snapshot: remove Versionize serialization functions

We do not need these any more, because we will never serialize to older
versions of Firecracker snapshots.

Signed-off-by: Babis Chalios <[email protected]>

Author: bchalios

src/vmm/src/device_manager/persist.rs

@@ -181,13 +181,13 @@ pub struct DeviceStates {
     /// Vsock device state.
     pub vsock_device: Option<ConnectedVsockState>,
     /// Balloon device state.
-    #[version(start = 2, ser_fn = "balloon_serialize")]
+    #[version(start = 2)]
     pub balloon_device: Option<ConnectedBalloonState>,
     /// Mmds version.
-    #[version(start = 3, ser_fn = "mmds_version_serialize")]
+    #[version(start = 3)]
     pub mmds_version: Option<MmdsVersionState>,
     /// Entropy device state.
-    #[version(start = 4, ser_fn = "entropy_serialize")]
+    #[version(start = 4)]
     pub entropy_device: Option<ConnectedEntropyState>,
 }
 
@@ -202,39 +202,6 @@ pub enum SharedDeviceType {
     Entropy(Arc<Mutex<Entropy>>),
 }
 
-impl DeviceStates {
-    fn balloon_serialize(&mut self, target_version: u16) -> VersionizeResult<()> {
-        if target_version < 2 && self.balloon_device.is_some() {
-            return Err(VersionizeError::Semantic(
-                "Target version does not implement the virtio-balloon device.".to_owned(),
-            ));
-        }
-
-        Ok(())
-    }
-
-    fn mmds_version_serialize(&mut self, target_version: u16) -> VersionizeResult<()> {
-        if target_version < 3 && self.mmds_version.is_some() {
-            warn!(
-                "Target version does not support persisting the MMDS version. The default will be \
-                 used when restoring."
-            );
-        }
-
-        Ok(())
-    }
-
-    fn entropy_serialize(&mut self, target_version: u16) -> VersionizeResult<()> {
-        if target_version < 4 && self.entropy_device.is_some() {
-            return Err(VersionizeError::Semantic(
-                "Target version does not support persisting the virtio-rng device.".to_owned(),
-            ));
-        }
-
-        Ok(())
-    }
-}
-
 pub struct MMIODevManagerConstructorArgs<'a> {
     pub mem: GuestMemoryMmap,
     pub vm: &'a VmFd,

src/vmm/src/devices/virtio/block/persist.rs

@@ -88,35 +88,17 @@ impl From<FileEngineTypeState> for FileEngineType {
 pub struct BlockState {
     id: String,
     partuuid: Option<String>,
-    #[version(
-        start = 2,
-        ser_fn = "block_cache_type_ser",
-        default_fn = "default_cache_type_flush"
-    )]
+    #[version(start = 2, default_fn = "default_cache_type_flush")]
     cache_type: CacheTypeState,
     root_device: bool,
     disk_path: String,
     virtio_state: VirtioDeviceState,
     rate_limiter_state: RateLimiterState,
     #[version(start = 3)]
-    // We don't need to specify a `ser_fn` for the `file_engine_type` since snapshots created in
-    // v1.0 are incompatible with older FC versions (due to incompatible notification suppression
-    // feature).
     file_engine_type: FileEngineTypeState,
 }
 
 impl BlockState {
-    fn block_cache_type_ser(&mut self, target_version: u16) -> VersionizeResult<()> {
-        if target_version < 3 && self.cache_type != CacheTypeState::Unsafe {
-            warn!(
-                "Target version does not implement the current cache type. Defaulting to \
-                 \"unsafe\" mode."
-            );
-        }
-
-        Ok(())
-    }
-
     fn default_cache_type_flush(_source_version: u16) -> CacheTypeState {
         CacheTypeState::Unsafe
     }

src/vmm/src/devices/virtio/net/persist.rs

@@ -31,7 +31,7 @@ use crate::vstate::memory::GuestMemoryMmap;
 pub struct NetConfigSpaceState {
     #[version(end = 2, default_fn = "def_guest_mac_old")]
     guest_mac: [u8; MAC_ADDR_LEN as usize],
-    #[version(start = 2, de_fn = "de_guest_mac_v2", ser_fn = "ser_guest_mac_v2")]
+    #[version(start = 2, de_fn = "de_guest_mac_v2")]
     guest_mac_v2: Option<MacAddr>,
 }
 
@@ -45,16 +45,6 @@ impl NetConfigSpaceState {
         Ok(())
     }
 
-    fn ser_guest_mac_v2(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        // v1.1 and older versions do not have optional MAC address.
-        warn!("Saving to older snapshot version, optional MAC address will not be saved.");
-        match self.guest_mac_v2 {
-            Some(mac) => self.guest_mac = mac.into(),
-            None => self.guest_mac = Default::default(),
-        }
-        Ok(())
-    }
-
     fn def_guest_mac_old(_: u16) -> [u8; MAC_ADDR_LEN as usize] {
         // v1.2 and newer don't use this field anyway
         Default::default()

src/vmm/src/devices/virtio/persist.rs

@@ -103,11 +103,7 @@ pub struct VirtioDeviceState {
     /// List of queues.
     pub queues: Vec<QueueState>,
     /// The MMIO interrupt status.
-    #[version(
-        start = 2,
-        de_fn = "de_interrupt_status",
-        ser_fn = "ser_interrupt_status"
-    )]
+    #[version(start = 2, de_fn = "de_interrupt_status")]
     pub interrupt_status: u32,
     /// The MMIO interrupt status as a usize.
     #[version(end = 2)]
@@ -188,12 +184,6 @@ impl VirtioDeviceState {
         }
         Ok(())
     }
-
-    fn ser_interrupt_status(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        // v1 uses a usize type for interrupt status.
-        self.interrupt_status_old = self.interrupt_status as usize;
-        Ok(())
-    }
 }
 
 /// Transport information saved in snapshot.

src/vmm/src/persist.rs

@@ -54,17 +54,13 @@ pub struct VmInfo {
     /// Guest memory size.
     pub mem_size_mib: u64,
     /// smt information
-    #[version(start = 2, default_fn = "def_smt", ser_fn = "ser_smt")]
+    #[version(start = 2, default_fn = "def_smt")]
     pub smt: bool,
     /// CPU template type
-    #[version(
-        start = 2,
-        default_fn = "def_cpu_template",
-        ser_fn = "ser_cpu_template"
-    )]
+    #[version(start = 2, default_fn = "def_cpu_template")]
     pub cpu_template: StaticCpuTemplate,
     /// Boot source information.
-    #[version(start = 2, default_fn = "def_boot_source", ser_fn = "ser_boot_source")]
+    #[version(start = 2, default_fn = "def_boot_source")]
     pub boot_source: BootSourceConfig,
 }
 
@@ -74,33 +70,15 @@ impl VmInfo {
         false
     }
 
-    fn ser_smt(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        // v1.1 and older versions do not include smt info.
-        warn!("Saving to older snapshot version, SMT information will not be saved.");
-        Ok(())
-    }
-
     fn def_cpu_template(_: u16) -> StaticCpuTemplate {
         warn!("CPU template field not found in snapshot.");
         StaticCpuTemplate::default()
     }
 
-    fn ser_cpu_template(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        // v1.1 and older versions do not include cpu template info.
-        warn!("Saving to older snapshot version, CPU template information will not be saved.");
-        Ok(())
-    }
-
     fn def_boot_source(_: u16) -> BootSourceConfig {
         warn!("Boot source information not found in snapshot.");
         BootSourceConfig::default()
     }
-
-    fn ser_boot_source(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        // v1.1 and older versions do not include boot source info.
-        warn!("Saving to older snapshot version, boot source information will not be saved.");
-        Ok(())
-    }
 }
 
 impl From<&VmResources> for VmInfo {

src/vmm/src/vstate/vcpu/aarch64.rs

@@ -258,7 +258,7 @@ pub struct VcpuState {
     #[version(end = 2, default_fn = "default_old_regs")]
     pub old_regs: Vec<Aarch64RegisterOld>,
     /// Vcpu registers.
-    #[version(start = 2, de_fn = "de_regs", ser_fn = "ser_regs")]
+    #[version(start = 2, de_fn = "de_regs")]
     pub regs: Aarch64RegisterVec,
     /// We will be using the mpidr for passing it to the VmState.
     /// The VmState will give this away for saving restoring the icc and redistributor
@@ -291,16 +291,6 @@ impl VcpuState {
         self.regs = regs;
         Ok(())
     }
-
-    fn ser_regs(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        self.old_regs = self
-            .regs
-            .iter()
-            .map(TryInto::try_into)
-            .collect::<Result<_, _>>()
-            .map_err(|e: &str| VersionizeError::Serialize(e.into()))?;
-        Ok(())
-    }
 }
 
 #[cfg(test)]

src/vmm/src/vstate/vcpu/x86_64.rs

@@ -550,7 +550,7 @@ pub struct VcpuState {
     #[version(end = 3, default_fn = "default_msrs")]
     pub msrs: Msrs,
     /// Saved msrs.
-    #[version(start = 3, de_fn = "de_saved_msrs", ser_fn = "ser_saved_msrs")]
+    #[version(start = 3, de_fn = "de_saved_msrs")]
     pub saved_msrs: Vec<Msrs>,
     /// Debug regs.
     pub debug_regs: kvm_debugregs,
@@ -569,7 +569,7 @@ pub struct VcpuState {
     /// Xsave.
     pub xsave: kvm_xsave,
     /// Tsc khz.
-    #[version(start = 2, default_fn = "default_tsc_khz", ser_fn = "ser_tsc")]
+    #[version(start = 2, default_fn = "default_tsc_khz")]
     pub tsc_khz: Option<u32>,
 }
 
@@ -579,18 +579,6 @@ impl VcpuState {
         None
     }
 
-    fn ser_tsc(&mut self, _target_version: u16) -> VersionizeResult<()> {
-        // v0.24 and older versions do not support TSC scaling.
-        warn!(
-            "Saving to older snapshot version, TSC freq {}",
-            self.tsc_khz
-                .map(|freq| freq.to_string() + "KHz not included in snapshot.")
-                .unwrap_or_else(|| "not available.".to_string())
-        );
-
-        Ok(())
-    }
-
     fn default_msrs(_source_version: u16) -> Msrs {
         // Safe to unwrap since Msrs::new() only returns an error if the number
         // of elements exceeds KVM_MAX_MSR_ENTRIES
@@ -603,30 +591,6 @@ impl VcpuState {
         }
         Ok(())
     }
-
-    fn ser_saved_msrs(&mut self, target_version: u16) -> VersionizeResult<()> {
-        match self.saved_msrs.len() {
-            0 => Err(VersionizeError::Serialize(
-                "Cannot serialize MSRs because the MSR list is empty".to_string(),
-            )),
-            1 => {
-                if target_version < 3 {
-                    self.msrs = self.saved_msrs[0].clone();
-                    Ok(())
-                } else {
-                    Err(VersionizeError::Serialize(format!(
-                        "Cannot serialize MSRs to target version {}",
-                        target_version
-                    )))
-                }
-            }
-            _ => Err(VersionizeError::Serialize(
-                "Cannot serialize MSRs. The uVM state needs to save
-                 more MSRs than the target snapshot version supports."
-                    .to_string(),
-            )),
-        }
-    }
 }
 
 #[cfg(test)]