virtio-devices: vhost_user: Enable snapshot/restore for vhost-user-*

Enable the DEVICE_STATE protocol feature negotiation for all vhost-user
devices (block, fs, net, and generic). Restoring the state (including
the backend state if present) and vrings.

Signed-off-by: Rob Bradford <rbradford@meta.com>

virtio-devices/src/vhost_user/blk.rs

@@ -72,6 +72,7 @@ impl Blk {
             vu_num_queues,
             config,
             paused,
+            vring_bases,
         ) = if let Some(state) = state {
             info!("Restoring vhost-user-block {id}");
 
@@ -80,6 +81,8 @@ impl Blk {
                 state.acked_protocol_features,
             )?;
 
+            vu.restore_state(&state)?;
+
             (
                 state.avail_features,
                 state.acked_features,
@@ -87,6 +90,7 @@ impl Blk {
                 state.vu_num_queues,
                 state.config,
                 true,
+                state.vring_bases,
             )
         } else {
             // Filling device and vring features VMM supports.
@@ -111,7 +115,8 @@ impl Blk {
                 | VhostUserProtocolFeatures::CONFIGURE_MEM_SLOTS
                 | VhostUserProtocolFeatures::REPLY_ACK
                 | VhostUserProtocolFeatures::INFLIGHT_SHMFD
-                | VhostUserProtocolFeatures::LOG_SHMFD;
+                | VhostUserProtocolFeatures::LOG_SHMFD
+                | VhostUserProtocolFeatures::DEVICE_STATE;
 
             let (acked_features, acked_protocol_features) =
                 vu.negotiate_features_vhost_user(avail_features, avail_protocol_features)?;
@@ -160,6 +165,7 @@ impl Blk {
                 num_queues,
                 config,
                 false,
+                None,
             )
         };
 
@@ -179,6 +185,7 @@ impl Blk {
                 acked_protocol_features,
                 socket_path: vu_cfg.socket,
                 vu_num_queues,
+                vring_bases,
                 ..Default::default()
             },
             id,

virtio-devices/src/vhost_user/fs.rs

@@ -101,6 +101,7 @@ impl Fs {
             vu_num_queues,
             config,
             paused,
+            vring_bases,
         ) = if let Some(state) = state {
             info!("Restoring vhost-user-fs {id}");
 
@@ -109,6 +110,8 @@ impl Fs {
                 state.acked_protocol_features,
             )?;
 
+            vu.restore_state(&state)?;
+
             (
                 state.avail_features,
                 state.acked_features,
@@ -116,6 +119,7 @@ impl Fs {
                 state.vu_num_queues,
                 state.config,
                 true,
+                state.vring_bases,
             )
         } else {
             // Filling device and vring features VMM supports.
@@ -125,7 +129,8 @@ impl Fs {
                 | VhostUserProtocolFeatures::CONFIGURE_MEM_SLOTS
                 | VhostUserProtocolFeatures::REPLY_ACK
                 | VhostUserProtocolFeatures::INFLIGHT_SHMFD
-                | VhostUserProtocolFeatures::LOG_SHMFD;
+                | VhostUserProtocolFeatures::LOG_SHMFD
+                | VhostUserProtocolFeatures::DEVICE_STATE;
 
             let (acked_features, acked_protocol_features) =
                 vu.negotiate_features_vhost_user(avail_features, avail_protocol_features)?;
@@ -168,6 +173,7 @@ impl Fs {
                 num_queues,
                 config,
                 false,
+                None,
             )
         };
 
@@ -187,6 +193,7 @@ impl Fs {
                 acked_protocol_features,
                 socket_path: path.to_string(),
                 vu_num_queues,
+                vring_bases,
                 ..Default::default()
             },
             id,

virtio-devices/src/vhost_user/generic_vhost_user.rs

@@ -68,20 +68,29 @@ impl GenericVhostUser {
         // Connect to the vhost-user socket.
         let mut vu = VhostUserHandle::connect_vhost_user(false, path, num_queues as u64, false)?;
 
-        let (avail_features, acked_features, acked_protocol_features, vu_num_queues, paused) =
+        let (
-            if let Some(state) = state {
+            avail_features,
+            acked_features,
+            acked_protocol_features,
+            vu_num_queues,
+            paused,
+            vring_bases,
+        ) = if let Some(state) = state {
             info!("Restoring generic vhost-user {id}");
             vu.set_protocol_features_vhost_user(
                 state.acked_features,
                 state.acked_protocol_features,
             )?;
 
+            vu.restore_state(&state)?;
+
             (
                 state.avail_features,
                 state.acked_features,
                 state.acked_protocol_features,
                 state.vu_num_queues,
                 true,
+                state.vring_bases,
             )
         } else {
             let avail_protocol_features = VhostUserProtocolFeatures::CONFIG
@@ -89,7 +98,8 @@ impl GenericVhostUser {
                 | VhostUserProtocolFeatures::CONFIGURE_MEM_SLOTS
                 | VhostUserProtocolFeatures::REPLY_ACK
                 | VhostUserProtocolFeatures::INFLIGHT_SHMFD
-                    | VhostUserProtocolFeatures::LOG_SHMFD;
+                | VhostUserProtocolFeatures::LOG_SHMFD
+                | VhostUserProtocolFeatures::DEVICE_STATE;
 
             let avail_features = super::DEFAULT_VIRTIO_FEATURES;
 
@@ -100,8 +110,7 @@ impl GenericVhostUser {
                 if acked_protocol_features & VhostUserProtocolFeatures::MQ.bits() != 0 {
                     vu.socket_handle()
                         .get_queue_num()
-                            .map_err(Error::VhostUserGetQueueMaxNum)?
+                        .map_err(Error::VhostUserGetQueueMaxNum)? as usize
-                            as usize
                 } else {
                     num_queues
                 };
@@ -124,6 +133,7 @@ since the backend only supports {backend_num_queues}\n",
                 acked_protocol_features,
                 num_queues,
                 false,
+                None,
             )
         };
 
@@ -143,6 +153,7 @@ since the backend only supports {backend_num_queues}\n",
                 acked_protocol_features,
                 socket_path: path.to_string(),
                 vu_num_queues,
+                vring_bases,
                 ..Default::default()
             },
             id,

virtio-devices/src/vhost_user/net.rs

@@ -82,6 +82,7 @@ impl Net {
             vu_num_queues,
             config,
             paused,
+            vring_bases,
         ) = if let Some(state) = state {
             info!("Restoring vhost-user-net {id}");
 
@@ -95,6 +96,8 @@ impl Net {
                 state.acked_protocol_features,
             )?;
 
+            vu.restore_state(&state)?;
+
             // If the control queue feature has been negotiated, let's
             // increase the number of queues.
             if state.acked_features & (1 << VIRTIO_NET_F_CTRL_VQ) != 0 {
@@ -108,6 +111,7 @@ impl Net {
                 state.vu_num_queues,
                 state.config,
                 true,
+                state.vring_bases,
             )
         } else {
             // Filling device and vring features VMM supports.
@@ -144,7 +148,8 @@ impl Net {
                 | VhostUserProtocolFeatures::CONFIGURE_MEM_SLOTS
                 | VhostUserProtocolFeatures::REPLY_ACK
                 | VhostUserProtocolFeatures::INFLIGHT_SHMFD
-                | VhostUserProtocolFeatures::LOG_SHMFD;
+                | VhostUserProtocolFeatures::LOG_SHMFD
+                | VhostUserProtocolFeatures::DEVICE_STATE;
 
             let (mut acked_features, acked_protocol_features) =
                 vu.negotiate_features_vhost_user(avail_features, avail_protocol_features)?;
@@ -187,6 +192,7 @@ impl Net {
                 vu_num_queues,
                 config,
                 false,
+                None,
             )
         };
 
@@ -208,6 +214,7 @@ impl Net {
                 socket_path: vu_cfg.socket,
                 vu_num_queues,
                 server,
+                vring_bases,
                 ..Default::default()
             },
             config,