virtio-devices: vhost_user: Add snapshot/restore support

Adding the support for snapshot/restore feature for all supported
vhost-user devices.

The complexity of vhost-user-fs device makes it only partially
compatible with the feature. When using the DAX feature, there's no way
to store and remap what was previously mapped in the DAX region. And
when not using the cache region, if the filesystem is mounted, it fails
to be properly restored as this would require a special command to let
the backend know that it must remount what was already mounted before.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

virtio-devices/src/vhost_user/blk.rs

@@ -18,6 +18,8 @@ use std::result;
 use std::sync::{Arc, Barrier, Mutex};
 use std::thread;
 use std::vec::Vec;
+use versionize::{VersionMap, Versionize, VersionizeResult};
+use versionize_derive::Versionize;
 use vhost::vhost_user::message::VhostUserConfigFlags;
 use vhost::vhost_user::message::VHOST_USER_CONFIG_OFFSET;
 use vhost::vhost_user::message::{VhostUserProtocolFeatures, VhostUserVirtioFeatures};
@@ -29,11 +31,22 @@ use virtio_bindings::bindings::virtio_blk::{
     VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_WRITE_ZEROES,
 };
 use vm_memory::{ByteValued, GuestAddressSpace, GuestMemoryAtomic};
-use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
+use vm_migration::{
+    Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable, VersionMapped,
+};
 use vmm_sys_util::eventfd::EventFd;
 
 const DEFAULT_QUEUE_NUMBER: usize = 1;
 
+#[derive(Versionize)]
+pub struct State {
+    pub avail_features: u64,
+    pub acked_features: u64,
+    pub config: VirtioBlockConfig,
+}
+
+impl VersionMapped for State {}
+
 struct SlaveReqHandler {}
 impl VhostUserMasterReqHandler for SlaveReqHandler {}
 
@@ -144,6 +157,20 @@ impl Blk {
             vu_num_queues: num_queues,
         })
     }
+
+    fn state(&self) -> State {
+        State {
+            avail_features: self.common.avail_features,
+            acked_features: self.common.acked_features,
+            config: self.config,
+        }
+    }
+
+    fn set_state(&mut self, state: &State) {
+        self.common.avail_features = state.avail_features;
+        self.common.acked_features = state.acked_features;
+        self.config = state.config;
+    }
 }
 
 impl Drop for Blk {
@@ -371,6 +398,15 @@ impl Snapshottable for Blk {
     fn id(&self) -> String {
         self.id.clone()
     }
+
+    fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
+        Snapshot::new_from_versioned_state(&self.id(), &self.state())
+    }
+
+    fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
+        self.set_state(&snapshot.to_versioned_state(&self.id)?);
+        Ok(())
+    }
 }
 impl Transportable for Blk {}
 impl Migratable for Blk {}

virtio-devices/src/vhost_user/fs.rs

@@ -19,6 +19,8 @@ use std::os::unix::io::AsRawFd;
 use std::result;
 use std::sync::{Arc, Barrier, Mutex};
 use std::thread;
+use versionize::{VersionMap, Versionize, VersionizeResult};
+use versionize_derive::Versionize;
 use vhost::vhost_user::message::{
     VhostUserFSSlaveMsg, VhostUserFSSlaveMsgFlags, VhostUserProtocolFeatures,
     VhostUserVirtioFeatures, VHOST_USER_FS_SLAVE_ENTRIES,
@@ -29,12 +31,23 @@ use vhost::vhost_user::{
 use vm_memory::{
     Address, ByteValued, GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryAtomic,
 };
-use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
+use vm_migration::{
+    Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable, VersionMapped,
+};
 use vmm_sys_util::eventfd::EventFd;
 
 const NUM_QUEUE_OFFSET: usize = 1;
 const DEFAULT_QUEUE_NUMBER: usize = 2;
 
+#[derive(Versionize)]
+pub struct State {
+    pub avail_features: u64,
+    pub acked_features: u64,
+    pub config: VirtioFsConfig,
+}
+
+impl VersionMapped for State {}
+
 struct SlaveReqHandler {
     cache_offset: GuestAddress,
     cache_size: u64,
@@ -263,11 +276,11 @@ impl VhostUserMasterReqHandler for SlaveReqHandler {
     }
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Versionize)]
 #[repr(C, packed)]
-struct VirtioFsConfig {
-    tag: [u8; 36],
-    num_request_queues: u32,
+pub struct VirtioFsConfig {
+    pub tag: [u8; 36],
+    pub num_request_queues: u32,
 }
 
 impl Default for VirtioFsConfig {
@@ -385,6 +398,20 @@ impl Fs {
             vu_num_queues: num_queues,
         })
     }
+
+    fn state(&self) -> State {
+        State {
+            avail_features: self.common.avail_features,
+            acked_features: self.common.acked_features,
+            config: self.config,
+        }
+    }
+
+    fn set_state(&mut self, state: &State) {
+        self.common.avail_features = state.avail_features;
+        self.common.acked_features = state.acked_features;
+        self.config = state.config;
+    }
 }
 
 impl Drop for Fs {
@@ -642,6 +669,15 @@ impl Snapshottable for Fs {
     fn id(&self) -> String {
         self.id.clone()
     }
+
+    fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
+        Snapshot::new_from_versioned_state(&self.id(), &self.state())
+    }
+
+    fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
+        self.set_state(&snapshot.to_versioned_state(&self.id)?);
+        Ok(())
+    }
 }
 impl Transportable for Fs {}
 impl Migratable for Fs {}

virtio-devices/src/vhost_user/net.rs

@@ -20,6 +20,8 @@ use std::sync::atomic::AtomicBool;
 use std::sync::{Arc, Barrier, Mutex};
 use std::thread;
 use std::vec::Vec;
+use versionize::{VersionMap, Versionize, VersionizeResult};
+use versionize_derive::Versionize;
 use vhost::vhost_user::message::{VhostUserProtocolFeatures, VhostUserVirtioFeatures};
 use vhost::vhost_user::{MasterReqHandler, VhostUserMaster, VhostUserMasterReqHandler};
 use virtio_bindings::bindings::virtio_net::{
@@ -29,11 +31,22 @@ use virtio_bindings::bindings::virtio_net::{
     VIRTIO_NET_F_MAC, VIRTIO_NET_F_MRG_RXBUF,
 };
 use vm_memory::{ByteValued, GuestAddressSpace, GuestMemoryAtomic};
-use vm_migration::{Migratable, MigratableError, Pausable, Snapshottable, Transportable};
+use vm_migration::{
+    Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable, VersionMapped,
+};
 use vmm_sys_util::eventfd::EventFd;
 
 const DEFAULT_QUEUE_NUMBER: usize = 2;
 
+#[derive(Versionize)]
+pub struct State {
+    pub avail_features: u64,
+    pub acked_features: u64,
+    pub config: VirtioNetConfig,
+}
+
+impl VersionMapped for State {}
+
 struct SlaveReqHandler {}
 impl VhostUserMasterReqHandler for SlaveReqHandler {}
 
@@ -195,6 +208,20 @@ impl Net {
             vu_num_queues,
         })
     }
+
+    fn state(&self) -> State {
+        State {
+            avail_features: self.common.avail_features,
+            acked_features: self.common.acked_features,
+            config: self.config,
+        }
+    }
+
+    fn set_state(&mut self, state: &State) {
+        self.common.avail_features = state.avail_features;
+        self.common.acked_features = state.acked_features;
+        self.config = state.config;
+    }
 }
 
 impl Drop for Net {
@@ -448,6 +475,15 @@ impl Snapshottable for Net {
     fn id(&self) -> String {
         self.id.clone()
     }
+
+    fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
+        Snapshot::new_from_versioned_state(&self.id(), &self.state())
+    }
+
+    fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
+        self.set_state(&snapshot.to_versioned_state(&self.id)?);
+        Ok(())
+    }
 }
 impl Transportable for Net {}
 impl Migratable for Net {}