Re: [Qemu-devel] [PATCH 1/2] vhost-user-blk: introduce a new vhost-user-blk host device

[Paolo Bonzini]

On 31/07/2017 16:51, Stefan Hajnoczi wrote:
> typedef enum VhostUserRequest {
>     ...
> 
>     /* Submitted by the vhost-user master when the guest writes to
>      * virtio config space and also after live migration on the
>      * destination host.
>      */
>     VHOST_USER_SET_CONFIG,
> 
>     /* Submitted by the vhost-user master to fetch the contents of the
>      * virtio config space.  The vhost-user master may cache the
>      * contents to avoid repeated VHOST_USER_GET_CONFIG calls.
>      */
>     VHOST_USER_GET_CONFIG,
> 
>     ...
> };

Also:

        /* Submitted by the vhost-user master if it would like to
         * be informed of virtio config space changes.   The slave
         * signals the eventfd whenever config space is modified.
         */
        VHOST_USER_SET_CONFIG_FD,

Paolo

> struct VuDev {
>     ...
>     int config_change_fd;
>     ...
> };