Introduce vhost_dev.backend_transfer field,

Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
---
 hw/virtio/vhost.c         | 121 +++++++++++++++++++++++++++++++++-----
 include/hw/virtio/vhost.h |   7 +++
 2 files changed, 113 insertions(+), 15 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 63036f8214..c46203eb9c 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1325,6 +1325,8 @@ out:
     return ret;
 }
 
+static void vhost_virtqueue_error_notifier(EventNotifier *n);
+
 int vhost_virtqueue_start(struct vhost_dev *dev,
                           struct VirtIODevice *vdev,
                           struct vhost_virtqueue *vq,
@@ -1350,7 +1352,13 @@ int vhost_virtqueue_start(struct vhost_dev *dev,
         return r;
     }
 
-    vq->num = state.num = virtio_queue_get_num(vdev, idx);
+    vq->num = virtio_queue_get_num(vdev, idx);
+
+    if (dev->backend_transfer) {
+        return 0;
+    }
+
+    state.num = vq->num;
     r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
     if (r) {
         VHOST_OPS_DEBUG(r, "vhost_set_vring_num failed");
@@ -1428,6 +1436,10 @@ static int do_vhost_virtqueue_stop(struct vhost_dev *dev,
 
     trace_vhost_virtque_stop_in(dev, vdev->name, idx);
 
+    if (dev->backend_transfer) {
+        return 0;
+    }
+
     if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
         /* Don't stop the virtqueue which might have not been started */
         return 0;
@@ -1565,10 +1577,14 @@ fail_call:
 
 static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
 {
-    event_notifier_cleanup(&vq->masked_notifier);
+    if (!vq->dev->backend_transfer) {
+        event_notifier_cleanup(&vq->masked_notifier);
+    }
     if (vq->dev->vhost_ops->vhost_set_vring_err) {
         event_notifier_set_handler(&vq->error_notifier, NULL);
-        event_notifier_cleanup(&vq->error_notifier);
+        if (!vq->dev->backend_transfer) {
+            event_notifier_cleanup(&vq->error_notifier);
+        }
     }
 }
 
@@ -1635,6 +1651,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
 
     hdev->vdev = NULL;
     hdev->migration_blocker = NULL;
+    hdev->_features_wait_incoming = true;
     hdev->busyloop_timeout = busyloop_timeout;
 
     for (i = 0; i < hdev->nvqs; ++i) {
@@ -1717,6 +1734,8 @@ int vhost_dev_connect(struct vhost_dev *hdev, Error 
**errp)
         goto fail;
     }
 
+    hdev->_features_wait_incoming = false;
+
     for (i = 0; i < hdev->nvqs; ++i, ++n_initialized_vqs) {
         r = vhost_virtqueue_connect(hdev->vqs + i, hdev->vq_index + i);
         if (r < 0) {
@@ -1808,8 +1827,11 @@ void vhost_dev_disable_notifiers_nvqs(struct vhost_dev 
*hdev,
      */
     memory_region_transaction_commit();
 
-    for (i = 0; i < nvqs; ++i) {
-        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
+    if (!hdev->backend_transfer) {
+        for (i = 0; i < nvqs; ++i) {
+            virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus),
+                                             hdev->vq_index + i);
+        }
     }
     virtio_device_release_ioeventfd(vdev);
 }
@@ -1967,6 +1989,11 @@ void vhost_get_features_ex(struct vhost_dev *hdev,
 {
     const int *bit = feature_bits;
 
+    if (hdev->_features_wait_incoming) {
+        /* Excessive set is enough for early initialization. */
+        return;
+    }
+
     while (*bit != VHOST_INVALID_FEATURE_BIT) {
         if (!vhost_dev_has_feature_ex(hdev, *bit)) {
             virtio_clear_feature_ex(features, *bit);
@@ -2001,6 +2028,54 @@ const VMStateDescription 
vmstate_backend_transfer_vhost_inflight = {
     }
 };
 
+const VMStateDescription vmstate_vhost_virtqueue = {
+    .name = "vhost-virtqueue",
+    .fields = (const VMStateField[]) {
+        VMSTATE_EVENT_NOTIFIER(error_notifier, struct vhost_virtqueue),
+        VMSTATE_EVENT_NOTIFIER(masked_notifier, struct vhost_virtqueue),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static int vhost_dev_post_load(void *opaque, int version_id)
+{
+    struct vhost_dev *hdev = opaque;
+    Error *err = NULL;
+    int i;
+
+    if (!check_memslots(hdev, &err)) {
+        error_report_err(err);
+        return -EINVAL;
+    }
+
+    hdev->_features_wait_incoming = false;
+
+    if (hdev->vhost_ops->vhost_set_vring_err) {
+        for (i = 0; i < hdev->nvqs; ++i) {
+            event_notifier_set_handler(&hdev->vqs[i].error_notifier,
+                                       vhost_virtqueue_error_notifier);
+        }
+    }
+
+
+    return 0;
+}
+
+const VMStateDescription vmstate_vhost_dev = {
+    .name = "vhost-dev",
+    .post_load = vhost_dev_post_load,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(_features, struct vhost_dev),
+        VMSTATE_UINT64(max_queues, struct vhost_dev),
+        VMSTATE_UINT32_EQUAL(nvqs, struct vhost_dev, NULL),
+        VMSTATE_STRUCT_VARRAY_POINTER_UINT32(vqs, struct vhost_dev,
+                                             nvqs,
+                                             vmstate_vhost_virtqueue,
+                                             struct vhost_virtqueue),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 void vhost_ack_features_ex(struct vhost_dev *hdev, const int *feature_bits,
                            const uint64_t *features)
 {
@@ -2127,19 +2202,24 @@ int vhost_dev_start(struct vhost_dev *hdev, 
VirtIODevice *vdev, bool vrings)
     hdev->started = true;
     hdev->vdev = vdev;
 
-    r = vhost_dev_set_features(hdev, hdev->log_enabled);
-    if (r < 0) {
-        goto fail_features;
+    if (!hdev->backend_transfer) {
+        r = vhost_dev_set_features(hdev, hdev->log_enabled);
+        if (r < 0) {
+            warn_report("%s %d", __func__, __LINE__);
+            goto fail_features;
+        }
     }
 
     if (vhost_dev_has_iommu(hdev)) {
         memory_listener_register(&hdev->iommu_listener, vdev->dma_as);
     }
 
-    r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
-    if (r < 0) {
-        VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
-        goto fail_mem;
+    if (!hdev->backend_transfer) {
+        r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
+        if (r < 0) {
+            VHOST_OPS_DEBUG(r, "vhost_set_mem_table failed");
+            goto fail_mem;
+        }
     }
     for (i = 0; i < hdev->nvqs; ++i) {
         r = vhost_virtqueue_start(hdev,
@@ -2179,13 +2259,13 @@ int vhost_dev_start(struct vhost_dev *hdev, 
VirtIODevice *vdev, bool vrings)
         }
         vhost_dev_elect_mem_logger(hdev, true);
     }
-    if (vrings) {
+    if (vrings && !hdev->backend_transfer) {
         r = vhost_dev_set_vring_enable(hdev, true);
         if (r) {
             goto fail_log;
         }
     }
-    if (hdev->vhost_ops->vhost_dev_start) {
+    if (hdev->vhost_ops->vhost_dev_start && !hdev->backend_transfer) {
         r = hdev->vhost_ops->vhost_dev_start(hdev, true);
         if (r) {
             goto fail_start;
@@ -2207,6 +2287,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice 
*vdev, bool vrings)
     }
     vhost_start_config_intr(hdev);
 
+    hdev->backend_transfer = false;
+
     trace_vhost_dev_start_out(hdev, vdev->name);
     return 0;
 fail_iotlb:
@@ -2262,9 +2344,18 @@ static int do_vhost_dev_stop(struct vhost_dev *hdev, 
VirtIODevice *vdev,
     if (hdev->vhost_ops->vhost_dev_start) {
         hdev->vhost_ops->vhost_dev_start(hdev, false);
     }
-    if (vrings) {
+    if (vrings && !hdev->backend_transfer) {
         vhost_dev_set_vring_enable(hdev, false);
     }
+
+    if (hdev->backend_transfer) {
+        for (i = 0; i < hdev->nvqs; ++i) {
+            struct vhost_virtqueue *vq = hdev->vqs + i;
+
+            event_notifier_set_handler(&vq->error_notifier, NULL);
+        }
+    }
+
     for (i = 0; i < hdev->nvqs; ++i) {
         rc |= do_vhost_virtqueue_stop(hdev,
                                       vdev,
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 94a0c75fc8..55ad822848 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -105,6 +105,9 @@ struct vhost_dev {
     VIRTIO_DECLARE_FEATURES(_features);
     VIRTIO_DECLARE_FEATURES(acked_features);
 
+    bool _features_wait_incoming;
+    bool backend_transfer;
+
     uint32_t busyloop_timeout;
     uint64_t max_queues;
     uint64_t backend_cap;
@@ -592,4 +595,8 @@ extern const VMStateDescription 
vmstate_backend_transfer_vhost_inflight;
     VMSTATE_STRUCT_POINTER(_field, _state, vmstate_inflight, \
                            struct vhost_inflight)
 
+extern const VMStateDescription vmstate_vhost_dev;
+#define VMSTATE_BACKEND_TRANSFER_VHOST(_field, _state) \
+    VMSTATE_STRUCT(_field, _state, 0, vmstate_vhost_dev, struct vhost_dev)
+
 #endif
-- 
2.48.1


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