Drop inflate or deflate descriptors whose len exceeds the Linux
driver maximum of VIRTIO_BALLOON_ARRAY_PFNS_MAX PFN entries of 4
bytes each. Without the cap, a guest can submit a descriptor with
a huge len over a small backing and drive an unbounded warn loop
in the device thread.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Address translation or memory release errors on the free page
reporting queue propagated up and killed the balloon device thread.
Log a warning and skip the offending descriptor so the device
continues operating.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-6
A single malformed descriptor — device-writable where device-readable
is expected, non-aligned length, overflowed address, unmapped PFN, or
a failed fallocate/madvise — propagated an error that killed the
balloon device thread. Skip bad descriptors and PFNs with a warning
so the device keeps operating.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-6
Only the first descriptor in each chain was processed. If the PFN
array spanned multiple chained descriptors the remaining PFNs were
silently dropped. Iterate the full chain so every descriptor is
validated and its PFNs are acted on.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-6
The inflate and deflate queues carry device-readable PFN arrays: the
driver writes them and the device only reads. The device never writes
to the descriptor buffers, so the used ring entry should report 0
bytes written rather than the descriptor length.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-6
Fix "Fail tp signal" typo, replace copy-pasted "entropy" comment
with "balloon", and remove EventFdWriteFail and QueueIterator error
variants that have no call sites.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-6
Worker threads spawned through spawn_virtio_thread previously wrote to
exit_evt on any clean Err return, taking the whole VMM down on a single
failed device worker. A guest induced fault in any virtio device thus
propagated into a host wide failure.
Route the Err return through the shared mark_device_needs_reset helper
instead. The helper sets the DEVICE_NEEDS_RESET bit on device_status
and triggers a config change interrupt, so the device goes idle and
the guest is informed. The thread exits cleanly without killing the
rest of the VMM.
The panic and the seccomp filter apply paths keep writing to exit_evt.
A panicked worker may have left poisoned locks or partially mutated
state, so a hard exit remains the right policy there.
spawn_virtio_thread now takes the device_status and the interrupt
callback. Every native virtio and vhost-user call site is updated to
pass them in.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Previously the interrupt was created in VirtioPciDevice, moved via the
Option::take() to the VirtioPciDeviceActivator and then moved to the
VirtioDevice upon activation. On reset it would be moved back ready for
reactivation.
Since this already an Arc type remove the wrapping Option and instead
refcount it such that the VirtioPciDevice can continue to hold onto it
for later activations.
This significantly simplifies the reset() logic as there is no need to
hand back the interrupt.
A few devices used whether the interrupt was Some to make triggering an
interrupt a no-op. However the MSI-X interrupt routing already drops the
interrupt if the driver hasn't yet configured the vector so it is safe
to trigger the interrupt before device activation (e.g. balloon resize
request before driver loaded).
VirtioCommon still retains an Option<..> for the interrupt as the
interrupt is not known until activation time (after this has been
created). A helper VirtioCommon::trigger_interrupt() has been added to
handle this.
Signed-off-by: Rob Bradford <rbradford@meta.com>
release_memory_range took (range_base, range_len) verbatim from a
guest-controlled descriptor (free-page-reporting and inflate paths) and
called fallocate(PUNCH_HOLE | KEEP_SIZE) on the backing file before any
length check ran. find_region only validates that range_base lands
inside *some* region; range_len can extend past the region's end. When
the operator uses --memory-zone file=PATH against a host file larger
than the zone, the punch zeroes host file content past the guest's
memory extent.
Free-page reporting is advisory, so the VMM is allowed to act on a
subset of a free range. Clamp range_len to the bytes that actually fit
within the region returned by find_region. Going past the end of a
region is most likely a guest bug so log it.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Following the pattern used by the existing virtio devices make the
balloon device work with confidential VMs (e.g. SEV-SNP). This requires
advertising the VIRTIO_F_ACCESS_PLATFORM feature. Do not expose this to
the user as a controllable option and instead only enable in on the
"force" case.
Signed-off-by: Rob Bradford <rbradford@meta.com>
This is a follow-up of [0].
# Advantages
- This saves dozens of unneeded clone()s across the whole code base
- Makes it much easier to reason about how parameters are used
(often we passed owned Arc/Rc versions without actually needing
ownership)
# Exceptions
For certain code paths, the alternatives would require awkward or overly
complex code, and in some cases the functions are the logical owners of
the values they take. In those cases, I've added
#[allow(clippy::needless_pass_by_value)].
This does not mean that one should not improve this in the future.
[0] 6a86c157af
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
This should be guaranteed by GuestMemory and GuestMemoryRegion, but
those traits are currently safe, so add checks to guard against
incorrect implementations of them.
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
Consuming `&Arc<T>` as argument is almost always an antipattern as it
hides whether the callee is going to take over (shared) ownership
(by .clone()) or not. Instead, it is better to consume `&dyn T` or
`Arc<dyn T>` to be more explicit. This commit cleans up the code.
The change is very mechanic and was very easy to implement across the
code base.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
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>
This streamlines the code base to follow best practices for
error handling in Rust: Each error struct implements
std::error::Error (most due via thiserror::Error derive macro)
and sets its source accordingly.
This allows future work that nicely prints the error chains,
for example.
So far, the convention is that each error prints its
sub error as part of its Display::fmt() impl.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
By introducing `imports_granularity="Module"` format strategy,
effectively groups imports from the same module into one line or block,
improving maintainability and readability.
Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>
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>
In accordance with reuse requirements:
- Place each license file in the LICENSES/ directory
- Add missing SPDX-License-Identifier to files.
- Add .reuse/dep5 to bulk-license files
Fixes: #5887
Signed-off-by: Ruslan Mstoi <ruslan.mstoi@intel.com>
Similar to balloon inflation, memory allocation is also constrained to
align with the page size. Therefore, memory is allocated in units of the
host page size, one page at a time, until all host pages that the memory
range requested by the guest are managed. If the requested size is
smaller than the page size, the entire page will still be allocated
because smaller allocations are not possible due to the page size
limitation.
Fixes: cloud-hypervisor#5369
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
Currently, virtio-balloon can't work well with page size other than 4k.
The virtio-balloon always works in units of 4kiB (BALLOON_PAGE_SIZE), but
we can only actually discard memory in units of the host page size.
We get some idea from [1] to solve this issue.
What has been done in this commit:
For balloon inflation:
A bitmap is employed to track the memory range to be released in 4k
granularity. Once it accumulates to one host page size, the corresponding
page is released, and the bitmap is cleared to handle the next record.
This process continues until all the memory range is managed. Memory will
only be released when a consecutive set of balloon request entries from
the same host page reaches the full host page size. If a balloon request
entry from a different host page is encountered, the bitmap and the base
host page address will be reset. Consequently, memory is released in
units of the page size, ensuring efficient memory management. That's say
if memory range length to be released smaller than page size or if the
guest scatters requests each of whose size is smaller than page size
across different host pages no memory will be released.
[1] https://patchwork.kernel.org/project/qemu-devel/patch/20190214043916.22128-6-david@gibson.dropbear.id.au/
Fixes: cloud-hypervisor#5369
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
This change is important to do a proper resource cleanup. We decided
to do this repetitive approach as VirtioCommon can't implement Drop
without major changes to the corresponding code. Also, devices such as
Net can't easily use the epoll_threads-abstraction from VirtioCommon as
it has multiple threads with different semantics.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
The information about the identifier related to a Snapshot is only
relevant from the BTreeMap perspective, which is why we can get rid of
the duplicated identifier in every Snapshot structure.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Following the new restore design, it is not appropriate to set every
virtio device threads into a paused state after they've been started.
This is why we remove the line of code pausing the devices only after
they've been restored, and replace it with a small patch in every virtio
device implementation. When a virtio device is created as part of a
restored VM, the associated "paused" boolean is set to true. This
ensures the corresponding thread will be directly parked when being
started, avoiding the thread to be in a different state than the one it
was on the source VM during the snapshot.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Following the new design proposal to improve the restore codepath when
migrating a VM, all virtio devices are supplied with an optional state
they can use to restore from. The restore() implementation every device
was providing has been removed in order to prevent from going through
the restoration twice.
Here is the list of devices now following the new restore design:
- Block (virtio-block)
- Net (virtio-net)
- Rng (virtio-rng)
- Fs (vhost-user-fs)
- Blk (vhost-user-block)
- Net (vhost-user-net)
- Pmem (virtio-pmem)
- Vsock (virtio-vsock)
- Mem (virtio-mem)
- Balloon (virtio-balloon)
- Watchdog (virtio-watchdog)
- Vdpa (vDPA)
- Console (virtio-console)
- Iommu (virtio-iommu)
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Considering error messages will be mostly nested, ensuring no
punctuation at the end will make the error log more readable.
Signed-off-by: Bo Chen <chen.bo@intel.com>
This function is for really for the transport layer to trigger a device
reset. Instead name it appropriately for the fuzzing specific use case.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
There's no need to delegate the resize operation to the virtio-balloon
thread. This can come directly from the vmm thread which will use the
Balloon object to update the VIRTIO configuration and trigger the
interrupt for the guest to be notified.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that we rely on pop_descriptor_chain() rather than iter() to iterate
over a queue, there's no more borrow on the queue itself, meaning we can
invoke add_used() directly for the iteration loop. This simplifies the
processing of the queues for each virtio device, and bring some possible
performance improvement given we don't have to iterate twice over the
list of descriptors to invoke add_used().
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Using pop_descriptor_chain() is much more appropriate than iter() since
it recreates the iterator every time, avoiding the queue to be borrowed
and allowing the virtio-net implementation to match all the other ones.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The new virtio-queue version introduced some breaking changes which need
to be addressed so that Cloud Hypervisor can still work with this
version.
The most important change is about removing a handle to the guest memory
from the Queue, meaning the caller has to provide the guest memory
handle for multiple methods from the QueueT trait.
One interesting aspect is that QueueT has been widely extended to
provide every getter and setter we need to access and update the Queue
structure without having direct access to its internal fields.
This patch ports all the virtio and vhost-user devices to this new crate
definition. It also updates both vhost-user-block and vhost-user-net
backends based on the updated vhost-user-backend crate. It also updates
the fuzz directory.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Instead of passing separately a list of Queues and the equivalent list
of EventFds, we consolidate these two through a tuple along with the
queue index.
The queue index can be very useful if looking for the actual index
related to the queue, no matter if other queues have been enabled or
not.
It's also convenient to have the EventFd associated with the Queue so
that we don't have to carry two lists with the same amount of items.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Implement the VIRTIO_BALLOON_F_REPORTING feature, indicating to the
guest it can report set of free pages. A new virtqueue dedicated for
receiving the information about the free pages is created. The VMM
releases the memory by punching holes with fallocate() if the guest
memory is backed by a file, and madvise() the host about the ranges of
memory that shouldn't be needed anymore.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Adding a new parameter free_page_reporting=on|off to the balloon device
so that we can enable the corresponding feature from virtio-balloon.
Running a VM with a balloon device where this feature is enabled allows
the guest to report pages that are free from guest's perspective. This
information is used by the VMM to release the corresponding pages on the
host.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Improving the existing code for better readability and in anticipation
for adding an additional virtqueue for the free page reporting feature.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Instead of relying on the virtio-queue crate to store the information
about the MSI-X vectors for each queue, we handle this directly from the
PCI transport layer.
This is the first step in getting closer to the upstream version of
virtio-queue so that we can eventually move fully to the upstream
version.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
