Add vsock cli param

Using an extra CLI parameter, we are able to specify a unix socket
to be used as a VSOCK endpoint for Guest-to-Host communication.

For now, the argument is just the socket path, with a hardcoded
Guest ID. The default value is empty so that the VSOCK endpoint
is not added by default.

Example invocation:

./dbs-cli --kernel-path ./vmlinux \
	  --rootfs ./rootfs.img \
	  --boot-args 'console=ttyS0 tty0 pci=off root=/dev/vda' \
	  --vsock vsock.sock

Signed-off-by: Anastassios Nanos <ananos@nubificus.co.uk>

README.md

@@ -58,6 +58,22 @@ Create a vsock console (communication with sock file)
   --serial-path "/tmp/dbs" ;
 ```
 
+Create a virtio-vsock tunnel for Guest-to-Host communication.
+
+> When the parameter `vsock` is not given, `dbs-cli` will not add a virtio-vsock device.
+> 
+> Otherwise, `dbs-cli` will create a unix socket on the host using the argument
+> specified with the `--vsock` parameter.
+
+```
+./dbs-cli \
+  --log-file dbs-cli.log --log-level ERROR \
+  --kernel-path ~/path/to/kernel/vmlinux.bin \
+  --rootfs ~/path/to/rootfs/bionic.rootfs.ext4 \
+  --boot-args "console=ttyS0 tty0 reboot=k debug panic=1 pci=off root=/dev/vda1" \
+  --vsock /tmp/vsock.sock;
+```
+
 # 2. Usage
 
 ## 1. Exit vm
@@ -90,4 +106,4 @@ make build
 
 # License
 
-`DBS-CLI` is licensed under [Apache License](http://www.apache.org/licenses/LICENSE-2.0), Version 2.0.
+`DBS-CLI` is licensed under [Apache License](http://www.apache.org/licenses/LICENSE-2.0), Version 2.0.

src/cli_instance.rs

@@ -19,7 +19,7 @@ use vmm_sys_util::eventfd::EventFd;
 use dragonball::{
     api::v1::{
         BlockDeviceConfigInfo, BootSourceConfig, InstanceInfo, VmmAction, VmmActionError, VmmData,
-        VmmRequest, VmmResponse,
+        VmmRequest, VmmResponse, VsockDeviceConfigInfo,
     },
     vm::{CpuTopology, VmConfigInfo},
 };
@@ -117,6 +117,20 @@ impl CliInstance {
         self.insert_block_device(block_device_config_info)
             .expect("failed to set block device");
 
+        if !args.create_args.vsock.is_empty() {
+            // VSOCK config
+            let mut vsock_config_info = VsockDeviceConfigInfo::default();
+            vsock_config_info = VsockDeviceConfigInfo {
+                guest_cid: 42, // dummy value
+                uds_path: Some(args.create_args.vsock.to_string()),
+                ..vsock_config_info
+            };
+
+            // set vsock
+            self.insert_vsock(vsock_config_info)
+                .expect("failed to set vsock socket path");
+        }
+
         // start micro-vm
         self.instance_start().expect("failed to start micro-vm");
 
@@ -153,6 +167,14 @@ impl CliInstance {
         Ok(())
     }
 
+    pub fn insert_vsock(&self, vsock_cfg: VsockDeviceConfigInfo) -> Result<()> {
+        self.handle_request(Request::Sync(VmmAction::InsertVsockDevice(
+            vsock_cfg.clone(),
+        )))
+        .with_context(|| format!("Failed to insert vsock device {:?}", vsock_cfg))?;
+        Ok(())
+    }
+
     fn send_request(&self, vmm_action: VmmAction) -> Result<VmmResponse> {
         if let Some(ref to_vmm) = self.to_vmm {
             to_vmm

src/parser/args.rs

@@ -170,6 +170,19 @@ pub struct CreateArgs {
         display_order = 2
     )]
     pub serial_path: String,
+
+    // The path to a vsock socket file
+    // FIXME: add more params:
+    // cid="contextid",socket_path="somepath",gid="guest_id"
+    #[clap(
+        short,
+        long,
+        value_parser,
+        default_value = "",
+        help = "Virtio VSOCK socket path",
+        display_order = 2
+    )]
+    pub vsock: String,
 }
 
 /// Config boot source including rootfs file path