Convert the still-needed #[allow]s to #[expect] so they warn if the
lints stop firing.
Part of #8326.
Signed-off-by: Tushar Khatri <hello@tusharkhatri.in>
Query and save the dirty log before shutting down the vhost-user device.
This allows any final dirty memory ranges to be recorded before it
becomes impossible to do that as the vhost-user handle has been closed.
This is required to ensure that all memory writes have been correctly
recorded that may be triggered by inflight I/O drains from vhost-user
device state capture.
One small implementation wrinkle: with local migrations there is no
dirty logging (since we just pass the memory FD over the socket) so
calling dirty_log() would generate an error. As there is no clean way to
query if dirty logging has been started add a boolean to track if its
active.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Rather than each device implementation holding a reference to the guest
memory move this to VhostUserCommon. This refactoring simplifies the
function signatures but also allows for methods that act on
VhostUserCommon that don't have the memory available to them.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Take the recent thread refactor further. Bundle a device's worker
JoinHandles together with the kill event that stops them into a single
WorkerThreads value, owned by VirtioCommon. Its Drop signals the workers
to exit, unparks any parked for migration, and joins them.
This makes a detached/leaked worker unrepresentable. reset(),
wait_for_epoll_threads() and VhostUserCommon::shutdown() now happen when
dropping the WorkerThreads, and the unpark-before-join teardown now
lives in one place.
Assisted-by: Claude:Opus-4.8
Signed-off-by: Dylan Reid <dgreid@fb.com>
Signed-off-by: Rob Bradford <rbradford@meta.com>
Replace manual thread management with the use of
VhostUserCommon::spawn_worker() which is just a thin layer over
VirtioCommon::spawn_worker() but handling VhostUserCommon reset. This
removes some manual thread management and also triggers a reset upon
spawn failure.
Assisted-by: Claude:Opus-4.7
Signed-off-by: Rob Bradford <rbradford@meta.com>
Wrap VirtioCommon::spawn_worker() to also include vhost-user specific
backend cleanup.
Assisted-by: Claude:Opus-4.7
Signed-off-by: Rob Bradford <rbradford@meta.com>
Rely on the vector of threads in VirtioCommon for storing all the
handles of the spawned threads rather than storing them in the devices
or in VhostUserCommon directly.
Assisted-by: Claude:Opus-4.7
Signed-off-by: Rob Bradford <rbradford@meta.com>
Quoting the spec:
> If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, and the back-end
> sets the VHOST_USER_NEED_REPLY flag, the front-end must respond with
> zero when operation is successfully completed, or non-zero
> otherwise.
cloud-hypervisor would previously not send a response to a
VHOST_USER_BACKEND_CONFIG_CHANGE_MSG message, even if
VHOST_USER_PROTOCOL_F_REPLY_ACK had been negotiated and
VHOST_USER_NEED_REPLY was set, in violation of the spec.
Link: https://qemu-project.gitlab.io/qemu/interop/vhost-user.html#back-end-message-types
Fixes: 8d6213338 ("virtio-devices: generic-vhost-user: Config change notification")
Signed-off-by: Alyssa Ross <hi@alyssa.is>
If a guest observes DEVICE_NEEDS_RESET, resets the device, and tries to
re-initialize it, but the VMM knows the backend is disconnected, we can
short-circuit the doomed activation.
This is not incorrect, but saves the VMM from making several round-trip
calls to a peer process that doesn't exist. It'll also make the logs
cleaner.
Signed-off-by: Dylan Reid <dgreid@fb.com>
resume() mirrors pause() for backend communication: it skips the
vhost-user backend call when the device is already disconnected, and it
marks newly failed resume_vhost_user() calls disconnected only when the
classifier identifies transport loss.
Signed-off-by: Dylan Reid <dgreid@fb.com>
pause() returns DeviceDisconnected without calling into the backend when
VhostUserCommon already knows the socket is gone. DeviceManager treats
only that sentinel as log-and-continue, so one dead vhost-user device
does not abort the whole pause iteration.
Signed-off-by: Dylan Reid <dgreid@fb.com>
For add memory region, if the backend is disconnected or returns an
error, forward the appropriate error type to the caller. If the error
indicates that the vhost user backend has disconnected, mark it as such.
Signed-off-by: Dylan Reid <dgreid@fb.com>
reset() is teardown and must still clean up local state even if the
vhost-user backend has already gone away. When the disconnected flag is
already set, it skips reset_vhost_user() and proceeds with kill-event,
worker-unblock, event logging, and interrupt callback cleanup.
Signed-off-by: Dylan Reid <dgreid@fb.com>
This function hasn't been used since '22.
All callers removed with:
1f0e5eb66 vmm: virtio-devices: Restore every VirtioDevice upon creation
TEST: build and cargo test all still pass, grep returns no results.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Add two explicit disconnected-backend error paths before wiring them
into the call sites.
MigratableError::DeviceDisconnected is the lifecycle sentinel for
operations that were skipped because a component is already known to be
disconnected. It lets the caller log and continue without treating it as
a VMM-fatal condition.
Error::BackendDisconnected is the vhost-user-local error used when
VhostUserCommon refuses to call a backend after its disconnected flag is
set. The transport classifier treats socket close/reset/EOF and
vhost-user partial-message/disconnected cases as transport loss, while
backend NACKs, invalid protocol state, and retry-able socket errors
remain ordinary operation failures.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Add a 'disconnected' flag shared between VhostUserCommon and
VhostUserEpollHandler. This flag is set whenever the run loop hits an
error that would cause an exit (failed reconnect, broken backend req
handler, unknown event).
Following commits will use this to gate backend calls in order to avoid
repeated timeouts and errors when a backend disappears. This will
simplify shutdown sequencing for orchestrators using vhost-user devices.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Currently when the socket is disconnected by the other end there is no
logging of such an event. Add a log to aid identifying when this has
happened.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Abandon the reconnection to the vhost-user socket if the kill_evt is
fired because e.g. a device removal request has come in during the
reconnection.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Replace the use of sleeps with a TimerFd. Initially this is functionally
equivalent but it can be extended to also handle other events.
Signed-off-by: Rob Bradford <rbradford@meta.com>
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>
Add support for backend that is connected via the vhost-user-generic
frontend to generate an interrupt into the guest when it has made a
change to the configuration. This is useful for devices that can change
the exposed configuration at runtime.
Assisted-by: Claude:Opus-4.7
Signed-off-by: Rob Bradford <rbradford@meta.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>
The virtio specification treats reset as the recovery operation and so
must take the device back to a fresh state, and the driver waits for the
status read-back to converge before continuing. There is no defined way
for the device to report a reset failure to the driver.
Previously the implementations of reset() would return early and not
complete all their cleanup leaving them in an inconsistent state. Now
log errors and continue through the execution.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-7
The four vhost-user device wrappers (blk, fs, generic_vhost_user, net)
each carried an identical reset() body that resumed the worker thread,
asked the backend to reset, signalled kill_evt and dropped interrupt_cb.
Move the shared body into VhostUserCommon::reset() so behaviour stays in
one place.
No behavioural change.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Assisted-by: Claude:claude-opus-4-7
Rename from iommu to access_platform_enabled. The original name was
iommu as this feature was exposed for devices behind an IOMMU however
this feature is also now used for confidential VMs so adopt a more
general name.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Make it easier to chase down which vhost user socket failed and why in
systems that have many vhost user devices.
Signed-off-by: Dylan Reid <dgreid@fb.com>
Now that the VhostUserCommon::shutdown implementation has been filled
out to support migration it can also be used for the drop
implementations in the vhost-user devices.
It's worth noting that the call to wait_for_epoll_threads() was a no-op
as those threads are only configured on conventional virtio devices.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Advertising support for this virtio feature is required to enable
support for migration. (Along with the LOG_SHMFD protocol feature.)
Signed-off-by: Rob Bradford <rbradford@meta.com>
If the epoll thread is paused, which would be expected as a part of live
migration/snapshot-restore unpause the thread so that it can receive the
kill event. This mirrors the reset() behaviour of virtio devices. It is
important here so as to close the connection with the vhost-user-backend
to allow same host and --local migration and since after getting the
device state the vhost-user backend should no longer be used.
As a result of this change we can do --local and same-host migration
with virtio-fs.
Signed-off-by: Rob Bradford <rbradford@meta.com>
This is used by all devices so it can be part of the common state.
Moving it simplifies the code and simplifies some future improvements
around shutdown for migration.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Since vhost-user devices are always virtio devices it makes sense to
structure this struct inside the VhostUserCommon struct. This then also
makes some of the methods on VhostUserCommon cleaner since they can now
act directly on the common virtio bits (e.g. for kill_evt)
Signed-off-by: Rob Bradford <rbradford@meta.com>
Enable the DEVICE_STATE protocol feature negotiation for all vhost-user
devices (block, fs, net, and generic). Restoring the state (including
the backend state if present) and vrings.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Add a common method for validating the state (checking vrings &
device_state) and then restoring the backend state if present.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Fetch the opaque device state from the backend and store it along with
the last vring used in the state used for the snapshot.
Signed-off-by: Rob Bradford <rbradford@meta.com>
The vhost-user protocol now has support for the backend to provide an
opaque blob of data (read or written through a pipe) that the VMM can
use to save/restore state after snapshot/restore or live migration.
It also adds a command for checking the backend accepts the uploaded
device state. One quirk of saving the state is that GET_VRING_BASE must
be used first to quiesce the state of the backend and flush any
in-flight requests. This then also requires saving that index for use on
the restore.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Rename update_supports_migration() to update_supported_features() as
this method will be extended to track additional capability flags beyond
just migration support (e.g. DEVICE_STATE for snapshot/restore.)
Signed-off-by: Rob Bradford <rbradford@meta.com>
This is a refactoring step in preparation for fetching backend device
state via SET_DEVICE_STATE_FD which can fail.
Signed-off-by: Rob Bradford <rbradford@meta.com>
In GenericVhostUser's read_config and write_config, access
vu_common.acked_protocol_features directly instead of going through
the state() method which creates a struct. This removes creating the
struct just to access two fields that are already directly accessible.
Signed-off-by: Rob Bradford <rbradford@meta.com>
With a common state structure for all vhost-user devices the state()
methods can also be refactored for reuse. This will make it easier to
add new common fields in the future for snapshot/restore.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Each vhost-user device type had near identical State structs.
Deduplicate those by introducing a new common struct (and parameterising
it when it needs to embed a config member.) This will make it easier to
reuse more code in the future and to add more struct members to handle
the requirements of snapshot/restore.
These changes have been designed to have no impact on the existing
snapshot/restore state.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Bump to the released versions that are compatible wherever possible but
for the vhost and vfio crates they are git hashes as no releases with
compatible versions have yet been made.
Signed-off-by: Rob Bradford <rbradford@meta.com>
Trigger the interrupts in the guest for the virtio device queues behind
the vhost-user devices when resuming. This avoids a situation where
interrupts from the backend get lost when they are dispatched from the
backend when then guest is paused leading to the guest/backend
effectively waiting for each other to move forward. This is more
reproducible with longer durations between pause and resume as there is
more opportunity for the backend to completely process it's queue and
fire all the interrupts.
It's perfectly safe and allowed by the virtio spec to generate these
interrupts and the performance impact is negligible and is a safe way to
ensure forward progress after a resume.
See: #7850
Signed-off-by: Rob Bradford <rbradford@meta.com>
This device is not called virtio-vhost-user; that's something else.
I don't think the comment really clarifies anything anyway, so just
remove it.
Fixes: 8c618ff5e ("virtio-devices: generic-vhost-user: implement device")
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Rename the transport feature bit constant from
VIRTIO_F_IOMMU_PLATFORM to VIRTIO_F_ACCESS_PLATFORM across
the entire virtio-devices crate.
The virtio specification as of v1.1 carries bit 33 as
VIRTIO_F_ACCESS_PLATFORM. The Linux kernel UAPI header
<linux/virtio_config.h> carries VIRTIO_F_IOMMU_PLATFORM
only as a backward-compatible alias.
This is a pure rename with no functional or behavioral
change.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
