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vmm: migration: ignore snapshots of removed devices #156

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95 changes: 50 additions & 45 deletions vmm/src/device_manager.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,7 @@ use pci::{
};
use rate_limiter::group::RateLimiterGroup;
use seccompiler::SeccompAction;
use serde::de::DeserializeOwned;
use serde::{Deserialize, Serialize};
use thiserror::Error;
use tracer::trace_scoped;
Expand Down Expand Up @@ -1155,6 +1156,29 @@ fn create_mmio_allocators(
}

impl DeviceManager {
fn has_restored_device(&self, id: &str) -> bool {
self.snapshot.is_some() && self.device_tree.lock().unwrap().contains_key(id)
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@phip1611 phip1611 May 19, 2026 •
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Very nice debugging! My very first impression is that this solution is more a workaround than a solution. To me it is odd why the snapshot could exist for that device when the device manager doesn't has that device. I'll look into the root cause today with high priority and then will come back

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@tpressure tpressure May 19, 2026

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thanks

}

fn restored_device_state<T: DeserializeOwned>(
&self,
id: &str,
) -> DeviceManagerResult<Option<T>> {
if !self.has_restored_device(id) {
return Ok(None);
}

state_from_id(self.snapshot.as_ref(), id).map_err(DeviceManagerError::RestoreGetState)
}

fn restored_device_snapshot(&self, id: &str) -> Option<&Snapshot> {
if !self.has_restored_device(id) {
return None;
}

snapshot_from_id(self.snapshot.as_ref(), id)
}

#[allow(clippy::too_many_arguments)]
pub fn new(
io_bus: Arc<Bus>,
Expand Down Expand Up @@ -1627,8 +1651,7 @@ impl DeviceManager {
.map_err(DeviceManagerError::EventFd)?,
self.get_msi_iova_space(),
iommu_address_width_bits,
state_from_id(self.snapshot.as_ref(), iommu_id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(iommu_id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioIommu)?;
let device = Arc::new(Mutex::new(device));
Expand Down Expand Up @@ -1732,7 +1755,7 @@ impl DeviceManager {

// Restore the vGic if this is in the process of restoration
let id = String::from(gic::GIC_SNAPSHOT_ID);
if let Some(vgic_snapshot) = snapshot_from_id(self.snapshot.as_ref(), &id) {
if let Some(vgic_snapshot) = self.restored_device_snapshot(&id) {
// PMU support is optional. Nothing should be impacted if the PMU initialization failed.
if self
.cpu_manager
Expand Down Expand Up @@ -1785,7 +1808,7 @@ impl DeviceManager {

// Restore the vAia if this is in the process of restoration
let id = String::from(aia::_AIA_SNAPSHOT_ID);
if let Some(_vaia_snapshot) = snapshot_from_id(self.snapshot.as_ref(), &id) {
if let Some(_vaia_snapshot) = self.restored_device_snapshot(&id) {
// TODO: vAia snapshotting and restoration is scheduled to next stage of riscv64 support.
// TODO: PMU support is scheduled to next stage of riscv64 support.
// PMU support is optional. Nothing should be impacted if the PMU initialization failed.
Expand All @@ -1811,8 +1834,7 @@ impl DeviceManager {
) -> DeviceManagerResult<Arc<Mutex<dyn InterruptController>>> {
let id = String::from(IOAPIC_DEVICE_NAME);

let state = state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?;
let state = self.restored_device_state(id.as_str())?;
// Create IOAPIC
let interrupt_controller = Arc::new(Mutex::new(
ioapic::Ioapic::new(
Expand Down Expand Up @@ -2099,8 +2121,7 @@ impl DeviceManager {
let gpio_device = Arc::new(Mutex::new(devices::legacy::Gpio::new(
id.clone(),
interrupt_group,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)));

self.bus_devices
Expand Down Expand Up @@ -2199,8 +2220,7 @@ impl DeviceManager {
id.clone(),
interrupt_group,
serial_writer,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)));

self.bus_devices
Expand Down Expand Up @@ -2256,8 +2276,7 @@ impl DeviceManager {
interrupt_group,
serial_writer,
self.timestamp,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)));

self.bus_devices
Expand Down Expand Up @@ -2319,8 +2338,7 @@ impl DeviceManager {
id.clone(),
interrupt_group,
serial_writer,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)));

self.bus_devices
Expand Down Expand Up @@ -2411,8 +2429,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioConsole)?;
let virtio_console_device = Arc::new(Mutex::new(virtio_console_device));
Expand Down Expand Up @@ -2678,8 +2695,7 @@ impl DeviceManager {
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
self.force_iommu,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
) {
Ok(vub_device) => vub_device,
Err(e) => {
Expand Down Expand Up @@ -2886,8 +2902,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
queue_affinity,
disk_cfg.sparse,
disable_sector0_writes,
Expand Down Expand Up @@ -2986,8 +3001,7 @@ impl DeviceManager {
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
self.force_iommu,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
net_cfg.offload_tso,
net_cfg.offload_ufo,
net_cfg.offload_csum,
Expand All @@ -3004,8 +3018,7 @@ impl DeviceManager {
vhost_user_net as Arc<Mutex<dyn Migratable>>,
)
} else {
let state = state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?;
let state = self.restored_device_state(id.as_str())?;
let virtio_net = if let Some(ref tap_if_name) = net_cfg.tap {
debug!("Creating virtio-net device from Tap device: {tap_if_name}");
Arc::new(Mutex::new(
Expand Down Expand Up @@ -3147,8 +3160,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioRng)?,
));
Expand Down Expand Up @@ -3209,8 +3221,7 @@ impl DeviceManager {
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
self.force_iommu,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioFs)?,
));
Expand Down Expand Up @@ -3398,8 +3409,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioPmem)?,
));
Expand Down Expand Up @@ -3475,8 +3485,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioVsock)?,
));
Expand Down Expand Up @@ -3537,8 +3546,7 @@ impl DeviceManager {
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
virtio_mem_zone.blocks_state().clone(),
state_from_id(self.snapshot.as_ref(), memory_zone_id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(memory_zone_id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioMem)?,
));
Expand Down Expand Up @@ -3630,8 +3638,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioBalloon)?,
));
Expand Down Expand Up @@ -3679,8 +3686,7 @@ impl DeviceManager {
self.exit_evt
.try_clone()
.map_err(DeviceManagerError::EventFd)?,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVirtioWatchdog)?,
));
Expand Down Expand Up @@ -3727,8 +3733,7 @@ impl DeviceManager {
device_path,
self.memory_manager.lock().unwrap().guest_memory(),
vdpa_cfg.num_queues as u16,
state_from_id(self.snapshot.as_ref(), id.as_str())
.map_err(DeviceManagerError::RestoreGetState)?,
self.restored_device_state(id.as_str())?,
)
.map_err(DeviceManagerError::CreateVdpa)?,
));
Expand Down Expand Up @@ -3952,7 +3957,7 @@ impl DeviceManager {
device_cfg.iommu,
pci_device_bdf,
memory_manager.lock().unwrap().memory_slot_allocator(),
vm_migration::snapshot_from_id(self.snapshot.as_ref(), vfio_name.as_str()),
self.restored_device_snapshot(vfio_name.as_str()),
device_cfg.x_nv_gpudirect_clique,
device_cfg.path.clone(),
)
Expand Down Expand Up @@ -4120,7 +4125,7 @@ impl DeviceManager {
legacy_interrupt_group,
pci_device_bdf,
memory_manager.lock().unwrap().memory_slot_allocator(),
vm_migration::snapshot_from_id(self.snapshot.as_ref(), vfio_user_name.as_str()),
self.restored_device_snapshot(vfio_user_name.as_str()),
)
.map_err(DeviceManagerError::VfioUserCreate)?;

Expand Down Expand Up @@ -4309,7 +4314,7 @@ impl DeviceManager {
pci_segment_id > 0 || device_type != VirtioDeviceType::Block as u32,
dma_handler,
self.pending_activations.clone(),
vm_migration::snapshot_from_id(self.snapshot.as_ref(), id.as_str()),
self.restored_device_snapshot(id.as_str()),
)
.map_err(DeviceManagerError::VirtioDevice)?,
));
Expand Down Expand Up @@ -4352,7 +4357,7 @@ impl DeviceManager {
let (pci_segment_id, pci_device_bdf, resources) =
self.pci_resources(&id, pci_segment_id, None)?;

let snapshot = snapshot_from_id(self.snapshot.as_ref(), id.as_str());
let snapshot = self.restored_device_snapshot(id.as_str());

let pvpanic_device = devices::PvPanicDevice::new(id.clone(), snapshot)
.map_err(DeviceManagerError::PvPanicCreate)?;
Expand Down Expand Up @@ -4389,7 +4394,7 @@ impl DeviceManager {

let (pci_segment_id, pci_device_bdf, resources) =
self.pci_resources(&id, pci_segment_id, None)?;
let snapshot = snapshot_from_id(self.snapshot.as_ref(), id.as_str());
let snapshot = self.restored_device_snapshot(id.as_str());

let ivshmem_ops = Arc::new(Mutex::new(IvshmemHandler {
memory_manager: self.memory_manager.clone(),
Expand Down
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