feat: Add Seqpacket support

CHANGELOG.md

@@ -10,6 +10,12 @@ and this project adheres to
 
 ### Added
 
+- [#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`
+- [#5595](https://github.com/firecracker-microvm/firecracker/pull/5595): Added
+  `conn_buffer_size` field to denote how many bytes we can internally buffer
+  during receiving large seqpacket packets from the host.
 - [#5323](https://github.com/firecracker-microvm/firecracker/pull/5323): Add
   support for Vsock Unix domain socket path overriding on snapshot restore. More
   information can be found in the

resources/seccomp/aarch64-unknown-linux-musl.json

@@ -323,6 +323,32 @@
                     }
                 ]
             },
+            {
+                "syscall": "socket",
+                "comment": "Called to open the vsock seqpacket UDS (SeqpacketConn::connect and SeqpacketListener::bind)",
+                "args": [
+                    {
+                        "index": 0,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 1,
+                        "comment": "libc::AF_UNIX"
+                    },
+                    {
+                        "index": 1,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 524293,
+                        "comment": "libc::SOCK_SEQPACKET | libc::SOCK_CLOEXEC"
+                    },
+                    {
+                        "index": 2,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 0
+                    }
+                ]
+            },
             {
                 "syscall": "sendto",
                 "comment": "Rust std uses it to write to unix socket"

resources/seccomp/x86_64-unknown-linux-musl.json

@@ -323,6 +323,32 @@
                     }
                 ]
             },
+            {
+                "syscall": "socket",
+                "comment": "Called to open the vsock seqpacket UDS (SeqpacketConn::connect and SeqpacketListener::bind)",
+                "args": [
+                    {
+                        "index": 0,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 1,
+                        "comment": "libc::AF_UNIX"
+                    },
+                    {
+                        "index": 1,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 524293,
+                        "comment": "libc::SOCK_SEQPACKET | libc::SOCK_CLOEXEC"
+                    },
+                    {
+                        "index": 2,
+                        "type": "dword",
+                        "op": "eq",
+                        "val": 0
+                    }
+                ]
+            },
             {
                 "syscall": "sendto",
                 "comment": "Rust std uses it to write to unix socket"

src/firecracker/src/api_server/parsed_request.rs

@@ -946,7 +946,7 @@ pub mod tests {
     fn test_try_from_put_vsock() {
         let (mut sender, receiver) = UnixStream::pair().unwrap();
         let mut connection = HttpConnection::new(receiver);
-        let body = "{ \"vsock_id\": \"string\", \"guest_cid\": 0, \"uds_path\": \"string\" }";
+        let body = "{ \"vsock_id\": \"string\", \"guest_cid\": 0, \"uds_path\": \"string\", \"vsock_type\": \"stream\" }";
         sender
             .write_all(http_request("PUT", "/vsock", Some(body)).as_bytes())
             .unwrap();

src/firecracker/src/api_server/request/vsock.rs

@@ -41,7 +41,8 @@ mod tests {
     fn test_parse_put_vsock_request() {
         let body = r#"{
             "guest_cid": 42,
-            "uds_path": "vsock.sock"
+            "uds_path": "vsock.sock",
+            "vsock_type": "stream"
         }"#;
         parse_put_vsock(&Body::new(body)).unwrap();
 
@@ -57,7 +58,8 @@ mod tests {
         let body = r#"{
             "vsock_id": "foo",
             "guest_cid": 42,
-            "uds_path": "vsock.sock"
+            "uds_path": "vsock.sock",
+            "vsock_type": "stream"
         }"#;
         depr_action_from_req(
             parse_put_vsock(&Body::new(body)).unwrap(),
@@ -66,7 +68,8 @@ mod tests {
 
         let body = r#"{
             "guest_cid": 42,
-            "uds_path": "vsock.sock"
+            "uds_path": "vsock.sock",
+            "vsock_type": "stream"
         }"#;
         let (_, mut parsing_info) = parse_put_vsock(&Body::new(body)).unwrap().into_parts();
         assert!(parsing_info.take_deprecation_message().is_none());

src/firecracker/swagger/firecracker.yaml

@@ -1858,6 +1858,22 @@ definitions:
       uds_path:
         type: string
         description: Path to UNIX domain socket, used to proxy vsock connections.
+      vsock_type:
+        description: Enumeration indicating the type of the underlying socket (stream or seqpacket)
+        type: string
+        enum:
+          - stream
+          - seqpacket
+        default: stream
+      conn_buffer_size:
+        type: integer
+        minimum: 4096
+        maximum: 262144
+        description:
+          The amount in bytes that can be buffered in firecracker if the data in the tx/rx queue is
+          too much to fit in a single descriptor. This parameter is ignored for stream sockets 
+          because connection buffering is a seqpacket only concept. The minimum is 4096 (one 
+          virtqueue descriptor) and the maximum is 256KB (kernel limit)
       vsock_id:
         type: string
         description:

src/vmm/src/builder.rs

@@ -984,7 +984,7 @@ 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/device_manager/pci_mngr.rs

@@ -634,7 +634,7 @@ 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() {
@@ -693,6 +693,8 @@ 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,
+                conn_buffer_size: None,
             };
             insert_vsock_device(&mut vmm, &mut cmdline, &mut event_manager, vsock_config);
             // Add an entropy device.
@@ -803,7 +805,8 @@ mod tests {
   ],
   "vsock": {{
     "guest_cid": 3,
-    "uds_path": "{}"
+    "uds_path": "{}",
+    "vsock_type": "stream"
   }},
   "entropy": {{
     "rate_limiter": null

src/vmm/src/device_manager/persist.rs

@@ -624,7 +624,7 @@ 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 {
@@ -723,6 +723,8 @@ 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,
+                conn_buffer_size: None,
             };
             insert_vsock_device(&mut vmm, &mut cmdline, &mut event_manager, vsock_config);
             // Add an entropy device.
@@ -830,7 +832,8 @@ mod tests {
   ],
   "vsock": {{
     "guest_cid": 3,
-    "uds_path": "{}"
+    "uds_path": "{}",
+    "vsock_type": "stream"
   }},
   "entropy": {{
     "rate_limiter": null

src/vmm/src/devices/virtio/generated/virtio_config.rs

@@ -16,6 +16,7 @@
     clippy::redundant_static_lifetimes
 )]
 
+pub const VIRTIO_VSOCK_F_SEQPACKET: u32 = 1;
 pub const VIRTIO_F_NOTIFY_ON_EMPTY: u32 = 24;
 pub const VIRTIO_F_ANY_LAYOUT: u32 = 27;
 pub const VIRTIO_F_VERSION_1: u32 = 32;

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

@@ -268,6 +268,8 @@ mod tests {
     use crate::devices::virtio::test_utils::default_mem;
     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 {
@@ -481,7 +483,7 @@ 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, None).unwrap();
         let vsock = Vsock::new(guest_cid, backend).unwrap();
         let vsock = Arc::new(Mutex::new(vsock));
         let mmio_transport =