feat(control): add ExportZone and ImportZone RPCs

protect/control/v1/common.proto

@@ -132,6 +132,28 @@ enum ZoneVirtualizationBackend {
   ZONE_VIRTUALIZATION_BACKEND_KVM = 4;
 }
 
+// Hypervisor family a zone snapshot was exported from. A snapshot may only be
+// imported on a host running the same backend: the guest-state records inside
+// it are backend-private, so a Xen stream carries nothing a KVM host can act
+// on, and vice versa. The tag is checked before any of that state is
+// interpreted, which is what lets a second backend be added later without
+// either being able to consume the other's stream.
+enum ZoneSnapshotBackend {
+  ZONE_SNAPSHOT_BACKEND_UNKNOWN = 0;
+  ZONE_SNAPSHOT_BACKEND_XEN_PV = 1;
+  ZONE_SNAPSHOT_BACKEND_XEN_PVH = 2;
+  ZONE_SNAPSHOT_BACKEND_KVM = 3;
+}
+
+// Guest instruction set a zone snapshot was exported for. Held separately from
+// the backend: one backend spans architectures whose guest state has nothing in
+// common.
+enum ZoneSnapshotArch {
+  ZONE_SNAPSHOT_ARCH_UNKNOWN = 0;
+  ZONE_SNAPSHOT_ARCH_X86_64 = 1;
+  ZONE_SNAPSHOT_ARCH_AARCH64 = 2;
+}
+
 // Strategy used when expanding the selected node set beyond the seed node.
 // - UNSPECIFIED is treated as COMPACT.
 // - COMPACT: Expand to the nearest unselected NUMA node by SLIT distance from the already-selected set, tie-breaking by most free memory.
@@ -261,6 +283,7 @@ enum ZoneState {
   ZONE_STATE_SUSPENDED = 9;
   ZONE_STATE_RESUMING = 10;
   ZONE_STATE_FORKING = 11;
+  ZONE_STATE_IMPORTING = 12;
 }
 
 enum ZoneNetworkIpVersion {

protect/control/v1/control.proto

@@ -31,6 +31,8 @@ service ControlService {
   rpc SuspendZone(SuspendZoneRequest) returns (SuspendZoneReply);
   rpc ResumeZone(ResumeZoneRequest) returns (ResumeZoneReply);
   rpc ForkZone(ForkZoneRequest) returns (ForkZoneReply);
+  rpc ExportZone(ExportZoneRequest) returns (stream ExportZoneReply);
+  rpc ImportZone(stream ImportZoneRequest) returns (ImportZoneReply);
 
   rpc ResolveZoneId(ResolveZoneIdRequest) returns (ResolveZoneIdReply);
   rpc ResolveZoneIds(ResolveZoneIdsRequest) returns (ResolveZoneIdsReply);
@@ -145,6 +147,83 @@ message ForkZoneReply {
   string zone_id = 1;
 }
 
+// Exports a zone's complete state -- vcpus, guest memory, hypervisor
+// configuration, device topology, the contents of its writable disks, and the
+// zone's own control-plane record and workloads -- as a snapshot: a stream of
+// opaque bytes the caller stores and later hands back to `ImportZone`.
+//
+// The zone is cooperatively suspended for the export and resumed afterwards
+// unless `leave_suspended` is set, so a snapshot is a consistent point rather
+// than a smear of a running guest.
+message ExportZoneRequest {
+  reserved 4;
+  reserved "include_disk_contents";
+
+  string zone_id = 1;
+  // Leave the zone suspended once the export completes instead of resuming it.
+  // Use this when the snapshot is about to become the live copy elsewhere.
+  bool leave_suspended = 2;
+  // Compress record payloads. Guest memory compresses well; the cost is host
+  // CPU during the export.
+  bool compress = 3;
+}
+
+// Streamed reply for `ExportZone`. The first message carries `start`,
+// describing the snapshot about to be streamed; then `chunk`s carrying its
+// bytes in order; then a final `complete`. The concatenation of every `chunk`
+// is the snapshot, and nothing else in the stream belongs in the stored bytes.
+message ExportZoneReply {
+  oneof reply {
+    ExportZoneStart start = 1;
+    bytes chunk = 2;
+    ExportZoneComplete complete = 3;
+  }
+}
+
+message ExportZoneStart {
+  string zone_id = 1;
+  ZoneSnapshotBackend backend = 2;
+  ZoneSnapshotArch arch = 3;
+  uint32 format_version = 4;
+}
+
+// Closes the reply stream once the export is complete, so a caller can check
+// that the snapshot it wrote is as long as what the daemon sent.
+message ExportZoneComplete {
+  uint64 total_bytes = 1;
+}
+
+// Recreates a zone from a snapshot produced by `ExportZone`. The first message
+// must carry `start`; every message after it carries a `chunk` of the
+// snapshot, in the order it was received.
+//
+// The daemon checks the snapshot against this host before acting on any of the
+// guest state it carries: the backend and architecture must match, and the
+// guest's CPU, clock, zone agent and hypervisor state must be ones this host
+// can continue. Read-only images the snapshot references by path must exist
+// here unchanged in size. A refusal names every incompatibility found.
+message ImportZoneRequest {
+  oneof request {
+    ImportZoneStart start = 1;
+    bytes chunk = 2;
+  }
+}
+
+message ImportZoneStart {
+  reserved 3;
+  reserved "allow_foreign_host";
+
+  // Overrides the zone name recorded in the snapshot. Empty keeps it.
+  string name = 1;
+  // Import under this zone id instead of a freshly allocated one. Empty
+  // allocates a new id, which is what lets one snapshot seed many zones.
+  string zone_id = 2;
+}
+
+message ImportZoneReply {
+  string zone_id = 1;
+}
+
 // Resolves zone "friendly name" to a singular zone UUID, if possible. Matching is exact.
 // See also `ResolveZoneIdsRequest` (plural).
 message ResolveZoneIdRequest {