[RFC PATCH v1 4/7] vhost: introduce wrappers to set guest notifiers for virtio device

[Dima Stepanov]

Introduce new wrappers to set/reset guest notifiers for the virtio
device in the vhost device module:
  vhost_dev_assign_guest_notifiers
    ->set_guest_notifiers(..., ..., true);
  vhost_dev_drop_guest_notifiers
    ->set_guest_notifiers(..., ..., false);
This is a preliminary step to refactor code, so the set_guest_notifiers
methods could be called based on the vhost device state.
Update all vhost used devices to use these wrappers instead of direct
method call.

Signed-off-by: Dima Stepanov <address@hidden>
---
 backends/cryptodev-vhost.c  | 26 +++++++++++++++-----------
 backends/vhost-user.c       | 16 +++++-----------
 hw/block/vhost-user-blk.c   | 15 +++++----------
 hw/net/vhost_net.c          | 30 +++++++++++++++++-------------
 hw/scsi/vhost-scsi-common.c | 15 +++++----------
 hw/virtio/vhost-user-fs.c   | 17 +++++++----------
 hw/virtio/vhost-vsock.c     | 18 ++++++++----------
 hw/virtio/vhost.c           | 38 ++++++++++++++++++++++++++++++++++++++
 hw/virtio/virtio.c          | 13 +++++++++++++
 include/hw/virtio/vhost.h   |  4 ++++
 include/hw/virtio/virtio.h  |  1 +
 11 files changed, 118 insertions(+), 75 deletions(-)

diff --git a/backends/cryptodev-vhost.c b/backends/cryptodev-vhost.c
index 8337c9a..4522195 100644
--- a/backends/cryptodev-vhost.c
+++ b/backends/cryptodev-vhost.c
@@ -169,16 +169,13 @@ vhost_set_vring_enable(CryptoDevBackendClient *cc,
 int cryptodev_vhost_start(VirtIODevice *dev, int total_queues)
 {
     VirtIOCrypto *vcrypto = VIRTIO_CRYPTO(dev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
-    VirtioBusState *vbus = VIRTIO_BUS(qbus);
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int r, e;
     int i;
     CryptoDevBackend *b = vcrypto->cryptodev;
     CryptoDevBackendVhost *vhost_crypto;
     CryptoDevBackendClient *cc;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(dev)) {
         error_report("binding does not support guest notifiers");
         return -ENOSYS;
     }
@@ -198,9 +195,13 @@ int cryptodev_vhost_start(VirtIODevice *dev, int 
total_queues)
         }
      }
 
-    r = k->set_guest_notifiers(qbus->parent, total_queues, true);
+    /*
+     * Since all the states are handled by one vhost device,
+     * use the first one in array.
+     */
+    vhost_crypto = cryptodev_get_vhost(b->conf.peers.ccs[0], b, 0);
+    r = vhost_dev_assign_guest_notifiers(&vhost_crypto->dev, dev, 
total_queues);
     if (r < 0) {
-        error_report("error binding guest notifier: %d", -r);
         goto err;
     }
 
@@ -232,7 +233,8 @@ err_start:
         vhost_crypto = cryptodev_get_vhost(cc, b, i);
         cryptodev_vhost_stop_one(vhost_crypto, dev);
     }
-    e = k->set_guest_notifiers(qbus->parent, total_queues, false);
+    vhost_crypto = cryptodev_get_vhost(b->conf.peers.ccs[0], b, 0);
+    e = vhost_dev_drop_guest_notifiers(&vhost_crypto->dev, dev, total_queues);
     if (e < 0) {
         error_report("vhost guest notifier cleanup failed: %d", e);
     }
@@ -242,9 +244,6 @@ err:
 
 void cryptodev_vhost_stop(VirtIODevice *dev, int total_queues)
 {
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
-    VirtioBusState *vbus = VIRTIO_BUS(qbus);
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     VirtIOCrypto *vcrypto = VIRTIO_CRYPTO(dev);
     CryptoDevBackend *b = vcrypto->cryptodev;
     CryptoDevBackendVhost *vhost_crypto;
@@ -259,7 +258,12 @@ void cryptodev_vhost_stop(VirtIODevice *dev, int 
total_queues)
         cryptodev_vhost_stop_one(vhost_crypto, dev);
     }
 
-    r = k->set_guest_notifiers(qbus->parent, total_queues, false);
+    /*
+     * Since all the states are handled by one vhost device,
+     * use the first one in array.
+     */
+    vhost_crypto = cryptodev_get_vhost(b->conf.peers.ccs[0], b, 0);
+    r = vhost_dev_drop_guest_notifiers(&vhost_crypto->dev, dev, total_queues);
     if (r < 0) {
         error_report("vhost guest notifier cleanup failed: %d", r);
     }
diff --git a/backends/vhost-user.c b/backends/vhost-user.c
index 2bf3406..e116bc6 100644
--- a/backends/vhost-user.c
+++ b/backends/vhost-user.c
@@ -60,15 +60,13 @@ vhost_user_backend_dev_init(VhostUserBackend *b, 
VirtIODevice *vdev,
 void
 vhost_user_backend_start(VhostUserBackend *b)
 {
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret, i ;
 
     if (b->started) {
         return;
     }
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(b->vdev)) {
         error_report("binding does not support guest notifiers");
         return;
     }
@@ -78,9 +76,8 @@ vhost_user_backend_start(VhostUserBackend *b)
         return;
     }
 
-    ret = k->set_guest_notifiers(qbus->parent, b->dev.nvqs, true);
+    ret = vhost_dev_assign_guest_notifiers(&b->dev, b->vdev, b->dev.nvqs);
     if (ret < 0) {
-        error_report("Error binding guest notifier");
         goto err_host_notifiers;
     }
 
@@ -104,7 +101,7 @@ vhost_user_backend_start(VhostUserBackend *b)
     return;
 
 err_guest_notifiers:
-    k->set_guest_notifiers(qbus->parent, b->dev.nvqs, false);
+    vhost_dev_drop_guest_notifiers(&b->dev, b->vdev, b->dev.nvqs);
 err_host_notifiers:
     vhost_dev_disable_notifiers(&b->dev, b->vdev);
 }
@@ -112,8 +109,6 @@ err_host_notifiers:
 void
 vhost_user_backend_stop(VhostUserBackend *b)
 {
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret = 0;
 
     if (!b->started) {
@@ -122,9 +117,8 @@ vhost_user_backend_stop(VhostUserBackend *b)
 
     vhost_dev_stop(&b->dev, b->vdev);
 
-    if (k->set_guest_notifiers) {
-        ret = k->set_guest_notifiers(qbus->parent,
-                                     b->dev.nvqs, false);
+    if (virtio_device_guest_notifiers_initialized(b->vdev)) {
+        ret = vhost_dev_drop_guest_notifiers(&b->dev, b->vdev, b->dev.nvqs);
         if (ret < 0) {
             error_report("vhost guest notifier cleanup failed: %d", ret);
         }
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 17df533..70d7842 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -109,11 +109,9 @@ const VhostDevConfigOps blk_ops = {
 static int vhost_user_blk_start(VirtIODevice *vdev)
 {
     VHostUserBlk *s = VHOST_USER_BLK(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int i, ret;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         error_report("binding does not support guest notifiers");
         return -ENOSYS;
     }
@@ -124,9 +122,8 @@ static int vhost_user_blk_start(VirtIODevice *vdev)
         return ret;
     }
 
-    ret = k->set_guest_notifiers(qbus->parent, s->dev.nvqs, true);
+    ret = vhost_dev_assign_guest_notifiers(&s->dev, vdev, s->dev.nvqs);
     if (ret < 0) {
-        error_report("Error binding guest notifier: %d", -ret);
         goto err_host_notifiers;
     }
 
@@ -163,7 +160,7 @@ static int vhost_user_blk_start(VirtIODevice *vdev)
     return ret;
 
 err_guest_notifiers:
-    k->set_guest_notifiers(qbus->parent, s->dev.nvqs, false);
+    vhost_dev_drop_guest_notifiers(&s->dev, vdev, s->dev.nvqs);
 err_host_notifiers:
     vhost_dev_disable_notifiers(&s->dev, vdev);
     return ret;
@@ -172,17 +169,15 @@ err_host_notifiers:
 static void vhost_user_blk_stop(VirtIODevice *vdev)
 {
     VHostUserBlk *s = VHOST_USER_BLK(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         return;
     }
 
     vhost_dev_stop(&s->dev, vdev);
 
-    ret = k->set_guest_notifiers(qbus->parent, s->dev.nvqs, false);
+    ret = vhost_dev_drop_guest_notifiers(&s->dev, vdev, s->dev.nvqs);
     if (ret < 0) {
         error_report("vhost guest notifier cleanup failed: %d", ret);
         return;
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 6b82803..c13b444 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -303,19 +303,15 @@ static void vhost_net_stop_one(struct vhost_net *net,
 int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
                     int total_queues)
 {
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
-    VirtioBusState *vbus = VIRTIO_BUS(qbus);
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
+    struct vhost_net *net;
     int r, e, i;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(dev)) {
         error_report("binding does not support guest notifiers");
         return -ENOSYS;
     }
 
     for (i = 0; i < total_queues; i++) {
-        struct vhost_net *net;
-
         net = get_vhost_net(ncs[i].peer);
         vhost_net_set_vq_index(net, i * 2);
 
@@ -328,9 +324,13 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
         }
      }
 
-    r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
+    /*
+     * Since all the states are handled by one vhost_net device,
+     * use the first one in array.
+     */
+    net = get_vhost_net(ncs[0].peer);
+    r = vhost_dev_assign_guest_notifiers(&net->dev, dev, total_queues * 2);
     if (r < 0) {
-        error_report("Error binding guest notifier: %d", -r);
         goto err;
     }
 
@@ -357,7 +357,8 @@ err_start:
     while (--i >= 0) {
         vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
     }
-    e = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
+    net = get_vhost_net(ncs[0].peer);
+    e = vhost_dev_drop_guest_notifiers(&net->dev, dev, total_queues * 2);
     if (e < 0) {
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", e);
         fflush(stderr);
@@ -369,16 +370,19 @@ err:
 void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
                     int total_queues)
 {
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
-    VirtioBusState *vbus = VIRTIO_BUS(qbus);
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
+    struct vhost_net *net;
     int i, r;
 
     for (i = 0; i < total_queues; i++) {
         vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
     }
 
-    r = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
+    /*
+     * Since all the states are handled by one vhost_net device,
+     * use the first one in array.
+     */
+    net = get_vhost_net(ncs[0].peer);
+    r = vhost_dev_drop_guest_notifiers(&net->dev, dev, total_queues * 2);
     if (r < 0) {
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", r);
         fflush(stderr);
diff --git a/hw/scsi/vhost-scsi-common.c b/hw/scsi/vhost-scsi-common.c
index 8ec49d7..8f51ec0 100644
--- a/hw/scsi/vhost-scsi-common.c
+++ b/hw/scsi/vhost-scsi-common.c
@@ -29,10 +29,8 @@ int vhost_scsi_common_start(VHostSCSICommon *vsc)
 {
     int ret, i;
     VirtIODevice *vdev = VIRTIO_DEVICE(vsc);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         error_report("binding does not support guest notifiers");
         return -ENOSYS;
     }
@@ -42,9 +40,8 @@ int vhost_scsi_common_start(VHostSCSICommon *vsc)
         return ret;
     }
 
-    ret = k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, true);
+    ret = vhost_dev_assign_guest_notifiers(&vsc->dev, vdev, vsc->dev.nvqs);
     if (ret < 0) {
-        error_report("Error binding guest notifier");
         goto err_host_notifiers;
     }
 
@@ -66,7 +63,7 @@ int vhost_scsi_common_start(VHostSCSICommon *vsc)
     return ret;
 
 err_guest_notifiers:
-    k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, false);
+    vhost_dev_drop_guest_notifiers(&vsc->dev, vdev, vsc->dev.nvqs);
 err_host_notifiers:
     vhost_dev_disable_notifiers(&vsc->dev, vdev);
     return ret;
@@ -75,14 +72,12 @@ err_host_notifiers:
 void vhost_scsi_common_stop(VHostSCSICommon *vsc)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(vsc);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret = 0;
 
     vhost_dev_stop(&vsc->dev, vdev);
 
-    if (k->set_guest_notifiers) {
-        ret = k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, false);
+    if (virtio_device_guest_notifiers_initialized(vdev)) {
+        ret = vhost_dev_drop_guest_notifiers(&vsc->dev, vdev, vsc->dev.nvqs);
         if (ret < 0) {
                 error_report("vhost guest notifier cleanup failed: %d", ret);
         }
diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index 6136768..6b101fc 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -38,12 +38,10 @@ static void vuf_get_config(VirtIODevice *vdev, uint8_t 
*config)
 static void vuf_start(VirtIODevice *vdev)
 {
     VHostUserFS *fs = VHOST_USER_FS(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret;
     int i;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         error_report("binding does not support guest notifiers");
         return;
     }
@@ -54,9 +52,9 @@ static void vuf_start(VirtIODevice *vdev)
         return;
     }
 
-    ret = k->set_guest_notifiers(qbus->parent, fs->vhost_dev.nvqs, true);
+    ret = vhost_dev_assign_guest_notifiers(&fs->vhost_dev, vdev,
+            fs->vhost_dev.nvqs);
     if (ret < 0) {
-        error_report("Error binding guest notifier: %d", -ret);
         goto err_host_notifiers;
     }
 
@@ -79,7 +77,7 @@ static void vuf_start(VirtIODevice *vdev)
     return;
 
 err_guest_notifiers:
-    k->set_guest_notifiers(qbus->parent, fs->vhost_dev.nvqs, false);
+    vhost_dev_drop_guest_notifiers(&fs->vhost_dev, vdev, fs->vhost_dev.nvqs);
 err_host_notifiers:
     vhost_dev_disable_notifiers(&fs->vhost_dev, vdev);
 }
@@ -87,17 +85,16 @@ err_host_notifiers:
 static void vuf_stop(VirtIODevice *vdev)
 {
     VHostUserFS *fs = VHOST_USER_FS(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         return;
     }
 
     vhost_dev_stop(&fs->vhost_dev, vdev);
 
-    ret = k->set_guest_notifiers(qbus->parent, fs->vhost_dev.nvqs, false);
+    ret = vhost_dev_drop_guest_notifiers(&fs->vhost_dev, vdev,
+            fs->vhost_dev.nvqs);
     if (ret < 0) {
         error_report("vhost guest notifier cleanup failed: %d", ret);
         return;
diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
index 09b6b07..52489dd 100644
--- a/hw/virtio/vhost-vsock.c
+++ b/hw/virtio/vhost-vsock.c
@@ -75,12 +75,10 @@ static int vhost_vsock_set_running(VHostVSock *vsock, int 
start)
 static void vhost_vsock_start(VirtIODevice *vdev)
 {
     VHostVSock *vsock = VHOST_VSOCK(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret;
     int i;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         error_report("binding does not support guest notifiers");
         return;
     }
@@ -91,9 +89,9 @@ static void vhost_vsock_start(VirtIODevice *vdev)
         return;
     }
 
-    ret = k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, true);
+    ret = vhost_dev_assign_guest_notifiers(&vsock->vhost_dev,
+            vdev, vsock->vhost_dev.nvqs);
     if (ret < 0) {
-        error_report("Error binding guest notifier: %d", -ret);
         goto err_host_notifiers;
     }
 
@@ -123,7 +121,8 @@ static void vhost_vsock_start(VirtIODevice *vdev)
 err_dev_start:
     vhost_dev_stop(&vsock->vhost_dev, vdev);
 err_guest_notifiers:
-    k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, false);
+    vhost_dev_drop_guest_notifiers(&vsock->vhost_dev,
+            vdev, vsock->vhost_dev.nvqs);
 err_host_notifiers:
     vhost_dev_disable_notifiers(&vsock->vhost_dev, vdev);
 }
@@ -131,11 +130,9 @@ err_host_notifiers:
 static void vhost_vsock_stop(VirtIODevice *vdev)
 {
     VHostVSock *vsock = VHOST_VSOCK(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int ret;
 
-    if (!k->set_guest_notifiers) {
+    if (!virtio_device_guest_notifiers_initialized(vdev)) {
         return;
     }
 
@@ -147,7 +144,8 @@ static void vhost_vsock_stop(VirtIODevice *vdev)
 
     vhost_dev_stop(&vsock->vhost_dev, vdev);
 
-    ret = k->set_guest_notifiers(qbus->parent, vsock->vhost_dev.nvqs, false);
+    ret = vhost_dev_drop_guest_notifiers(&vsock->vhost_dev,
+            vdev, vsock->vhost_dev.nvqs);
     if (ret < 0) {
         error_report("vhost guest notifier cleanup failed: %d", ret);
         return;
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 01ebe12..fa3da9c 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1419,6 +1419,44 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, 
VirtIODevice *vdev)
     virtio_device_release_ioeventfd(vdev);
 }
 
+/*
+ * Assign guest notifiers.
+ * Should be called after vhost_dev_enable_notifiers.
+ */
+int vhost_dev_assign_guest_notifiers(struct vhost_dev *hdev,
+                                     VirtIODevice *vdev, int nvqs)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+
+    ret = k->set_guest_notifiers(qbus->parent, nvqs, true);
+    if (ret < 0) {
+        error_report("Error binding guest notifier: %d", -ret);
+    }
+
+    return ret;
+}
+
+/*
+ * Drop guest notifiers.
+ * Should be called before vhost_dev_disable_notifiers.
+ */
+int vhost_dev_drop_guest_notifiers(struct vhost_dev *hdev,
+                                   VirtIODevice *vdev, int nvqs)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+
+    ret = k->set_guest_notifiers(qbus->parent, nvqs, false);
+    if (ret < 0) {
+        error_report("Error reset guest notifier: %d", -ret);
+    }
+
+    return ret;
+}
+
 /* Test and clear event pending status.
  * Should be called after unmask to avoid losing events.
  */
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index b6c8ef5..8a95618 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3812,6 +3812,19 @@ bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
     return virtio_bus_ioeventfd_enabled(vbus);
 }
 
+/*
+ * Check if set_guest_notifiers() method is set by the init routine.
+ * Return true if yes, otherwise return false.
+ */
+bool virtio_device_guest_notifiers_initialized(VirtIODevice *vdev)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+
+    return k->set_guest_notifiers;
+}
+
+
 static const TypeInfo virtio_device_info = {
     .name = TYPE_VIRTIO_DEVICE,
     .parent = TYPE_DEVICE,
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 085450c..4d0d2e2 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -100,6 +100,10 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice 
*vdev);
 void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
 int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
 void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
+int vhost_dev_assign_guest_notifiers(struct vhost_dev *hdev,
+                                     VirtIODevice *vdev, int nvqs);
+int vhost_dev_drop_guest_notifiers(struct vhost_dev *hdev,
+                                   VirtIODevice *vdev, int nvqs);
 
 /* Test and clear masked event pending status.
  * Should be called after unmask to avoid losing events.
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index b69d517..d9a3d72 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -323,6 +323,7 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue 
*vq, AioContext *ctx,
                                                 VirtIOHandleAIOOutput 
handle_output);
 VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector);
 VirtQueue *virtio_vector_next_queue(VirtQueue *vq);
+bool virtio_device_guest_notifiers_initialized(VirtIODevice *vdev);
 
 static inline void virtio_add_feature(uint64_t *features, unsigned int fbit)
 {
-- 
2.7.4