[PATCH v4 05/15] vdpa: move vhost reset after get vring base

["Eugenio Pérez" <eperezma@redhat.com>]

The function vhost.c:vhost_dev_stop calls vhost operation
vhost_dev_start(false). In the case of vdpa it totally reset and wipes
the device, making the fetching of the vring base (virtqueue state) totally
useless.

The kernel backend does not use vhost_dev_start vhost op callback, but
vhost-user do. A patch to make vhost_user_dev_start more similar to vdpa
is desirable, but it can be added on top.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/vhost-backend.h |  4 ++++
 hw/virtio/vhost-vdpa.c            | 22 ++++++++++++++++------
 hw/virtio/vhost.c                 |  3 +++
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index c5ab49051e..ec3fbae58d 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -130,6 +130,9 @@ typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
 
 typedef int (*vhost_set_config_call_op)(struct vhost_dev *dev,
                                        int fd);
+
+typedef void (*vhost_reset_status_op)(struct vhost_dev *dev);
+
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_backend_init vhost_backend_init;
@@ -177,6 +180,7 @@ typedef struct VhostOps {
     vhost_get_device_id_op vhost_get_device_id;
     vhost_force_iommu_op vhost_force_iommu;
     vhost_set_config_call_op vhost_set_config_call;
+    vhost_reset_status_op vhost_reset_status;
 } VhostOps;
 
 int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 4fac144169..8cc9c98db9 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -1134,14 +1134,23 @@ static int vhost_vdpa_dev_start(struct vhost_dev *dev, bool started)
     if (started) {
         memory_listener_register(&v->listener, &address_space_memory);
         return vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
-    } else {
-        vhost_vdpa_reset_device(dev);
-        vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
-                                   VIRTIO_CONFIG_S_DRIVER);
-        memory_listener_unregister(&v->listener);
+    }
 
-        return 0;
+    return 0;
+}
+
+static void vhost_vdpa_reset_status(struct vhost_dev *dev)
+{
+    struct vhost_vdpa *v = dev->opaque;
+
+    if (dev->vq_index + dev->nvqs != dev->vq_index_end) {
+        return;
     }
+
+    vhost_vdpa_reset_device(dev);
+    vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
+                               VIRTIO_CONFIG_S_DRIVER);
+    memory_listener_unregister(&v->listener);
 }
 
 static int vhost_vdpa_set_log_base(struct vhost_dev *dev, uint64_t base,
@@ -1328,4 +1337,5 @@ const VhostOps vdpa_ops = {
         .vhost_vq_get_addr = vhost_vdpa_vq_get_addr,
         .vhost_force_iommu = vhost_vdpa_force_iommu,
         .vhost_set_config_call = vhost_vdpa_set_config_call,
+        .vhost_reset_status = vhost_vdpa_reset_status,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index eb8c4c378c..a266396576 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -2049,6 +2049,9 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
                              hdev->vqs + i,
                              hdev->vq_index + i);
     }
+    if (hdev->vhost_ops->vhost_reset_status) {
+        hdev->vhost_ops->vhost_reset_status(hdev);
+    }
 
     if (vhost_dev_has_iommu(hdev)) {
         if (hdev->vhost_ops->vhost_set_iotlb_callback) {
-- 
2.31.1