Re: [PATCH v12 5/7] vhost_user.rst: Add GET_SHMEM_CONFIG message

[Alyssa Ross <hi@alyssa.is>]

[-- Attachment #1: Type: text/plain, Size: 3136 bytes --]

Albert Esteve <aesteve@redhat.com> writes:

> Add GET_SHMEM_CONFIG vhost-user frontend
> message to the spec documentation.
>
> Reviewed-by: Alyssa Ross <hi@alyssa.is>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Albert Esteve <aesteve@redhat.com>
> ---
>  docs/interop/vhost-user.rst | 41 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
>
> diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> index 6c1d66d7d3..e314313806 100644
> --- a/docs/interop/vhost-user.rst
> +++ b/docs/interop/vhost-user.rst
> @@ -371,6 +371,22 @@ MMAP request
>    - 0: Pages are mapped read-only
>    - 1: Pages are mapped read-write
>  
> +VIRTIO Shared Memory Region configuration
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> ++-------------+---------+------------+----+--------------+
> +| num regions | padding | mem size 0 | .. | mem size 255 |
> ++-------------+---------+------------+----+--------------+
> +
> +:num regions: a 32-bit number of regions
> +
> +:padding: 32-bit
> +
> +:mem size: an array of 256 64-bit fields representing the size of each
> +           VIRTIO Shared Memory Region. ``num regions`` specifies the
> +           number of valid regions (non-zero size). The array index
> +           corresponds to the shared memory ID (shmid).
> +
>  C structure
>  -----------
>  
> @@ -397,6 +413,7 @@ In QEMU the vhost-user message is implemented with the following struct:
>            VhostUserShared object;
>            VhostUserTransferDeviceState transfer_state;
>            VhostUserMMap mmap;
> +          VhostUserShMemConfig shmem;
>        };
>    } QEMU_PACKED VhostUserMsg;
>  
> @@ -1761,6 +1778,30 @@ Front-end message types
>    Using this function requires prior negotiation of the
>    ``VHOST_USER_PROTOCOL_F_DEVICE_STATE`` feature.
>  
> +``VHOST_USER_GET_SHMEM_CONFIG``
> +  :id: 44
> +  :equivalent ioctl: N/A
> +  :request payload: N/A
> +  :reply payload: ``struct VhostUserShMemConfig``
> +
> +  When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been
> +  successfully negotiated, this message can be submitted by the front-end
> +  to gather the VIRTIO Shared Memory Region configuration. The back-end will
> +  respond with the number of VIRTIO Shared Memory Regions it requires, and
> +  each shared memory region size in an array. The shared memory IDs are
> +  represented by the array index. The information returned shall comply
> +  with the following rules:
> +
> +  * The shared information will remain valid and unchanged for the entire
> +    lifetime of the connection.
> +
> +  * The Shared Memory Region size must be a multiple of the page size
> +    supported by mmap(2).
> +
> +  * The size may be 0 if the region is unused. This can happen when the
> +    device does not support an optional feature but does support a feature
> +    that uses a higher shmid.

This is still phrased as if unused regions after the last used one can
be ommitted.  If 256 sizes are always sent, then size must be 0 for all
unused regions.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 227 bytes --]