Re: [Qemu-devel] [PATCH v5 15/21] vhost user: add rarp sending after live migration for legacy guest

[Thibaut Collet]

On Thu, Sep 24, 2015 at 6:22 PM,  <address@hidden> wrote:
> From: Thibaut Collet <address@hidden>
>
> 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 <address@hidden>
> [Rebased and fixed checkpatch errors - Marc-André]
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  docs/specs/vhost-user.txt         | 15 +++++++++++++++
>  hw/net/vhost_net.c                | 17 +++++++++++++++++
>  hw/virtio/vhost-user.c            | 30 ++++++++++++++++++++++++++++++
>  include/hw/virtio/vhost-backend.h |  3 +++
>  include/net/vhost_net.h           |  1 +
>  net/vhost-user.c                  | 24 ++++++++++++++++++++++--
>  6 files changed, 88 insertions(+), 2 deletions(-)
>
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index e0292a0..e0d71e2 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -194,6 +194,7 @@ Protocol features
>
>  #define VHOST_USER_PROTOCOL_F_MQ             0
>  #define VHOST_USER_PROTOCOL_F_LOG_SHMFD      1
> +#define VHOST_USER_PROTOCOL_F_RARP           2
>
>  Message types
>  -------------
> @@ -381,3 +382,17 @@ Message types
>        Master payload: vring state description
>
>        Signal slave to enable or disable corresponding vring.
> +
> + * VHOST_USER_SEND_RARP
> +
> +      Id: 19
> +      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.
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 840f443..da66b64 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -388,6 +388,18 @@ void vhost_net_cleanup(struct vhost_net *net)
>      g_free(net);
>  }
>
> +int vhost_net_notify_migration_done(struct vhost_net *net, char* mac_addr)
> +{
> +    const VhostOps *vhost_ops = net->dev.vhost_ops;
> +    int r = -1;
> +
> +    if (vhost_ops->vhost_migration_done) {
> +        r = vhost_ops->vhost_migration_done(&net->dev, mac_addr);
> +    }
> +
> +    return r;
> +}
> +
>  bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
>  {
>      return vhost_virtqueue_pending(&net->dev, idx);
> @@ -479,6 +491,11 @@ void vhost_net_virtqueue_mask(VHostNetState *net, 
> VirtIODevice *dev,
>  {
>  }
>
> +int vhost_net_notify_migration_done(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 455caba..b7f3699 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"
> @@ -30,6 +31,7 @@
>  #define VHOST_USER_PROTOCOL_FEATURE_MASK 0x3ULL
>  #define VHOST_USER_PROTOCOL_F_MQ         0
>  #define VHOST_USER_PROTOCOL_F_LOG_SHMFD  1
> +#define VHOST_USER_PROTOCOL_F_RARP       2

The VHOST_USER_PROTOCOL_FEATURE_MASK  must be changed and set to 0x7ULL

>
>  typedef enum VhostUserRequest {
>      VHOST_USER_NONE = 0,
> @@ -51,6 +53,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_SET_PROTOCOL_FEATURES = 16,
>      VHOST_USER_GET_QUEUE_NUM = 17,
>      VHOST_USER_SET_VRING_ENABLE = 18,
> +    VHOST_USER_SEND_RARP = 19,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>
> @@ -561,6 +564,32 @@ static bool vhost_user_requires_shm_log(struct vhost_dev 
> *dev)
>                                VHOST_USER_PROTOCOL_F_LOG_SHMFD);
>  }
>
> +static int vhost_user_migration_done(struct vhost_dev *dev, char* mac_addr)
> +{
> +    VhostUserMsg msg = { 0 };
> +    int err;
> +
> +    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
> +
> +    /* If guest supports GUEST_ANNOUNCE do nothing */
> +    if (virtio_has_feature(dev->acked_features, 
> VIRTIO_NET_F_GUEST_ANNOUNCE)) {
> +        return 0;
> +    }
> +
> +    /* if backend supports VHOST_USER_PROTOCOL_F_RARP ask it to send the 
> RARP */
> +    if (virtio_has_feature(dev->protocol_features,
> +                           VHOST_USER_PROTOCOL_F_RARP)) {
> +        msg.request = VHOST_USER_SEND_RARP;
> +        msg.flags = VHOST_USER_VERSION;
> +        memcpy((char *)&msg.u64, mac_addr, 6);
> +        msg.size = sizeof(m.u64);
> +
> +        err = vhost_user_write(dev, &msg, NULL, 0);
> +        return err;
> +    }
> +    return -1;
> +}
> +
>  const VhostOps user_ops = {
>          .backend_type = VHOST_BACKEND_TYPE_USER,
>          .vhost_backend_init = vhost_user_init,
> @@ -582,4 +611,5 @@ const VhostOps user_ops = {
>          .vhost_get_vq_index = vhost_user_get_vq_index,
>          .vhost_set_vring_enable = vhost_user_set_vring_enable,
>          .vhost_requires_shm_log = vhost_user_requires_shm_log,
> +        .vhost_migration_done = vhost_user_migration_done,
>  };
> diff --git a/include/hw/virtio/vhost-backend.h 
> b/include/hw/virtio/vhost-backend.h
> index e07118c..5918c01 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -67,6 +67,8 @@ typedef int (*vhost_get_vq_index_op)(struct vhost_dev *dev, 
> int idx);
>  typedef int (*vhost_set_vring_enable_op)(struct vhost_dev *dev,
>                                           int enable);
>  typedef bool (*vhost_requires_shm_log_op)(struct vhost_dev *dev);
> +typedef int (*vhost_migration_done_op)(struct vhost_dev *dev,
> +                                       char *mac_addr);
>
>  typedef struct VhostOps {
>      VhostBackendType backend_type;
> @@ -94,6 +96,7 @@ typedef struct VhostOps {
>      vhost_get_vq_index_op vhost_get_vq_index;
>      vhost_set_vring_enable_op vhost_set_vring_enable;
>      vhost_requires_shm_log_op vhost_requires_shm_log;
> +    vhost_migration_done_op vhost_migration_done;
>  } VhostOps;
>
>  extern const VhostOps user_ops;
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 0188c4d..3389b41 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -27,6 +27,7 @@ void vhost_net_ack_features(VHostNetState *net, uint64_t 
> features);
>  bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
>  void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
>                                int idx, bool mask);
> +int vhost_net_notify_migration_done(VHostNetState *net, char* mac_addr);
>  VHostNetState *get_vhost_net(NetClientState *nc);
>
>  int vhost_set_vring_enable(NetClientState * nc, int enable);
> diff --git a/net/vhost-user.c b/net/vhost-user.c
> index 87917a5..cfe11b8 100644
> --- a/net/vhost-user.c
> +++ b/net/vhost-user.c
> @@ -106,9 +106,29 @@ err:
>  static ssize_t vhost_user_receive(NetClientState *nc, const uint8_t *buf,
>                                    size_t size)
>  {
> -    /* Discard the request that is received and managed by backend
> -     * by an other way.
> +    /* In case of RARP (message size is 60) notify backup to send a fake 
> RARP.
> +       This fake RARP will be sent by backend only for guest
> +       without GUEST_ANNOUNCE capability.
>       */
> +    if (size == 60) {
> +        VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
> +        int r;
> +        static int display_rarp_failure = 1;
> +        char mac_addr[6];
> +
> +        /* extract guest mac address from the RARP message */
> +        memcpy(mac_addr, &buf[6], 6);
> +
> +        r = vhost_net_notify_migration_done(s->vhost_net, mac_addr);
> +
> +        if ((r != 0) && (display_rarp_failure)) {
> +            fprintf(stderr,
> +                    "Vhost user backend fails to broadcast fake RARP\n");
> +            fflush(stderr);
> +            display_rarp_failure = 0;
> +        }
> +    }
> +
>      return size;
>  }
>
> --
> 2.4.3
>