Re: [Qemu-devel] [PATCH v5 2/2] vhost user: add rarp sending after live migration for legacy guest

[Jason Wang <jasowang@redhat.com>]

On 08/03/2015 05:22 PM, Thibaut Collet wrote:
> A new vhost user message is added to allow QEMU to ask to vhost user backend to
> broadcast a fake RARP after live migration for guest without GUEST_ANNOUNCE
> capability.
>
> This new message is sent only if the backend supports the new
> VHOST_USER_PROTOCOL_F_RARP protocol feature.
> The payload of this new message is the MAC address of the guest (not known by
> the backend). The MAC address is copied in the first 6 bytes of a u64 to avoid
> to create a new payload message type.
>
> This new message has no equivalent ioctl so a new callback is added in the
> userOps structure to send the request.
>
> Upon reception of this new message the vhost user backend must generate and
> broadcast a fake RARP request to notify the migration is terminated.
>
> Signed-off-by: Thibaut Collet <thibaut.collet@6wind.com>
> ---
>  docs/specs/vhost-user.txt         |   15 +++++++++++++++
>  hw/net/vhost_net.c                |   16 ++++++++++++++++
>  hw/virtio/vhost-user.c            |   32 ++++++++++++++++++++++++++++++--
>  include/hw/virtio/vhost-backend.h |    2 ++
>  include/net/vhost_net.h           |    1 +
>  net/vhost-user.c                  |   18 ++++++++++++++++++
>  6 files changed, 82 insertions(+), 2 deletions(-)
>
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index c2d2e2a..8c05301 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -140,6 +140,7 @@ Protocol features
>  -----------------
>  
>  #define VHOST_USER_PROTOCOL_F_LOG_SHMFD 0
> +#define VHOST_USER_PROTOCOL_F_RARP      1
>  
>  Message types
>  -------------
> @@ -308,6 +309,20 @@ Message types
>        invalid FD flag. This flag is set when there is no file descriptor
>        in the ancillary data.
>  
> + * VHOST_USER_SEND_RARP
> +
> +      Id: 17
> +      Equivalent ioctl: N/A
> +      Master payload: u64
> +
> +      Ask vhost user backend to broadcast a fake RARP to notify the migration
> +      is terminated for guest that does not support GUEST_ANNOUNCE.
> +      Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in
> +      VHOST_USER_GET_FEATURES and protocol feature bit VHOST_USER_PROTOCOL_F_RARP
> +      is present in VHOST_USER_GET_PROTOCOL_FEATURES.
> +      The first 6 bytes of the payload contain the mac address of the guest to
> +      allow the vhost user backend to construct and broadcast the fake RARP.
> +
>  Migration

If for some reason the announce packet was changed in the future, we may
then need another kind of message type. Just wonder whether allowing
qemu to inject packet directly to vhost-user is better.

>  ---------
>  
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 9850520..c3b9664 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -383,6 +383,17 @@ void vhost_net_cleanup(struct vhost_net *net)
>      g_free(net);
>  }
>  
> +int vhost_net_migrate(struct vhost_net *net, char* mac_addr)
> +{
> +    const VhostOps *vhost_ops = net->dev.vhost_ops;
> +    int r = -1;
> +
> +    if (vhost_ops->vhost_backend_migrate)
> +        r = vhost_ops->vhost_backend_migrate(&net->dev, mac_addr);
> +
> +    return r;
> +}
> +
>  bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
>  {
>      return vhost_virtqueue_pending(&net->dev, idx);
> @@ -456,6 +467,11 @@ void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
>  {
>  }
>  
> +int vhost_net_migrate(struct vhost_net *net)
> +{
> +    return -1;
> +}
> +
>  VHostNetState *get_vhost_net(NetClientState *nc)
>  {
>      return 0;
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index fe75618..693840f 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -10,6 +10,7 @@
>  
>  #include "hw/virtio/vhost.h"
>  #include "hw/virtio/vhost-backend.h"
> +#include "hw/virtio/virtio-net.h"
>  #include "sysemu/char.h"
>  #include "sysemu/kvm.h"
>  #include "qemu/error-report.h"
> @@ -27,8 +28,9 @@
>  
>  #define VHOST_USER_F_PROTOCOL_FEATURES 30
>  
> -#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x1ULL
> +#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x3ULL
>  #define VHOST_USER_PROTOCOL_F_LOG_SHMFD 0
> +#define VHOST_USER_PROTOCOL_F_RARP      1
>  
>  typedef enum VhostUserRequest {
>      VHOST_USER_NONE = 0,
> @@ -48,6 +50,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_SET_VRING_ERR = 14,
>      VHOST_USER_GET_PROTOCOL_FEATURES = 15,
>      VHOST_USER_SET_PROTOCOL_FEATURES = 16,
> +    VHOST_USER_SEND_RARP = 17,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>  
> @@ -409,9 +412,34 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
>      return 0;
>  }
>  
> +static int vhost_user_migrate(struct vhost_dev *dev, char* mac_addr)
> +{

Not sure migrate is a good name since migration was not done in this
function and it was called in vhost_user_receive().