vm-migration: Define the Snapshottable and Transportable traits

A Snapshottable component can snapshot itself and
provide a MigrationSnapshot payload as a result.

A MigrationSnapshot payload is a map of component IDs to a list of
migration sections (MigrationSection). As component can be made of
several Migratable sub-components (e.g. the DeviceManager and its
device objects), a migration snapshot can be made of multiple snapshot
itself.
A snapshot is a list of migration sections, each section being a
component state snapshot. Having multiple sections allows for easier and
backward compatible migration payload extensions.

Once created, a migratable component snapshot may be transported and this
is what the Transportable trait defines, through 2 methods: send and recv.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>

vmm/src/cpu.rs

@@ -26,8 +26,8 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Barrier, Mutex};
 use std::thread;
 use std::{fmt, io, result};
-use vm_device::{Migratable, MigratableError, Pausable, Snapshotable};
 use vm_memory::{Address, GuestAddress, GuestAddressSpace, GuestMemoryAtomic, GuestMemoryMmap};
+use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
 use vmm_sys_util::eventfd::EventFd;
 use vmm_sys_util::signal::{register_signal_handler, SIGRTMIN};
 
@@ -1068,5 +1068,6 @@ impl Pausable for CpuManager {
     }
 }
 
-impl Snapshotable for CpuManager {}
+impl Snapshottable for CpuManager {}
+impl Transportable for CpuManager {}
 impl Migratable for CpuManager {}

vmm/src/device_manager.rs

@@ -51,11 +51,11 @@ use vm_allocator::SystemAllocator;
 use vm_device::interrupt::{
     InterruptIndex, InterruptManager, LegacyIrqGroupConfig, MsiIrqGroupConfig,
 };
-use vm_device::{Migratable, MigratableError, Pausable, Snapshotable};
 use vm_memory::guest_memory::FileOffset;
 use vm_memory::{
     Address, GuestAddress, GuestAddressSpace, GuestRegionMmap, GuestUsize, MmapRegion,
 };
+use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
 #[cfg(feature = "pci_support")]
 use vm_virtio::transport::VirtioPciDevice;
 use vm_virtio::transport::VirtioTransport;
@@ -2373,7 +2373,8 @@ impl Pausable for DeviceManager {
     }
 }
 
-impl Snapshotable for DeviceManager {}
+impl Snapshottable for DeviceManager {}
+impl Transportable for DeviceManager {}
 impl Migratable for DeviceManager {}
 
 #[cfg(feature = "pci_support")]

vmm/src/lib.rs

@@ -27,7 +27,7 @@ use std::path::PathBuf;
 use std::sync::mpsc::{Receiver, RecvError, SendError, Sender};
 use std::sync::{Arc, Mutex};
 use std::{result, thread};
-use vm_device::Pausable;
+use vm_migration::Pausable;
 use vmm_sys_util::eventfd::EventFd;
 
 pub mod api;

vmm/src/memory_manager.rs

@@ -23,6 +23,7 @@ use vm_memory::{
     GuestMemory, GuestMemoryAtomic, GuestMemoryMmap, GuestMemoryRegion, GuestRegionMmap,
     GuestUsize, MmapRegion,
 };
+use vm_migration::{Migratable, Pausable, Snapshottable, Transportable};
 
 const HOTPLUG_COUNT: usize = 8;
 
@@ -884,3 +885,8 @@ impl Aml for MemoryManager {
         bytes
     }
 }
+
+impl Pausable for MemoryManager {}
+impl Snapshottable for MemoryManager {}
+impl Transportable for MemoryManager {}
+impl Migratable for MemoryManager {}

vmm/src/vm.rs

@@ -48,11 +48,11 @@ use std::path::PathBuf;
 use std::sync::{Arc, Mutex, RwLock};
 use std::{result, str, thread};
 use vm_allocator::{GsiApic, SystemAllocator};
-use vm_device::{Migratable, MigratableError, Pausable, Snapshotable};
 use vm_memory::{
     Address, Bytes, GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryMmap,
     GuestMemoryRegion, GuestUsize,
 };
+use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
 use vmm_sys_util::eventfd::EventFd;
 use vmm_sys_util::terminal::Terminal;
 
@@ -966,7 +966,8 @@ impl Pausable for Vm {
     }
 }
 
-impl Snapshotable for Vm {}
+impl Snapshottable for Vm {}
+impl Transportable for Vm {}
 impl Migratable for Vm {}
 
 #[cfg(test)]