devices: vhost-user: Vring should be enabled after initialization

Based on cloud-hypervisor 97699a521fbdffd0166bc55be37c13bb6bc1949f.

> vm-virtio: vhost-user: Vring should be enabled after initialization
>
> As mentioned in the vhost-user specification, each ring is initialized
> in a stopped state. This means each ring should be enabled only after
> it has been correctly initialized.

2 files changed, 4 insertions, 11 deletions

diff --git a/devices/src/virtio/vhost_user/mod.rs b/devices/src/virtio/vhost_user/mod.rs
index a4ebb6d..a032d90 100644
--- a/devices/src/virtio/vhost_user/mod.rs
+++ b/devices/src/virtio/vhost_user/mod.rs
@@ -68,8 +68,6 @@ pub enum Error {
     VhostUserSetVringKick(VhostError),
     /// Set vring enable failed.
     VhostUserSetVringEnable(VhostError),
-    /// Vhost-user setup vring failed.
-    VhostUserSetupVringFailed,
     /// Failed to create vhost eventfd.
     VhostIrqCreate(std::io::Error),
     /// Failed to read vhost eventfd.
diff --git a/devices/src/virtio/vhost_user/vu_common_ctrl.rs b/devices/src/virtio/vhost_user/vu_common_ctrl.rs
index 38b7b4f..b594b17 100644
--- a/devices/src/virtio/vhost_user/vu_common_ctrl.rs
+++ b/devices/src/virtio/vhost_user/vu_common_ctrl.rs
@@ -87,6 +87,9 @@ pub fn setup_vhost_user_vring(
 
         vu.set_vring_kick(queue_index, &queue_evts[queue_index])
             .map_err(Error::VhostUserSetVringKick)?;
+
+        vu.set_vring_enable(queue_index, true)
+            .map_err(Error::VhostUserSetVringEnable)?;
     }
 
     Ok(vu_interrupt_list)
@@ -99,17 +102,9 @@ pub fn setup_vhost_user(
     queue_evts: Vec<EventFd>,
     acked_features: u64,
 ) -> Result<Vec<(vmm_sys_util::eventfd::EventFd, Queue)>> {
-    for i in 0..queues.len() {
-        vu.set_vring_enable(i, true)
-            .map_err(Error::VhostUserSetVringEnable)?;
-    }
-
     let backend_features = vu.get_features().unwrap();
     vu.set_features(acked_features & backend_features)
         .map_err(Error::VhostUserSetFeatures)?;
 
-    match setup_vhost_user_vring(vu, mem, queues, queue_evts) {
-        Ok(vu_interrupt_list) => Ok(vu_interrupt_list),
-        Err(_) => Err(Error::VhostUserSetupVringFailed),
-    }
+    setup_vhost_user_vring(vu, mem, queues, queue_evts)
 }