Wire the new `downtime_ms`, `timeout_s`, and `timeout_strategy` fields
from `VmSendMigrationData` into the precopy loop, replacing the previous
hard-coded 5-iteration cap.
Each iteration now evaluates three convergence criteria in order:
- no dirty pages remain;
- the estimated final-iteration downtime is within the configured budget
- or the overall migration timeout has elapsed.
On timeout, `TimeoutStrategy::Cancel` aborts and keeps the VM live on
the source, while `TimeoutStrategy::Force` proceeds regardless of the
downtime target. The convergence callback is updated to return a Result
to propagate the cancel error cleanly up the call stack.
With the recent changes [0], it is fairly easy to implement the new
checks and operate on actual metrics.
These changes are inspired by [1] but differ significantly in details.
[0] https://github.com/cloud-hypervisor/cloud-hypervisor/pull/7799
[1] https://github.com/cloud-hypervisor/cloud-hypervisor/pull/7033
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
When memory_restore_mode=ondemand is specified on the restore command,
the memory manager creates a userfaultfd descriptor, registers each
guest RAM range for missing-page fault interception, and spawns a
handler thread that serves page faults from the snapshot file using
UFFDIO_COPY. This avoids reading the entire memory-ranges file into
guest RAM before restore completes.
The handler uses epoll to multiplex the userfaultfd and a stop eventfd
for clean shutdown. Concurrent faults from multiple vCPUs are handled
by treating EEXIST as a benign race and waking blocked threads with
UFFDIO_WAKE. Once all pages have been served the handler exits
automatically. If the handler thread panics the VMM is signalled to
exit since the VM cannot continue without page fault service.
MemoryZone gains a backing_page_size field so the handler resolves
fault granularity from the zone rather than the top-level config.
Errors from the UFFD setup path use a structured UffdError enum
and a new MigratableError::OnDemandRestore variant, with a From
impl to keep call sites concise.
The seccomp filter is updated to allow the userfaultfd syscall and
the four uffd ioctls (UFFDIO_API, UFFDIO_COPY, UFFDIO_REGISTER,
UFFDIO_WAKE) under the VMM thread profile.
Signed-off-by: Shayon Mukherjee <shayonj@gmail.com>
Introduce MemoryMigrationContext to track internal metrics of an ongoing
precopy memory migration.
The context aggregates information such as iteration count, transferred
bytes, durations, bandwidth, and estimated downtime. This enables
migration logic to make decisions based on runtime characteristics,
such as terminating iterations once the expected downtime is below a
target threshold.
The type is used in the next commit to implement iteration-based
migration metrics.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
Moves the MSRV requirement to the workspace and expands it to all
cloud-hypervisor dependencies and dev-dependencies.
This improves discoverability for new contributors working on crates
other than the cloud-hypervisor itself and creates consistency regarding
the MSRV of cloud-hypervisor dependencies.
Functionally, this doesn't change anything for dependencies of the
cloud-hypervisor crate as the MSRV requirement is already enforced by CI
when building the cloud-hypervisor with the MSRV versioned compiler.
On-behalf-of: SAP julian.schindel@sap.com
Signed-off-by: Julian Schindel <julian.schindel@cyberus-technology.de>
The pointer created by `Vec::as_ptr` may not be used for mutation of the
underlying data [0].
This PR switches to `Vec::as_mut_ptr` and uses `cast` to avoid
mutability changes when casting.
Also improves safety reasoning, separates the unsafe call from the
call to `read_exact` to improve clarity and simplifies the vector
creation.
[0]: https://doc.rust-lang.org/alloc/vec/struct.Vec.html#method.as_ptr
On-behalf-of: SAP julian.schindel@sap.com
Signed-off-by: Julian Schindel <julian.schindel@cyberus-technology.de>
This helps to uncover expensive and needless clones in the code base.
For example, I prevented extensive clones in the snapshot path where
(nested) BTreeMap's have been cloned over and over again. Further,
the lint helps devs to much better reason about the ownership of
parameters.
All of these changes have been done manually with the necessary
caution. A few structs that are cheap to clone are now `copy` so that
this lint won't trigger for them.
I didn't enable the lint so far as it is a massive rabbit hole and
needs much more fixes. Nevertheless, it is very useful.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
This better aligns with the rest of the code and makes it clearer
that these tests can run "as is" in a normal hosted environments
without the special test environment.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
A major improvement to the developer experience of clippy in
Cloud Hypervisor.
1. Make `cargo clippy` just work with the same lints we use in CI
2. Simplify adding new lints
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
Adding itertools as dependency improves the iteration code in the
following significantly.
With this change, we don't need a copy of the vector. Just something
that can be coerced into an iterator. We also use the bit position
iterator to make the code somewhat clearer. The new code is much
faster, because it will not iterate over every bit, just each 1 bit in
the input.
The next commit will complete this optimization and have some concrete
numbers.
On-behalf-of: SAP julian.stecklina@sap.com
Signed-off-by: Julian Stecklina <julian.stecklina@cyberus-technology.de>
Fix clippy warning `uninlined_format_args` reported by rustc rustc
1.89.0 (29483883e 2025-08-04).
```console
warning: variables can be used directly in the `format!` string
--> block/src/lib.rs:649:17
|
649 | info!("{} failed to create io_uring instance: {}", error_msg, e);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
= note: `#[warn(clippy::uninlined_format_args)]` on by default
help: change this to
|
649 - info!("{} failed to create io_uring instance: {}", error_msg, e);
649 + info!("{error_msg} failed to create io_uring instance: {e}");
|
```
Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>
Many of the workspace members in the Cloud-hypervisor workspace share
common dependencies. Making these workspace dependencies reduces
duplication and improves maintainability.
Signed-off-by: Oliver Anderson <oliver.anderson@cyberus-technology.de>
On-behalf-of: SAP oliver.anderson@sap.com
# What
This commit introduces file-based advisory locking for the files backing
up the block devices by using the fcntl() syscall with OFD locks. The
per-open-file-descriptor (OFD) locks are more robust than traditional
POSIX locks (F_SETLK) as they are not tied to process IDs and avoid
common issues in multithreaded or multi-fd scenarios [1]. Therefore,
we don't use `std::fs::File::try_lock()`, which is backed by F_SETLKW.
The locking mechanism is aware of the `readonly` property and allows
`n` readers or `1` writer (exclusive mode).
As the locks are advisory, multiple cloud-hypervisor processes can
prevent themselves from writing to the same file. However, this is not
a system-wide file-system level locking mechanism preventing to open()
a file.
The introduced new locking mechanism does not cover vhost-user devices.
# Why
To prevent misconfiguration and improve safety, it is good practice to
protect disk image files with a locking mechanism. Experience and common
best practices suggest that advisory locks are preferable over mandatory
locks due to better compatibility and fewer pitfalls (in fs space).
The introduced functionality is aligned with the approach taken by
QEMU [0], and is also recommended in [1].
# Implementation Details
We need to ensure that not only normal operation keeps working but also
state save/resume and live-migration. Especially for live migration,
it is crucial that the sender VMM releases the locks when the VM stops
so the receiver VMM can acquire them right after that.
Therefore, the locking and releasing happen directly on the block
device struct. The device manager knows all block devices and can
forward requests to these types.
Last but not least, this commit uses on explicit lock acquiring
but implicit lock releasing (FD close). It only explicitly releases
the locks where this integrates more smoothly into the existing
code.
# Testing
I tested
- normal operation
- state save/resume,
- device hot plugging,
- and live-migration
with read/shared and write/exclusive locks.
One can use the `fcntl-tool` to test if locks are actually acquired
or released [2].
# Links
[0] 825b96dbce/util/osdep.c (L266)
[1] https://apenwarr.ca/log/20101213
[2] https://crates.io/crates/fcntl-tool
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
`serde_json` crate is referenced by multiple components, centralize it
to workspace to better manage this crate.
Signed-off-by: Jinank Jain <jinankjain@microsoft.com>
Historically the Cloud Hypervisor coding style has been to ensure that
all imports are ordered and placed in a single group. Unfortunately
cargo fmt has no support for ensuring that all imports are in a single
group so if whitespace lines were added as part of the import statements
then they would only be odered correctly in the group.
By adopting "group_imports="StdExternalCrate" we can enforce a style
where imports are placed in at most three groups for std, external
crates and the crate itself. Choosing a style enforceable by the tooling
reduces the reviewer burden.
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
Modify `Cargo.toml` in each member crate to follow the dependencies
specified in root `Cargo.toml` file.
Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>
An example warning output is:
error: first doc comment paragraph is too long
--> virtio-devices/src/lib.rs:158:1
|
158 | / /// Convert an absolute address into an address space (GuestMemory)
159 | | /// to a host pointer and verify that the provided size define a valid
160 | | /// range within a single memory region.
161 | | /// Return None if it is out of bounds or if addr+size overlaps a single region.
| |_
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph
= note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]`
Signed-off-by: Bo Chen <chen.bo@intel.com>
This method will return the existing Response if the status is
successful (Status::Ok) otherwise issue a command to abandon the
migration and return the desired error.
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
In 42e9632c53 a fix was made to address a
typo in the taplo configuration file. Fixing this typo indicated that
many Cargo.toml files were no longer adhering to the formatting rules.
Fix the formatting by running `taplo fmt`.
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
