VMM: networking mode management

dstack/dstack-mr/cli/src/main.rs

@@ -66,6 +66,10 @@ struct MachineConfig {
     #[arg(long, default_value = "0")]
     num_nvswitches: u32,
 
+    /// Number of virtio-net NICs
+    #[arg(long, default_value = "1")]
+    num_nics: u32,
+
     /// Disable hotplug
     #[arg(long, default_value = "false")]
     hotplug_off: Bool,
@@ -133,6 +137,7 @@ fn main() -> Result<()> {
                 .hugepages(config.hugepages)
                 .num_gpus(config.num_gpus)
                 .num_nvswitches(config.num_nvswitches)
+                .num_nics(config.num_nics)
                 .hotplug_off(config.hotplug_off)
                 .root_verity(config.root_verity)
                 .maybe_qemu_version(config.qemu_version.clone())

dstack/dstack-mr/src/acpi.rs

@@ -55,10 +55,18 @@ impl Machine<'_> {
             &format!("file={dummy_disk},if=none,id=hd1,format=raw,readonly=on"),
             "-device",
             "virtio-blk-pci,drive=hd1",
-            "-netdev",
-            "user,id=net0",
-            "-device",
-            "virtio-net-pci,netdev=net0",
+        ]);
+
+        // One virtio-net-pci per NIC. Emitted at the same position and, for the
+        // default single-NIC case, with the exact same args as the previous
+        // hardcoded layout so RTMR0 stays byte-for-byte unchanged.
+        for i in 0..self.num_nics {
+            cmd.arg("-netdev").arg(format!("user,id=net{i}"));
+            cmd.arg("-device")
+                .arg(format!("virtio-net-pci,netdev=net{i}"));
+        }
+
+        cmd.args([
             "-object",
             "tdx-guest,id=tdx",
             "-device",

dstack/dstack-mr/src/machine.rs

@@ -28,6 +28,11 @@ pub struct Machine<'a> {
     pub hugepages: bool,
     pub num_gpus: u32,
     pub num_nvswitches: u32,
+    /// Number of virtio-net NICs. Each NIC contributes a PCI device to the
+    /// ACPI/DSDT layout measured into RTMR0. Defaults to 1 so callers that
+    /// predate this field keep the historical single-NIC layout.
+    #[builder(default = 1)]
+    pub num_nics: u32,
     pub hotplug_off: bool,
     pub root_verity: bool,
     #[builder(default)]

dstack/dstack-mr/src/tdx.rs

@@ -82,6 +82,7 @@ fn select_mrtd(measurement: &TdxOsImageMeasurement, vm_config: &VmConfig) -> Res
         })
         .hugepages(vm_config.hugepages)
         .num_gpus(vm_config.num_gpus)
+        .num_nics(vm_config.num_nics)
         .num_nvswitches(vm_config.num_nvswitches)
         .host_share_mode(vm_config.host_share_mode.clone())
         .ovmf_variant(measurement.tdvf.ovmf_variant)
@@ -472,6 +473,7 @@ pub fn tdx_measurements_for_image_dir_without_rtmr0(
         })
         .hugepages(vm_config.hugepages)
         .num_gpus(vm_config.num_gpus)
+        .num_nics(vm_config.num_nics)
         .num_nvswitches(vm_config.num_nvswitches)
         .host_share_mode(vm_config.host_share_mode.clone())
         .ovmf_variant(ovmf_variant)
@@ -567,6 +569,7 @@ pub fn tdx_measurements_for_image_dir_with_acpi_hashes(
         })
         .hugepages(vm_config.hugepages)
         .num_gpus(vm_config.num_gpus)
+        .num_nics(vm_config.num_nics)
         .num_nvswitches(vm_config.num_nvswitches)
         .host_share_mode(vm_config.host_share_mode.clone())
         .ovmf_variant(ovmf_variant)

dstack/dstack-types/src/lib.rs

@@ -643,6 +643,14 @@ impl SysConfig {
     }
 }
 
+fn default_num_nics() -> u32 {
+    1
+}
+
+fn is_default_num_nics(n: &u32) -> bool {
+    *n == default_num_nics()
+}
+
 #[derive(Deserialize, Serialize, Debug, Clone)]
 pub struct VmConfig {
     #[serde(with = "hex_bytes", default)]
@@ -666,6 +674,16 @@ pub struct VmConfig {
     pub num_gpus: u32,
     #[serde(default)]
     pub num_nvswitches: u32,
+    /// Number of virtio-net NICs attached to the guest. Each NIC adds a PCI
+    /// device to the ACPI/DSDT layout and therefore changes RTMR0, so it must
+    /// be measured. Defaults to 1 and is omitted from the serialized form when
+    /// equal to 1, keeping configs (and their cache keys / hashes) produced
+    /// before this field existed byte-for-byte stable.
+    #[serde(
+        default = "default_num_nics",
+        skip_serializing_if = "is_default_num_nics"
+    )]
+    pub num_nics: u32,
     #[serde(default)]
     pub hotplug_off: bool,
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -1529,3 +1547,44 @@ impl Platform {
         }
     }
 }
+
+#[cfg(test)]
+mod vm_config_num_nics_tests {
+    use super::VmConfig;
+
+    fn legacy_json() -> serde_json::Value {
+        serde_json::json!({
+            "cpu_count": 4,
+            "memory_size": 4294967296u64,
+            "num_gpus": 0,
+            "num_nvswitches": 0,
+        })
+    }
+
+    #[test]
+    fn legacy_config_without_num_nics_defaults_to_one() {
+        let cfg: VmConfig = serde_json::from_value(legacy_json()).unwrap();
+        assert_eq!(cfg.num_nics, 1);
+    }
+
+    #[test]
+    fn single_nic_is_omitted_to_keep_cache_key_stable() {
+        // A config with the default single NIC must serialize identically to a
+        // legacy config, so the verifier's measurement cache key (a hash of the
+        // serialized VmConfig) is unchanged for existing deployments.
+        let cfg: VmConfig = serde_json::from_value(legacy_json()).unwrap();
+        let serialized = serde_json::to_value(&cfg).unwrap();
+        assert!(
+            serialized.get("num_nics").is_none(),
+            "num_nics must be omitted when equal to 1, got {serialized}"
+        );
+    }
+
+    #[test]
+    fn multi_nic_is_serialized() {
+        let mut cfg: VmConfig = serde_json::from_value(legacy_json()).unwrap();
+        cfg.num_nics = 2;
+        let serialized = serde_json::to_value(&cfg).unwrap();
+        assert_eq!(serialized.get("num_nics").and_then(|v| v.as_u64()), Some(2));
+    }
+}

dstack/verifier/src/verification.rs

@@ -312,6 +312,7 @@ impl CvmVerifier {
             })
             .hugepages(vm_config.hugepages)
             .num_gpus(vm_config.num_gpus)
+            .num_nics(vm_config.num_nics)
             .num_nvswitches(vm_config.num_nvswitches)
             .host_share_mode(vm_config.host_share_mode.clone())
             .ovmf_variant(ovmf_variant)

dstack/vmm/rpc/proto/vmm_rpc.proto

@@ -37,6 +37,21 @@ message VmInfo {
   string image_version = 13;
   // Events
   repeated GuestEvent events = 14;
+  // Effective network interfaces resolved against node config.
+  repeated NetworkInterfaceStatus interfaces = 15;
+}
+
+// Runtime status of a resolved VM network interface.
+message NetworkInterfaceStatus {
+  // Product-facing mode: "user", "bridge", or "custom".
+  string mode = 1;
+  // QEMU/network backend shape: "slirp", "tap_bridge", or "custom".
+  string backend = 2;
+  string mac = 3;
+  // Linux bridge name for tap_bridge backend.
+  optional string bridge_name = 4;
+  // QEMU netdev id, e.g. "net0".
+  optional string netdev_id = 5;
 }
 
 // Structured log or lifecycle event emitted by the guest or runtime.
@@ -101,12 +116,16 @@ message VmConfiguration {
   bool no_tee = 17;
   // Per-VM networking mode override (if unset, uses global cvm.networking).
   optional NetworkingConfig networking = 18;
+  // Per-VM networking overrides. If set, wins over singular networking.
+  repeated NetworkingConfig networks = 19;
 }
 
 // Per-VM networking configuration.
 message NetworkingConfig {
   // Networking mode: "bridge", "user"
   string mode = 1;
+  // Per-VM bridge interface name. Empty = node default bridge.
+  string bridge_name = 2;
 }
 
 // Requested GPU layout for a CVM.
@@ -163,6 +182,10 @@ message UpdateVmRequest {
   optional string image = 17;
   // Disable or re-enable TEE for an existing VM.
   optional bool no_tee = 18;
+  // Optional update networking.
+  bool update_networking = 19;
+  // Networking list. Empty + update_networking=true resets to node default.
+  repeated NetworkingConfig networks = 20;
 }
 
 // Parameters for listing CVMs with pagination and keyword filtering.
@@ -262,11 +285,20 @@ message ResourcesSettings {
   uint32 max_allocable_memory_in_mb = 3; // in MB.
 }
 
+message NetworkingCapabilities {
+  repeated string supported_modes = 1;
+  string default_mode = 2;
+  bool forward_service_enabled = 3;
+  // Default bridge configured in vmm.toml [cvm.networking].bridge.
+  string default_bridge = 4;
+}
+
 // Aggregated metadata exposed through GetMeta.
 message GetMetaResponse {
   KmsSettings kms = 1;
   GatewaySettings gateway = 2;
   ResourcesSettings resources = 3;
+  NetworkingCapabilities networking = 4;
 }
 
 // Build information for the running VMM binary.