[Qemu-devel] [PATCH v3 7/7] Add vhost-user reconnection

[Antonios Motakis <a.motakis@virtualopensystems.com>]

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.

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         | 21 +++++++++++++++
 include/hw/virtio/vhost-backend.h |  2 ++
 include/net/vhost_net.h           |  1 +
 net/vhost-user.c                  | 56 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 96 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 c280936..2c0b4f0 100644
--- a/hw/virtio/vhost-backend.c
+++ b/hw/virtio/vhost-backend.c
@@ -168,6 +168,10 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
 
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 
+    if (fd < 0) {
+        return 0;
+    }
+
     msg.request = vhost_user_request_translate(request);
     msg.flags = 0;
 
@@ -251,9 +255,24 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
         }
     }
 
+    /* mark the backend non operational */
+    if (result < 0) {
+        dev->control = -1;
+        return 0;
+    }
+
     return result;
 }
 
+static int vhost_user_status(struct vhost_dev *dev)
+{
+    uint64_t features = 0;
+
+    vhost_user_call(dev, VHOST_GET_FEATURES, &features);
+
+    return (dev->control >= 0);
+}
+
 static int vhost_user_init(struct vhost_dev *dev, const char *devpath)
 {
     int fd = -1;
@@ -295,6 +314,7 @@ 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
 };
@@ -327,6 +347,7 @@ 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