[PATCH v4 4/5] vhost-user-scsi: start vhost when guest kicks

[Li Feng]

Let's keep the same behavior as vhost-user-blk.

Some old guests kick virtqueue before setting VIRTIO_CONFIG_S_DRIVER_OK.

Signed-off-by: Li Feng <fen...@smartx.com>
---
 hw/scsi/vhost-user-scsi.c | 51 +++++++++++++++++++++++++++++++++++----
 1 file changed, 46 insertions(+), 5 deletions(-)

diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
index dc109154ad..0effbb4787 100644
--- a/hw/scsi/vhost-user-scsi.c
+++ b/hw/scsi/vhost-user-scsi.c
@@ -115,8 +115,48 @@ static void vhost_user_scsi_reset(VirtIODevice *vdev)
     }
 }
 
-static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+static void vhost_user_scsi_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
+    VHostUserSCSI *s = (VHostUserSCSI *)vdev;
+    DeviceState *dev = &s->parent_obj.parent_obj.parent_obj.parent_obj;
+    VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
+
+    Error *local_err = NULL;
+    int i, ret;
+
+    if (!vdev->start_on_kick) {
+        return;
+    }
+
+    if (!s->connected) {
+        return;
+    }
+
+    if (vhost_dev_is_started(&vsc->dev)) {
+        return;
+    }
+
+    /*
+     * Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
+     * vhost here instead of waiting for .set_status().
+     */
+    ret = vhost_user_scsi_start(s, &local_err);
+    if (ret < 0) {
+        error_reportf_err(local_err, "vhost-user-scsi: vhost start failed: ");
+        qemu_chr_fe_disconnect(&vs->conf.chardev);
+        return;
+    }
+
+    /* Kick right away to begin processing requests already in vring */
+    for (i = 0; i < vsc->dev.nvqs; i++) {
+        VirtQueue *kick_vq = virtio_get_queue(vdev, i);
+
+        if (!virtio_queue_get_desc_addr(vdev, i)) {
+            continue;
+        }
+        event_notifier_set(virtio_queue_get_host_notifier(kick_vq));
+    }
 }
 
 static int vhost_user_scsi_connect(DeviceState *dev, Error **errp)
@@ -198,7 +238,8 @@ static void vhost_user_scsi_event(void *opaque, 
QEMUChrEvent event)
     case CHR_EVENT_CLOSED:
         /* defer close until later to avoid circular close */
         vhost_user_async_close(dev, &vs->conf.chardev, &vsc->dev,
-                               vhost_user_scsi_disconnect);
+                               vhost_user_scsi_disconnect,
+                               vhost_user_scsi_event);
         break;
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
@@ -246,9 +287,9 @@ static void vhost_user_scsi_realize(DeviceState *dev, Error 
**errp)
         return;
     }
 
-    virtio_scsi_common_realize(dev, vhost_dummy_handle_output,
-                               vhost_dummy_handle_output,
-                               vhost_dummy_handle_output, &err);
+    virtio_scsi_common_realize(dev, vhost_user_scsi_handle_output,
+                               vhost_user_scsi_handle_output,
+                               vhost_user_scsi_handle_output, &err);
     if (err != NULL) {
         error_propagate(errp, err);
         return;
-- 
2.41.0