feat: Add seqpacket support

Modify the multiplexer and vsock backend to be able to
handle vsock seqpacket connections based on the passed config parameter

Co-authored-by: aerosouund <aerosound161@gmail.com>
Signed-off-by: aerosouund <aerosound161@gmail.com>

Author: aerosouund

CHANGELOG.md

@@ -12,6 +12,10 @@ and this project adheres to
 
 ### Changed
 
+- [#5595](https://github.com/firecracker-microvm/firecracker/pull/5595): Added `vsock_type` 
+field to the vsock device API to denote the type of the underlying socket. Can be `stream`
+or `seqpacket`
+
 ### Deprecated
 
 ### Removed

Cargo.lock

@@ -33,6 +33,7 @@ or_fun_call = "warn"
 
 [profile.dev]
 panic = "abort"
+incremental = true
 
 [profile.release]
 panic = "abort"

Cargo.toml

@@ -46,6 +46,8 @@ serde = { version = "1.0.228", features = ["derive", "rc"] }
 serde_json = "1.0.145"
 slab = "0.4.11"
 thiserror = "2.0.17"
+timerfd = "1.5.0"
+uds = "0.4.2"
 userfaultfd = "0.9.0"
 utils = { path = "../utils" }
 uuid = "1.19.0"

src/vmm/Cargo.toml

@@ -941,7 +941,7 @@ pub(crate) mod tests {
         vsock_config: VsockDeviceConfig,
     ) {
         let vsock_dev_id = VSOCK_DEV_ID.to_owned();
-        let vsock = VsockBuilder::create_unixsock_vsock(vsock_config).unwrap();
+        let vsock = VsockBuilder::create_unixsock_vsock(&vsock_config).unwrap();
         let vsock = Arc::new(Mutex::new(vsock));
 
         attach_unixsock_vsock_device(

src/vmm/src/builder.rs

@@ -665,7 +665,7 @@ mod tests {
     use crate::vmm_config::memory_hotplug::MemoryHotplugConfig;
     use crate::vmm_config::net::NetworkInterfaceConfig;
     use crate::vmm_config::pmem::PmemConfig;
-    use crate::vmm_config::vsock::VsockDeviceConfig;
+    use crate::vmm_config::vsock::{VsockDeviceConfig, VsockType};
 
     #[test]
     fn test_device_manager_persistence() {
@@ -723,6 +723,7 @@ mod tests {
                 vsock_id: Some(vsock_dev_id.to_string()),
                 guest_cid: 3,
                 uds_path: tmp_sock_file.as_path().to_str().unwrap().to_string(),
+                vsock_type: VsockType::Stream,
             };
             insert_vsock_device(&mut vmm, &mut cmdline, &mut event_manager, vsock_config);
             // Add an entropy device.

src/vmm/src/device_manager/pci_mngr.rs

@@ -636,7 +636,7 @@ mod tests {
     use crate::vmm_config::memory_hotplug::MemoryHotplugConfig;
     use crate::vmm_config::net::NetworkInterfaceConfig;
     use crate::vmm_config::pmem::PmemConfig;
-    use crate::vmm_config::vsock::VsockDeviceConfig;
+    use crate::vmm_config::vsock::{VsockDeviceConfig, VsockType};
 
     impl<T> PartialEq for VirtioDeviceState<T> {
         fn eq(&self, other: &VirtioDeviceState<T>) -> bool {
@@ -734,6 +734,7 @@ mod tests {
                 vsock_id: Some(vsock_dev_id.to_string()),
                 guest_cid: 3,
                 uds_path: tmp_sock_file.as_path().to_str().unwrap().to_string(),
+                vsock_type: VsockType::Stream,
             };
             insert_vsock_device(&mut vmm, &mut cmdline, &mut event_manager, vsock_config);
             // Add an entropy device.

src/vmm/src/device_manager/persist.rs

@@ -269,6 +269,7 @@ mod tests {
     use crate::devices::virtio::transport::mmio::tests::DummyDevice;
     use crate::devices::virtio::vsock::{Vsock, VsockUnixBackend};
     use crate::snapshot::Snapshot;
+    use crate::vmm_config::vsock::VsockType;
 
     const DEFAULT_QUEUE_MAX_SIZE: u16 = 256;
     impl Default for QueueState {
@@ -486,7 +487,7 @@ mod tests {
         // Remove the file so the path can be used by the socket.
         temp_uds_path.remove().unwrap();
         let uds_path = String::from(temp_uds_path.as_path().to_str().unwrap());
-        let backend = VsockUnixBackend::new(guest_cid, uds_path).unwrap();
+        let backend = VsockUnixBackend::new(guest_cid, uds_path, VsockType::Stream).unwrap();
         let vsock = Vsock::new(guest_cid, backend).unwrap();
         let vsock = Arc::new(Mutex::new(vsock));
         let mmio_transport =

src/vmm/src/devices/virtio/persist.rs

@@ -95,6 +95,7 @@ use crate::devices::virtio::vsock::metrics::METRICS;
 use crate::devices::virtio::vsock::packet::{VsockPacketHeader, VsockPacketRx, VsockPacketTx};
 use crate::logger::IncMetric;
 use crate::utils::wrap_usize_to_u32;
+use crate::vmm_config::vsock::VsockType;
 
 /// Trait that vsock connection backends need to implement.
 ///
@@ -139,6 +140,8 @@ pub struct VsockConnection<S: VsockConnectionBackend> {
     /// Instant when this connection should be scheduled for immediate termination, due to some
     /// timeout condition having been fulfilled.
     expiry: Option<Instant>,
+    /// Vsock type (stream or seqpacket)
+    vsock_type: VsockType,
 }
 
 impl<S> VsockChannel for VsockConnection<S>
@@ -509,6 +512,7 @@ where
         local_port: u32,
         peer_port: u32,
         peer_buf_alloc: u32,
+        vsock_type: VsockType,
     ) -> Self {
         Self {
             local_cid,
@@ -525,6 +529,7 @@ where
             last_fwd_cnt_to_peer: Wrapping(0),
             pending_rx: PendingRxSet::from(PendingRx::Response),
             expiry: None,
+            vsock_type,
         }
     }
 
@@ -535,6 +540,7 @@ where
         peer_cid: u64,
         local_port: u32,
         peer_port: u32,
+        vsock_type: VsockType,
     ) -> Self {
         Self {
             local_cid,
@@ -551,6 +557,7 @@ where
             last_fwd_cnt_to_peer: Wrapping(0),
             pending_rx: PendingRxSet::from(PendingRx::Request),
             expiry: None,
+            vsock_type,
         }
     }
 
@@ -671,9 +678,12 @@ where
             .set_dst_cid(self.peer_cid)
             .set_src_port(self.local_port)
             .set_dst_port(self.peer_port)
-            .set_type(uapi::VSOCK_TYPE_STREAM)
             .set_buf_alloc(defs::CONN_TX_BUF_SIZE)
             .set_fwd_cnt(self.fwd_cnt.0);
+        match self.vsock_type {
+            VsockType::Seqpacket => hdr.set_type(uapi::VSOCK_TYPE_SEQPACKET),
+            VsockType::Stream => hdr.set_type(uapi::VSOCK_TYPE_STREAM),
+        };
     }
 }
 
@@ -882,9 +892,15 @@ mod tests {
                     LOCAL_PORT,
                     PEER_PORT,
                     PEER_BUF_ALLOC,
+                    VsockType::Stream,
                 ),
                 ConnState::LocalInit => VsockConnection::<TestStream>::new_local_init(
-                    stream, LOCAL_CID, PEER_CID, LOCAL_PORT, PEER_PORT,
+                    stream,
+                    LOCAL_CID,
+                    PEER_CID,
+                    LOCAL_PORT,
+                    PEER_PORT,
+                    VsockType::Stream,
                 ),
                 ConnState::Established => {
                     let mut conn = VsockConnection::<TestStream>::new_peer_init(
@@ -894,6 +910,7 @@ mod tests {
                         LOCAL_PORT,
                         PEER_PORT,
                         PEER_BUF_ALLOC,
+                        VsockType::Stream,
                     );
                     assert!(conn.has_pending_rx());
                     conn.recv_pkt(&mut rx_pkt).unwrap();