostUserProtocolFeature {
>      VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
>      VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
>      VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
> +    VHOST_USER_PROTOCOL_F_RESET_DEVICE = 13,
>      VHOST_USER_PROTOCOL_F_MAX
>  };
>  
> @@ -98,6 +99,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_GET_INFLIGHT_FD = 31,
>      VHOST_USER_SET_INFLIGHT_FD = 32,
>      VHOST_USER_GPU_SET_SOCKET = 33,
> +    VHOST_USER_RESET_DEVICE = 34,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>  
> @@ -890,10 +892,14 @@ static int vhost_user_set_owner(struct vhost_dev *dev)
>  static int vhost_user_reset_device(struct vhost_dev *dev)
>  {
>      VhostUserMsg msg = {
> -        .hdr.request = VHOST_USER_RESET_OWNER,
>          .hdr.flags = VHOST_USER_VERSION,
>      };
>  
> +    msg.hdr.request = virtio_has_feature(dev->protocol_features,
> +                                         VHOST_USER_PROTOCOL_F_RESET_DEVICE)
> +        ? VHOST_USER_RESET_DEVICE
> +        : VHOST_USER_RESET_OWNER;
> +
>      if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
>          return -1;
>      }
> -- 
> 1.8.3.1