Re: [Qemu-devel] [PATCH v5 7/7] Add vhost-user reconnection

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

On Fri, Jan 10, 2014 at 11:59:24AM +0100, Antonios Motakis wrote:
> 
> 
> 
> On Thu, Jan 9, 2014 at 5:16 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> 
>     On Thu, Jan 09, 2014 at 04:00:01PM +0100, Antonios Motakis wrote:
>     > At runtime vhost-user netdev will detect if the vhost backend is up or
>     down.
>     > Upon disconnection it will set link_down accordingly and notify
>     virtio-net.
> 
>     And then what happens?
> 
> 
> The virtio-net interface goes down. On the next polling cycle the connection
> will be re-attempted (see vhost_user_timer_handler).
> 

I'm guessing user should have control over how often to retry then,
it's a policy thing.


> 
>     >
>     > Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
>     > Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
>     > ---
>     >  hw/net/vhost_net.c                | 16 +++++++++++
>     >  hw/virtio/vhost-backend.c         | 16 +++++++++++
>     >  include/hw/virtio/vhost-backend.h |  2 ++
>     >  include/net/vhost_net.h           |  1 +
>     >  net/vhost-user.c                  | 56
>     +++++++++++++++++++++++++++++++++++++++
>     >  5 files changed, 91 insertions(+)
>     >
>     > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
>     > index e42f4d6..56c218e 100644
>     > --- a/hw/net/vhost_net.c
>     > +++ b/hw/net/vhost_net.c
>     > @@ -304,6 +304,17 @@ void vhost_net_virtqueue_mask(VHostNetState *net,
>     VirtIODevice *dev,
>     >      vhost_virtqueue_mask(&net->dev, dev, idx, mask);
>     >  }
>     >
>     > +int vhost_net_link_status(VHostNetState *net)
>     > +{
>     > +    int r = 0;
>     > +
>     > +    if (net->dev.vhost_ops->vhost_status) {
>     > +        r = net->dev.vhost_ops->vhost_status(&net->dev);
>     > +    }
>     > +
>     > +    return r;
>     > +}
>     > +
>     >  VHostNetState *get_vhost_net(NetClientState *nc)
>     >  {
>     >      VHostNetState *vhost_net = 0;
>     > @@ -372,6 +383,11 @@ void vhost_net_virtqueue_mask(VHostNetState *net,
>     VirtIODevice *dev,
>     >  {
>     >  }
>     >
>     > +int vhost_net_link_status(VHostNetState *net)
>     > +{
>     > +    return 0;
>     > +}
>     > +
>     >  VHostNetState *get_vhost_net(NetClientState *nc)
>     >  {
>     >      return 0;
>     > diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
>     > index 50ea307..fcd274f 100644
>     > --- a/hw/virtio/vhost-backend.c
>     > +++ b/hw/virtio/vhost-backend.c
>     > @@ -350,9 +350,23 @@ static int vhost_user_call(struct vhost_dev *dev,
>     unsigned long int request,
>     >          }
>     >      }
>     >
>     > +    /* mark the backend non operational */
>     > +    if (result < 0) {
>     > +        error_report("%s: Connection break detected\n", __func__);
>     > +        vhost_user_cleanup(dev);
>     > +        return 0;
>     > +    }
>     > +
>     >      return result;
>     >  }
>     >
>     > +static int vhost_user_status(struct vhost_dev *dev)
>     > +{
>     > +    vhost_user_echo(dev);
>     > +
>     > +    return (dev->control >= 0);
>     > +}
>     > +
>     >  static int vhost_user_init(struct vhost_dev *dev, const char *devpath)
>     >  {
>     >      int fd = -1;
>     > @@ -432,6 +446,7 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
>     >  static const VhostOps user_ops = {
>     >          .backend_type = VHOST_BACKEND_TYPE_USER,
>     >          .vhost_call = vhost_user_call,
>     > +        .vhost_status = vhost_user_status,
>     >          .vhost_backend_init = vhost_user_init,
>     >          .vhost_backend_cleanup = vhost_user_cleanup
>     >  };
>     > @@ -464,6 +479,7 @@ static int vhost_kernel_cleanup(struct vhost_dev
>     *dev)
>     >  static const VhostOps kernel_ops = {
>     >          .backend_type = VHOST_BACKEND_TYPE_KERNEL,
>     >          .vhost_call = vhost_kernel_call,
>     > +        .vhost_status = 0,
>     >          .vhost_backend_init = vhost_kernel_init,
>     >          .vhost_backend_cleanup = vhost_kernel_cleanup
>     >  };
>     > diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/
>     vhost-backend.h
>     > index ef87ffa..f2b4a6c 100644
>     > --- a/include/hw/virtio/vhost-backend.h
>     > +++ b/include/hw/virtio/vhost-backend.h
>     > @@ -22,12 +22,14 @@ struct vhost_dev;
>     >
>     >  typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int
>     request,
>     >               void *arg);
>     > +typedef int (*vhost_status)(struct vhost_dev *dev);
>     >  typedef int (*vhost_backend_init)(struct vhost_dev *dev, const char
>     *devpath);
>     >  typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
>     >
>     >  typedef struct VhostOps {
>     >      VhostBackendType backend_type;
>     >      vhost_call vhost_call;
>     > +    vhost_status vhost_status;
>     >      vhost_backend_init vhost_backend_init;
>     >      vhost_backend_cleanup vhost_backend_cleanup;
>     >  } VhostOps;
>     > diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
>     > index abd3d0b..6390907 100644
>     > --- a/include/net/vhost_net.h
>     > +++ b/include/net/vhost_net.h
>     > @@ -31,5 +31,6 @@ void vhost_net_ack_features(VHostNetState *net,
>     unsigned 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_link_status(VHostNetState *net);
>     >  VHostNetState *get_vhost_net(NetClientState *nc);
>     >  #endif
>     > diff --git a/net/vhost-user.c b/net/vhost-user.c
>     > index 6fd5afc..56f7dd4 100644
>     > --- a/net/vhost-user.c
>     > +++ b/net/vhost-user.c
>     > @@ -12,6 +12,7 @@
>     >  #include "net/vhost_net.h"
>     >  #include "net/vhost-user.h"
>     >  #include "qemu/error-report.h"
>     > +#include "qemu/timer.h"
>     >
>     >  typedef struct VhostUserState {
>     >      NetClientState nc;
>     > @@ -19,6 +20,9 @@ typedef struct VhostUserState {
>     >      char *devpath;
>     >  } VhostUserState;
>     >
>     > +static QEMUTimer *vhost_user_timer;
>     > +#define VHOST_USER_TIMEOUT  (1*1000)
>     > +
>     >  VHostNetState *vhost_user_get_vhost_net(NetClientState *nc)
>     >  {
>     >      VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
>     > @@ -31,6 +35,11 @@ static int vhost_user_running(VhostUserState *s)
>     >      return (s->vhost_net) ? 1 : 0;
>     >  }
>     >
>     > +static int vhost_user_link_status(VhostUserState *s)
>     > +{
>     > +    return (!s->nc.link_down) && vhost_net_link_status(s->vhost_net);
>     > +}
>     > +
>     >  static int vhost_user_start(VhostUserState *s)
>     >  {
>     >      VhostNetOptions options;
>     > @@ -59,6 +68,48 @@ static void vhost_user_stop(VhostUserState *s)
>     >      s->vhost_net = 0;
>     >  }
>     >
>     > +static void vhost_user_timer_handler(void *opaque)
>     > +{
>     > +    VhostUserState *s = opaque;
>     > +    int link_down = 0;
>     > +
>     > +    if (vhost_user_running(s)) {
>     > +        if (!vhost_user_link_status(s)) {
>     > +            link_down = 1;
>     > +        }
>     > +    } else {
>     > +        vhost_user_start(s);
>     > +        if (!vhost_user_running(s)) {
>     > +            link_down = 1;
>     > +        }
>     > +    }
>     > +
>     > +    if (link_down != s->nc.link_down) {
>     > +
>     > +        s->nc.link_down = link_down;
>     > +
>     > +        if (s->nc.peer) {
>     > +            s->nc.peer->link_down = link_down;
>     > +        }
>     > +
>     > +        if (s->nc.info->link_status_changed) {
>     > +            s->nc.info->link_status_changed(&s->nc);
>     > +        }
>     > +
>     > +        if (s->nc.peer && s->nc.peer->info->link_status_changed) {
>     > +            s->nc.peer->info->link_status_changed(s->nc.peer);
>     > +        }
>     > +
>     > +        if (link_down) {
>     > +            vhost_user_stop(s);
>     > +        }
>     > +    }
>     > +
>     > +    /* reschedule */
>     > +    timer_mod(vhost_user_timer,
>     > +              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) +
>     VHOST_USER_TIMEOUT);
>     > +}
>     > +
>     >  static void vhost_user_cleanup(NetClientState *nc)
>     >  {
>     >      VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
>     > @@ -93,6 +144,11 @@ static int net_vhost_user_init(NetClientState *peer,
>     const char *device,
>     >
>     >      r = vhost_user_start(s);
>     >
>     > +    vhost_user_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
>     > +            vhost_user_timer_handler, s);
>     > +    timer_mod(vhost_user_timer,
>     > +            qemu_clock_get_ms(QEMU_CLOCK_REALTIME) +
>     VHOST_USER_TIMEOUT);
>     > +
>     >      return r;
>     >  }
>     >
>     > --
>     > 1.8.3.2
>     >
> 
>